Cannabis Legalization and Rising Rates of Psychosis
A February 2025 study in JAMA Network Open found that regions following cannabis legalization saw measurable increases in schizophrenia and psychosis diagnoses, particularly among young people and heavy users. The link between high-potency cannabis and psychotic disorders is one of the most replicated findings in modern psychiatric research — and modern legal markets have made potency dramatically higher than it was even ten years ago.
The risk is not evenly distributed: it concentrates in people who use daily, start in adolescence, or have a family history of psychosis. For those users, the relative-risk increase is multiples higher than for occasional adults.
This page is a draft. The full writeup will cover the absolute-risk numbers, the dose-response curve, and what the evidence says about whether quitting reverses risk.