Overview
A landmark longitudinal study published in JAMA Health Forum followed 463,396 adolescents ages 13-17 through age 26. Past-year cannabis use during adolescence was associated with a doubled risk of developing psychotic and bipolar disorders, plus elevated risks for depression and anxiety. Cannabis use preceded psychiatric diagnoses by an average of 1.7-2.3 years. Conducted by Kaiser Permanente, UCSF, and USC researchers using electronic health records from 2016-2023. With THC potency in flower exceeding 20% and concentrates far higher, the study underscores the urgency for youth-focused prevention regardless of legalization status.
Clinical Perspective
THE JAMA STUDY: 460,000 TEENS AND THE PSYCHOSIS QUESTION
A landmark JAMA Health Forum study followed 463,396 adolescents ages 13-26. Cannabis use doubled psychosis and bipolar risk, preceded diagnoses by 1.7-2.3 years.
The massive cohort, clinical health record data, and high-potency era timing make this different from previous research. As a clinician, this reinforces that adolescent brains are uniquely vulnerable. Legalization advocates should lead the youth prevention conversation—not resist it. Acknowledging risk doesn’t undermine reform. It strengthens it.
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