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

The takeaway

In 545 at-risk military personnel followed for a year, marijuana use interacted with PTSD symptoms to predict worsening PTSD, suicidal ideation, and suicidal behavior, while alcohol and opioid use did not show the same interactive effect.

Veterans and military personnel, PTSD researchers, and clinicians considering cannabis-based PTSD treatments.

Marijuana + PTSD = worse outcomes

What the researchers found

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.

Why it matters

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.

The numbers in context

545 participants (mean age 31.9, 88.2% male). Follow-up at 1, 3, 6, and 12 months. Marijuana use predicted suicidal ideation likelihood at 1 month and suicidal behavior over the 11-month follow-up. The PTSD-marijuana interaction was significant for both worsening PTSD and suicidal behavior.

How the study worked

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.

What this study cannot tell us

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.

How to read the evidence

Rated moderate because this is a longitudinal study with over 500 participants and multiple follow-up points, though the observational design limits causal conclusions.

When this study was published

Published in 2019. The debate over cannabis for PTSD treatment continues with additional studies since.

The bigger picture

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.

Questions still open

Is marijuana worsening PTSD or are those with worsening PTSD using more marijuana? Would controlled cannabinoid therapy (specific doses and compositions) show different results than self-directed use? Are these findings specific to military populations?

Common questions

Does marijuana help PTSD?

This study found the opposite in military personnel. Marijuana use interacted with PTSD symptoms to predict worse outcomes, including increased suicidal ideation and behavior, particularly at high PTSD severity levels.

Why was marijuana different from alcohol and opioids in this study?

Alcohol and opioid use did not show the same interactive effect with PTSD on suicidality. The authors suggest marijuana may have unique effects on PTSD-related neurobiological pathways, though the mechanism is unclear.

Does this mean veterans should not use marijuana?

The study found an association between marijuana use and worse outcomes in those with severe PTSD, but could not prove causation. Controlled clinical trials of specific cannabinoid formulations may yield different results than self-directed use.

Read the original research

Interactive effects of PTSD and substance use on suicidal ideation and behavior in military personnel: Increased risk from marijuana use.

Depression and anxiety, 36(11), 1072-1079

View on PubMed ↗Publisher’s paper ↗

Citation

Allan, Nicholas P; Ashrafioun, Lisham; Kolnogorova, Kateryna; Raines, Amanda M; Hoge, Charles W; Stecker, Tracy. (2019). Interactive effects of PTSD and substance use on suicidal ideation and behavior in military personnel: Increased risk from marijuana use.. Depression and anxiety, 36(11), 1072-1079. https://doi.org/10.1002/da.22954