By Pat Anson, PNN Editor

Medical cannabis is mildly effective in relieving pain and other symptoms in patients with multiple sclerosis (MS), according to a new study published in JAMA Network Open.

Spanish researchers analyzed 17 clinical trials involving over 3,100 patients – one of the largest reviews to date on the efficacy of cannabinoids in treating MS. Overall, they found that cannabis was safe, but had limited effectiveness in relieving pain, muscle spasticity and bladder dysfunction.

“Small but statistically significant differences were found in favor of cannabinoids for all 3 symptoms,” Marissa Slaven, MD, and Oren Levine, MD, of Ontario’s McMaster University said in a JAMA commentary. “The authors conclude that cannabinoids provide a mild reduction in subjective outcome assessment of uncertain clinical significance and that they are safe.”

MS is a chronic and incurable disease which attacks the body’s central nervous system, causing numbness in the limbs, difficulty walking, paralysis, loss of vision, fatigue and pain.

Medications and disease modifying drugs currently used to treat MS can cost tens of thousands of dollars a year – so a low-cost alternative treatment would be welcomed by many patients.

Four different medical cannabinoids were used in the 17 trials that were evaluated. They contained different levels of cannabidiol (CBD) and tetrahydrocannabinol (THC), the active ingredient in marijuana that makes people high. A lot of uncertainty remains about whether CBD or THC are more effective in relieving MS symptoms – something the JAMA study failed to resolve.

“It is critical that researchers gain a deeper understanding of both of the major (THC and CBD) and minor components of this therapy to unlock its full potential,” said Slaven.

“Given the relative safety of these agents, lack of strong evidence of other effective treatment options, and increasing access in some jurisdictions, it may seem appealing to include cannabinoids in the armamentarium of therapies for MS. But carefully conducted, high-quality studies with thought given to the biologic activity of different cannabis components are still required to inform on the benefits of cannabinoids for patients with MS.  

"The bottom line is there is certainly something happening with cannabinoids in regard to symptoms," Nicholas LaRocca, vice president of healthcare delivery and policy research at the National Multiple Sclerosis Society, told HealthDay. "In spite of very strong interest in cannabinoid therapy, we really have relatively little in terms of good research to guide us in terms of what does and what doesn't work, what works for which types of individuals, and so forth."

A small study was recently launched in Australia that might answer some of those questions. Emerald Health Pharmaceuticals of San Diego is using a synthetic version of CBD – called EHP-101 -- to treat about 100 people who suffer from MS or scleroderma, another autoimmune disease. The placebo controlled Phase I trial is meant to determine whether EHP-101 is safe and has any side effects. Results are expected next year.