Cognition and long-term use of ganja (Cannabis)

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Science  24 Jul 1981:
Vol. 213, Issue 4506, pp. 465-466
DOI: 10.1126/science.6972600


Neuropsychological variables and urine cannabinoid metabolites were evaluated in ten subjects born, raised, and educated in the United States and having histories of heavy or prolonged use of cannabis. No impairment of cognitive function was found. Cannabinoid metabolites in excess of 50 nanograms per milliliter were present in the ten urine samples. The tetrahydrocannabinol content of cannabis exceeded 8.0%.