News this Week

Science  29 Jul 2011:
Vol. 333, Issue 6042, pp. 504
1. Around the World

1 - London
Royal Society Accepts Role As U.K. Border Guard
2 - Washington, D.C.
More Human-Subject Safeguards
3 - Tokyo
Research Activism, Rural Development Net Blue Planet Prizes
4 - London
Mice With Human Brain Cells? More Oversight, Says U.K. Panel
5 - Australia
Gunboat Climatology

London

Royal Society Accepts Role As U.K. Border Guard

The U.K. Border Agency (UKBA) announced 20 July that it would be instituting a new set of work visas for up to 1000 non–European Union immigrants with “exceptional talent.” Rather than judging the talent of visa applicants itself, UKBA will shift that responsibility to various British academic bodies, including the Royal Society and Royal Academy of Engineering.

Royal Society officials—and, according to President Paul Nurse, most academics—are far from thrilled about the new visa. “The fact is the Royal Society does not believe there should be restrictions” on the number of scientifically talented individuals who can work in the United Kingdom, Nurse says. “I think that when you're attracting the best scientific talent, we should be welcoming them with open arms.”

The visas are intended for senior scientists who are leaders in their fields. It will allow them to work in the United Kingdom for an initial period of 3 years and 4 months, with a possible extension and a permanent settlement option.

But the red tape may be tough. “We're very concerned this will be bureaucratic and laborious and that will put people off even on short-term visits,” Nurse says. “But given that the government is introducing it, we've decided we should work with them to get it as effective as possible so we don't limit the … scientific talent coming from overseas.” http://scim.ag/TalentVisa

Washington, D.C.

More Human-Subject Safeguards

The U.S. Department of Health and Human Services (HHS) is soliciting comments on a plan to beef up protections for people who are participating in research. Among other things, HHS hopes to change how biospecimens are handled, something that's become a huge area of interest and controversy. These days, specimens such as blood, skin, and cancer tissue collected for one study may be stored indefinitely and used in dozens of others, often without the original donor having any idea. HHS says that donors should give explicit permission for this kind of research. HHS also wants its rules to cover more research. Right now, it governs federally funded work, as well as some supported by industry. But there are still gaps, and the new proposal states that at any university that gets any federal funding—which, practically speaking, means all of them—researchers' work will fall under the rules. http://scim.ag/HHShumansubjects

Tokyo

Research Activism, Rural Development Net Blue Planet Prizes

Speaking out on policy issues doesn't always earn a scientist respect. But it has paid off for marine ecologist Jane Lubchenco, head of the U.S. National Oceanic and Atmospheric Administration. Her willingness to talk about forging a social contract between scientists and society—as well as a sterling research track record—has won her one of this year's Blue Planet Prizes for contributions to solving global environmental problems. The prize-giving Asahi Glass Foundation, based in Tokyo, cited Lubchenco for her research on how marine ecosystems are affected by human activities and climate change. The foundation also praised her efforts “to incorporate sound and clearly stated scientific, ecological principles into responsibly enacted public policy.” (Lubchenco has served as president and chair of the board of AAAS, which publishes Science.)

This year's other Blue Planet Prize goes to the Barefoot College, a nongovernmental organization based in Tilonia, India, that fosters autonomous and sustainable rural development based on technologies such as solar power electrification and rainwater harvesting. The college also promotes the education of girls and rural health. Founded in 1972, the Barefoot College has expanded operations throughout India and to developing countries in Africa and Central and South America.

The awardees will get a certificate, a trophy, and $640,000 at a ceremony in Tokyo in November. London Mice With Human Brain Cells? More Oversight, Says U.K. Panel Mice with human-derived livers and goats with human blood cells can raise ethical questions—so a report issued 21 July by the British Academy of Medical Sciences recommends that the U.K. government establish a commission to help regulate experiments involving “animals containing human material” (ACHM). The report proposes dividing ACHM experiments into three categories: those that should be subject to the same oversight and regulation as other animal experiments, those that should undergo extra review, and a few that should be off-limits. Experiments requiring extra scrutiny include modifying an animal's brain to make it more “human-like,” placing functional human germ cells in animals, and adding human genes or cells to nonhuman primates. Off-limits experiments include breeding animals that have or could develop human germ cells in their gonads, transplanting enough human-derived neural cells into a nonhuman primate to prompt human-like behavior, and allowing embryos that mix human and nonhuman primate cells to develop beyond 14 days. The vast majority of ACHM experiments fall into the first category, the report notes, and several category two experiments have been proposed or are underway in Britain. For example, researchers studying infertility have grafted human testis and ovary cells under the skin of animals to better understand their development. However, “We haven't come across any scientists who want to do category three [off-limits] experiments,” working group member Robin Lovell-Badge said at a press conference 21 July. http://scim.ag/_chimera Australia Gunboat Climatology Under threat from pirates, Australian researchers have enlisted naval muscle to plug a critical gap in climate monitoring in the Indian Ocean. Over the past 2 years, pirates operating out of conflict-riven Somalia have severely disrupted research, says Ann Thresher, an oceanographer at the Wealth from Ocean Flagship program of the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia's national science agency. Particularly hard hit is ARGO, an international program under which Australian researchers track the Indian Ocean Dipole, a fluctuation of sub-surface temperatures in the equatorial region of the southeastern and the western Indian Ocean. The fluctuation's strength is used to predict floods or droughts across Australia. To measure the Indian Ocean dipole, 2-meter-long lithium battery–powered buoys, which look like bright yellow rockets, record temperature, pressure, and salinity. CSIRO usually receives assistance from commercial ships to deploy buoys. But piracy has forced ships to change their routes.“We have not been able to seed about one-quarter of the Indian Ocean [with buoys] since the increase in piracy,” Thresher says.“Without that our predictions are suffering; that's why we had to find another way.” That help is coming in part from the Australian navy, which has agreed to deploy eight or nine buoys in the Gulf of Aden in the next 4 to 6 months. 2. Newsmaker Cognitive Scientist Marc Hauser Resigns From Harvard Marc Hauser will resign his post in the Harvard University psychology department as of 1 August, The Boston Globe reported 19 July. Hauser is well-known for his research on the cognitive abilities of nonhuman animals. He was put on leave last August following a university investigation that found him guilty of eight instances of scientific misconduct. At least one federal investigation is still ongoing. One paper authored by Hauser, a 2002 study in the journal Cognition, has been retracted, and questions have been raised about several others, including a 2007 Science paper on the ability of nonhuman primates to understand human gestures. Science recently published an apparent replication of the key findings from that study (http://scim.ag/HauserReplication). In April, Harvard psychology department faculty members voted not to allow Hauser to return to teach at the university in the fall. Department Chair Susan Carey says Hauser had no current grad students or postdocs: “All found other advisers last year.” In his resignation letter, Hauser says he plans to focus on “new and interesting challenges” that have come up during his year on leave, including “extremely interesting and rewarding work focusing on the educational needs of at-risk teenagers” and “exciting opportunities in the private sector.” 3. Random Sample Heavy Armor Gave Knights a Workout Knights in shining armor paid a heavy price for protection: The steel plate-mail armor worn during the 15th century, which weighed 30 to 50 kilograms, required its wearers to expend about twice the usual amount of energy when they walked or ran. Physiologist Graham Askew of the University of Leeds in the United Kingdom and colleagues recruited four historical interpreters at the Royal Armouries to help determine the energy toll the heavy armor can take. The armor-clad interpreters ran on a treadmill while scientists monitored their oxygen consumption, heart and respiration rates, and stride length. Weighted down by heavy leg protection such as cuisses on their thighs and greaves on their calves, swinging these limbs forced the interpreters to expend far more energy to walk or run. And a breastplate compressed their chests, forcing them to take rapid, shallow breaths, the team reported online 19 July in the Proceedings of the Royal Society B. http://scim.ag/heavyarmor They Said It “It'd be like sticking your finger in a light socket.” —Professor Reuben Goforth of Purdue University in West Lafayette, Indiana, telling the Detroit Free Press about his plans for a backpack “ray gun” that would deliver a jolt of electricity to the eggs and larvae of Asian carp in the Great Lakes. About 60 scientists around the country are devising poisons, water guns, and altered pheromones to combat the invasive species. Spinning Milk Into Silk A microbiologist in Hanover, Germany, has a new ingredient for high-end fashion: It's got milk. Anke Domaske, lead researcher and designer at Qmilch, uses the proteins in dairy milk to create the first industrial, all-natural, and eco-friendly fiber fit for the runway. Her dairy-produced threads won an innovation award at the July 2011 Berlin Fashion Week. “There is something special about cow milk,” Domaske says. Goat, sheep, and cow milk all contain casein, a protein that has been used as a binding agent in processed foods, as well as industrial glues and paints. But only the type of casein in cow's milk has the right structure for creating the Qmilch fiber, Domaske says. Taking dairy milk that's usually thrown out or burned, Domaske converts the casein biopolymers into a fiber using a process the company has declined to divulge. The fibers can then be combined with cotton or synthetics; when used alone, however, they form a silky fabric that she says is biodegradable and antiallergenic. While the milk fabrics aren't as affordable as cotton or wool, Domaske says the possibilities for their use are endless: Besides dresses and tops worn by celebs, she says, look to see Qmilch in hospitals, bed sheets, and car interiors. The best part? The entire production process uses no chemicals or pesticides, giving Qmilch a smaller—yet fashionable—carbon footprint. 4. The Invisible Wounds of War Healing the Brain, Healing the Mind 1. Greg Miller At a new clinic for troops, doctors tackle a complex interplay between head injuries and posttraumatic stress. On his second deployment to Iraq in 2005, U.S. Marine Captain Jason Berner's company was working to secure an area south of Haditha when they were ambushed by insurgents. A rocket-propelled grenade exploded right behind Berner, slamming his head against the concrete structure he was standing on. If he lost consciousness, it wasn't for long. Some of his men were pinned down behind a barrier by enemy fire, and Berner scaled a 3-meter wall to try to help them. He ultimately had to drop off the wall to avoid getting shot, and in the process, his head took another jolt. After a third tour in Iraq, Berner returned home in 2007 and endured 3 years of constant headaches, intense anxiety, and vivid nightmares that a relative of someone he'd killed in combat was coming after him. On a few occasions, he loaded a gun and swept through his house to secure it. He angered easily, but he refused to admit he had a problem. “I didn't want to let the team down,” he says. “As a Marine, that's more important than going through hell personally. So I kept pushing through, not knowing why I couldn't get along [with people], why my wife and I were arguing, why my kids were most of the time afraid of me.” Finally, in 2010 someone took Berner aside and insisted he get help. He'd enrolled at the Expeditionary Warfare School in Quantico, Virginia, and his adviser there made a phone call on his behalf. A few months later, Berner was admitted to the National Intrepid Center of Excellence (NICoE), a new clinic on the National Naval Medical Center campus in Bethesda, Maryland, that specializes in diagnosing and treating the toughest cases of traumatic brain injury (TBI) and psychological health problems to arise from the wars in Iraq and Afghanistan. The confluence of TBI and posttraumatic stress disorder (PTSD) may be the hardest problem confronting veterans of the current conflicts and those who care for them. Physical and psychological trauma have traditionally been considered different entities, the former treated by neurologists and the latter by psychiatrists. Yet the two conditions have many overlapping symptoms (see graphic, p. 516), and people with a history of both seem to have an especially difficult time recovering. There is even some evidence to suggest the two traumas may involve overlapping mechanisms in the brain. NICoE takes an integrated approach to treating veterans like Berner and plans to undertake research to help unravel the knot of TBI and PTSD. Built with$65 million raised by a nonprofit foundation, the Intrepid Fallen Heroes Fund, NICoE began admitting patients in the fall of 2010. Now run by the Department of Defense (DOD), the center is led by James Kelly, a neurologist and leading expert on sports concussion on leave from the University of Colorado School of Medicine in Denver. Kelly and other NICoE staff members like to describe the clinic's approach as “high-tech, high-touch,” using the latest neuroimaging and virtual-reality equipment to assess patients, while incorporating yoga, acupuncture, and art therapy for a more holistic approach to treating patients. “There isn't any such place elsewhere on Earth, let alone in the military system,” Kelly says.

DOD, which has been widely criticized for not doing enough to help troops with TBI and PTSD, has hailed NICoE as a cutting-edge effort to diagnose, treat, and study these two signature injuries of the current wars. It's far too early to gauge the ultimate impact of NICoE, and even if it is successful, a major challenge will be exporting this model of care to help more than just the 400 to 500 patients a year the center can handle. But Berner, who spent 4 weeks there earlier this year, says the experience was transformative. “I don't think it's an exaggeration to say NICoE gave me my life back,” he says.

A tale of two traumas

Estimates on the prevalence of TBI and PTSD in troops serving in the current wars vary. The Defense and Veterans Brain Injury Center, which tracks TBI for DOD, reports just over 200,000 cases of TBI confirmed by a physician between 2001 and March 2011. That includes all U.S. forces, not just those deployed to the war zone. Surveys of returning troops produce much higher estimates. A widely cited 2008 study by the RAND Corp. estimated that of the 1.6 million troops deployed through October 2007, 300,000 had experienced PTSD or major depression and 320,000 had experienced a probable TBI.

