Cannabis use at 16 predicted first suicide attempt by age 21 among at-risk adolescents

Cannabis use at age 16 predicted first suicide attempt by 21 in both high-risk groups: OR 2.61 (95% CI 1.11-6.14) among those with suicidal thoughts and OR 2.14 (95% CI 1.04-4.41) among those with non-suicidal self-harm. Other key predictors included illicit drug use, sleep problems, and exposure to others' self-harm. Many commonly cited risk factors were NOT predictive.

Population-based birth cohort study (ALSPAC, UK) following 1,025 adolescents at elevated risk (456 with suicidal thoughts, 569 with self-harm at age 16) through age 21, using prospectively recorded risk factors and logistic regression.

Most adolescents with suicidal thoughts or self-harm will NOT attempt suicide. Identifying which few will is clinically crucial. This study shows cannabis use is one of the strongest markers, while many traditional risk factors failed to predict escalation.

Clinicians assessing suicide risk in teenagers are often told to ask about many factors. This study narrows the field: substance use (especially cannabis), sleep problems, and exposure to self-harm are the factors that actually distinguish who will escalate from ideation to action.

Observational design cannot establish causality. Cannabis use may be a marker for other risk factors or self-medication for distress rather than a causal factor. UK birth cohort may not generalize globally. Self-reported measures.