Study: Youth Cannabis Exposure Not Associated with Residual Cognitive Deficits

Berlin, Germany: Adolescents with moderate exposure to cannabis show no decline in neurocognitive skills compared to controls, according to longitudinal data published in the journal Cognitive Development.

An international team of investigators from Canada, France, Germany, Ireland, and the United States examined the relationship between adolescent marijuana use at age 14 and cognitive performance at age 19. Researchers reported that those subjects with light-to-moderate cannabis use after age 15 demonstrated little difference in neurocognitive performance compared to non-users.

Authors determined: “Our data suggests that decision-making is not impaired when cannabis is used in moderation, and onset of use occurs after the age of 15. … [A]fter controlling for confounders, we found no evidence of effects of cannabis on the remaining neurocognitive variables such as attention, working memory, short-term memory and risk-taking.”

They concluded, “In summary, we find no evidence to support the presumption that cannabis consumption leads to a decline in neurocognitive ability.”

Full text of the study, “Residual effects of cannabis use on neuropsychological functioning,” appears in Cognitive Decline. Additional information is available from NORML’s fact sheet, “Marijuana Exposure and Cognitive Performance.”