A new study by University College London has found that prescriptions of cannabis to treat post-traumatic stress disorder (PTSD) may not be supported by adequate evidence.
The systematic review, published in the Journal of Dual Diagnosis, found that cannabinoids may hold promise as a treatment for PTSD, particularly in reducing nightmares and helping people sleep, but more research is needed to determine whether these drugs should be used in routine clinical practice.
"There has been a recent surge of interest in the use of cannabinoids to treat PTSD, particularly from military veterans, many of whom are already self-medicating or obtaining prescriptions in some American states," said study lead author Chandni Hindocha, PhD, UCL Clinical Psychopharmacology Unit.
According to the National Institute of Health, PTSD is a disorder that develops in people who have experienced a terrifying event. It typically involves re-experiencing a traumatic event through intrusive memories, flashbacks or nightmares, and often involves hyper-reactivity, and insomnia.
Psychotherapies, including trauma-focused cognitive behavioral therapy, have been shown to be effective for PTSD, according to the study authors. However, not everyone can access these therapies and they do not work for everyone, so many people still need to take prescribed medications. Existing drugs approved for PTSD do not work for everyone and can have adverse events, so researchers noted there is an urgent need to identify new treatments.
A growing number of people have turned to cannabinoids, which is an approved treatment for PTSD in most states in that permit medical cannabis. These cannabinoids act on the brain's in-built endocannabinoid system, which also regulates other brain functions that are affected by PTSD.
The study authors conducted a systematic review of all studies in which someone with a PTSD diagnosis had been using a cannabinoid to reduce their symptoms. They identified 10 studies that met their quality criteria, which included products such as smoked cannabis, THC, or cannabidiol separately in oil or pill form, and a synthetic cannabinoid called nabilone.
Every study had medium- to high-risk of bias and all were assessed as low in quality due to limitations such as small sample size, retrospective study design, lack of a control group or placebo, short follow-up periods, and not reporting other medication use or addiction. Only one study was a randomized controlled trial, investigating nabilone, but it was in a small sample over a relatively short period of time.
The researchers said there are still many unanswered questions about the safety and efficacy of cannabis-based medications for PTSD and potential long-term effects such as addiction or a risk of psychosis.
The existing evidence shows promise, however, as some studies showed that cannabis products appeared to reduce PTSD symptoms such as insomnia and nightmares.