Adolescent Cannabis Use and Brain Structure in Young Adulthood

Cannabis is the most commonly used illicit substance in the world. Grey matter cortical thickness in young adulthood was compared in a sample of over 500 male participants from the ALSPAC prospective longitudinal cohort study based their cannabis use status (Never, Early User, Late User) at age 21, and their cumulative cannabis use at age 16.5. Thickness did not differ between early late and never users, however among early users those with the largest cumulative use had a thinner cortex relative to those who used the least after controlling for biological, environmental, behavioural, and substance use confounders in a GLM. Using CB1 receptor gene expression data from the online Allen Human Brain Atlas (restricted to the left hemisphere), we determined the heaviest users exhibited a thinner cortex in regions with the highest and lowest densities of CB1 receptors; psychosocial, pharmacological, and hormonal mechanisms could potentially explain our findings.M.A