Systematic review of 22 cohort studies finds no consensus on whether cannabis use causes suicidal behavior
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.
Quick Facts
What This Study 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.
Key Numbers
22 cohort studies identified. No consensus across studies. Studies finding an association suggest dose-response relationships (greater intensity or earlier onset = stronger association).
How They Did This
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.
Why This Research 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 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.
What This Study Doesn't 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.
Questions This Raises
- ?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?
Trust & Context
- Key Stat:
- 22 cohort studies reviewed with no clear consensus
- Evidence Grade:
- Systematic review with quality assessment, but the underlying evidence is heterogeneous and inconclusive.
- Study Age:
- Published in 2022 with searches through January 2020.
- Original Title:
- Association between cannabis use and suicidal behavior: A systematic review of cohort studies.
- Published In:
- Psychiatry research, 312, 114555 (2022)
- Database ID:
- RTHC-03746
Evidence Hierarchy
Analyzes all available research on a topic using a structured method.
What do these levels mean? →Frequently Asked Questions
Does cannabis use increase suicide risk?
Based on 22 cohort studies, there is no clear consensus. Some studies found associations, particularly for heavier or earlier-onset use, while others did not. The relationship is complex and confounded by shared risk factors like depression and social disadvantage.
Why is the evidence so unclear?
Studies used different definitions of cannabis use, different suicide-related outcomes, and varied in how well they controlled for other risk factors. The authors call for standardized definitions and better confounding control in future research.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-03746APA
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
MLA
Carvalho, João Victor, et al. "Association between cannabis use and suicidal behavior: A systematic review of cohort studies.." Psychiatry research, 2022. https://doi.org/10.1016/j.psychres.2022.114555
RethinkTHC
RethinkTHC Research Database. "Association between cannabis use and suicidal behavior: A sy..." RTHC-03746. Retrieved from https://rethinkthc.com/research/carvalho-2022-association-between-cannabis-use
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.