Changes in psychosis-related emergency department and hospitalization rates among youth following cannabis legalization in Colorado
Spruha Joshi, Kyle M. Snyder, Christian Thurstone, Bianca D. Rivera, J. Feldman, Magdalena Cerdá, Noa Krawczyk
Drug and Alcohol Dependence May 1, 2025 DOI: 10.1016/j.drugalcdep.2025.112719 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational study using interrupted time series analysis Peer reviewed |
|---|---|
| Population | Youth aged 10-29 with psychosis-related emergency department and hospital visits at Denver Health, 2005-2020; predominantly male (68%), white (53%), and Medicaid recipients (59%) |
| Duration | 2005-2020 |
| Topics | Cannabis |
| Key findings | Monthly average psychosis hospitalization rates among youth rose from 21.9 per 100,000 before Colorado's Ogden Memo to 28.0 after it and 32.3 after recreational legalization, while psychosis hospitalizations involving cannabis use disorder rose from 2.0 to 3.4 to 8.5 per 100,000. Interrupted time series modeling showed a significant acceleration in the trend for cannabis-use-disorder psychosis hospitalizations after recreational legalization, with the change in average monthly rate increasing from 0.02 to 0.11 per 100,000. The authors suggest these findings indicate a need for public health planning. |
Abstract
An increasing number of U.S. states have legalized cannabis, but the effect on adolescent and young adult psychosis-related hospitalizations remains under-studied. Using data from Denver Health between 2005–2020, we examined associations between implementation of the Ogden Memo (expanding use of medical cannabis in Colorado, October 2009) and Amendment 64 (legalizing adult-use cannabis in Colorado, November 2012) and trends in psychosis-related emergency department and hospital visits with and without cannabis use disorder (CUD) among youth aged 10–29. Patients with psychosis hospitalizations were predominately male (68%), white (53%), and Medicaid recipients (59%). Significant increases (p<0.05) were observed in the monthly average rate of psychosis hospitalizations pre-Ogden memo (21.9 per 100,000), post-Ogden memo and pre-legalization (28.0 per 100,000) and post-legalization (32.3 per 100,000). Similarly, significant increases (p<0.05) were observed in the monthly average rate of psychosis hospitalizations involving CUD pre-Ogden memo (2.0 per 100,000), post-Ogden memo and pre-legalization (3.4 per 100,000), and post-legalization (8.5 per 100,000). Interrupted time series modeling found a significant difference in the trends for psychosis hospitalizations involving CUD following recreational legalization (change in average monthly rate went from 0.02/100,000 (95% CI −0.02, 0.06) to 0.11/100,000 (95% CI 0.09, 0.13), (difference (0.09 (95%CI 0.05, 0.14)). Findings suggest an increase in overall hospital encounters for psychosis among youth after the legalization of recreational cannabis. Given the adoption of increasingly permissive cannabis laws, there is a need to plan effective public health responses that could mitigate unintended consequences related to cannabis use.
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
Cited by 3
- The rising tide of drug-induced psychosis Neuropsychiatrie August 20, 2025
- Cannabis, psychosis, and violence: case reports and comprehensive evidence review Frontiers in Psychiatry July 21, 2026
- Emergency department use by individuals with and without psychosis after state-level cannabis legalization and commercialization Nature Mental Health June 19, 2026
Cites 10
- High-potency cannabis and the risk of psychosis The British Journal of Psychiatry November 30, 2009
- Cannabis Use during Adolescent Development: Susceptibility to Psychiatric Illness Frontiers in Psychiatry 2013
- The Association Between Cannabis Use and Schizophrenia: Causative or Curative? A Systematic Review Cureus July 21, 2020
- 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
- Are we any closer to identifying a causal relationship between cannabis and psychosis? Current Opinion in Psychology April 1, 2021
and 5 more in the library