cannabis use & neuropsychological decline

Meier et al. (2012) assessed cognitive functioning at ages 13 and 38. Cannabis use was assessed at ages 18, 21, 26, 32, and 38.

“Persistent cannabis use was associated with neuropsychological decline broadly across domains of functioning [...]. Informants also reported noticing more cognitive problems for persistent cannabis users. Impairment was concentrated among adolescent-onset cannabis users, with more persistent use associated with greater decline. Further, cessation of cannabis use did not fully restore neuropsychological functioning among adolescent-onset cannabis users. Further, cessation of cannabis use did not fully restore neuropsychological functioning among adolescent-onset cannabis users. Findings are suggestive of a neurotoxic effect of cannabis on the adolescent brain and highlight the importance of prevention and policy efforts targeting adolescents.”