The cognitive effects of adolescent cannabis use

30 Oct

A paper, given at a meeting of the European College of Neuropsychopharmacology in Berlin reports:

“occasional adolescent cannabis use does not lead to poorer educational and intellectual performance, but that heavy cannabis use is associated with slightly poorer exam results at age 16.”

You can read the press release here. The main points:

“Cannabis use appeared to be associated with decreased intellectual performance. Cannabis use was, however, highly correlated with other risky behaviours such as alcohol, cigarette and other drug use. When the researchers took these other behaviours into account, they found there was no relationship between cannabis use and lower IQ at age 15.
Heavier cannabis users (at least 50 times by age 15) however, did show marginally impaired educational abilities. These children tended to have poorer exam results (3% lower) on compulsory school exams taken at age 16, even after adjusting for childhood educational performance, as well as alcohol, cigarette and other drug use.”

A pdf of the presentation can be found here. Note that this is not a claim that cannabis use is safe, only that occasional use may not have negative effects on cognition, heavier use was found to be “linked to marginally worse educational performance.” The authors suggest that cannabis use may be a proxy for risky lifestyle:

 “The pattern of attenuation suggests rather than a specific effect of cannabis on IQ and education, any substance use at a young age, and the ‘risky’ lifestyle such behaviours reveal, are related to poorer outcomes.”


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