Medicinal cannabinoids are likely safe for individuals with multiple sclerosis (MS), but the drugs’ efficacy in relieving symptoms appears to be slight, a recent systematic review and meta-analysis finds.
An estimated 2.3 million people worldwide have MS, according to the National Multiple Sclerosis Society. The lack of a cure adds urgency to the quest to mitigate symptoms.
In recent years, cannabinoids — drugs that contain active components of cannabis — have garnered attention as a possible means of symptom relief. In 2014 guidelines, the American Academy of Neurology concluded that certain cannabinoids likely are effective for reducing some patient-reported symptoms, including spasticity and pain, but questions about the drugs’ efficacy remained.
A multi-institutional Spanish research group investigated the issue further with a systematic review and meta-analysis of studies published in JAMA Network Open. The researchers “aimed to evaluate the therapeutic efficacy and tolerability of medicinal cannabinoids to treat the symptoms of spasticity, pain and bladder dysfunction in patients with MS,” they wrote. Their study encompassed randomized, double-blind and placebo-controlled trials.
The researchers included 17 trials and 3,161 patients in their analysis. The team compared four types of oral or oromucosal cannabinoids with placebo. They found modest but statistically significant advantages for cannabinoids for treating pain, bladder dysfunction and — measured subjectively — spasticity.
However, “[n]one of the interventions demonstrated clear efficacy in the treatment of spasticity when evaluated in a more objective form,” such as clinical screening tools, they note. Cannabinoids led to a higher risk of adverse events and related withdrawals, but the number of serious adverse events attributable to the drugs vs. placebo was not statistically significant, which led the authors to deem cannabinoids safe.
Marissa Slaven, MD, Assistant Professor at McMaster University in Ontario, who was not involved with the study, says the heterogeneity of the trials and dearth of information about the patient populations included in the meta-analysis are concerning, although she describes the study as comprehensive and the methodology as sound.
“This study supports the safety of medicinal cannabinoids for treating symptoms of MS, including pain, spasticity and bladder spasms,” Dr. Slaven says. “Given the alternatives available in clinical practice, this meta-analysis lends support to trials of cannabinoids in people suffering from MS.”