A systematic review of 108 studies found a consistent positive association between substance use (including cannabis) and suicidal ideation and behavior across low- and middle-income countries.
Read this if you are interested in the global connection between substance use, including cannabis, and suicide risk.
Consistent positive association across all substances and all suicidal behavior types
What the researchers found
Researchers systematically reviewed 108 studies examining the relationship between substance use and suicidal ideation and behavior in low- and middle-income countries, where 75% of global suicides occur.
The association between substance use and suicidal behavior was remarkably consistent across all substances studied (alcohol, tobacco, cannabis, illicit drugs, prescription drug misuse), all dimensions of substance use (intoxication, use, and pathological use), and all dimensions of suicidal behavior (ideation, non-fatal attempts, and completed suicide).
However, the review revealed significant gaps. Most research came from upper-middle-income countries, with only 22% from lower-middle-income and low-income countries. Research focused heavily on alcohol and tobacco while neglecting cannabis, opioids, sedatives, stimulants, and other substances. Most studies used cross-sectional designs, limiting causal conclusions.
Why it matters
Substance use is one of the most modifiable risk factors for suicide. In low- and middle-income countries where mental health resources are scarce, addressing substance use could be a practical suicide prevention strategy. The consistent association across all substance types, including cannabis, highlights the importance of integrated substance use and mental health approaches.
The numbers in context
108 studies included. 75% of global suicides occur in LMICs. Only 22% of studies came from lower-middle-income and low-income countries. Positive association found across all substance types, all use dimensions, and all suicidal behavior dimensions. Most studies were cross-sectional.
How the study worked
Systematic search of five databases identified English-language quantitative studies published between January 2006 and February 2016 examining associations between substance use and suicidal ideation and behavior in LMICs. Methodological quality was assessed using the SIGN checklist. 108 studies were included.
What this study cannot tell us
Most studies were cross-sectional, preventing causal conclusions. Research was concentrated in upper-middle-income countries, limiting generalizability to the poorest nations. Cannabis-specific findings were limited by the small number of studies focusing on this substance. Cultural and methodological heterogeneity across 108 studies complicates synthesis.
How to read the evidence
This is a large systematic review of 108 studies, providing strong evidence of association, though the underlying cross-sectional studies limit causal conclusions.
When this study was published
Published in 2018 covering studies from 2006-2016.
The bigger picture
This review underscores that the substance use-suicide connection is global and extends well beyond alcohol. Cannabis, often discussed separately from "harder" substances, showed the same consistent association with suicidal behavior. For countries with limited resources, substance use reduction may be one of the most cost-effective suicide prevention approaches.
Questions still open
- What mechanisms link cannabis use to suicidal behavior in LMIC populations? Would cannabis-specific prevention efforts reduce suicide rates in developing countries? How should suicide prevention programs in LMICs address the full spectrum of substance use?
Common questions
Is cannabis use linked to suicide risk?
Is substance use a modifiable suicide risk factor?
Read the original research
Substance use and suicidal ideation and behaviour in low- and middle-income countries: a systematic review.
BMC public health, 18(1), 549
Citation
Breet, Elsie; Goldstone, Daniel; Bantjes, Jason. (2018). Substance use and suicidal ideation and behaviour in low- and middle-income countries: a systematic review.. BMC public health, 18(1), 549. https://doi.org/10.1186/s12889-018-5425-6
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