Lack of High-Quality Clinical Evidence Hampers Cannabis Treatment for PTSD

Are cannabinoids really effective for posttraumatic stress disorder (PTSD) symptoms? Researchers examine recent and past studies for the answer.


Researchers from University College London in the United Kingdom and University of Amsterdam in the Netherlands who conducted a systematic review of available research found a “striking” lack of evidence, considering the vast interest in the potential of the treatment and the “overwhelming demand by veterans.”

The researchers wanted to conduct a “fine-grained evaluation” of cannabinoid effectiveness in posttraumatic stress disorder (PTSD). They identified 10 studies investigating medicinal cannabinoids for patients with PTSD who were experiencing symptoms that were measured by a clinical psychometric, such as the Clinician-Administered PTSD Scale. Only 1 was a randomized, double-blind, placebo-controlled crossover clinical trial. Three studies used nabilone, a synthetic delta9-tetrahydrocannabinol (THC) analog; 1 used oral THC; 2 used cannabidiol (CBD) oil, and 4 used smoked herbal preparations of cannabis.

More evidence supports psychotherapy as first-line therapy for PTSD

In line with previous reviews, the researchers found insufficient evidence to support the use of cannabinoids as a psychopharmacologic treatment for PTSD. In fact, they suggest that the lack of evidence poses a public health risk. However, the researchers say, this is mainly because the available support so far has been limited to small, “low-quality” studies, anecdotal reports, and some experimental evidence. There are reasons to keep investigating the possibilities, they conclude.

For instance, there is concurrence among studies that medicinal cannabinoids can help with sleep disturbances, and thus may be more effective, with less risk of addiction than benzodiazepines or opiate-based medications. Self-reports, anecdotal accounts, and case reports suggest that medical cannabis can dramatically reduce not only sleep symptoms, such as insomnia and nightmares, but may help with traumatic intrusions, hyperarousal, stress, anxiety, and depression.

The researchers also cite a study that found veterans who use cannabis believe it to be more effective and less complicated by adverse effects (AEs) than are alcohol and other psychopharmaceuticals. The AEs are generally mild to moderate, such as dry mouth and feeling “stoned,” but compared with the AEs of currently prescribed drugs are considered less burdensome.

Safety concerns are particularly critical in this population, though. Some research has shown that rates of cannabis use disorder are greater among patients who have PTSD compared with those who do not. A study of veterans admitted to US Department of Veterans Affairs treatment programs found recreational cannabis users with PTSD had poorer outcomes on severity of symptoms, violent behavior, and other drug use. Cannabinoids have also been associated with severe AEs in people with a history of psychosis—a consideration in combat veterans who have hallucinations or delusions.

Although they used strict inclusion criteria, the researchers say the studies they used still had “significant” limitations. Future well-controlled, randomized, double-blind clinical trials are highly warranted, they add, to address the “large unmet need” for effective PTSD treatments.

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