Cannabis Use Linked to Suicide Attempts and Death in People With Schizophrenia
A meta-analysis of 29 studies found cannabis use in schizophrenia was associated with 40% higher odds of suicide attempts and 21% higher risk of suicide death.
Quick Facts
What This Study Found
Across 29 studies (36 samples), cannabis use was associated with 40% higher odds of attempted suicide (OR=1.40, 95% CI: 1.16-1.68) and 21% higher risk of suicide death (HR=1.21, 95% CI: 1.04-1.40). Cannabis was not significantly associated with suicidal ideation alone.
Key Numbers
29 studies, 36 samples. Attempted suicide OR=1.40 (95% CI: 1.16-1.68). Suicide death HR=1.21 (95% CI: 1.04-1.40). Suicidal ideation: not significant. Heterogeneity moderate for attempts (I2=39.6%).
How They Did This
Systematic review and meta-analysis of cross-sectional, case-control, and longitudinal studies from Medline, Embase, and PsycINFO through November 2024, using random effects models.
Why This Research Matters
Suicide is a leading cause of death in schizophrenia. Identifying cannabis use as a risk factor for suicide attempts and death provides an actionable target for clinical intervention.
The Bigger Picture
Cannabis is the most commonly used substance in schizophrenia. If it increases suicide risk by 20-40%, this has major implications for clinical management, especially given the already elevated baseline suicide risk in this population.
What This Study Doesn't Tell Us
Cannot establish causality from meta-analysis of observational studies. Cannabis use may be a marker for severity rather than a direct cause. Some subgroup analyses lost significance. Confounding by other substance use possible.
Questions This Raises
- ?Does reducing cannabis use lower suicide risk in schizophrenia?
- ?What mechanisms link cannabis to increased suicide risk?
- ?Should cannabis screening be part of suicide risk assessment in psychosis?
Trust & Context
- Key Stat:
- 40% higher suicide attempt odds with cannabis use in schizophrenia
- Evidence Grade:
- Large meta-analysis with comprehensive search and appropriate statistical methods, though underlying studies are observational.
- Study Age:
- 2025 meta-analysis with search through November 2024.
- Original Title:
- Cannabis use and suicide in people with a diagnosis of schizophrenia: a systematic review and meta-analysis of longitudinal, case control, and cross-sectional studies.
- Published In:
- Psychological medicine, 55, e79 (2025)
- Database ID:
- RTHC-07204
Evidence Hierarchy
Combines results from multiple studies to find an overall pattern.
What do these levels mean? →Frequently Asked Questions
Does cannabis increase suicide risk in people with schizophrenia?
This meta-analysis of 29 studies found cannabis use was associated with 40% higher odds of attempting suicide and 21% higher risk of dying by suicide in people with schizophrenia. However, the relationship with suicidal thoughts alone was not significant.
Should cannabis use be screened as part of suicide risk in psychosis?
These findings suggest yes. Cannabis use appears to be an independent risk factor for suicidal behavior in schizophrenia, making it a potentially modifiable target in suicide prevention efforts.
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Cite This Study
https://rethinkthc.com/research/RTHC-07204APA
Mulligan, Lee D; Varese, Filippo; Harris, Kamelia; Haddock, Gillian. (2025). Cannabis use and suicide in people with a diagnosis of schizophrenia: a systematic review and meta-analysis of longitudinal, case control, and cross-sectional studies.. Psychological medicine, 55, e79. https://doi.org/10.1017/S0033291725000236
MLA
Mulligan, Lee D, et al. "Cannabis use and suicide in people with a diagnosis of schizophrenia: a systematic review and meta-analysis of longitudinal, case control, and cross-sectional studies.." Psychological medicine, 2025. https://doi.org/10.1017/S0033291725000236
RethinkTHC
RethinkTHC Research Database. "Cannabis use and suicide in people with a diagnosis of schiz..." RTHC-07204. Retrieved from https://rethinkthc.com/research/mulligan-2025-cannabis-use-and-suicide
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.