A study published last week in JAMA Psychiatry found that marijuana use by people with psychosis increased nearly 10% after marijuana legalization. This is a striking finding at the intersection of public health and public safety, linking legalization to increased use among those most at risk. It reinforces more than a decade of evidence showing that legalization lowers risk perception and drives higher consumption. Put simply: marijuana can cause psychosis — and psychosis endangers us all.

The JAMA research points out that the segment of the population most psychologically vulnerable to marijuana use — both in using it and reacting to it — is also the most vulnerable to marijuana legalization. Yet, despite these findings, pro-marijuana activists continue to press for federal legalization. Major shifts in state policy began in the Nineties with the rise of “medical” marijuana, as the industry persuaded much of the public and many lawmakers that the drug was not only harmless but beneficial. That false narrative has since fostered a culture of denial among the stoner class, who still refuse to acknowledge the growing body of research linking marijuana to serious health risks.

“Big Marijuana” built its campaign for liberalization on a foundation of misinformation about the drug’s harms, using that narrative to push through ballot measures and legislation for recreational use throughout the 2010s. But what began as a wave of victories in states such as Colorado and California has since stalled: marijuana legalization has been defeated in seven of the last 10 state initiatives.

The tide is turning because the public is beginning to catch on. In a recent Gallup poll between 2022 and 2024, there was a 10-point reduction in the number of Americans who thought marijuana had a positive effect on those who use it (53% to 43%).

This drop in support for legalization likely reflects a growing public recognition of the drug’s harms. Legalization and commercialization have normalized use, and vulnerable populations are visibly paying the price. Advocates once promised that legalization would pose no threat to public health, yet both new research and lived experience tell a different story. Study after study shows that increased marijuana use, beginning in adolescence or later, makes it far more likely that someone will develop schizophrenia or a form of psychosis.

Those experiencing psychological distress often turn to marijuana for relief, encouraged by marketing that downplays its risks. The industry has little incentive to be transparent, especially about the dangers of heavy use. Without stronger accountability measures — such as clear health warnings and potency limits in legal states — that is unlikely to change.

Policymakers should treat marijuana as a serious public-health issue, not a cultural symbol. That means stronger regulation where it is legal, honest messaging, and a willingness to confront the uncomfortable truth that legalization has consequences. It’s time to act on what the data clearly shows.

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Kevin Sabet, a former three-time White House senior drug-policy adviser, is president of Smart Approaches to Marijuana.

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