Impact of non-medical cannabis legalization with market restrictions on health service use and incident cases of psychotic disorder in Ontario, Canada.
Kelly K. Anderson, Rebecca Rodrigues, Britney Le, Maliha Mamun, Suzanne Archie, Jordan Edwards, Tara Elton-Marshall, Jason Gilliland, Daniel Thomas Myran, Lena Palaniyappan, Christopher M Perlman, Jamie A Seabrook, Robin Murray, Salimah Z Shariff
The International journal on drug policy January 2024 DOI: 10.1016/j.drugpo.2023.104285 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Cross-sectional interrupted time-series analysis Peer reviewed |
|---|---|
| Population | People aged 14 to 60 years in Ontario, Canada, identified through linked population-based health administrative data |
| Duration | January 2014 to March 2020 observation window; 17-month post-legalization period |
| Topics | Cannabis |
| Keywords | Epidemiology Mental health services Psychotic disorders Public mental health |
| Key findings | The authors found no evidence of increases in psychosis-related health service use or incident psychotic disorder cases in the 17 months after non-medical cannabis legalization under tight market restrictions. They did find clear increasing trends in health service use and incident substance-induced psychotic disorders across the full 2014-2020 observation window. They caution that longer follow-up including commercial market expansion is needed before concluding legalization had no effect. |
Abstract
Cannabis is a risk factor in the onset and persistence of psychotic disorders. There is concern that non-medical cannabis legalization in Canada may have population-level impacts on psychotic disorders. We sought to examine changes in health service use and incident cases of psychotic disorder following cannabis legalization, during a period of tight restrictions on retail stores and product types. We conducted a cross-sectional interrupted time-series analysis using linked population-based health administrative data from Ontario (Canada) from January 2014 to March 2020. We identified psychosis-related outpatient visits, emergency department visits, hospitalizations, and inpatient length of stay, as well as incident cases of psychotic disorders, among people aged 14 to 60 years. We did not find evidence of increases in health service use or incident cases of psychotic disorders over the short-term (17 month) period following cannabis legalization. However, we found clear increasing trends in health service use and incident cases of substance-induced psychotic disorders over the entire observation window (2014-2020). Our findings suggest that the initial period of tight market restriction following legalization of non-medical cannabis was not associated with an increase in health service use or frequency of psychotic disorders. A longer post-legalization observation period, which includes expansion of the commercial cannabis market, is needed to fully understand the population-level impacts of non-medical cannabis legalization; thus, it would be premature to conclude that the legalization of non-medical cannabis did not lead to increases in health service use and incident cases of psychotic disorder.
Comparable studies
Other cross-sectional and survey studies on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Cannabis use before age 15 and subsequent executive functioning 104 chronic cannabis users (49 early-onset before age 15, 55 late-onset after age 15)... | 2011 | Observational cross-sectional study | n = 148 |
| Patterns of simultaneous polysubstance use in drug using university students Drug-using university students | 2006 | Cross-sectional survey | n = 149 |
| Persisting Reductions in Cannabis, Opioid, and Stimulant Misuse After Naturalistic Psychedelic Use: An Online Survey Online survey respondents | 2020 | Cross-sectional survey | |
| User perceptions of the benefits and harms of hallucinogenic drug use: A web-based questionnaire study Users of hallucinogenic drugs who completed a web-based questionnaire | 2010 | Cross-sectional survey | n = 600 |
| Illicit Use of LSD or Psilocybin, but not MDMA or Nonpsychedelic Drugs, is Associated with Mystical Experiences in a Dose-Dependent Manner Adults recruited from the MAPS website and newsletter, most reporting use of various... | 2012 | Cross-sectional survey | n = 337 |
Citations in the library
Cited by 3
- Emergency department use by individuals with and without psychosis after state-level cannabis legalization and commercialization Nature Mental Health June 19, 2026
- Changes in Incident Schizophrenia Diagnoses Associated With Cannabis Use Disorder After Cannabis Legalization JAMA Network Open February 1, 2025
- [Impact of the legalization of recreational cannabis on the risk of psychosis: A systematic review of the literature]. L'Encephale September 1, 2024
Cites 10
- 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
- State Cannabis Legalization and Psychosis-Related Health Care Utilization JAMA Network Open January 25, 2023
- Associations Between Canada's Cannabis Legalization and Emergency Department Presentations for Transient Cannabis-Induced Psychosis and Schizophrenia Conditions: Ontario and Alberta, 2015–2019 The Canadian Journal of Psychiatry August 1, 2022
- Impact of cannabis legalization on healthcare utilization for psychosis and schizophrenia in Colorado International Journal of Drug Policy April 13, 2022
- Geographical variation in hospitalization for psychosis associated with cannabis use and cannabis legalization in the United States Psychiatry Research 2022
and 5 more in the library