the Psychiatry Advisor take:

Treating post-traumatic stress disorder (PTSD) with medical marijuana may lead to worsened symptoms and increased violent behavior.

The number of states that have approved marijuana for PTSD treatment is on the rise, but a new study shows that it may actually worsen symptoms, according to Samuel T. Wilkinson, MD, of the Yale University School of Medicine in New Haven, Connecticut, and colleagues.

The observational study included 2,276 participants who had been admitted to specialized Veterans Administration treatment programs for PTSD between 1991 and 2011. Participants were split into four groups: 831 who started taking marijuana (“starters”), 850 who never used marijuana (“never used”), 296 who used marijuana at admission and after discharge (“continuing use”), and 299 who stopped using marijuana after treatment (“stoppers”).

Each participant was evaluated at admission and four months after discharge, with measurements taken using the short version of the Mississippi Scale (MISS) to evaluate PTSD symptom severity, the drug and alcohol subscales of the Addiction Severity Index (ASI), and reports of violent behavior.

Those in the “never used” group had significantly lower MISS scores than those in the “starters” and the “continuing use” groups, the researchers reported at the recent American Academy of Addiction Psychiatry meeting. The “stoppers” had significantly lower MISS scores at follow-up than they did at baseline. Those in the “starters” group also had the highest level of violent behavior and the highest ASI scores. The “stoppers” group had significantly lower ASI scores than the other three groups.