There may be considerable overlap in these populations. A 2008 report in The New England Journal of Medicine (NEJM), for example, found that 44% of soldiers who reported being knocked unconscious in Iraq or Afghanistan met the criteria for a PTSD diagnosis, compared with 27% of those who reported being “dazed, confused, or seeing stars,” 16% of those with injuries not involving the head, and 9% of those without injuries. A study published the same year in the American Journal of Epidemiology found that PTSD was more than twice as common in service members who reported a mild TBI, while those who screened positive for PTSD were nearly four times as likely to report lingering postconcussive symptoms such as dizziness, headaches, and memory problems.

“What we've been seeing since these conflicts started is that there were patients with a combination of TBI and psych health issues that really was more than the sum of their parts,” says Thomas DeGraba, a neurologist and the medical director of NICoE. In civilian populations, most people who suffer a mild TBI (or concussion, as it's more commonly called outside of the military) usually recover in a week or two, and people who experience PTSD often respond well to behavioral therapy and drugs. But many troops with both TBI and PTSD don't seem to follow the usual course. “Everyone who's been treating these patients has seen that if they don't start getting better within 6 months to a year, they actually start getting worse,” DeGraba says. While most NICoE patients are several months to a couple of years postdeployment, researchers elsewhere are investigating the possibility that military TBI may increase the risk of dementia later in life (see p. 517).

The comorbidity of TBI and PTSD isn't surprising in that the types of events that result in a head injury are often traumatic, especially in the context of war. But there is also some reason to think that the two traumas may affect common circuitry in the brain, says Murray Stein, a psychiatrist at the University of California (UC), San Diego. Neuroimaging studies have found that people with PTSD have hyperactivity in the limbic system, a network of brain regions involved in evaluating threats and processing fear and other emotions. At the same time, Stein says, some of the brain regions most vulnerable to TBI include areas of the prefrontal cortex that normally have a dampening effect on the limbic system and emotion. “It's not a stretch to think that if you have these frontal systems taken offline as a result of a TBI, you'd sort of unleash the limbic system and that could contribute to PTSD symptoms,” Stein says. He adds that these frontal regions have other roles in cognition that may be important for coping. Damage from a TBI may reduce the intellectual resources available as people try to make sense of what has happened to them, Stein says. However, he cautions, “this is all theoretical.”

Yet it's not completely unfounded. In the 2 June NEJM, a team led by Christine MacDonald and David Brody of Washington University in St. Louis, Missouri, reported abnormalities in one of these prefrontal regions in troops exposed to blasts in Iraq or Afghanistan. The researchers used a relatively new method called diffusion tensor imaging to scan the brains of 63 soldiers with TBI who'd been evacuated to a military hospital in Germany. In 18 patients, they found hints of possible damage in the white matter, the nerve fibers that convey signals within and between brain regions. The damage mainly affected two areas: the orbitofrontal cortex and the middle cerebellar peduncle. “These are not areas that are typically injured in civilian mild TBI,” Brody says. But they are potentially relevant to the symptoms that plague many returning service members. “The orbitofrontal cortex is known to be involved in emotional regulation,” Brody says. “The cerebellum in general is involved in balance and coordination.” At NICoE, DeGraba estimates that 85% of patients have problems with balance and coordination.

Visualizing the invisible

On a recent morning, NICoE's director of neuroimaging, Gerard Riedy, pulled up a series of brain scans on a large monitor. The clinical evaluation of TBI, particularly the most common, mild variety, is a subjective practice, Riedy says. Doctors have to rely on the memory of someone who took a blow to the head in the midst of a chaotic combat situation to remember what happened and what their symptoms were. “We get these stories of guys coming back and they were all in a blast and one guy says, ‘I didn't lose consciousness,’ and the other guys say, ‘No, dude, you were out!’”

Riedy is one of a growing number of investigators trying to develop more objective assessments based on the latest brain imaging technology. “If you get a mild brain injury, our current imaging doesn't show much,” he says. In fact, the absence of abnormalities on routine computed tomography (CT) and magnetic resonance imaging (MRI) scans is part of the military's definition of mild TBI. In work begun at Walter Reed Army Medical Center in Washington, D.C., Riedy and collaborators have been developing MRI protocols to pick up scarring and small hemorrhages from broken blood vessels.

Riedy points to a CT scan on his monitor from a soldier injured in a rocket attack in Iraq. It looks normal. A routine MRI scan from the same patient shows a possible abnormality, a dark spot in the corpus callosum, the major bundle of nerve fibers bridging the two hemispheres of the brain. Next, Riedy displays a scan done with a new protocol that detects evidence of hemorrhages. “Blood leaks out and creates a little pool of iron,” he explains. “That creates a local magnetic field that disrupts the signal.” In this scan, the outline of the patient's brain is ghostly white, but several black dots stand out. “There's six of them there, three of them over here, and four more up here,” Riedy says, poking at the screen. “It's obviously not normal.”

