In a large longitudinal study, daily cannabis use was associated with a 4-fold increased risk of developing suicidal thoughts in men, while suicidal thoughts predicted new cannabis use in women, revealing sex-specific directional relationships.
Read this if you use cannabis and have experienced suicidal thoughts, or if you work in mental health and want to understand sex-specific risk patterns.
Daily cannabis use was associated with 4.28x increased risk of developing suicidal thoughts in men.
What the researchers found
Using data from over 30,000 participants followed over 3 years, researchers found strikingly different patterns between men and women in the cannabis-suicidality relationship.
In men, cannabis use predicted the development of new suicidal ideation. Any cannabis use nearly doubled the risk (AOR = 1.91), and daily use increased the risk more than 4-fold (AOR = 4.28). This association was not found in women.
The direction reversed for women: baseline suicidal ideation predicted the initiation of cannabis use (AOR = 2.34). Women who were already experiencing suicidal thoughts were more likely to start using cannabis, while this pattern was not found in men.
Neither direction showed a significant association with actual suicide attempts in either sex.
Why it matters
This is one of the first studies to examine sex differences in the cannabis-suicidality relationship bidirectionally. The finding that the direction of the relationship is opposite in men and women has important clinical implications: in men, cannabis use may be a risk factor for developing suicidal thoughts, while in women, suicidal thoughts may drive cannabis use as a form of self-medication.
The numbers in context
Men: any cannabis use AOR = 1.91 (1.02-3.56) for suicidality. Daily use AOR = 4.28 (1.32-13.82). Women: baseline suicidality AOR = 2.34 (1.42-3.87) for cannabis initiation. Over 30,000 participants followed for 3 years.
How the study worked
Longitudinal population-based study using Waves 1 and 2 of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). Bidirectional analyses were conducted separately by sex. Cannabis users (n=963) were compared with non-users (n=30,586), and suicidal individuals (n=1,805) were compared with non-suicidal individuals (n=25,729). Multivariate logistic regression controlled for multiple covariates.
What this study cannot tell us
Suicidality was assessed only in individuals who reported depressed mood or anhedonia, potentially missing cases in non-depressed individuals. The wide confidence intervals for daily cannabis use in men (1.32-13.82) reflect relatively few daily users with suicidality outcomes. Observational data cannot prove causation even with longitudinal design. Self-reported cannabis use may be underreported.
How to read the evidence
Strong evidence from a large, nationally representative longitudinal study with bidirectional analysis and appropriate statistical controls.
When this study was published
Published in 2016 using NESARC data. The sex-specific nature of the cannabis-suicidality relationship continues to be studied.
The bigger picture
The relationship between cannabis and mental health is often discussed as a simple cause-and-effect. This study demonstrates that the direction of causality may depend on sex, with cannabis potentially worsening mental health in men while women may turn to cannabis as a response to pre-existing mental health difficulties. This has implications for how clinicians screen and intervene.
Questions still open
- What biological or psychosocial mechanisms explain the sex difference? Does treating depression or suicidality in women reduce their likelihood of initiating cannabis use? Would the male association hold after controlling for other substance use more thoroughly?
Common questions
Does cannabis cause suicidal thoughts?
Why is the relationship different for men and women?
Read the original research
The association between cannabis use and suicidality among men and women: A population-based longitudinal study.
Journal of affective disorders, 205, 216-224
Citation
Shalit, Nadav; Shoval, Gal; Shlosberg, Dan; Feingold, Daniel; Lev-Ran, Shaul. (2016). The association between cannabis use and suicidality among men and women: A population-based longitudinal study.. Journal of affective disorders, 205, 216-224. https://doi.org/10.1016/j.jad.2016.07.010
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