How does cannabis affect the developing adolescent brain?

The adolescent brain is uniquely vulnerable to cannabis because the endocannabinoid system plays a critical role in brain development through approximately age 25. CB1 receptors are more densely expressed in the adolescent brain than the adult brain, and the ECS guides synaptic pruning, myelination, and the maturation of prefrontal-limbic circuits. Regular cannabis use during adolescence is associated with: reduced gray matter volume in the hippocampus and prefrontal cortex; impaired working memory, attention, and executive function; earlier onset of psychosis in genetically susceptible individuals; higher rates of cannabis use disorder (17% vs. 9% for adult-onset users); and lower educational attainment. A key question is whether these effects are permanent or reversible with abstinence — evidence suggests some but not full recovery after extended abstinence.