Clinical Trial: Short-Term Improvements in PTSD Symptoms Following Cannabis Exposure Similar to Those of Placebo

Philadelphia, PA: The short-term use of cannabis in subjects with post-traumatic stress disorder (PTSD) is associated with “significant improvements” in symptom management; however, this improvement is not superior to changes seen following the administration of placebo cannabis (marijuana consisting of 0.03 percent THC and 0.01 percent CBD), according to randomized clinical trial data published in the journal PLOS One

A team of researchers from the University of Pennsylvania, the Scottsdale Research Institute in Arizona, and the Multidisciplinary Association for Psychedelic Studies (MAPS) evaluated the short-term (three weeks) safety and efficacy of three distinct varieties of whole-plant cannabis (12 percent THC, 11 percent CBD, approximately equal percentages of THC and CBD) versus placebo in a cohort of military veterans with PTSD. 

Authors identified “no significant between-group differences” in total severity scores. Specifically, they determined that “all four treatment groups, including placebo, achieved significant within-subject reductions in total CAPS-5 Total Severity scores from Stage 1 baseline (visit 0) to end of treatment (visit 5). Specifically, participants who received placebo in Stage 1 reported a mean reduction of 13.1 points, participants who received High THC reported a mean reduction of 15.2 points, High CBD participants reported a mean reduction of 8.4 points, and THC+CBD participants reported a mean reduction of 8.5 points.”

They concluded: “The present study served as the first randomized placebo-controlled trial of smoked cannabis for symptoms of PTSD in US military veterans. Study-related AEs (adverse events) were generally mild to moderate and did not significantly differ by treatment condition. … All treatment groups (placebo, High CBD, High THC, THC+CBD) achieved statistically significant reductions in PTSD severity on the CAPS-5 in Stage 1. … The failure to differentiate treatment groups from placebo is likely attributable to the higher than average treatment response in the placebo condition and to the shorter than average duration of treatment…. Additional well-controlled and adequately powered studies with cannabis suitable for FDA drug development are needed to determine whether smoked cannabis improves symptoms of PTSD.”

The results are inconsistent with those of another recent study, published in the journal Cannabis and Cannabinoid Research in December, which reported that PTSD patients who consume high-THC products obtained from state-licensed retailers possessed “a greater than two-fold rate of remission from their PTSD” as compared to non-users over one year. 

Authors of the latest study speculated that the disparate results could be because their trial was shorter duration or because they were unable to obtain similarly “high quality cannabis flower” from federal government sources.

Last week, state officials in Michigan announced plans to appropriate up to $40 million to find state-sponsored clinical trials assessing the effects of cannabis upon veterans with PTSD.

Full text of the study, “The short-term impact of 3 smoked cannabis preparations versus placebo on PTSD symptoms: A randomized cross-over clinical trial,” appears in PLOS One. Additional information regarding cannabis and post-traumatic stress is available from NORML.