Cannabis Use Was Not Linked to Suicidality After Accounting for Family Factors in High-Risk Siblings | Research

The takeaway

In a longitudinal sibling study of 1,261 high-risk adolescents, cannabis use frequency was not associated with suicidal thoughts or behaviors after accounting for shared genetic and environmental influences.

suicide prevention researchers, cannabis policy analysts, psychiatric geneticists

What the researchers found

Cannabis use was not associated with suicidality (all p's > 0.05) in cross-sectional or prospective models accounting for within-family clustering. Exploratory analyses suggested tobacco might be more relevant (Wave 1 within-family OR 1.037, p=0.016), though this was reduced to non-significance after adjusting for other substance use.

Why it matters

By using siblings, this study controls for shared genetic and environmental factors that confound most cannabis-suicidality research. The null finding in a high-risk clinical sample challenges the assumed direct link between cannabis and suicidality.

The numbers in context

1,261 adolescent siblings across 3 waves (2001-2019). Cannabis-suicidality association: all p's > 0.05. Tobacco-suicidality exploratory finding: OR 1.037, p=0.016, reduced after adjustment. Recruited from clinical/high-risk settings.

How the study worked

Longitudinal sibling study (N=1,261) recruited from substance use treatment, alternative schools, and juvenile probation in Denver and San Diego. Three waves (2001-2019). Multilevel models accounted for shared familial influences. Covariates included alcohol, tobacco, other substance use, age, and sex.

What this study cannot tell us

High-risk sample may not generalize to general population. Attrition over 18 years. Self-reported substance use and suicidality. Sibling design controls for shared factors but cannot eliminate all confounders. May be underpowered for rarer outcomes.

How to read the evidence

Sibling design with longitudinal data provides stronger causal inference than typical observational studies, but high-risk sample and attrition limit to moderate.

When this study was published

Data collected across three waves from 2001-2019.

The bigger picture

Previous studies finding cannabis-suicidality links in community samples may be confounded by shared familial factors. When these are accounted for, the association disappears, suggesting the relationship may be driven by underlying vulnerability rather than cannabis itself.

Questions still open

Would these null findings replicate in a larger sibling study?
Is the cannabis-suicidality link in community samples entirely explained by shared vulnerability?

Common questions

Does cannabis cause suicidal thoughts?

This sibling study found no association after accounting for shared family factors, suggesting that previous findings may reflect shared vulnerability (genetics, environment) rather than a direct effect of cannabis.

Why is a sibling study important?

Siblings share genetics and home environment. When the cannabis-suicidality link disappears in sibling comparisons, it suggests the association seen in other studies may be driven by these shared factors rather than cannabis itself.

Read the original research

Associations between cannabis use frequency and suicidal thoughts and behaviors: A clinical longitudinal sibling study.

Addictive behaviors reports, 22, 100620

View on PubMed ↗Publisher’s paper ↗

Citation

Stern, Elisa F; Ellingson, Jarrod M; Schaefer, Jonathan D; Hinckley, Jesse D; Stallings, Michael C; Corley, Robin P; Hopfer, Christian; Wall, Tamara L; Rhee, Soo Hyun. (2025). Associations between cannabis use frequency and suicidal thoughts and behaviors: A clinical longitudinal sibling study.. Addictive behaviors reports, 22, 100620. https://doi.org/10.1016/j.abrep.2025.100620