Frequent cannabis use linked to suicidal thoughts in males over 30-year follow-up
In a 30-year longitudinal study, intensive cannabis use (several times per week or more) was associated with increased suicidal ideation in males, but suicidal thoughts did not lead to increased cannabis use.
Quick Facts
What This Study Found
Using data from a 30-year birth cohort study, researchers examined the directional relationship between cannabis use and suicidal ideation. They found that intensive cannabis use, defined as several times per week or more, was associated with a higher rate of transitioning into suicidal ideation among males.
Importantly, the analysis tested the reverse direction as well: whether suicidal ideation led to cannabis use. No evidence supported this pathway for either males or females. The one-directional nature of the finding strengthens the case for a meaningful link between heavy cannabis use and suicidal thinking in males, though the study did not establish direct causation.
Key Numbers
The study followed a birth cohort for 30 years. Intensive cannabis use (several times per week or more) was associated with increased suicidal ideation in males. No reverse-direction effect was found for either sex.
How They Did This
This was a longitudinal analysis based on the Christchurch Health and Development Study, a 30-year follow-up of a birth cohort in New Zealand. Researchers used hazard rate models to examine both whether cannabis use predicted transitions into suicidal ideation and whether suicidal ideation predicted transitions into cannabis use.
Why This Research Matters
Suicide is the second leading cause of death among youth aged 10 to 24 globally. Understanding modifiable risk factors is critical. The directional finding that heavy cannabis use preceded suicidal ideation, rather than the reverse, contributes important evidence to the public health picture.
The Bigger Picture
This study is part of a growing body of evidence linking heavy cannabis use to mental health outcomes. The directional analysis adds strength beyond simple cross-sectional associations by showing that cannabis use preceded the outcome rather than following from it.
What This Study Doesn't Tell Us
The association was observed only in males, limiting generalizability. Even with longitudinal data and directional modeling, uncontrolled confounders could explain the relationship. The study defined "intensive" use broadly and did not assess cannabis potency or specific cannabinoid exposure.
Questions This Raises
- ?Why was the association observed only in males?
- ?Does cannabis potency or THC content modify this risk?
- ?What biological or psychological mechanisms might link heavy cannabis use to suicidal thinking?
Trust & Context
- Key Stat:
- Heavy cannabis use preceded suicidal ideation in males across 30 years of follow-up
- Evidence Grade:
- Thirty-year birth cohort study with directional analysis. Strong longitudinal design from a well-established cohort.
- Study Age:
- Published in 2013, based on data from the Christchurch Health and Development Study beginning in 1977.
- Original Title:
- Cannabis use and suicidal ideation.
- Published In:
- Journal of health economics, 32(3), 524-37 (2013)
- Authors:
- van Ours, Jan C, Williams, Jenny, Fergusson, David(2), Horwood, L John
- Database ID:
- RTHC-00746
Evidence Hierarchy
Follows a group of people over time to track how outcomes develop.
What do these levels mean? →Frequently Asked Questions
Does cannabis use cause suicidal thoughts?
This study found that intensive cannabis use (several times per week or more) was associated with transitioning into suicidal ideation in males, but it did not establish direct causation. The directional analysis showed that cannabis use preceded the outcome, not the reverse.
Was this finding the same for males and females?
No. The association between intensive cannabis use and suicidal ideation was found only in males. No evidence of this relationship was observed in females in this study.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-00746APA
van Ours, Jan C; Williams, Jenny; Fergusson, David; Horwood, L John. (2013). Cannabis use and suicidal ideation.. Journal of health economics, 32(3), 524-37. https://doi.org/10.1016/j.jhealeco.2013.02.002
MLA
van Ours, Jan C, et al. "Cannabis use and suicidal ideation.." Journal of health economics, 2013. https://doi.org/10.1016/j.jhealeco.2013.02.002
RethinkTHC
RethinkTHC Research Database. "Cannabis use and suicidal ideation." RTHC-00746. Retrieved from https://rethinkthc.com/research/van-2013-cannabis-use-and-suicidal
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.