A systematic review of 22 cohort studies found no clear consensus on whether cannabis use is associated with suicidal ideation, attempts, or completed suicide, though some studies suggest greater intensity or earlier use strengthens the association.
Psychiatrists, suicide prevention professionals, cannabis users with mental health concerns, and policymakers.
22 cohort studies reviewed with no clear consensus
What the researchers found
Twenty-two cohort articles were identified with no clear consensus on the cannabis-suicide relationship, regardless of outcome type (ideation, attempt, or completion) or study quality. Studies that did find an association highlighted the endocannabinoid system and psychosocial context, with some showing that greater intensity or earlier onset of cannabis use strengthened the relationship.
Why it matters
With cannabis use increasing globally and suicide being a leading cause of death, understanding whether cannabis contributes to suicidal behavior has major public health implications, but the evidence remains frustratingly inconclusive.
The numbers in context
22 cohort studies identified. No consensus across studies. Studies finding an association suggest dose-response relationships (greater intensity or earlier onset = stronger association).
How the study worked
Systematic review of MEDLINE, Embase, PsycINFO, and LILACS databases plus supplementary search for cohort studies published through January 2020. No age restrictions. Studies assessed using the Newcastle-Ottawa scale for quality.
What this study cannot tell us
Heterogeneous definitions of "cannabis use" across studies. Varied and inconsistent outcome measures. Most studies did not control adequately for confounders. Self-reported cannabis use. Publication bias possible.
How to read the evidence
Systematic review with quality assessment, but the underlying evidence is heterogeneous and inconclusive.
When this study was published
Published in 2022 with searches through January 2020.
The bigger picture
The lack of consensus likely reflects the complexity of both cannabis use and suicidal behavior, involving shared risk factors like mental health conditions, trauma, and social disadvantage that are difficult to disentangle.
Questions still open
- Would standardized cannabis use definitions produce clearer results? Does cannabis affect suicide risk directly (via endocannabinoid system disruption) or indirectly (via depression, impulsivity)? Should suicide risk screening be standard for heavy cannabis users?
Common questions
Does cannabis use increase suicide risk?
Why is the evidence so unclear?
Read the original research
Association between cannabis use and suicidal behavior: A systematic review of cohort studies.
Psychiatry research, 312, 114555
Citation
Carvalho, João Victor; Souza, Lucca S; Moreira, Esdras Cabus. (2022). Association between cannabis use and suicidal behavior: A systematic review of cohort studies.. Psychiatry research, 312, 114555. https://doi.org/10.1016/j.psychres.2022.114555
Explore the wider topic
- LGBTQ+ and Cannabis: Higher Use Rates and Recovery
- Cannabis-Induced Psychosis: What It Is, Who's at Risk, and What to Do
- BetterHelp, Cerebral, and Online Therapy: Honest Review
- Quitting Weed with ADHD: Why It Is Harder and What Actually Helps
- Quitting Weed with Depression: What You Need to Know
- Quitting Weed with PTSD: A Practical Guide
- Self-Medicating with Weed: Why It Works Until It Doesn't
- Weed and OCD: Self-Medicating Intrusive Thoughts
- Weed and PTSD: What the Research Actually Shows
- Weed and Childhood Trauma: ACEs, Self-Medication, and the Path to Real Healing
- Weed and Suicidal Thoughts: What You Need to Know