More Permissive Cannabis Policies Were Linked to Higher Cannabis and Opioid Involvement in Suicide Deaths
Analysis of nearly 69,000 suicide and undetermined-intent deaths found that more liberal cannabis policies were associated with higher rates of both cannabis and opioid involvement in these deaths.
Quick Facts
What This Study Found
Cannabis involvement in death was associated with increased odds of opioid involvement (AOR=1.29). More restrictive cannabis policies were associated with reduced odds of both cannabis involvement (AOR=0.87 per 10% policy increase) and opioid involvement (AOR=0.88 per 10% policy increase) in suicide and undetermined-intent deaths.
Key Numbers
68,924 decedents from suicide and undetermined intent deaths (2003-2018). Cannabis involvement increased odds of opioid involvement: AOR=1.29 (95% CI: 1.22-1.37). A 10% more restrictive cannabis policy: AOR=0.87 for cannabis involvement, AOR=0.88 for opioid involvement.
How They Did This
Repeated cross-sectional study using restricted-access National Violent Death Reporting System data (2003-2018) linked to the Cannabis Policy Scale measuring state-level cannabis policy permissiveness. Mixed effects logistic regression analyzed 68,924 decedents across states that expanded from 7 to 41 during the study period.
Why This Research Matters
This challenges the hypothesis that liberalizing cannabis policies might reduce opioid deaths through substitution. Instead, the data suggest that more permissive cannabis environments are associated with higher involvement of both substances in deaths of despair.
The Bigger Picture
The relationship between cannabis policy, cannabis use, opioid use, and deaths of despair is more complex than simple substitution theories suggest. These findings add important data to the ongoing policy debate about cannabis legalization and public health.
What This Study Doesn't Tell Us
Observational design cannot prove cannabis policies cause these deaths. Not all states participated throughout the study period. Toxicology testing practices vary across jurisdictions. Cannabis involvement does not mean cannabis caused the death.
Questions This Raises
- ?Does cannabis use directly contribute to suicide risk, or does it mark a population already at higher risk?
- ?Would the relationship between cannabis policy and opioid involvement hold in more recent data after wider legalization?
Trust & Context
- Key Stat:
- More restrictive cannabis policies were linked to 12-13% lower odds of cannabis and opioid involvement in suicide deaths
- Evidence Grade:
- Moderate: large dataset with validated policy scale and adjusted models, but observational design and varying state participation limit causal inference.
- Study Age:
- 2025 study using 2003-2018 data.
- Original Title:
- Cannabis Policies, Cannabis, and Opioids in Suicide and Undetermined Intent Death.
- Published In:
- American journal of preventive medicine, 68(3), 475-484 (2025)
- Authors:
- Lira, Marlene C(4), Pacula, Rosalie Liccardo(18), Smart, Rosanna(5), Pessar, Seema Choksy, Blanchette, Jason, Naimi, Timothy S
- Database ID:
- RTHC-06959
Evidence Hierarchy
A snapshot of a population at one point in time.
What do these levels mean? →Frequently Asked Questions
Does this mean cannabis legalization increases suicides?
The study found an association between more permissive policies and higher substance involvement in these deaths, but cannot prove causation. Many factors influence suicide rates beyond cannabis policy.
Were cannabis and opioids found together in these deaths?
Yes. Cannabis involvement was associated with 29% higher odds of opioid involvement, suggesting co-use patterns rather than substitution in this population.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-06959APA
Lira, Marlene C; Pacula, Rosalie Liccardo; Smart, Rosanna; Pessar, Seema Choksy; Blanchette, Jason; Naimi, Timothy S. (2025). Cannabis Policies, Cannabis, and Opioids in Suicide and Undetermined Intent Death.. American journal of preventive medicine, 68(3), 475-484. https://doi.org/10.1016/j.amepre.2024.11.009
MLA
Lira, Marlene C, et al. "Cannabis Policies, Cannabis, and Opioids in Suicide and Undetermined Intent Death.." American journal of preventive medicine, 2025. https://doi.org/10.1016/j.amepre.2024.11.009
RethinkTHC
RethinkTHC Research Database. "Cannabis Policies, Cannabis, and Opioids in Suicide and Unde..." RTHC-06959. Retrieved from https://rethinkthc.com/research/lira-2025-cannabis-policies-cannabis-and
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.