Riedy is also trying to detect abnormal brain function in TBI patients at NICoE using functional MRI, positron emission tomography, and magnetoencephalography. “There's about $10 million in equipment down this hallway,” he says proudly. In preliminary studies, he and colleagues have found hints of differences in the brain activity of mild TBI patients engaged in tests of memory, attention, and language—functions that many TBI patients struggle with. For patients like Berner, the new scans relieve a big burden. “When they told me they could see my brain had been injured, that was a huge vindication,” Berner says. “For the longest time I thought I was just going crazy.” Art therapy for Marines? For a clinic run by DOD, NICoE has a surprisingly Zen vibe. Natural materials and organic curves define an interior suffused with sunlight. In the lobby, plants and water trickling over a wall of rocks contribute to a soothing atmosphere. Even battle-hardened Marines seem to appreciate the soft touches. “Being in the building just makes me relax,” Berner says. “Especially with a head injury, the environment is one of the most vital things for successful rehab,” says another recent patient, Army staff sergeant Victor Medina. “It put me at ease and allowed me to focus.” The first stop for patients is a room with a large sectional couch. Here, patients tell their story to a team of specialists who will follow them throughout their stay, including a neurologist, psychiatrist, internist, physical therapist, and a spiritual adviser of their choosing. This arrangement eliminates the need for patients to relive their trauma each time they tell another doctor their story, DeGraba says. Family members also attend this introductory session, and patients leave with a set of goals and a rehab plan for their stay of typically 2 to 3 weeks. “High-touch” features at NICoE include a large room for art therapy. “That was something I initially wanted to avoid at all costs,” Berner says. “I thought it was a waste of time and somewhat childish.” But in the process Berner says he was able to express things he never would have verbalized, including bottled up emotions from growing up with a violent, alcoholic father. “Looking back now,” he says, “I'm so glad I participated.” The “high-tech” component includes several virtual-reality environments, including a CAREN system, one of only seven in North America. A 180-degree video screen wraps around a 3-meter circular platform with a treadmill, and 12 infrared cameras monitor a patient's movement as the platform rotates and tilts (patients wear a harness). Therapists use the system to assess patients' balance and coordination in situations that mimic real life, such as walking down a city street. Many patients can walk a straight line down the hall in a doctor's office, DeGraba says. But reality is more complicated, and a patient's balance problems can be compounded by attention deficits (a symptom of TBI) or hyper-vigilance (a symptom of PTSD). Other virtual environments at NICoE include a firing range equipped with standard service weapons reconfigured to fire WiFi signals, and a simulator that enables patients (only if they're ready for it) to undergo exposure therapy that puts them back on patrol in a simulated Iraq or Afghanistan. A driving simulator helps patients make the transition from the mindset needed to safely pilot an armored Humvee down a road potentially littered with mines to one needed to pilot a minivan to the mall. “We put in everything we could think of, and we tried to think outside the box,” says David Hovda, who directs the Brain Injury Research Center at UC Los Angeles and has advised NICoE leaders since the project's conception. “They're doing some great things there,” says Geoffrey Manley, a neurosurgeon specializing in TBI at UC San Francisco. “They're providing very multidisciplinary and high-end treatment and building in research that will hopefully refine and improve treatment in the future.” However, a big challenge will be ensuring that NICoE patients continue to recover when they leave, says Colonel Michael Roy, an internist who studies PTSD at the Uniformed Services University of the Health Sciences in Bethesda. Roy helped develop a center with a similarly multidisciplinary philosophy for veterans with Gulf War illness, and he says patients often backslid when they returned home. Berner is taking his recovery step by step. He recently graduated from Expeditionary Warfare School and joined the Marine Corps Warfighting Laboratory, which develops new military technology. His nightmares persist, but they're less vivid than they used to be, and he says he's getting his anger under control. “I'm on the bell curve going up,” he says. “I'm making progress, but I'm not over the hump yet.” 5. Neuropathology A Battle No Soldier Wants to Fight 1. Greg Miller Could brain injuries suffered in battle put troops at risk for dementia? Recent findings of pathology in athletes, among other evidence, are raising concerns. A few years ago, Elaine Peskind noticed something peculiar about the young soldiers she was interviewing as part of a clinical trial at Joint Base Lewis-McChord in Tacoma, Washington. Peskind, a psychiatrist based at the Veterans Affairs (VA) Puget Sound Health Care System in Seattle, has studied Alzheimer's disease for more than 25 years, and her interests include the effects of stress on the brain and cognition across the life span. She was on base to interview active-duty soldiers enrolled in a drug trial for posttraumatic stress disorder (PTSD). In one interview after another, she noticed, a soldier would pull a standard-issue spiral notebook from a shirt pocket and start writing down everything she said. “It seemed a little odd to me,” Peskind recalls. Finally, she asked a 20-something soldier why he was doing this. He said that otherwise he wouldn't be able to remember anything she told him. Peskind was stunned. “I said to myself, ‘Uh oh, I think we have a problem.’ ” The troops in the PTSD trial had served in Iraq and Afghanistan, and many, including the soldier with the notebook, had been exposed to blasts from roadside bombs and other improvised explosive devices. Memory problems are a common symptom of traumatic brain injury (TBI), and the soldiers' problems certainly weren't severe enough to meet the criteria for Alzheimer's disease. But they were enough to worry Peskind about what the future might hold for them. She knew that head injuries are a risk factor for Alzheimer's and other types of dementia. And around the same time, evidence was emerging that American football players and other athletes in contact sports can develop a type of dementia called chronic traumatic encephalopathy (CTE) after suffering multiple head injuries on the field (Science, 7 August 2009, p. 670). Whether military troops might be at risk for Alzheimer's, CTE, or other dementia is still very much an open question, but Peskind says neuroimaging studies she's done recently have given her even greater cause for concern. And she's not alone. The evidence so far is only suggestive, but it's coming from several directions, says Daniel Perl, a neuropathologist at the Uniformed Services University of the Health Sciences in Bethesda, Maryland. At a meeting* last month in Washington, D.C., Perl presented preliminary findings from two brains autopsied by his collaborator Ann McKee at the VA hospital in Bedford, Massachusetts. Both cases, from veterans exposed to blasts, showed early signs of the type of damage McKee and others have reported in the autopsied brains of football players with CTE. Estimates vary, but it's possible that 300,000 U.S. troops in Iraq and Afghanistan have suffered head injuries, the majority from blast exposure. “We've got several hundred thousand of our young men in uniform who've been exposed to this, and we don't know what it's done to their brains and what it's going to lead to in their brains,” Perl says. “We've got to find out.” Cause for concern Very little research has been done on the long-term effects of TBI in the armed forces. A study presented last week at the Alzheimer's Association International Conference in Paris is the first to look for a link between TBI and dementia in military veterans, says senior author and psychiatric epidemiologist Kristine Yaffe of the University of California, San Francisco (UCSF). Yaffe and colleagues examined a national database of 281,540 veterans aged 55 or older who visited a VA hospital at least once between 1997 and 2000 and again between 2001 and 2007. All were free of dementia on their initial visit. Of those who had a history of any type of TBI, 15.3% had received a diagnosis of dementia (Alzheimer's or any other type) by the time of their second visit, compared with 6.8% of those with no history of TBI. Even mild TBIs seemed to increase the risk: 11.6% of veterans with a history of concussion developed dementia during the study period. Far more research has been done in civilian populations. These studies suggest that people who suffer a single severe TBI in a car accident or nasty fall have roughly double the risk of Alzheimer's disease, says Samuel Gandy, an Alzheimer's researcher at Mount Sinai Medical Center in New York City. Combine a bad blow to the head with a bad genetic draw, in the form of a copy of the dreaded ε4 version of the APOE gene, and the risk jumps to up to 10 times the risk for someone with no APOE ε4 and no head injuries. Studies with lab animals and humans have found that a moderate to severe TBI produces a spike in amyloid-β, the peptide that piles up in the characteristic plaques found in the brains of Alzheimer's patients. In one study, researchers at the University of Pittsburgh examined brain tissue removed in the course of surgery to relieve pressure on the brain in 18 people who'd suffered a severe TBI. Their findings, reported in 2004 in Experimental Neurology, suggested that amyloid deposits begin accumulating in the brain within hours of severe trauma, a process thought to happen over years or even decades in most Alzheimer's patients. Some researchers see the recent evidence linking head injuries in athletes to dementia as potentially more relevant to the mild TBIs, or concussions, that are the most common head injuries in Iraq and Afghanistan. For nearly a century, doctors have observed cognitive and movement problems in professional boxers. More recently, American football has received scrutiny as several former stars have unraveled in midlife, with some dying by suicide or in reckless accidents. In the autopsied brains of players who died prematurely, in a few cases as young as their late teens and early 20s, pathologists have found clumps of protein indicative of CTE. McKee, at the Bedford VA hospital, is one of the leading researchers on CTE in football players. Like Alzheimer's disease, CTE can be definitively diagnosed only by autopsy, but McKee says the symptoms in many veterans with mild TBI, including irritability, attention deficits, impulsivity, drug and alcohol abuse, sleep problems, headaches, and suicide, look disturbingly similar to what she sees in the clinical histories of the athletes whose brains end up under her microscope. “We're seeing that across both populations, and we're wondering if they have parallel pathology.” McKee won't disclose additional details of the two cases Perl presented until the work is published. Later this summer, she plans to establish a new brain bank for veterans analogous to the one she and colleagues have established for athletes at nearby Boston University. Perl too hopes to launch a postmortem study soon in collaboration with the Office of the Armed Forces Medical Examiner on hundreds of brains donated by veterans. “We have very detailed clinical records on these people, including their exposure to explosives,” Perl says. He and McKee plan to collaborate to compare any pathological findings in veterans with those in athletes. Proteins behaving badly Exactly how head injuries might increase the risk of dementia is far from clear. Repetitive concussions in athletes appear to trigger a somewhat different biochemical cascade than a single severe TBI does. Most athletes diagnosed with CTE have not had substantial amyloid deposits in their brains on autopsy, McKee and others have found. Instead, their brains are littered with tangles of a different protein called tau. Tangles of tau are also found in Alzheimer's patients along with amyloid plaques, but in CTE they usually appear alone. The emerging picture, Gandy says, is that a single severe brain trauma may sow the seeds for amyloid deposition and Alzheimer's disease, while multiple mild traumas encourage tau accumulation and predispose the brain to CTE. Gandy suspects there are yet-to-be-discovered interactions between amyloid and tau. He notes that the APOE ε4 genetic variant, which recent evidence suggests reduces the brain's ability to clear amyloid (Science Translational Medicine, http://scim.ag/human-apoe), also appears to be a risk factor for CTE. In 1997, he and colleagues reported in The Journal of the American Medical Association that boxers with a copy of APOE ε4 exhibit more severe neurological impairments than those who don't have that variant. “My working model, for which I have no long-term evidence yet, is that each time you get a whack [to the head], there's a little burst of amyloid, and if you can clear it properly, it's just swept away. If you can't, it may allow these tau tangles to build up.” How a physical injury to the brain leads to accumulation of either protein remains murky, says David Hovda, a neuroscientist who studies TBI at the University of California, Los Angeles. Animal studies have identified a number of neurochemical changes at the time of injury that may play an instigating role, including metabolic changes and ion imbalances inside neurons, as well as the influx of reactive free radical compounds and inflammatory signaling molecules. Murkier still is the physics and physiology of blast injuries. Shock waves from blasts injure the lungs, eyes, ears, gastrointestinal tract, and other tissues, but their effect on the brain has been controversial (Science, 25 January 2008, p. 406). “There's not enough evidence to pin down a single mechanism that could be responsible for this injury,” said Michael Leggieri, who heads the Department of Defense's blast injury research program, speaking at a meeting last month in San Francisco. An important insight may come from a pair of papers published last week by Harvard University bioengineer Kevin Kit Parker and colleagues (ScienceNOW, http://scim.ag/tbraininjury). Their findings suggest that the mechanical force generated by a blast may disrupt proteins called integrins, which anchor neurons and other cells in the brain to the protein matrix that surrounds them. A resulting biochemical cascade injures axons and blood vessels, both of which seem to be damaged in veterans exposed to blasts, according to recent neuroimaging studies. Another wildcard to contend with is the high prevalence of PTSD, which goes hand in hand with TBI in many returning troops (see p. 514). Work by Yaffe and colleagues, published last year in the Archives of General Psychiatry, suggests that PTSD may be a risk factor for dementia. Probing the VA database, they found that veterans with a diagnosis of PTSD were roughly twice as likely to develop dementia as those without. It's possible that PTSD increases the risk of dementia indirectly by increasing the likelihood of another dementia risk factor such as cardiovascular disease or substance abuse, for example. But Yaffe says the 2010 study controlled for several such factors. Yaffe's colleague, UCSF psychiatrist Thomas Neylan, notes that rodent studies have found that chronic stress inhibits the generation of new neurons in the hippocampus, a brain region instrumental to learning and memory, and one of the first to deteriorate in humans with Alzheimer's disease. In addition, neuroimaging studies in PTSD patients by the UCSF group and others have found evidence of reduced hippocampal volume, especially in a subregion called the dentate gyrus, one of the most active sites of neurogenesis in the adult brain. It's possible, then, although far from proven, that the chronic stress of PTSD may increase susceptibility to dementia by suppressing the hippocampus's ability to make new neurons. Altered activity Definitive answers about human brain pathology caused by TBI and mechanistic insights from animal research will likely take years. In the meantime, several groups are using brain imaging to search for abnormalities that may reflect early signs of brain damage or dementia in veterans with TBI. In the Seattle area, Peskind and her colleagues have been using a variety of neuroimaging methods to scan 33 veterans of the conflicts in Iraq and Afghanistan who've experienced blasts. Peskind says the participants have an average of 16 blasts documented in their medical records. “If you get a moderate to severe TBI, you're airlifted out; the war is over for you,” Peskind says. “But this mild TBI is just a way of life.” In one study, she and her colleagues used positron emission tomography to compare brain metabolism in a group of blast-exposed veterans with a group of 14 Iraq veterans who were not exposed to a blast. The veterans exposed to blasts had reduced metabolism in the posterior cingulate and parietal cortex, two regions that also exhibit reduced metabolism in people with mild cognitive impairment, a condition that often precedes Alzheimer's disease. “The pattern of those changes is reminiscent, but not nearly as severe, to what we see in the earliest changes of Alzheimer's disease,” Peskind says. Functional MRI scans also hint at possible problems in the posterior cingulate and parietal cortex, Peskind says: “Those areas aren't communicating normally with other regions.” Whether these changes are related to combat experience and whether they are indeed signs of impending dementia remain to be seen. Peskind notes that many veterans are athletes too. Hand-to-hand combat is a part of basic training, and she's seen that mixed-martial-arts “cage fighting” competitions are popular events on base. “Frankly, I don't think any of this is very good for your brain,” she says. She plans to follow her initial group of veterans over the coming years with more brain scans as well as tests for compounds in the cerebrospinal fluid that may predict amyloid and tau accumulation in the brain. She also intends to expand the study to investigate whether the intense heat of Iraq or the high altitude and reduced oxygen environment of Afghanistan may influence the prognosis after brain injury. And, perhaps most important, she'll follow their memory and cognitive function over the coming years. So far the veterans in her study perform in the normal range. “There's evidence of a slight decrement of performance, but nothing major,” Peskind says. “Most of these guys are working, or in school, or in one way or another moving on in their lives. They're committed to not having a lifetime of disability.” The question is what battles they may face in the future. • * Federal Interagency Conference on Traumatic Brain Injury, 13–15 June 2011, Washington, D.C. • The Brain at War, 23 June 2011, San Francisco, California. 6. Mental Health Predicting the Psychological Risks of War 1. Greg Miller Can predeployment tests identify—and possibly help—the soldiers most susceptible to posttraumatic stress disorder and depression? Troops serving in Iraq and Afghanistan face tremendous stress—ambushes, firefights, roadside bombs, and the difficulty of distinguishing civilians from insurgents, to name a few. It's no surprise that as many as 300,000 American troops have returned home with symptoms of posttraumatic stress disorder (PTSD) or depression. Even so, those thousands constitute only a minority of the nearly 2 million U.S. troops deployed in the current conflicts. Why do some people seem to endure the grinding stress and sudden horrors of war better than others? Several research projects are now exploring that question in active-duty troops, drawing on an emerging understanding of the biological roots of fear, anxiety, and depression. Combining modern genetics and neuroimaging with traditional methods such as clinical interviews and surveys, researchers hope to learn more about the biological effects of war-fighting and to identify risk factors that influence individuals' vulnerability to combat stress. This work is just getting started, and it's too early to predict where it will lead. But the ultimate goal is to develop tests to identify the most vulnerable soldiers and find ways to protect them, perhaps with prophylactic medication or extra training before deployment, says Alan Peterson, a clinical psychologist at the University of Texas Health Science Center in San Antonio (UTHSCSA) and director of STRONG STAR, a PTSD research consortium launched in 2008 with a$35 million grant from the Department of Defense. The trauma of war is unavoidable, says Peterson, who as a lieutenant colonel in the Air Force spent time in both Iraq and Afghanistan. But some risk factors might be more amenable to modification. “We want to find things we can have an impact on,” Peterson says.

Michael Telch, a psychologist at UT Austin, is leading one effort to identify such risk factors. Between 2007 and 2009, Telch and colleagues collected clinical histories and a variety of behavioral, psychological, genetic, and neuroimaging measurements from 177 soldiers at Fort Hood, Texas, before they deployed to Iraq.

The researchers kept in touch with the soldiers throughout their deployment using a Web-based program developed by Han Joo Lee, a graduate student with Telch at the time. Once a month, participants logged on to a Web site and answered questions about their recent combat experience and whether they had any symptoms of stress, anxiety, or depression. It's the first attempt to monitor combat stress in the war zone, says Lee, now an assistant professor at the University of Wisconsin, Milwaukee. Lee and Telch say the approach gives a more accurate picture of soldiers' experiences than do the retrospective questionnaires that have long been the mainstay of research on combat stress. Postdeployment, Lee says, memories can be biased by a soldier's current mood or by a desire to play down symptoms to stay on active duty (or play them up to get out).

Now that the soldiers have completed their tours, the researchers are combing their predeployment data for measurements that predicted how individuals responded to combat stress. Already, some interesting findings have emerged.

In this month's issue of The American Journal of Psychiatry, a team led by Telch's UT Austin collaborator, Christopher Beevers, describes a gaze-tracking experiment that predicted symptoms of PTSD and depression during deployment. Before deployment, a soldier looked at a series of photographs on a computer monitor while a camera tracked his or her eye movements. Each photo had four panels in which the same actor displayed facial expressions of fear, sadness, happiness, or a lack of emotion. Previous studies have found that people with anxiety disorders quickly orient to the fearful face in this task but then quickly look away and avoid it, whereas people with depression tend to dwell on the sad face. None of the soldiers had a preexisting anxiety or mood disorder, but they displayed modest biases that predicted their subsequent responses to wartime stress. Not surprisingly, self-reported symptoms of anxiety and depression increased whenever soldiers reported more exposure to combat stressors like taking incoming fire. But for those who had avoided fearful faces on the gaze-tracking test, anxiety symptoms showed an even more pronounced jump. And for those who dwelt on the sad faces, symptoms of depression increased even more during stressful times of their deployment.

In another test, results of which Telch has presented at several conferences but not yet published, soldiers inhale air enriched with carbon dioxide (CO2) through a plastic mask. CO2 makes people feel lightheaded and on the verge of fainting, but individuals can have very different emotional reactions to that experience, Telch says. At one extreme, inhaling CO2 can trigger a panic attack in people with a diagnosis of panic disorder. At the other end of the spectrum, some people find it slightly exhilarating, Telch says. After the gas wore off, soldiers filled out a questionnaire that assessed how much anxiety the experience caused them. Again using the Web-based monitoring program, the researchers found that soldiers who'd reacted more strongly to the CO2 test predeployment also exhibited more symptoms of anxiety and PTSD during stressful times of their deployment. Whether those symptoms translate into a greater risk of full-blown PTSD or anxiety disorder after they get home is not known. To find out, Telch hopes to follow this group of soldiers and to repeat the study with a larger group.

Brains and genes

The gaze-tracking task and the CO2 challenge may have predictive value because they provide an indication of the sensitivity of the brain's emotion-processing circuitry, says Ahmad Hariri, a neuroscientist at Duke University in Durham, North Carolina. Hariri has collaborated with Telch to investigate soldiers' brain activity more directly using functional magnetic resonance imaging (fMRI). Their initial studies focused on the amygdala, a region important for assessing threats and one that researchers have found to be hyperactive in people with anxiety disorders. Hariri's team is still analyzing those data, but he says there does seem to be a correlation between the amygdala's sensitivity to emotional stimuli predeployment and soldiers' subsequent reactions to combat stress. Amygdala reactivity predeployment also predicted symptoms of PTSD in an fMRI study of Israeli combat paramedics, researchers reported in 2009 in the Proceedings of the National Academy of Sciences.

