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MAPS Announces that the First Controlled Trial of Cannabis for the Treatment of PTSD Raises No Safety Concerns

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A peer-reviewed paper published today in PLOS ONE analyses the results of a randomized cross-over clinical trial of the Short-Term Impact of 3 Smoked Cannabis Preparations Versus Placebo on PTSD Symptoms. The study was funded by a $2.2 million grant from the Colorado Department of Public Health and Environment (CDPHE) to the Multidisciplinary Association of Psychedelic Studies (MAPS) and was conducted by MAPS Public Benefit Corporation (MAPS PBC), a wholly-owned subsidiary of MAPS. Though no statistically significant difference was shown between the groups, all showed improvement in PTSD symptoms during treatment with the THC group having the largest response.

“This study served as the first randomized placebo-controlled trial comparing the therapeutic potential of varying ratios of THC and CBD for treating symptoms of PTSD” said Dr. Marcel O. Bonn-Miller, Coordinating Principal Investigator and lead author of the study. “These data, coupled with those of a recently completed accompanying study also funded by CDPHE, provide better insight into why individuals with PTSD are turning to predominantly-THC-cannabis as a treatment. We now require larger randomized placebo-controlled trials to determine minimally-effective doses of THC needed to safely treat individuals suffering from PTSD while also mitigating risks of cannabis dependence in this vulnerable population.”

“One of the biggest take-aways from this study is that Veterans with PTSD can use cannabis at self-managed doses, at least in the short term, and not experience a plethora of side effects or a worsening of symptoms,” said Mallory Loflin, Ph.D., co-author of the paper and Volunteer Assistant Professor of Psychiatry at UC San Diego School of Medicine. “That’s what most providers are worried about when their patients with PTSD decide to try cannabis.”

Co-author, Site Principal Investigator, and President of The Scottsdale Research Institute Sue Sisley, M.D., notes that “This study’s safety data and other research in PTSD patients in Colorado using real-world cannabis flower are promising. Despite the absurd restrictions federal prohibitionists have placed on research for more than 50 years, we are squarely focused on launching further Phase 2 trials with imported cannabis of tested, higher potency, fresher flowers that will provide a valid comparison for the millions of Veterans and others with PTSD who are looking for new options.”

Inspired by preclinical evidence suggesting cannabis may be effective in the treatment of PTSD, this study was the first to evaluate its safety and efficacy in an FDA-regulated placebo controlled double-blind clinical trial in order to measure the effect size. Seventy-six predominantly male Veterans between the ages of 24 and 77 completed the study. In Stage 1, participants were randomized to receive prepared cannabis that was 9% THC,11% CBD, a mix of 8%THC and 8% CBD, or placebo. All preparations were supplied by the National Institute on Drug Abuse (NIDA) which, despite MAPS’ best efforts for the last 20 years, still maintains the only license in the U.S. for production of cannabis preparations for federally regulated clinical trials. PTSD symptom severity decreased among all groups but demonstrated no statistical significance between the placebo group or the groups that received cannabis as measured by the Clinician-Administered PTSD Scale (CAPS-5).

“This study took seven years to obtain approval and three years to conduct at a cost of $2.2 million. The difference between anecdotal reports and these results may be the quality of the marijuana,” said Rick Doblin, Ph.D, Executive Director of MAPS, “which highlights the need for further well-controlled clinical trials that more closely represent currently available marijuana products. Higher quality cannabis flower suitable for Food and Drug Administration (FDA) approval is currently unavailable domestically due to restrictions on production imposed by the U.S. Department of Justice and Drug Enforcement Administration and must be imported.”

It is estimated that 6-10% of the general population and 13-31% of U.S. Veterans experience PTSD. The condition is associated with high rates of comorbid physical conditions, substance use disorder, depression, and suicidality. While currently approved treatments can be effective for some, the majority of military veterans with PTSD who receive one of the best practices psychotherapies for PTSD still qualify for a diagnosis of PTSD by the end of treatment. Self-treatment of PTSD with cannabis has been increasing alongside interest among patients, clinicians, and researchers to determine if cannabis may be an effective and appropriate treatment for PTSD.


This study was supported by funding from the Colorado Department of Public Health and Environment (CDPHE). The content and opinions are those of the grantee/authors and do not represent the official views of CDPHE.



Betty Aldworth, Director of Communications or

831-429-6362 ext 303


Founded in 1986, MAPS is a 501(c)(3) non-profit research and educational organization that develops medical, legal, and cultural contexts for people to benefit from the careful uses of psychedelics and marijuana. MAPS is sponsoring the most advanced psychedelic therapy research in the world: Phase 3 clinical trials of MDMA-assisted therapy for PTSD. Since its founding, MAPS has raised over $100 million for psychedelic therapy and medical marijuana research and education and has earned the Guidestar Platinum Seal of Transparency.


MAPS Public Benefit Corporation (MAPS PBC) catalyzes healing and well-being through psychedelic drug development, therapist training programs, and sales of prescription psychedelics while prioritizing public benefit above profit. Founded in 2014, MAPS PBC is a wholly owned subsidiary of the Multidisciplinary Association for Psychedelic Studies (MAPS), a 501(c)(3) non-profit organization

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