More cannabis dispensaries in Colorado counties were linked to 24% more psychosis ER visits
After recreational cannabis legalization in Colorado, increasing dispensary density was associated with a 24% increase in psychosis-related ER visits, while schizophrenia visits showed no significant change.
Quick Facts
What This Study Found
As recreational dispensaries per 10,000 residents increased, psychosis ED visits increased 24% (IRR 1.24, 95% CI 1.02-1.49) while schizophrenia ED visits showed no significant change (IRR 0.95). Counties previously unexposed to medical dispensaries may have experienced larger increases.
Key Numbers
Psychosis ED visits: IRR 1.24 (significant). Schizophrenia ED visits: IRR 0.95 (not significant). Counties with low baseline medical exposure had lower psychosis increases than high-exposure counties (IRR 0.83).
How They Did This
Difference-in-difference analysis of Colorado Hospital Association county-level quarterly ED data from January 2013 to December 2018. Compared how new recreational dispensary exposure affected psychosis and schizophrenia ED visit rates across counties with different baseline medical dispensary exposure.
Why This Research Matters
This is one of the first studies to use a natural experiment design to examine whether cannabis dispensary access directly impacts psychosis-related healthcare utilization at the population level.
The Bigger Picture
The association between dispensary density and psychosis visits raises important questions for states and countries considering legalization, particularly regarding the mental health impact of increased cannabis availability.
What This Study Doesn't Tell Us
Observational, cannot prove causation. Administrative coding may not distinguish cannabis-induced psychosis from other causes. Dispensary density may correlate with other county-level factors. Short post-legalization period.
Questions This Raises
- ?Is it the number of dispensaries, the type of products available, or increased overall use driving psychosis visits?
- ?Why was schizophrenia not affected?
- ?Would the same pattern be seen in other legalized states?
Trust & Context
- Key Stat:
- 24% increase in psychosis ER visits with increasing dispensary density
- Evidence Grade:
- Moderate: natural experiment design with administrative data, but observational with potential confounders.
- Study Age:
- Published in 2022.
- Original Title:
- Impact of cannabis legalization on healthcare utilization for psychosis and schizophrenia in Colorado.
- Published In:
- The International journal on drug policy, 104, 103685 (2022)
- Authors:
- Wang, George Sam(15), Buttorff, Christine(4), Wilks, Asa(4), Schwam, Daniel, Tung, Gregory, Pacula, Rosalie Liccardo
- Database ID:
- RTHC-04289
Evidence Hierarchy
Looks back at existing records to find patterns.
What do these levels mean? →Frequently Asked Questions
Does this prove dispensaries cause psychosis?
No. It shows an association between dispensary density and psychosis-related ER visits. The increase could be driven by greater cannabis access, higher-potency products, more use, or increased willingness to seek emergency care.
Why did schizophrenia visits not increase?
The authors suggest psychosis ED visits may capture acute cannabis-related episodes more than chronic schizophrenia. Schizophrenia diagnoses tend to be established conditions less responsive to changes in cannabis access.
Did prior medical dispensary exposure matter?
Yes. Counties that already had medical dispensaries before recreational legalization appeared somewhat buffered from the increase, possibly because they had already absorbed some cannabis-related mental health impact.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-04289APA
Wang, George Sam; Buttorff, Christine; Wilks, Asa; Schwam, Daniel; Tung, Gregory; Pacula, Rosalie Liccardo. (2022). Impact of cannabis legalization on healthcare utilization for psychosis and schizophrenia in Colorado.. The International journal on drug policy, 104, 103685. https://doi.org/10.1016/j.drugpo.2022.103685
MLA
Wang, George Sam, et al. "Impact of cannabis legalization on healthcare utilization for psychosis and schizophrenia in Colorado.." The International journal on drug policy, 2022. https://doi.org/10.1016/j.drugpo.2022.103685
RethinkTHC
RethinkTHC Research Database. "Impact of cannabis legalization on healthcare utilization fo..." RTHC-04289. Retrieved from https://rethinkthc.com/research/wang-2022-impact-of-cannabis-legalization
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.