Emergency department use by individuals with and without psychosis after state-level cannabis legalization and commercialization
A. Hyatt, M. Flores, Lindsay N. Overhage, Danta Bien-Aime, A. Evins, D. Öngür, Benjamin Le Cook
Nature Mental Health June 19, 2026 DOI: 10.1038/s44220-026-00673-x (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Longitudinal cohort study using difference-in-difference analysis Peer reviewed |
|---|---|
| Population | Individuals with psychosis compared with the general population without a history of psychosis, drawn from a nationally representative survey in the USA |
| Duration | 3 years of follow-up; data collection 2013–2022 |
| Topics | Cannabis |
| Key findings | The opening of cannabis retail outlets was associated with an increase in emergency department visits among individuals with psychosis (0.43 more visits per person per year) but not among those without a history of psychosis. The authors report this as early evidence and argue for policy collaboration to minimize harms among people with serious mental illness. |
Abstract
Recreational cannabis legalization and commercialization are expanding rapidly in the USA, with potential negative effects for individuals with psychotic disorders. Here, to assess potential health risks associated with the opening of cannabis retail outlets, we conducted a longitudinal cohort study using a nationally representative survey to evaluate trends in emergency department utilization among individuals with psychosis compared with the general population with 3 years of follow-up. Data collection occurred in 2013–2022. Utilizing difference-in-difference (DiD) methods, we found that the opening of cannabis retail outlets was associated with an overall increase in emergency department visits among individuals with psychosis in legalization states (DiD estimate of 0.43 more visits per-person per-year, 95% CI −0.014 to 0.85, P = 0.043) but not among those with no history of psychosis (DiD estimate −0.015, 95% CI −0.03 to 0.06, P = 0.54). Exploratory analyses found this change was driven by more emergency department utilization among individuals with psychosis and past-year cannabis use, and not among other subgroups. This provides early evidence that cannabis commercialization is associated with worsening health among individuals with psychosis, and indicates a need for researchers, regulators and policymakers to collaborate to develop policies to minimize harms of cannabis legalization and commercialization among individuals with serious mental illnesses. The opening of cannabis retail outlets in the USA was associated with an overall increase in emergency department visits among individuals with psychosis but not among those with no history of psychosis.
Comparable studies
Other observational and cohort studies on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| High-potency cannabis and the risk of psychosis People with first episode of psychosis and healthy controls from the local population | 2009 | Case-control study | n = 454 |
| Ayahuasca-Assisted Therapy for Addiction: Results from a Preliminary Observational Study in Canada Rural aboriginal population | 2013 | Observational study | |
| Impaired cognitive performance in drug free users of recreational ecstasy (MDMA) Otherwise healthy young people | 2000 | Observational | |
| Continued cannabis use and risk of incidence and persistence of psychotic symptoms: 10 year follow-up cohort study Individuals from the general population in Germany aged 14-24 at baseline | 2011 | Observational cohort | n = 1,923 |
| Cannabis-induced psychosis and subsequent schizophrenia-spectrum disorders: follow-up study of 535 incident cases Patients treated for cannabis-induced psychotic symptoms in Denmark between 1994 and... | 2005 | Observational cohort | n = 535 |
Citations in the library
Cites 13
- Association Between Continued Cannabis Use and Risk of Relapse in First-Episode Psychosis JAMA Psychiatry September 28, 2016
- Daily use of high-potency cannabis is associated with more positive symptoms in first-episode psychosis patients: the EU-GEI case–control study Psychological Medicine March 18, 2020
- Changes in psychosis-related emergency department and hospitalization rates among youth following cannabis legalization in Colorado Drug and Alcohol Dependence May 1, 2025
- Changes in Incident Schizophrenia Diagnoses Associated With Cannabis Use Disorder After Cannabis Legalization JAMA Network Open February 1, 2025
- A systematic evidence map of the association between cannabis use and psychosis-related outcomes across the psychosis continuum: An umbrella review of systematic reviews and meta-analyses. Psychiatry Research November 1, 2023
and 8 more in the library