Efficacy and safety data remain mixed on Multiple Sclerosis and cannabis, leaving clinicians to make treatment decisions on a case-by-case basis.
Approximately 75 to 86% of people with multiple sclerosis (MS) experience pain. While there are treatments available, particularly for muscle spasticity, adequate pain control, not to mention improved quality of life, is hard to achieve in many.1 A 2016 web-based investigation by the Michael J. Fox Foundation and the National Multiple Sclerosis Society found that 24% of 595 respondents reported overall high efficacy of cannabis use among those with MS,2 prompting further research into the safety and efficacy of cannabinoids for treating MS-related pain.
Muscle spasticity, which may occur in up to 80% of patients with MS, is caused by cytokines, prostaglandins, and reactive oxygen species that change neuronal pathways and lead to fluctuations in motor circuit function and muscle tone.3 Available pharmacological options (eg, baclofen, gabapentin, tizanidine, dantrolene, and botulinum toxin-A) often fail to reduce pain and improve quality of life.4,5 Nonpharmacological approaches include passive stretching, relaxation techniques (eg, guided imagery, deep breathing), acupuncture, and aquatic therapy.6
Mixed Results for Cannabinoids on MS Pain and Spasticity
Conclusive data on the efficacy of cannabinoids in MS patients is sparse but most available studies do focus on spasticity-related pain. Nielsen, et al, led a systematic review that examined 32 papers on the use of cannabis and cannabinoids in MS. Reviews included both experimental and epidemiological studies ranging from 2006 to 2014 which analyzed the effects of smoked cannabis sativa, CBD extract, dronabinol, nabilone, nabiximols, and THC extract in MS patients. This review was broad and inclusion criteria and analyzed outcomes were diverse, likely due to the limited evidence available.
When focusing on the effects of cannabinoids on generalized pain as part of MS, Nielsen’s team reported mixed results. Specifically, two medium quality reviews concluded that THC extracts were likely effective in reducing spasticity. The evidence quality of these two reviews was considered “medium,” but the studies involved were actually of “low” or “very low” quality. Other reviews of THC extracts reported positive effects but did not draw conclusions due to insufficient or questionable evidence. See Table Ia for details.
Results were mixed for spasticity as well. Many of the reviews assessed outcomes on the Ashworth scale of spasticity, a widely used 5-point scale based on a clinician’s subjective assessments of limb rigidity. Interestingly, improvements were self-reported by participants, even though measured data on the scale did not always match these results. These inconsistent findings suggest cannabinoids may provide spasticity relief via other unknown mechanisms.
Further analysis demonstrated a positive effect in spasticity reduction in all reviewed studies of smoked cannabis and THC extract alone, while mixed findings were reported in other cannabis variations and combinations (see Table Ib).7 Regrettably, there is still much we do not know about the mechanism of cannabinoids, and without a standard for dosing and administration route, conducting clinical studies is challenging.
Safety must also be considered. According to the COMPASS trial,8 which evaluated safety concerns of cannabis in MS patients, the most common adverse effects (seen in 2% to 5% of 215 total participants) were headache, nasopharyngitis, nausea, somnolence, dizziness, upper respiratory tract infection, vomiting, and cough. Additional adverse events deemed likely related to use of cannabis included amnesia, euphoria, sweating and paranoia, which were experienced by <0.5% of patients.
Nielsen’s review7 also examined the diverse adverse effects of cannabis and cannabinoid use in multiple sclerosis. While many of the side effects were considered mild with few severe adverse events, the rate of side effects was greater for cannabinoids than controls in all evaluated studies. The authors noted that while the rate of overall events was higher for cannabinoids, the rate of serious adverse events was comparable to placebo. They concluded that adverse effect profiles were comparable for each cannabinoid and route of administration.7
In response to subjective survey data,2 patients were in favor of using cannabis and self-reported relief from their pain conditions. At this time, however, the appropriateness of using cannabinoids for MS-related pain should be evaluated on a patient-by-patient basis.
Last updated on: August 3, 2020