Many researchers suspect that both genetics and life experience calibrate the sensitivity of emotion-processing brain regions like the amygdala and that this sensitivity in turn may influence the risk of mental health problems after a traumatic event. One gene that might play a role is the so-called serotonin transporter gene, which encodes a protein that helps clear the neurotransmitter serotonin after it has been released by neurons. Previous fMRI studies have linked certain variants of this gene to stronger brain responses to negative emotional cues (such as angry or fearful faces). Some studies have found that those same variants increase the risk of mental illness after stressful life events, but those findings have been controversial (Science, 26 June 2009, p. 1628). Hariri's lab is examining DNA samples from Telch's cohort of soldiers at Fort Hood, but Hariri says the sample is probably too small to resolve whether the variants of the serotonin transporter gene influence symptoms of combat stress during deployment, especially given the soldiers' diverse ethnic backgrounds. He notes that studies on the serotonin transporter gene have had mixed results in different ethnic groups, with the most robust effects reported in Caucasian subjects.

A much larger study on genetic risk factors for combat stress is under way as part of the STRONG STAR project. Led by UTHSCSA genetic epidemiologist Douglas Williamson, researchers have collected DNA, RNA, and blood plasma samples from 4115 soldiers at Fort Hood who deployed or will deploy to Iraq between February and August of 2011. Based on the latest prevalence estimates, Williamson expects roughly 720 of these soldiers will return home with symptoms of PTSD. A major arm of the project will use genomewide gene expression arrays to examine how gene expression changes from pre- to postdeployment in soldiers who develop PTSD. For comparison, Williamson and colleagues will also look at gene expression changes in a group of 720 soldiers who were exposed to similar levels of combat but did not develop symptoms. “What I'm trying to answer is how does combat stress affect the biology of a soldier and what effect does that have on whether they develop PTSD,” Williamson says.

He and colleagues will also investigate whether soldiers in the PTSD and non-PTSD groups tend to have different variants of the serotonin transporter gene and other genes implicated in civilian studies of PTSD, including several that regulate the brain's response to stress hormones. In addition, the team plans to look for differences between the two groups in so-called epigenetic markers, chemical modifications to DNA that alter gene expression. Recent research has suggested that early life stress, such as growing up in an abusive or a deprived environment, can cause epigenetic changes that alter the brain's response to stress and may predispose people to anxiety disorders and depression (Science, 2 July 2010, p. 24). The team will screen soldiers for childhood abuse, which studies in both civilian and military populations have identified as a risk factor for PTSD later in life.

If practical methods can be developed to identify the soldiers with the greatest risk, the next challenge is how to help them, Peterson says. Military training already builds resiliency by preparing troops for the situations they're likely to face in the war zone, Peterson says. One program at Lackland Air Force Base in San Antonio, for example, is trying to prepare soldiers for the unexpected by incorporating into their predeployment training mock experiences of the kinds of events that troops returning from the war zone have found most troubling, including ambushes and blasts from roadside bombs and other improvised explosive devices. Atrisk individuals might benefit from additional or more intensive training of this kind, Peterson says: “The better you can train someone on what's likely to occur in the war zone, the better they're going to do.”

7. 9 Billion?

1. Leslie Roberts

The population projections in these graphics compiled by Science can be considered best scientific guesses, not destiny. Still, they offer a window into what the world might look like in 2050.

Video Feature

In 1900, there were 1.6 billion people on earth. By 2000, that number had skyrocketed to 6.1 billion. This astounding rate of growth has slowed, but the trend is still heading dramatically upward. It varies substantially by region, however, with the less developed countries growing rapidly and the more developed countries growing slowly, if at all. World population is expected to pass 7 billion in late October and is projected to top 9 billion by 2050; the latest U.N. projections put it at about 10 billion in 2100. In truth, no one knows exactly how high population will grow or when it might flat-line. All population projections are uncertain, as they are entirely dependent on assumptions about the future—for instance, how many children a woman will have 20 or 30 years hence. In that sense, these numbers can be considered best scientific guesses, not destiny. What's more, the further out one looks, the cloudier these projections become. Still, they offer a window into what the world might look like in 2050.

8. Are More People Necessarily a Problem?

1. David Malakoff*

As world population surges, debate surrounds studies suggesting that population growth can have economic and environmental benefits.

Video Feature

[Watch a video on the "Machakos Miracle," featuring reporter David Malakoff.]

In 1937, A bureaucrat serving in the British Empire's Kenya Colony penned an alarming memo to his bosses about conditions in the Machakos Reserve, a hilly, drought-prone farming region 50 kilo meters south of Nairobi. “Benevolent British rule” had encouraged the explosive “multiplication” of the “natives,” he reported, leading to massive environmental degradation. “Every phase of misuse of land is vividly and poignantly displayed in this Reserve, the inhabitants of which are rapidly drifting to a state of hopeless and miserable poverty and their land to a parching desert of rocks, stones and sand.” The apocalyptic warning came as the region's population approached 250,000.

Today, more than 1.5 million people call Machakos home. Rather than a cautionary example of the perils of overpopulation, however, for some experts Machakos has become a symbol of something very different: the idea that rapid human population growth, even in some of Earth's driest, most challenging environments, is not necessarily a recipe for disaster—and can even bring benefits. They argue that, over the past 75 years, population growth in Machakos and nearby Nairobi has triggered social and economic shifts that have made it possible for residents to regreen once-barren hillsides, reinvigorate failing soils, reduce birth rates, and increase crop production and incomes. “A landscape that was once declared good for nothing is now like a garden when the rain falls,” says Michael Mortimore, a geographer with Drylands Research, a United Kingdom–based nonprofit organization, who helped document the turnaround in More People, Less Erosion, a 1994 study that is still influential—and controversial—today. “Too many people still have the simplistic notion that too many people is a problem,” he says. “What happened in Machakos challenges that pessimism.”

And Machakos isn't alone. In other hard-pressed regions, researchers are finding that even explosive population growth can be accompanied by some surprising trends—such as increased tree cover, more productive farms and economies, and improved well-being. Such results are adding new fuel to long-standing arguments that sheer numbers alone don't determine the consequences of population growth, and that a complex mix of culture, socioeconomics, and biology also plays a role. The findings are also renewing interest in the work of a pioneering Danish economist who challenged conventional notions about the dire consequences of more people—and are raising hopes that even the poorest, fastest-growing regions could, with the right mix of policies, ride out the global population tsunami.

Along with this cautious optimism, however, come profound doubts. Some experts wonder whether the “Machakos miracle” can be replicated elsewhere or sustained in regions experiencing unprecedented population growth. “Although local successes offer hope, it is dangerous to generalize,” warns Jules Siedenberg of the University of East Anglia in Norwich, U.K. “We need to be sure we are drawing the right lessons, since people's lives are at stake.”

Doomsters and boomsters

The question of whether population growth poses a dire threat or a potential opportunity is an old one. Not long after Thomas Robert Malthus made his now-famous 1798 prediction that more people would doom us to “gigantic inevitable famine,” an opposing camp of population “boomsters” emerged, highlighting the potential benefits of reproduction. More people, they argued, meant more labor, technological innovation, and economic growth. Ever since, the rhetorical doomster-versus-boomster battle lines have barely shifted: Today, for instance, even as many experts warn that more people threaten to exacerbate hunger, poverty, and environmental problems, others respond by noting that nations with some the world's highest population densities—such as Singapore and the Netherlands—also have some of the world's strongest economies and environmental commitments.

One recurring flashpoint in the debate has been the ultimate impact of population growth in the world's “drylands,” the driest and often poorest farming areas of Africa, Asia, and Latin America. They hold nearly one-third of Earth's people, and some of these populations, especially in Africa, are growing rapidly at 2% to 3% per year. Many see crisis looming in those numbers for people and the environment. Others, however, see some hope for a transition to more sustainable livelihoods and cite Ester Boserup, a Danish economist who died in 1999, as one source of their optimism.

In 1965, the then-little-known Boserup, who spent most of her career consulting for international development institutions, published a slim volume titled The Conditions of Agricultural Growth: The Economics of Agrarian Change under Population Pressure. It examined the history of subsistence farming and offered a theory that essentially turned Malthus upside down. Instead of rising population density leading to barren fields and starvation, Boserup suggested it could naturally trigger “intensification”: the use of new technologies and more labor to get bigger harvests from less land. “The idea was that people weren't just mouths to feed but also brains that could think and hands and legs that could work very hard,” Mortimore says. So, for instance, a farmer who once might have been able to weed a field just once during the growing season could now justify using more abundant labor to weed it three times, increasing yields and maybe even providing the income needed to dig an irrigation ditch or haul in animal manure to restore soil fertility.

Boserup's work carried some provocative implications. One was that “underpopulation,” not overpopulation, was a barrier to development. Another was that, contrary to the conventional wisdom, dry areas might not have a fixed “carrying capacity”; instead, with more labor, they might be able to sustain more people over time and thus hasten the “demographic transition” to lower birth rates. Finally, her work suggested that dryland farmers, given the right incentives, could be counted on to invest in and take care of their land, solving, rather than aggravating, natural resource damage. Still, many were skeptical: Was this another beautiful theory destined to be destroyed by ugly facts?

Malthus controverted?

In the 1990s, such questions prompted the World Bank and other institutions to launch a range of studies, including the one that enabled a large team led by Mortimore and Mary Tiffen of the U.K.'s Oversees Development Institute and Francis Gichuki of the University of Nairobi, to spend 2 years dissecting what had transpired in Machakos between 1930 and 1990, as its population roughly quadrupled. Drawing on a trove of data—including historical documents and photos, field surveys of everything from soil fertility to household finances, and numerous interviews—the team charted the demographic and socio economic forces that had buffeted Machakos households and how they responded. The researchers documented how, for example, farmers built terraces to control erosion, stepped up their use of animal fertilizers, and began selling food to burgeoning markets in nearby Nairobi. They also examined the growing influence of women, the church and community groups, the impact of the end of colonialism, and how local men who went off to fight in World War II brought new ideas back home. In 1994, the researchers distilled their conclusions into a detailed, nuanced, and often provocative 300-page compendium with a bold, counterintuitive bottom line: More People, Less Erosion.

The book “hit the policy world with a storm,” the Association of American Geographers noted in giving Mortimore a major award in 2008. In particular, the study “controverted” Malthus and backed Boserup, concluding that “increasing population density has had positive effects.” In Machakos, more people had provided both the labor and the “necessity” for a transition to intensification and better land stewardship. Rising populations had also created a rich social milieu for innovation, information-sharing, and political involvement. Meanwhile, in nearby Nairobi, more people had helped create demand for the farm products grown in Machakos and also seasonal jobs for young people from the region. This provided Machakos with income for further, capital-intensive improvements. Greater economic stability also led families to have fewer children and invest more in education. Politicians had helped out by mostly getting out of the way and letting markets create the right incentives for farmers. What's more, the authors argued, “Machakos is not unique.” Other places in Kenya, and communities in Nigeria and Indonesia, had also experienced restoration miracles despite growing populations, they noted in a 1994 follow-up paper in the journal World Development. It was a message, Mortimore says, “very out of step with the doom and gloom about population at the time.”

Nearly 2 decades later, More People, Less Erosion has become an important—and contentious—scholarly classic. Recently, the head of the United Nations agency that deals with desertification paid homage to the study in a speech, hailing a promising trend of “more people, more trees, and less erosion” in some drylands. Critics, however, have raised questions about the study's methods and conclusions and argued that it ignored or downplayed some issues, such as a coffee-planting boom in the 1970s that may have provided a one-time economic jolt. Although overall incomes are up and birth rates are now down in Machakos, some experts note that it still doesn't grow enough food to feed its population. And the poorest families may not have benefited from the “miracle,” which appears to have favored families that already had land and other assets, British scholar John Murton concluded in a 1999 study published in The Geographical Journal. Conservationists, meanwhile, note that intensification can actually worsen problems like biodiversity loss and water pollution. Researchers have also added to the debate over whether Machakos is an exception or the rule in a string of technical papers. They have titles such as “Fewer people, less erosion: The twentieth century in southern Bolivia,” and “More people, more soil degradation: The Malawi experience.”

East Anglia's Seidenburg, for one, believes it is a mistake to assume that the Boserupian processes seen in Machakos are “an automatic result” of population growth. The study showed “solid outcomes” for one region but has perpetuated “unhelpful hyperbole,” he argued in a 2006 critique in Development Policy Review. The problem, he says, is that there are countless instances where fast-growing farming communities have not been innovative enough and are suffering as a result. Some farmers lack the market demand created by a nearby city, whereas others lack access to capital, fertilizers, or information. He fears that “focusing on simple take-home messages, like ‘farmers will figure it out,’ distracts from addressing the barriers that often prevent scaling-up local successes.”

Mortimore sees merit in some of the critiques and agrees that there is no single recipe for success. And many drylands experts believe that more people need not mean catastrophe. “The trick is getting good policy that addresses local conditions and recognizes the needs and knowledge of local people,” Mortimore says. “Local ‘win-win’ outcomes are clearly possible,” Siedenburg says.

