Use of cannabis in Multiple Sclerosis

Despite the ever-increasing acceptance of medical cannabis and its notably common use in patients with multiple sclerosis (MS), clinicians treating those patients still may be poorly informed about risks, benefits, regulations, and proper uses, experts say.

"There is evidence of a 'clinical void,' with clinicians on one side and people with MS and other conditions on the other that doesn't usually exist regarding therapies that people with MS are using," said Allen C. Bowling, MD, PhD, director of the NeuroHealth Institute and clinical professor of neurology at the University of Colorado, in Aurora. His presentation was part of a symposium during the Consortium of Multiple Sclerosis Centers (CMSC) 2020 Annual Meeting.

While approximately 8% of the general population uses cannabis, evidence shows that the proportion of people with MS who do so ranges from 9% to 38%, for an average of about 20%, Bowling noted.

Yet, according to research, only about 20% of those actually discuss their cannabis use with their clinicians, which could have potentially adverse implications in the management of the disease.

Studies underscore that such misconceptions could be common - one recent study showed that as many as 90% of residents and fellows did not feel prepared to recommend or answer questions on cannabis use, and in fact most states do not even require physicians to have training in medical uses of cannabis.

Other research shows that the rates of clinicians with high knowledge in medical cannabis use are in the single digits, while many have no cannabis training at all.

In a survey of 556 physicians taken as recently as January 2020, 47% gave incorrect responses regarding tetrahydrocannabinol (THC), while 33% reported being familiar with "nano-cannabinoids" - which don't even exist, and the term was created for the sake of the survey.

Among the most recent research of cannabis use among MS patients is a real-world study of more than 2000 patients with MS in Denmark.

Said to be the most comprehensive survey of cannabis use among MS patients to date, the researchers found that 21% of patients reported cannabis use in the past year, with only 21% of those having a prescription to use the drug legally because of strict regulations in Denmark.

Respondents reported that the primary reasons for use in MS were to alleviate pain (61%), spasticity (52%), and sleep disturbances (46%). The most common adverse effects were drowsiness (30%), feeling quiet/subdued (23%), and dizziness (13%), with effects that were mild to moderate.

Other recent evidence on cannabis use in MS suggests important benefits once patients abstain from its use.

The study included 40 MS patients who reported smoking cannabis regularly - at least 4 days per week for multiple years - who were randomized to continue their cannabis use or withdraw.

While there were no cognitive differences among the patients at baseline, after 28 days, the abstinence group showed significant improvements on functional MRI in every cognitive index (P < .0001 for all).

On the Symbol Digit Modalities Test at day 28, the withdrawal group completed more trials correctly (P < .012) and had a faster reaction time (P < .002) that was associated with significantly increased activation in brain regions known to be associated with performance of the test, including the bilateral inferior frontal gyri, caudate, and cerebellum (P < .001 for all regions), the authors said.

Addiction to cannabis in MS in fact may be more common than many realize, and comes with a host of other adverse effects.

The RCVS risk is another concern, and changes in liver enzymes should also raise a red flag when MS patients are cannabis users.ç

Pure CBD or CBD-enriched products would be expected to produce less cognitive dysfunction than regular cannabis smoking, however, it's important to keep in mind that a 'CBD-enriched' product could have low but still significant THC content.