Medical cannabis use in Canadians with multiple sclerosis

Background: The extent of medical cannabis use by people with multiple sclerosis (MS) in Canada has not been evaluated for more than a decade since recreational cannabis was legalized. Legalization provided an avenue for those to whom legal cannabis was previously inaccessible to access it as an alternative therapy. Our objective was to evaluate the prevalence of medical cannabis use by Canadians with MS, the reasons it is used, adverse effects, as well as the context surrounding how it is obtained and where users learned about it.

Methods: An anonymous questionnaire was distributed to prospective participants through various channels. The questionnaire included questions about participant characteristics and quality of life, their MS, and their medical cannabis use. It also employed two validated patient-reported outcome measures, the PDDS and the MSQOL-54.

Results: Completed questionnaires were submitted by 344 individuals. Among respondents, 215/344 (64.5%) reported having used medical cannabis at least once, and 180 (52.3%) reported still currently using it. Based on disease and quality of life data, we found that respondents with more severe or progressive forms of MS were more likely to have tried medical cannabis. Medical cannabis was used most by current and former users to treat sleep problems (84.2%), pain (80.0%), and spasticity (68.4%), while the most reported adverse effects were drowsiness (57.2%), feeling quiet/subdued (48.8%), and difficulty concentrating (28.4%). Most current and former users obtained their cannabis from a legal, reliable source (76.1%) and many (74%) learned about medical cannabis from someone other than a healthcare provider.

Conclusions: This study showed that nearly two-thirds of survey respondents, comprised of Canadians living with MS, have tried medical cannabis at least once and that those with a greater disease burden were more likely to have tried it. Users reported that cannabis is moderately to highly effective in treating several symptoms and that adverse effects are not generally severe, nor are they the main factor driving medical cannabis cessation. Our results support the need for more research examining medical cannabis use in MS and for evidence-based resources to be publicly available for those exploring it as a potential therapy.