New synthesis

At the same time, many scholars are developing a view of population impacts that fuses Malthusian and Boserupian perspectives. And, like realtors, they say one key factor in predicting consequences is location, location, location. “The dynamics play out differently, depending on where you are,” says Erle Ellis of the University of Maryland, Baltimore County. His own studies in China of areas that have been farmed for thousands of years, for instance, taught him that “Boserup was right.” Intensification has supported extensive population growth and ultimately urbanization, which has led to the abandonment and revegetation of less fertile lands (a process experts call “land release”). But the trend “doesn't necessarily mean life is easier,” he cautions. “People are working harder than ever,” as Boserup predicted. And the specter of Malthus looms over China's coercive one-child policy—which implicitly recognizes the downside of population growth—and in the nation's growing environmental problems.

In some parts of Africa, meanwhile, researchers are documenting a notable, Machakos-like “regreening” of arid areas with fast-growing populations. Studies by geographer Chris Reij of the University of Amsterdam in the Netherlands and others have shown that in the Sahel, the tree- and shrub-growing trend has been boosted by policy changes, such as giving farmers ownership of trees that grow on their land and some technical assistance. There's some evidence that the extra greenery is helping to make poor farm communities more resilient to droughts and economic setbacks, but the long-term outlook remains at best unclear.

In the forest frontiers of South and Central America, researchers have found both Malthusian and Boserupian forces at work in deforestation. Depending on local circumstances, families faced with growing population densities have responded by both migrating to clear new farms in forested areas, the agricultural “extensification” predicted by Malthus, and intensified land use à la Boserup, a team led by David Carr of the University of California, Santa Barbara, reported in a 2009 study in Population and Development. Paradoxically, the result is that areas with relatively low population densities can have much higher deforestation rates than those with higher densities.

What's needed now, Carr's team argues, are careful, Machakos-like studies that “tease out the effects” of changing demographics in remote forest frontiers. Other research has found that a farmer's age, gender, and land tenure, for instance, can affect his or her willingness to put capital and labor into the land, with older male farmers sometimes deciding to forgo improvements. Understanding such nuances could help forge better forest-protection and land-use policies, experts say. And Carr and his colleagues predict that new studies “will surely test” what they say has become a Boserupian “orthodoxy of population density leading to agricultural intensification.” If so, it will open a new chapter in the long and rich debate over how population growth affects the planet, and when and where more people are a problem. Maybe the book could be titled Less People, More Deforestation.

• * David Malakoff is a writer living in Alexandria, Virginia.

9. The Upside of Downsizing

1. Dennis Normile

Increasing numbers of countries are facing population shrinkage, and that could be good for both humanity and the planet.

Japan's population will soon start shrinking, if it hasn't already. Despite worries about a shriveling economy and the burdens of the aged, Japanese have collectively resisted calls to boost the birth rate and embrace immigration. And some demographers think this will be fine.

“I'm not saying, ‘Banzai, the population is shrinking!’ But shrinkage is inevitable, and there could be benefits,” says Akihiko Matsutani, who studies population issues at the National Graduate Institute for Policy Studies in Tokyo. He believes that per capita income could rise even as GDP shrinks, providing a more comfortable lifestyle for individuals despite diminished national economic clout.

Japan is not alone. Populations are shrinking in much of Eastern Europe and Germany, according to United Nations statistics. Italy, South Korea, and even China will follow suit by around 2030. Some environmentalists see this as a boon for the planet. “Humanity is already consuming resources at an unsustainable rate; population shrinkage is the cheapest and surest contribution to sustainability that we know of,” says Simon Ross, chief executive of Population Matters, a London-based group pushing to restrain population growth to reduce stresses on the environment.

Japan is leading this trend because it deliberately cut short its post–World War II baby boom. Alarmed by rapid population growth amid postwar scarcity, in 1948 the government started promoting family planning, including allowing abortion on demand. The average number of children born to each woman has trended downward ever since, hitting a low of 1.26 in 2005 before a slight rebound to 1.39 in 2010, according to Japan's Ministry of Health, Labour and Welfare. (The replacement fertility rate for developed countries is roughly 2.1.) Immigration has always been minimal. As a result, preliminary data from the 2010 census indicates that there are just over 128 million people living in Japan, up a scant 0.2% from the previous official count in 2005. And from here, the government projects steady shrinkage, to 123 million by 2020 and 115 million in 2030.

More important for the economy, the working population is shrinking even as the number of elderly people grows. Japan already has the highest old-age dependency ratio, with 38 people 65 years or older for every 100 in the 15- to 64-year-old working population. By 2030, that number will rise to 70 for every 100.

Matsutani, thinks worries about spiraling health care costs, depleted pension funds, and economic decline are overblown, though there are concerns. For example, the assumption that people retire at 65 is out of date. Japanese seniors are continuing to work—and pay taxes—well beyond that age. He also foresees benefits from a shrinking population for all age groups. He thinks economic forces could push Japanese corporations to focus on making higher-value-added products less subject to competition from manufactuers in low wage countries. To attract employees from a shrinking labor pool, such companies will have to pay more and be more flexible, by accommodating working mothers, for example. Higher wages would also prop up domestic consumption.

Some economists think Matsutani is overly optimistic. But Hal Kendig, a sociologist at the University of Sydney, says that in Australia, too, a tightening labor market is increasing opportunities for seniors. “There is a lot of work going on to find ways to make the workplace age-friendly,” Kendig says.

Studies of older workers are turning up surprises, as a group at the Mannheim Research Institute for the Economics of Aging at Mannheim University in Germany found by studying a truck assembly line. Contrary to expectations, “We [found] productivity does not decrease up to age 65,” says Matthias Weiss, a Mannheim economist who led the study. Their contributions could be even greater in less physically demanding jobs. Weiss says that their work suggests that raising the retirement age won't affect workplace productivity.

Delayed retirement is disproving some dire projections about aging populations. Kendig says his examination of the Australian government's 2007 intergenerational report indicates an overall budgetary deficit, driven partly by aging-related factors emerging by 2022. The 2010 report, taking into account recent trends in employment, population growth, and immigration, shows that deficit won't occur until 2030.

There will be challenges. Matsutani says that Japan's current public pension plan isn't sustainable. But creative support for the elderly could help. He says subsidized apartments tailored for the elderly could serve several generations of seniors. Kendig does worry that many baby boomers are heading into old age with chronic conditions, such as obesity and diabetes, that can seriously affect health care costs. But encouraging healthier lifestyles could ameliorate this trend, he says. He remains optimistic that societies can adapt, especially if the elderly are encouraged to be part of the solution.

10. Does Family Planning Bring Down Fertility?

1. Jocelyn Kaiser

Experts have long debated how much access to modern contraceptives matters in places where couples want large families.

Video Feature

[Watch a video on the effect of fertility programs, featuring reporter Jocelyn Kaiser.]

It's a long-running debate in the development field: whether family planning programs help reduce high fertility rates. Many demographers say that millions of women lack access to contraception, and if that gap is filled, they will have fewer children. But some economists argue that couples have large families because they want them, and until desired family size drops, family planning programs are a waste of money.

More data from countries with strong family planning programs and falling birth rates have brought the two sides closer together. Now some are urging policymakers to test new projects to make sure they work in target communities before they are widely deployed. “What we need is evidence of what brings fertility down,” says Yale University economist T. Paul Schultz.

The demographers' argument is based on health surveys done in developing countries every few years. Women are asked whether they want to delay or stop having children and whether they are using modern contraceptives. By dividing this number by the total number of married women of childbearing age, researchers get an “unmet need”—for example, 18% for Latin America and 28% for sub-Saharan Africa, according to 2009 figures from the Guttmacher Institute. Overall, 215 million women, or 15%, in the less developed countries have an “unmet need” for family planning.

The problem with “unmet need” numbers is that “they don't tell us anything about causation,” says social demographer Amy Tsui of John Hopkins University in Baltimore, Maryland. Just because women aren't using contraceptives doesn't mean that they would if they were available or that they would have fewer children overall.

Adding to these doubts is an influential 1994 study from former World Bank economist Lant Pritchett. When Pritchett, now at Harvard University, plotted survey data on desired fertility versus actual fertility for more than 50 developing countries, the data clustered along a straight line—desired family size explained 90% of the correlation. And places with greater access to birth control didn't necessarily have lower fertility, he found. Pritchett's conclusion: The sky-high fertility rates in some countries will drop only when couples decide they want fewer children. And the strongest predictors of a woman's desired family size are her income, her education level, and her infant's chances of surviving, many studies have found.

That suggests development dollars will be far more effective if they're spent on schooling girls, not on family planning, argues Pritchett, who says updated data show his study is still “fundamentally right.”

Some blame the Pritchett study—along with a shift in health funding to the HIV/AIDS epidemic, conservative governments, and concerns about coercive programs such as China's one-child rule—for a decline in donor and country spending on family planning after a 1994 United Nations meeting on population in Cairo.

Since then, the family planning camp has continued to make its case. One new argument is that focusing solely on education won't work in countries like Niger, where if average fertility rates remain at 7.4 births per woman, the population could soar from 16 million today to 58 million by 2050, says political scientist Martha Campbell, a lecturer at the University of California, Berkeley. “You can't expand [schools] fast enough,” she says. Others argue that even if family planning programs only help women space births, the benefits far outweigh the costs because wider spacing cuts maternal deaths and improves child health.

Family planning advocates also say that looking only at access, as Pritchett did, leaves out many other factors that determine whether women will use birth control, such as cultural taboos and fears of side effects that can be addressed only with intense public education campaigns. “A strong government can overcome many of those barriers,” says demographer John Cleland of the London School of Hygiene and Tropical Medicine, and also bring down desired family size by convincing people that they're better off with fewer mouths to feed.

Cleland points to Kenya, where fertility rates dropped from 8 to 4.8 births per woman after the government launched aggressive family planning efforts in the early 1980s. In comparison, in culturally and economically similar Uganda, which has a weaker family planning program, fertility has remained high, notes demographer John Bongaarts of the Population Council in New York City. He says other country comparisons also bolster the case for family planning (see p. 574).

Still, those examples don't directly show that family planning programs lower fertility rates. One of the few studies that provides such evidence was conducted in Matlab, a region of Bangladesh where Muslim practices and frequent floods discourage women from leaving home. Starting in 1977, family planning workers regularly visited homes in half of Matlab's 141 villages to offer married women birth control methods. By 1996, while fertility had dropped across Matlab, it was 16% lower in the study villages than in control villages (or at least one fewer birth per woman over 30), according to estimates by Schultz and Shareen Joshi. Elements of the program were extended to all of Bangladesh, and women now have on average just 2.7 children, “which is astonishing for a country that poor,” Bongaarts says.

Although the debate isn't over, “there's been a little bit of convergence” about the role of family planning versus education, says economist David Lam of the University of Michigan, Ann Arbor. “It was either-or. I think most people agree now it's both.” Pritchett says he now believes that family planning can accelerate a drop in fertility rates in countries in a “sweet spot” where desired family size has begun to fall.

As family planning makes a comeback, some researchers are calling for policymakers to test projects with controlled experiments, such as the Matlab study. One recent example is a study in Zambia that gave about 1000 women vouchers for free contraceptives. While contraception use rose over the next year, fertility fell only among women who received the vouchers without their husbands present. In this group, births unwanted by the woman dropped 57%. This made sense because often the wives wanted fewer children than their husbands did, says study leader Nava Ashraf, an economist at Harvard.

Such studies show that “differences in design can make a huge difference in the impact,” Ashraf says.

11. A Pitched Battle Over Life Span

1. Jennifer Couzin-Frankel

Predicting whether life expectancies will keep rising is as much art as science. Two demographers disagree about what the coming years will bring.

Demographers might not seem the sort to engage in fiery debate—until you talk to James Vaupel and S. Jay Olshansky. The two sit at opposite poles of a dispute (although never in the same place at the same time) that has long fueled speculation: What will human life expectancy look like in the years to come? Will it continue with steady, almost linear upticks? Or will it veer in a different direction?

Vaupel, an American who works mainly at the Max Planck Institute for Demographic Research in Rostock, Germany, and Olshansky of the University of Illinois in Chicago, appear to have sourced their crystal balls from very different manufacturers. For 20 years they've been arguing, joined by demographers worldwide, trying to answer a question that is essentially unanswerable: whether the future will resemble the past. Vaupel says it will, with life expectancies at birth rising unabated by about 3 months a year in countries where residents live the longest. Olshansky counters that sober realities, such as widespread obesity, will cut life spans short.

