People with Psychosis Show Large Increases in Cannabis Use After Legalization | Research

The takeaway

Individuals with a history of psychosis increased their cannabis use by nearly 10 percentage points after recreational legalization — a larger increase than the general population — raising serious concerns about legalization's impact on mental health.

Psychiatrists, mental health policy advocates, cannabis regulators, legislators designing legalization frameworks, and individuals with psychotic conditions.

What the researchers found

Individuals with psychosis in recreational cannabis legalization states increased 30-day cannabis use by 9.53 percentage points (95% CI=3.05-16.00, p=0.004), with sensitivity analyses showing significant increases after retail outlets opened but not before, and no changes in higher-frequency use.

Why it matters

Cannabis can worsen psychosis outcomes, increase hospitalizations, and complicate treatment — yet this vulnerable population shows the largest increase in use after legalization, suggesting current policies inadequately protect high-risk individuals.

The numbers in context

N=1,856 with psychosis; 7,465 responses; mean age 36.6; 31.8% baseline 30-day use; 9.53 pp increase post-RCL (p=0.004); significant after retail opening; no change in higher-frequency use; larger than general population estimates

How the study worked

Difference-in-differences analysis using 2014-2022 Population Assessment of Tobacco and Health longitudinal data from 1,856 adults with lifetime psychosis history (7,465 responses), comparing cannabis use changes in RCL vs. control states.

What this study cannot tell us

Self-reported psychosis history may include misclassification; cannot determine what types of cannabis were used; 30-day use measure doesn't capture daily patterns; sample size limits subgroup analysis; cannot determine if increased use worsened outcomes.

How to read the evidence

Rigorous quasi-experimental design with nationally representative longitudinal data and consistent sensitivity analyses, providing strong evidence for this concerning association.

When this study was published

Published 2026 in JAMA Psychiatry; covers 2014-2022.

The bigger picture

This finding challenges the assumption that legalization primarily affects casual users — the largest per-population increase is among those most vulnerable to cannabis harms, demanding targeted policy responses.

Questions still open

Should cannabis regulations include specific protections for people with psychotic disorders? Would health warnings about psychosis risk reduce use in this group? Does the type of cannabis product matter for psychosis outcomes?

Common questions

Does cannabis legalization affect people with mental illness?

Yes — this study found that people with a history of psychosis increased their cannabis use by nearly 10 percentage points after legalization, more than the general population, with the increase tied specifically to when retail stores opened.

Why is cannabis use concerning for people with psychosis?

Cannabis can worsen psychotic symptoms, increase relapse rates, and lead to more hospitalizations. The fact that this vulnerable population shows the largest legalization-related increase in use suggests policies need specific protections for high-risk groups.

Read the original research

Cannabis Use Among Individuals With Psychosis After State-Level Commercial Cannabis Legalization.

JAMA psychiatry, 83(1), 74-77

View on PubMed ↗Publisher’s paper ↗

Citation

Hyatt, Andrew S; Flores, Michael William; Johnson, Julie; Bien-Aime, Danta; Evins, A Eden; Öngür, Dost; Cook, Benjamin Lê. (2026). Cannabis Use Among Individuals With Psychosis After State-Level Commercial Cannabis Legalization.. JAMA psychiatry, 83(1), 74-77. https://doi.org/10.1001/jamapsychiatry.2025.2539