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May 18, 2026 – Accumulating research on cannabis use among teenagers suggests it may alter their brain’s structure in measurable ways. Findings reported in June 2021 in JAMA Psychiatry suggest that when teens use cannabis, it causes increased thinning of the cerebral cortex, the outermost layer of the brain, compared with those who don’t use it or use it less. The cortex is composed of gray matter that’s responsible for high-level thinking, which plays a role in learning, memory, problem-solving, emotions and consciousness. The study followed nearly 800 adolescents who had their brain imaged prior to using cannabis at an average age of 14, and then five years later after they reported having used the drug in varying amounts.