This all might sound philosophical, with little practical value—but in fact, it has very real-world implications. For example, every year of life expectancy costs the U.S. Social Security Administration $50 billion. Knowing whether a 90-year-old who needs heart surgery is likely to live much longer helps determine whether she receives that care. Meanwhile, the Vaupel-versus-Olshansky divide is so deep that it's pulled others into the fray. “I didn't really begin studying this until a decade ago,” says John Bongaarts of the Population Council in New York City. “I was intrigued by the fierceness of the passions on both sides. I said, ‘What the heck is going on here?’” He would quickly find out. Lighting the fires For Olshansky, the debate over limits to the human life span began in 1990, when he published a paper in Science (2 November 1990, p. 634). Called “In Search of Methuselah: Estimating the Upper Limits to Human Longevity,” the paper postulated that “it seems highly unlikely that life expectancy at birth will exceed the age of 85.” At the time, the idea that life span couldn't keep on rising was popular. Life expectancy had nearly doubled in some countries in the previous 150 years. Many demographers concluded “that this is not going to last forever,” says Juha Alho, a statistician at the University of Eastern Finland in Joensuu. But these were gut feelings, “a judgment call,” he says, assumptions not grounded in data. Life-span limits had been postulated many times in the past. Meanwhile, people just kept on living beyond when they'd been predicted to expire. Olshansky examined how much mortality from heart disease, cancer, and other killers would need to drop in order to boost life expectancy. “Most of the past increases in life expectancy occurred because we saved the young,” he says. “That can only happen once.” Even a cure for cancer, he calculated, would add only 4 or 5 years of life across a population. The 85-year limit is a “soft” one, he says, guided by aspects of human biology that appear fairly fixed, such as the timing of menopause. The idea that a population's life expectancy would be grounded in evolution, as Olshansky postulates, makes sense. Salmon, for example, literally self-destruct after they reproduce, says Shripad Tuljapukar, a professor of biology and population studies at Stanford University in Palo Alto, California. “Evolution can do all sorts of things,” he notes. “But it hasn't done them to us.” Tuljapukar, who falls more in Vaupel's camp, points out that women live well beyond when they're capable of reproducing, as do whales and some primates. In 1990, when Olshansky published his Science paper, life expectancy at birth for people in Japan—record-holders in this regard—was 79. In 2009, it was a shade over 83. Vaupel doesn't hide his delight that, in his view, the Japanese are torpedoing Olshansky's careful mathematics. Olshansky's paper proposes “the prediction he's famous for that I suppose he'd like people to forget,” Vaupel says. (Olshansky warns that “when you call Jim, you are going to get misrepresentation” and disputes that the 85-year limit was a fixed one; he also says that for Japan, getting from 83 to 85 won't be easy.) These days, “I think the Vaupel school is larger than the Olshansky school,” says Steven Austad, a biogerontologist at the University of Texas Health Science Center in San Antonio. Austad has a friendly wager with Olshansky: He's betting that as of the year 2000, the first 150-year-old human had already been born. Olshansky doesn't think so. The two have put$150 each into an investment account, to be accessed in the year 2150, when the winner will become clear. “In the best-case scenario I would get the proceeds,” Austad says. “Or, more likely, my kids or grandkids.”

Like many biologists, Austad has been struck by the varied interventions, from modifying genes to restricting calories, that extend life. “We would have said that you can't make a mouse live longer than 3.5 years; now we can make a mouse live 5 years,” he says. Even if that doesn't translate into a pill that forestalls human aging, the incremental advances happening now in people are significant, he believes. In 1970, for example, half of the 70-year-olds in Sweden had no teeth at all. In 2000, only 7% were toothless, thanks partly to fluoridated toothpaste. Tooth decay is associated with heart disease, and Austad believes that hanging on to one's teeth translates into something meaningful across a population.

Olshansky says that's all well and good, but other health trends are far more alarming. In 2005, he forecast in The New England Journal of Medicine a potential decline in U.S. life expectancy because of widespread obesity. “You can't ignore the health of living people,” he says. Of Vaupel and his ilk, he minces no words: “It's easy to come up with a life expectancy of 100 if you close your eyes, pull out a ruler, and you extend historical trends into the future.”

Deaths past and future

One reason for disagreement is that although we think of life expectancy as a single number, it's really not. There are different mortality rates for different ages, sexes, and parts of the world. “Life expectancy is a one-number summary of 100 numbers,” Alho says. “What actually is the most relevant way of looking at these things? It's not obvious.”

In 1980, epidemiologist James Fries of Stanford postulated that the percentage of people surviving past age 100 was fixed. In the late 1980s, Vaupel decided to test this. He traveled to Stockholm, which holds some of the world's best mortality data, and found that since 1860, death rates for centenarians had fallen in half. This meant that centenarians were dying off more slowly than they used to, which ran counter to what Fries had predicted.

Along those lines, Vaupel published another experiment in Science in 2003 (19 September 2003, p. 1679), with his colleague Kaare Christensen, an epidemiologist and physician at the University of Southern Denmark, and entomologist James Carey of the University of California, Davis. Titled “It's Never Too Late,” the researchers reported that mortality rates in East and West Germany converged just years after the Berlin Wall fell. Previously, mortality rates in East Germany were 20% higher. In Christensen's view, “it's the most frail and sick that benefit most from progress,” including better medical care and a willingness to treat the very old. He's currently working with Vaupel to study whether centenarians today are healthier than those in the recent past.

Like many demographers, Vaupel relies heavily on historical data because he considers it by far the best we've got. Still, even if many side with Vaupel, some consider his approach to be limiting. Vaupel does “great work [and is] very imaginative,” says Richard Miller, a biogerontologist at the University of Michigan, Ann Arbor. But he and others like him have “cut themselves off at the knees by saying, ‘If you can't take it from a life table, don't talk to me about it.’” Vaupel admits that one nagging question is how to incorporate ancillary data like new biological insights, which aren't directly connected to life expectancy but could, when melded with it, prove useful.

When push comes to shove, Vaupel and Olshansky “disagree about everything, [and] they do it very articulately,” Austad says. “It took me a while before I realized, ‘Why don't I ever see these two at the same conference?’”

Vaupel says he's steered clear of Olshansky since they were each invited to present their case, about a week apart, at the Cass Business School in London about 6 years ago. A British member of Parliament acted as the moderator and strove for a middle ground. “Of course when you adjudicate, the truth is always in between,” Vaupel says. “I said, ‘I'm sick and tired of the truth being in between, and I'm not going to do this anymore.’”

12. How to Engineer a Baby Boom

1. Mara Hvistendahl

East Asia's "tigers" are striving to boost falling birth rates. But will their pronatalist policies work?

Coming from National Governments, the tactics are bold: posters urging couples to forgo birth control, free weekend getaways for single civil servants, and a state-condoned sex fair featuring displays of toys and lingerie. So concerned are East Asia's powerhouses about their sluggish birth rates that they're doing everything they can to persuade residents to have more children.

Over the past few years, South Korea, Taiwan, and Singapore—with Hong Kong, sometimes called the “Asian tigers” for their rapid economic growth in the 1970s and '80s—have unveiled policies directed at filling maternity wards, and fast. The impetus is a fear that the pool of workers that drove the East Asian boom will soon dry up. The three countries' total fertility rates, or the number of children a woman is expected to have over her lifetime, hover between 1.1 and 1.3—beneath the threshold of what demographers call “lowest-low fertility” and among the lowest in the world.

Not long ago, South Korea, Taiwan, and Singapore were determined to reduce, not increase, their birth rates. In the 1960s and '70s, East Asian governments legalized or improved access to abortion, provided incentives for sterilizations and intrauterine device insertions, and pushed other measures, some of them draconian. Western money and expertise helped. In South Korea, the U.S. Agency for International Development furnished reconditioned Army ambulances that became mobile birth control clinics.

Some now question the wisdom of these methods, which resulted in high abortion rates and left other lasting social effects, and in the case of Singapore included eugenic policies at moments. But few dispute that they contributed to a rapid drop in births. In South Korea, the total fertility rate fell from an average of six children per woman in 1960 to replacement rate, 2.1 children, in 1984. Demographers say falling birth rates contributed to what is called a “demographic dividend”: a period of breakneck economic growth as the proportion of working-age people in the population rises. But few anticipated how far birth rates would ultimately fall. “The family planning program was maybe too successful,” says Ik-ki Kim, a sociologist at Dongguk University in Seoul. The decrease in South Korea's fertility rate, he says, was “very rapid.”

Leaders worry that a ballooning dependency ratio, signaled by a large proportion of retirees, will strain their economies, bankrupting the education system and burdening hospitals and clinics. And so they have shifted course, unveiling new comprehensive policies—this time with the goal of encouraging rather than deterring births.

In Singapore, the first of the Asian tigers to adopt a pro-natalist stance, the transition was abrupt. The country closed its Family Planning and Population Board in 1986 and launched its New Population Policy in 1987, disseminating the slogans “Have Three or More Children If You Can Afford It” and “Abortion is Not a Method of Family Planning.”

