September 06, 2019
3 min read

More research needed for cannabis use in PTSD treatment

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Chandni Hindocha

Two recent studies concluded that although interest is strong, more research is needed before clinicians make treatment decisions regarding cannabis use in PTSD.

Although findings published in Depression & Anxiety indicated that marijuana may increase suicidality in military personnel with elevated PTSD symptoms, findings published in Journal of Dual Diagnosis indicated that cannabinoids may reduce PTSD symptomology.

Shows potential

“There are shifting legal and political moves ongoing around medical cannabis around the world, and one of the main areas that has received a lot of attention, mostly because of the campaigning of military veterans to get access to medical cannabis, is PTSD,” Chandni Hindocha, PhD, research fellow of University College London, told Healio Psychiatry. “PTSD is also a hugely debilitating disorder, and current treatments have limited efficacy and also side effects, so the need for a novel treatment is high.”

Hindocha and colleagued conducted a systematic review and examined the quality of available clinical evidence on the effectiveness of cannabinoids for PTSD treatment.

The researchers evaluated the reduction in the severity of symptoms in studies published until December 2018 where a patient with PTSD was prescribed/used a cannabinoid to reduce PTSD symptoms. Cannabinoids included nabilone, THC, CBD and whole-plant cannabis products (herbal and resin).

The review yielded no randomized controlled trials; therefore, these findings were based on evidence from observational and retrospective studies and case reports.

Overall, 10 studies were included in the review, one of which was a pilot randomized, placebo-controlled clinical trial that investigated nabilone in a small sample over the short-term.

Although all studies had medium to high risk of bias and were low quality, the results indicated that cannabinoids may hold promise for PTSD. The investigators found that cannabinoid use appeared to decrease PTSD symptoms, such as sleep disturbances and nightmares.

“Clinicians should note that although there is not enough evidence to make any clinical recommendations on the use of cannabinoids for PTSD, that an absence of evidence is not evidence of absence and trials are ongoing,” Hindocha said. “There is potential to have clinical guidance on this area by 2020. There are also many people in the U.S. and Canada already using cannabinoids in the management of PTSD, so to seek advice from other clinicians if planning on prescribing.”

Negative impacts

In the other study, Nicholas P. Allan, PhD, from department of psychology, Ohio University, and colleagues prospectively examined the effects of heavy alcohol use, opioid use and marijuana use over the past 30 days on PTSD symptoms, suicidal thoughts and suicidal behaviors over 12 months in at-risk service members or veterans not in mental health treatment.


“There has been a recent surge in legislative efforts to prescribe medical marijuana for PTSD symptoms in civilians and in military personnel, despite inadequate evidence of efficacy involving small sample nonrandomized control trials, and some evidence that harm outweighs benefits,” Allan and colleagues wrote.

In total, 545 participants at risk for suicide reported PTSD symptoms, past 30-day substance use and current suicidal ideation by telephone at baseline and after 1, 3, 6 and 12 months.

Allan and colleagues reported that the effects of baseline PTSD symptoms, days of marijuana use and the interaction between days of marijuana use and PTSD symptoms significantly predicted suicidal behavior.

The results showed that PTSD symptoms and marijuana use predicted the likelihood of suicidal ideation 1 month later and suicidal behavior over an 11-month followup.

In addition, the interaction between PTSD symptoms and marijuana use significantly predicted greater PTSD symptoms over time and suicidal behavior.

The probability of suicidal behavior for participants with high PTSD symptoms using marijuana daily was greater than the probability for those with low symptoms (22% vs. 10.1%), according to the results. Allan and colleagues also reported that more days using marijuana predicted greater PTSD symptoms over time and the likelihood of suicidal behavior among those with high levels of symptoms, but not among those with low levels.

“This study suggests that prescribing marijuana for military personnel or veterans with PTSD who are at risk for suicide based on their clinical presentation could be harmful and should be avoided until more evidence is gathered,” they wrote. “The combination of elevated PTSD symptoms and daily marijuana use are important to consider as predictors of both suicidal ideation and behavior. Research is urgently needed in this area, especially considering recent legislative efforts to legalize medical and recreational marijuana usage.” – by Savannah Demko

Disclosure: Hindocha and colleagues report no relevant financial disclosures. The Allan el al. study was supported by a Department of Defense grant.