Marijuana use combined with PTSD symptoms increased suicide risk in military personnel

PTSD symptoms and marijuana use both independently predicted suicidal ideation and behavior at follow-up. Critically, their interaction was also significant: at high (but not low) levels of PTSD symptoms, more days using marijuana predicted increased PTSD symptoms over time and greater likelihood of suicidal behavior. This interactive effect was not found for alcohol or opioid use.

Longitudinal cohort study of 545 current and former military personnel at risk for suicide but not in active mental health treatment. Self-report measures of PTSD, substance use, and suicidality were collected by telephone at baseline and 1, 3, 6, and 12 months.

Medical marijuana has been proposed as a PTSD treatment, but this study found that among military personnel with elevated PTSD symptoms, marijuana use was associated with worse outcomes. The interaction pattern suggests marijuana may be particularly harmful for those with severe PTSD.

This study complicates the narrative that cannabis is broadly helpful for PTSD. While some people report symptom relief, this data suggests that for military personnel with the most severe PTSD symptoms, marijuana use may compound rather than alleviate distress.

Observational design cannot establish causation. Self-report measures may underestimate substance use. Participants were not in active treatment, which may limit generalizability. Cannabis type, dose, and cannabinoid content were not assessed.