South Korea followed suit in 2005. Its latest government plan allots $67 billion for increasing the birth rate. Taiwan's efforts have been more gradual, starting with an emphasis on marriage in 1990 and picking up steam in 2008, when the government issued a white paper on low fertility and aging. All three countries now give subsidies for births, or so-called baby bonuses, in amounts varying from$200 for middle-class Singaporean families to $2800 for third births on one Taiwanese island. More fantastically, Taiwan offers all-expenses-paid getaways for single state employees, and once they've partnered up urges them to participate in group marriages of dozens of couples presided over by dignitaries. The Singapore government, meanwhile, operates a dating site, http://www.lovebyte.org.sg/, aimed at boosting the marriage rate. Scholars in both Singapore and Taiwan are also studying the example of countries like Sweden and France, which have successfully reversed declining birth rates after unveiling a slew of profamily policies. But even there, says Hans-Peter Kohler, an expert on low fertility at the University of Pennsylvania's Population Studies Center, there is little concrete evidence explaining why the birth rate has risen. “There is not a clear consensus on the policy mix that would translate into higher fertility,” he says. Minja Kim Choe, a demographer at the East-West Center in Honolulu, says baby bonuses have been shown to influence the timing but not the number of births in the countries outside Asia where they've been tried. In the end, East Asia really needs a comprehensive, parent-centered approach to fertility, she wrote in an e-mail: “Only policies that reduce the economic, social, and psychological costs of raising children have some hope of raising fertility.” Wen-shan Yang, a demographer at Academia Sinica in Taipei who advises the Taiwanese government on its birth policy, agrees. After decades of furious development, he says, the answer may lie not in extolling marriage or sex but in simply enabling couples to live more balanced lives. “Young people work until 9 or 10 p.m.,” he says. “They don't have time to have babies. They are too tired.” Next year, East Asia may be helped along by the lunar calendar: 2012 is the year of the dragon, which is considered a lucky time to have a child. Leaders hope any rise in the birth rate will be more than temporary. 13. Young and Restless Can Be a Volatile Mix 1. Mara Hvistendahl A new theory proposes that swelling groups of young people, or "youth bulges," lead to conflict Soon after protesters took to the streets across North Africa and the Middle East last winter, experts began casting about for explanations. A series of WikiLeaks cables had just revealed the extent of corruption among greedy dictators. Or the uprisings were a technological phenomenon made possible by Facebook and Twitter organizing. But one group of scholars looked no further than demographics. The Arab Spring, they point out, occurred at a time when Tunisia, Egypt, Yemen, and other countries had a large share of young people in the adult population. In this interpretation, a so-called youth bulge, or a large proportion of adults concentrated in the 15-to-29 age group, is a good predictor of conflict and instability. The theory makes intuitive sense—the foot soldiers of protests and insurrections are, after all, typically young. Proponents also make their case through historical examples and predictive models. That growing body of research may explain why youth bulge analysis has taken hold in intelligence circles, cropping up in foreign policy briefs from the U.S. Agency for International Development (USAID), groups affiliated with the U.S. Central Intelligence Agency (CIA), and elsewhere. Others contend evidence is limited, outbreaks of unrest depend on a slew of other factors, and a large number of young adults may be an asset as well as a threat. A youth bulge is “incendiary,” says John Weeks, a demographer at San Diego State University in California who is among the theory's proponents. Although a growing number of youth doesn't alone translate into unrest, he adds, the increase can be the kindling that sparks rebellion. When conditions deteriorate, “you have more young people who will be out there protesting,” he says. The demographers and political scientists who study the phenomenon say the balance starts to tip when the proportion of adults in the troublesome youth demographic reaches 35% to 40%. Tunisia and Bahrain each have youth bulges of 38%, Egypt has one of 43%, and Yemen has one of 53%, according to United Nations population estimates for 2010. As the ranks of young people swell, demand for jobs soars, and governments often have a hard time providing work. A rise in unemployment leaves already malleable young people even easier to recruit to various causes, says Richard Cincotta, a political scientist at the Stimson Center in Washington, D.C., and a consultant to the U.S. National Intelligence Council (NIC), which advises the White House and policymakers on long-term intelligence strategy. Whether revolutionary ideas take hold, he contends, depends in part on “how easy it is to get this ideologically naïve, experimental, risk-taking, perhaps creative group of people into politics.” In North Africa and the Middle East last spring, Cincotta and others say, recruitment was a cinch. Nearly a quarter of 15- to 24-year-olds in the region are unemployed, according to the International Labor Organization (ILO), compared with a global average of 12.7%. Many more are what ILO deems “inactive,” or not seeking work for various reasons. “If the economy doesn't provide jobs for a large number of people with a high school or college education, you can get a cohort-focused spike in unemployment,” says Jack Goldstone, a political scientist at George Mason University in Arlington, Virginia. “That's what we saw very strongly across North Africa and the Middle East.” Predicting violence Scholars like Cincotta and Goldstone were predicting trouble in the region well before protests broke out after a Tunisian street vendor named Mohamed Bouazizi set himself on fire last December. For the cluster of government agencies where their ideas have taken hold, too, the uprisings would not have come as a surprise. In 2008, then–CIA Director Michael Hayden highlighted population growth as one of the trends threatening to undermine global stability. The Political Instability Task Force, a panel of scholars funded by the agency, had also been studying the youth bulge issue. (Goldstone sits on the task force.) Last year, USAID issued a report on youth bulges and conflict. And NIC's recent Global Trends report forecasting geopolitical developments out to 2025 contains a section on youth bulges, describing an “arc of instability” stretching from Latin America across sub-Saharan Africa and the Middle East to South Asia. The document singles out Pakistan, Yemen, Nigeria, and Afghanistan as particular threats. An interplay between volatile young populations and upheaval is not new, according to proponents of youth bulge analysis. They say an imbalanced age structure has contributed to several major historical conflicts, including everything from the English rebellion of the 1640s to World War I and II, which occurred when Europe's population was youthful. More recently, they contend, a large number of young people helped fuel both the Iranian revolution and Latin America's Marxist revolts of the 1970s. And yet, although friction sparked by youth bulges is easy to pinpoint in hindsight, using the indicator to predict future conflict, and conversely, where stability might take hold, is much more difficult. Cincotta is among the few scholars who have tried to translate the new research into a forward-looking model. Analyzing population and governance trends beginning in 1970, he tracked the share of youth in the working-age population in countries that have achieved liberal democracy, qualifying as “free” in democracy watchdog Freedom House's annual rankings of political freedom. (Cincotta calculates a youth bulge differently from the way Goldstone does, using the 15-to-29 age group as a proportion of the working-age population rather than of the total adult population.) Although a young country was prone to conflict, Cincotta found, as its population matured and the proportion of 15- to 64-year-olds concentrated in the youth bracket declined, the chance it would adopt and maintain democracy improved. The tipping point came when the share of youth in the working-age population fell to between 36% and 42%. At that point, a country has a 50-50 chance of achieving liberal democracy, and chances improve if it can get beyond its youth bulge and on a path toward maturity. In addition to predicting where democracy might take hold, Cincotta says, his model can indicate which countries might be roiled by unrest. There is hope for democracy in Tunisia, he says. Thanks to a declining birth rate, the country is now at the tail end of its youth bulge, with a median age of 29. But prospects for Egypt and Yemen, with median ages of 24 and 18, are dimmer, he adds. “For those two populations, one would expect more violence,” Cincotta says. Angry young men The belief that demography drives conflict is hardly new. At the turn of the 19th century, Thomas Robert Malthus wrote of population growth being checked only by the “vices of mankind.” That specter reemerged in the 1960s and '70s, as concern about overpopulation heightened in the West. Scholars connected a mushrooming population to a scramble for resources, predicting that scarcity would spark conflict. Several decades later, the Canadian political scientist Thomas Homer-Dixon refined neo-Malthusian ideas to account for urbanization, resource ownership, and other factors. Some of the recent research on youth bulges grew out of this earlier body of work. In 2001, Henrik Urdal, now a political scientist at the Peace Research Institute Oslo and a research fellow at Harvard Kennedy School, looked into neo-Malthusian theories for his dissertation and found “a high interaction between resource use and conflict” was difficult to prove, he says. Instead, Urdal stumbled across Goldstone's work and shifted his own focus to include youthfulness. In one study, he found that in some cases youth bulges can exacerbate the risk of low-intensity conflicts, in which at least 25 people are killed in 1 year, breaking out. In another analysis, Urdal determined that youth bulges were significant factors in sparking two types of conflict in India between 1956 and 2002: Hindu-Muslim riots and general political violence. Such research is specific to certain regions and conditions. In drawing broader conclusions about youth bulges, however, Columbia University population historian Matthew Connelly cautions that the collapse of past theoretical frameworks should give social scientists pause. “Scholars have been looking into the purported link between population trends and economic and political problems for decades,” he says, with little concrete data to show for it. The youth bulge analysis would have failed to predict events such as the civil wars in the former Yugoslavia and the 2008 Russian invasion of Georgia—bloody conflicts that occurred following periods of relatively low fertility. Indeed, the demographers and political scientists working on the question differ on how heavily to weight demography. Goldstone says various trends exacerbated demographic risk in Egypt and neighboring countries ahead of the Arab Spring. Governments in North Africa hugely expanded higher education, he says, even as they scaled back public sector employment and state subsidies. As the number of educated young people increased, he says, “the private economy was not taking up the slack and providing jobs for these people.” Related to soaring unemployment, Goldstone says, is a low marriage rate. The lack of jobs has prevented many men from amassing the capital necessary to attract a wife, so that in Egypt fully 50% of men age 25 to 29 remain unmarried. “That's very difficult in a family-centered society,” Goldstone says. The unusually low marriage rate may have contributed to the recent unrest, he adds: Unmarried men have been found to be more volatile than married men. Cincotta agrees that other factors play a role but maintains that looking at demographic indicators in isolation can help predict where conflict might break out—a key concern within the U.S. government agencies studying the issue. Because a skewed age structure affects employment and education, he says, a youth bulge “mirrors other things that are happening at the same time.” Cincotta is candid about where his predictive model falls short. Although it works for military caretaker regimes, weak personal dictatorships, and partial democracies, it holds less true for countries ruled by strong, single-party governments or charismatic leaders, he says. His model suggests that Russia and Cuba should be liberalizing, which they're not. And China and Singapore both got through their youthful stages without either a significant conflict or a transition in government. In East Asia, in fact, a surge in the number of young workers in the 1970s and '80s may have been an asset that contributed to the region's economic boom. “So much depends on whether there are overall reforms that loosen up the economy,” says Nancy Birdsall, president of the Center for Global Development in Washington, D.C. She is wary of using youth bulges to foretell conflict, although she agrees that the swelling proportion of young people in countries like Pakistan is a concern. Another region that defies prediction is sub-Saharan Africa, the site of the world's fastest growing populations. AIDS has hit hardest there among the working-age population, killing the very people who might form a youth bulge—and yet the region is often the site of strife. The situation in sub-Saharan Africa is “truly puzzling,” Cincotta acknowledges. “The age structure is not necessarily representative of what's happening there.” And although the youth bulge analysis examines only the total youth population, both male and female, other scholars say a sex ratio skewed toward males, or a low status of women vis-à-vis men, is also an indication of conflict. The USAID report acknowledges that “fears about youth bulges are really fears of young men.” But studies examining the role that gender inequality plays in sparking conflict are relatively rare. In the end, Goldstone says, demography has turned out to be a better tool for analysis than any alternatives—and the youth bulge theory works more than it fails. “In terms of broad probabilities,” he says, “demography tells you almost everything you ought to know.” But Connelly, the historian, submits that population projections are not more accurate than other ways of forecasting conflict. The youth bulge theory has taken hold, he says, not because it is better than other approaches but simply because it is more straightforward, with United Nations population projections readily available online to researchers. Connelly says, “Projecting demographic trends is easier than projecting trends in religious national fervor or future discoveries in biotechnology.” The theory that explained the 2011 Arab Spring may not work as well for the next bout of unrest. 14. Gray Ladies in The Spotlight 1. David Malakoff* A growing corps of graying women are actively engaged in the civic life of their often male-dominated communities, taking on stabilizing social roles that others sometimes can't. Vast throngs of angry young men may be one of the lasting images of the protests that toppled Egyptian strongman Hosni Mubarak earlier this year. But it's a member of another rapidly growing demographic group—call it “wise old women”—that some Egyptians have named “the mother of the revolution.” At the height of the fray, a silver-haired, 79-year-old activist, author, and physician named Nawal El Saadawi appeared in the streets and on television screens to counsel and encourage her younger allies. “We will win!” she assured one interviewer. For researchers who chart the growing numbers and shifting roles of women older than 65, El Saadawi represents one emerging trend: a growing corps of graying women who are actively engaged in the civic life of their often male-dominated communities, taking on stabilizing social roles that others sometimes can't. Already, studies show older women are a major source of community cohesion in many cultures by taking care of grandchildren and ailing family members, often men who typically die at younger ages than women. And “go-getter grannies” are also a disproportionately high source of volunteer labor in many nations, including the United States. Not all women, however, are experiencing “active aging.” In another trend, more older women are living alone on meager financial resources, with a disability or an illness. In the United States, for example, 40% of women over 65 years old now live alone, according to census figures, compared with just 19% of older men, and many other nations are seeing similar trends. That's feeding growing concerns about isolation and poverty among older women, as demographers predict that their global number will surge from some 300 million today to more than 850 million in 2050. One nation paying close attention to these twin trends is China, which expects to have more than 100 million older women by 2050, many left behind in rural villages as young workers move to the city. “Aged women are seen as a burden” but also as possible “contributors to building a civil society” in China, says Xiangxian Wang, a sociologist at Tianjin Normal University in China who has been studying the issue. But they are often frozen out of village leadership committees due to “pervasive public and private” gender discrimination that has “systemically destroyed women's fair representation,” she concluded in a 2009 study published in the journal Asian Women. What may help turn this tide, Wang says, are hundreds of “Aging Associations” that have come into existence in the past few decades. Originally established to help care for older people, in some places they have now become “the main force to promote rural democracy” by providing training in leadership and activism. Many older women will need such “outside help to have the chance to fully contribute,” she says. In the meantime, the Chinese government is pondering other solutions, including a law that would provide pensions to elderly women and require children to regularly visit their aged mothers. • * David Malakoff is a writer in Alexandria, Virginia. 15. Regional Snapshots 1. Gretchen Vogel Science has created several "snapshots," descriptions of composite characters, to try to capture some of the demographic trends that set countries and regions apart. The pull of the city Wei is 45 and lives in Shenzhen, a city on the Pearl River delta just north of Hong Kong. During his lifetime, the city has grown from around 30,000 people in 1979 to 350,000 in 1985 to an estimated 14 million today, making it China's fastest growing city. In 1980, the Chinese government established the Shenzhen Special Economic Zone, with tax breaks for foreign investors and liberal trade rules. The plan took off, transforming the small fishing town into a metropolis in just over a decade. Wei grew up in a small town in Hubei Province, an 18-hour train ride from Shenzhen. His parents still live there, but he sees them only a few times a year. After completing secondary school at age 17, Wei went to Nanjing to study, ultimately earning a Ph.D. in genetics. He now works at one of the city's many high-tech companies. Wei lives in a two-bedroom apartment in one of the city's high-rise apartment buildings, for which he pays$600 a month. He earns roughly $3000 per month, which puts him firmly in the upper middle class, allowing his family to buy luxuries such as a car and a flat-screen TV. On his way to work, however, he passes housing for the city's underclass—several million people who work in factories for 80 hours a week at the minimum wage of roughly$200 per month. An estimated 8% of the city's residents are thought to live on $3 a day or less. Wei married at age 32; he and his wife have one 10-year-old son. That's consistent with China's one-child policy, but it is also what the couple says they would have chosen even without state encouragement. A growing share of Wei's younger female colleagues say they don't want any children. According to the 2000 census, the total fertility rate for urban China is 0.8, dropping as low as 0.4 in some cities. That means more than half the women of childbearing age are expected to have no children at all. Growing pains Like many rural Ugandan women, Anita wants a large family. She was 18 when she had her first child; now, at 29, she is expecting her sixth. The country average is 6.67 children born per woman, one of the highest in the world. (Her second-born died in infancy from diarrhea, not unusual in a country where more than 6% of babies do not survive their first year.) In a good year, the maize, millet, cassava, beans, and other vegetables Anita and her husband grow on their hectare of land provide most of their family's food. Although the family, which also keeps a few chickens and a goat, generally has enough to eat, Anita's two youngest children are both anemic, as are 70% of Uganda's children age 5 and younger. Like the vast majority of rural Ugandans, the family uses a crude pit latrine, and their water comes from the village well nearly a kilometer away. Part of the year, Anita's husband goes to Kampala to work at a construction job; the family needs the money, but his city job increases Anita's risk of eventually acquiring HIV and developing AIDS. (6.5% of Ugandans are infected, and the rate is higher—and rising—in urban areas and among migrant workers.) Anita completed fourth grade and is able to read and write. Her two oldest children are now attending primary school. The government eliminated fees for primary schools in 1997, which more than doubled enrollment within 5 years. However, in fast-growing countries like Uganda, where there are 117 children for every 100 working adults, even the best-intentioned governments don't have the resources to provide adequate schooling. The average primary school teacher in rural Uganda is responsible for more than 50 students. Three or more students share each desk, and six or more students share each textbook. In a few years, Anita's oldest child will have to walk 5 km to reach secondary school, if she qualifies and if the family can afford to send her. Shrinking pains Jens, 25, lives in Prenzlau, a rural town of 20,000 people 100 kilometers northeast of Berlin. He is single and, statistically at least, is likely to stay that way: He faces a sex ratio worse than a young man in China. Since German reunification, the former east has lost hundreds of thousands of residents between the ages of 18 and 29, and migration of young women has consistently outpaced that of young men. On average, girls do better in school, so they have more opportunities to study and work elsewhere. That lack of young women has led to very low birth rates. Fewer than 300 babies per year were born in Prenzlau in recent years—so few that the local hospital closed its obstetrics ward in December. The town has shrunk by 20% in Jens' lifetime. Sharp population declines are common across former Sovietbloc regions, but the trends are more pronounced in the former East Germany, in part because migration from east to west doesn't involve language barriers or national borders. Under the East German government, the town hosted a sugar factory, a dairy, a mill, and a brewery. A refrigeration valve factory employed as many as 1000 workers in the 1980s. The total fertility rate was an average of close to two children per woman. But shortly after reunification, many of the factories closed or shrank drastically—for instance, the valve factory employs just 100 people today. The unemployment rate in Prenzlau is 17%. Jens is fortunate: After finishing secondary school, he found a job in a factory that makes solar panels, a plant that opened in 2002. And one advantage of the declining population is that rent is relatively cheap. Jens pays just €270 ($395) per month for a roomy two-bedroom apartment near the center of town. Some city planners and demographers say that Prenzlau and other cities in eastern Germany can be a model of smart shrinking. Some towns and cities have already demolished entire apartment blocks, converting the land into parks.

The high unemployment rate and declining population leave plenty of residents frustrated and frightened, however. A few of Jens' friends have begun attending events organized by right-wing political groups. A member of the far-right NPD party was elected to the county council in 2008.

There are some bright spots: In addition to the factory where Jens works, several other “green energy” companies have set up shop in or near Prenzlau. One employs several dozen people to make environmentally friendly insulation and other construction materials from industrial-grade hemp grown in the region. Another plans and operates wind-energy farms across Europe.

During the harvest season, José, 19, lives in the southern Mexican state of Chiapas, where he works on a coffee plantation 12 hours a day, 6 days a week, for roughly $4 a day. He grew up in the Guatemalan state of San Marcos, just across the border. He and his four siblings attended primary school, but none of them completed secondary school. This is José's third year working in Mexico. The first year, he sneaked across the border undocumented. But last year and this one, he received one of the more than 120,000 permits issued by the Mexican immigration authorities for temporary workers in Chiapas's mango, papaya, sugar cane, coffee, and banana plantations. In 2010, Guatemalans working in Mexico sent an estimated$104 million home in remittances. The country received an estimated $4.3 billion in total remittances, close to 10% of GDP, mostly from the United States. While working at the plantation, José receives two light meals a day and sleeps on a wooden bunk crammed in with dozens of other migrant workers. At home in Guatemala, José helps out on his parents' farm, where they grow fruits and vegetables on 1.5 hectares. There aren't many other options. Although a Canadian company opened a gold mine nearby in 2005, it employs only a handful of local workers. While birthrates in most of Latin America have fallen to close to replacement level—Mexico's is just above two children per women—Guatemala's has stayed relatively high, at around four children per woman. José has an uncle and a cousin who have made it to the United States. He has considered trying to join them, but the stories he hears from his fellow workers of the treacherous journey across Mexico have discouraged him—at least for now. Growing older—quickly Retiring in Thailand may sound like an attractive option for sun seekers from Europe or North America—but only if you bring your pension with you. Thanks to a rapidly falling birthrate and rapidly increasing life expectancy, Thailand's population is aging faster than almost anywhere else. That is worrisome in a place where older citizens have traditionally relied on family ties. Suchin, for example, is 68 and lives in Chiang Rai, a city of about 100,000 people near the Burmese border. She has four children, eight grandchildren, and one great-grandchild. Like most women her age, Suchin completed just a few years of primary school. Only 6% of Thai women over the age of 60 attended any secondary school. Since her husband died several years ago, Suchin has relied on her children for support, as the government's typical “elderly allowance” is 500 baht, or about$16 per month.

Suchin is fortunate: She lives with her son, a teacher, and his family. A daughter in Bangkok and a son working in Taiwan also send money. Suchin keeps in touch with her far-flung children by telephone. Telephone access was a rarity among older Thais 15 years ago, but more than three-quarters report having telephone access today. Her son's family has a refrigerator, a television, and a motorcycle—all are common in Thai homes, both rural and urban.

In 2000, 9% of Thailand's population was 60 or older. That percentage is expected to double by 2020. During that transition, the ratio of working-age people to retirees will fall from seven to about four. In 2002, 62% of Thai women over 60 had four or more living children. In 2020, 60% will have two or fewer. Suchin's children, who range in age from 35 to 50, each have two children; they may not be able to depend on their offspring as their primary source of food and shelter.

In the coming decades, however, older Thais will also be more educated, which correlates with better cognitive and physical health, higher incomes, and the ability to work longer. By 2045, nearly half of Thais over 60 will have completed primary school, and more than a quarter will have had some secondary education.

Young mothers, small families

Chandni lives in Hyderabad, a city of 4 million people in the southern state of Andhra Pradesh in India. Like one-third of the city's residents, she lives in an area that city officials categorize as “slums or other poor settlements.” She attended school through sixth grade but dropped out when she married at age 16. She is now 24 and has two children, ages 6 and 4. Two years ago, she had a tubal ligation. Female sterilization is the birth control method of choice for 75% of couples who use what demographers and health officials call “modern contraceptive methods.” In Andhra Pradesh, a mostly rural state, more than 60% of married women are sterilized, and the median age of sterilization is 23.

Although Andhra Pradesh, along with the rest of southern India, has an overall fertility rate slightly below replacement level—the average is 1.8 children per woman—the fact that women have their children so young means that population growth isn't falling as quickly as in other regions with similar birthrates. In the neighboring state of Maharashtra, a government program pays cash bonuses to persuade couples to wait a few years before having their first child. Chandni is anemic, like 70% of women of reproductive age in India. It is a condition that is correlated with early motherhood and closely spaced pregnancies. Siblings who are more than 2 years apart tend to be healthier as well. Like half of India's children under the age of 4, Chandni's children are malnourished.

Chandni lives with her husband, her children, and her mother-in-law in a two-room dwelling with walls of concrete bricks, a dirt floor, and a corrugated metal roof. She usually fetches water from a pump house just a few minutes away, but the supply is available for only a few hours a day. It is sometimes turned off for days at a time. Waterborne diseases are common in Chandni's neighborhood, where very few homes have modern toilet facilities. Community toilets are available, but they are so poorly maintained that many people simply use the open sewers.

Chandni's husband has a mechanic shop, where he works with his brother. He earns roughly $70 per month, half of which the family spends on food. 16. A World of Chronic Disease 1. Sara Reardon The public health community is sounding the alarm about the global epidemic of chronic diseases, but there are no easy fixes. When the global fund to fight AIDS, Tuberculosis and Malaria was created in 2001, the world responded enthusiastically. In the ensuing decade, wealthy countries and donors have poured more than$11 billion into fighting these three diseases. But an increasing chorus of global health experts believes the world has been ignoring another health crisis of equal or even greater magnitude: the spiraling epidemic of noncommunicable diseases (NCDs). Long the scourge of Western nations, cardiovascular disease, cancer, diabetes, and respiratory diseases like asthma now kill more people worldwide than all other causes combined. And the trend will only accelerate as the global population ages and sedentary lifestyles and unhealthy food become more common around the world.

“The rise of chronic diseases calls for some serious thinking about what the world really means by progress,” said World Health Organization Director-General Margaret Chan in her opening address at the WHO global forum on noncommunicable diseases in Moscow in April. WHO's report found that 80% of deaths from NCDs occur in middle-or low-income countries. Sub-Saharan Africa is still an exception, but WHO expects NCDs to surpass all other causes of death there, too, by 2020. The epidemic's spread to the developing world, Chan and other experts say, has been too long overlooked.

That's about to change. In September, the United Nations will hold a special high-level meeting to address the global NCD epidemic. It's only the second time the U.N. has convened a meeting on a health issue, HIV/AIDS being the first. Heeding strident calls from WHO, the U.N. will implore heads of state to tackle the risk factors for NCDs—and funders to open their wallets—but it may be a tough sell.

One of the biggest challenges may be convincing often cash-strapped health ministries to add NCDs to their priority lists. Donors and the broader global health community tend to see preventable infectious diseases and maternal and child health as more urgent problems, says Rachel Nugent, a development economist and researcher at the University of Washington, Seattle, so it's hard to imagine there's enough money to go around.

“When I'm asked to talk to global health groups, the first question is always ‘You don't mean we should do NCDs before we've cured AIDS?’” Nugent says. And without question, the image of an obese middle-aged woman on dialysis simply does not evoke the sympathy, or the outpouring of dollars, of a child feverish with malaria or a grandmother dying of cholera. The worldwide rally around HIV/AIDS, a single disease with a known cause and proven prevention strategies, is unlikely to happen for a collection of unrelated diseases with various causes that even experts cannot agree on.

Despite massive health budgets and efforts to promote healthy lifestyles, fighting NCDs has proved to be a losing battle in wealthy countries. In low- and middle-income countries, where 80% of NCD deaths now occur, it's clear that the same strategies will be even less effective. Furthermore, researchers have little data about which particular NCDs plague the populations of many struggling countries—and why.

Too many lists

Undeterred, WHO an noun ced in April that it had identified four major risk factors for chronic disease: tobacco, physical inactivity, alcohol abuse, and poor diets. Governments, it recommended, should set these four as priorities when allocating their limited health resources for NCDs. Catalyzed by the unexpected attention, numerous other groups and advocacy organizations have crafted their own lists of “best buys,” most of which tend to dovetail with WHO's list. But priorities such as breast cancer screening, HPV vaccination, and—controversially absent from the U.N. agenda—mental health also appear frequently. “There are too many lists out there,” says Nugent, who thinks policymakers could easily be overwhelmed.

Alan Lopez, a global health expert at the University of Queensland in Herston, Australia, agrees. “Countries can't be asked to monitor 200 things, because then they'll monitor nothing,” he says. Indeed, ministries of health in many countries are understaffed, causing these countries to lag in gathering and reporting figures on their NCD rates.

Nugent stops short of saying that the public health world is unprepared for a concerted focus on chronic diseases. “It's never premature to pay greater attention to NCDs,” she says. But she worries about the “off-the-shelf” solutions, such as smoking bans, that many are recommending. “You have to understand both what the evidence says and what's politically possible,” she says, no matter how scientifically sound these “best buys” may be. For instance, although heavy taxation and laws prohibiting advertising have effectively reduced smoking in Western countries, pushing these strategies elsewhere may be naïve. Governments such as China's, which own the tobacco industry, are unlikely to accede to this demand, and forcing fast food companies to cut the amount of salt in their food fails to curb the high salt content of traditional Mediterranean diets.

“It's one thing for organizations to publicize what countries should be doing, but on the ground, there are hard choices to make with limited resources,” says epidemiologist Bridget Kelly of the National Academies' Institute of Medicine in Washington, D.C.

Double whammy

For the poorest countries, struggling with HIV/AIDS, tuberculosis, and malaria, the risk factors brought on by Western lifestyles have added to their burden of disease. Gene Bukhman, director of Harvard Medical School's Program in Global Non-Communicable Disease and Social Change and a cardiologist with the nonprofit Partners in Health, both in Boston, calls poor countries' NCD rates a “long-tail distribution”: Although each chronic disease affects a very small percentage of people, they add up to a large percentage. But in truth, infectious diseases still cause more deaths than any chronic disease. Bukhman hopes the U.N. meeting will show donors and policymakers that the same poor populations that deal with infectious disease are now doubly strained.

Bukhman is concerned that by lumping NCDs together and focusing on specific risk factors that affect large populations, “the poorest populations could become even more marginalized.” Often, the NCDs of the poorest are not those that have WHO so concerned, and neither are their risk factors. Diabetes is the result of starvation, not obesity; rheumatic heart disease, not coronary, kills teenagers in the “bottom billion”; and children die of Burkitt lymphoma, a cancer entirely treatable in wealthy countries.

No one advocates that other countries adopt the U.S health care system, which in 2003 spent $300 billion, or about$1000 per capita, on cardiovascular disease alone. Equivalent care for Ghana, whose GDP per capita is about \$1600, is unthinkable.

Chronic disease advocates probably can't expect much new money in the face of the global economic crisis, Kelly says: “It's unlikely there will be a Global Fund for NCDs.” But those researchers and health workers on the ground say they're not asking for much. Many envision a comprehensive health system that piggybacks on existing funds for infectious disease and serves the patients who suffer from both.

This kind of integrated health care, Bukhman says, is a crucial investment—and cheaper than wealthy countries may think. In Rwanda, Partners in Health has had success building a hospital infrastructure where patients coming in for malaria treatment, for instance, can get their blood sugar checked as well. Specialist doctors are scarce in the developing world, but nurses and pharmacists can monitor blood pressure and hand out over-the-counter drugs such as the inexpensive “polypill”: a concoction of several generic heart medications in a single pill that is currently in clinical trials. But for this piggyback approach to work, says Alafia Samuels, a chronic disease consultant and lecturer at the University of the West Indies in Cave Hill, Barbados, “we cannot be disease-focused. We have to be patient-focused. We cannot cure [a patient's] HIV and then send them off to die of diabetes.”

Whether the world is prepared for this epidemic, Bukhman says it can no longer avoid addressing it. “Otherwise,” he says, “we'll look back in 20 years and say, ‘This is horrible, this 8-year-old kid died because they didn't have insulin because they happened to be born in Mali.’”