Multiple Sclerosis Society of Canada

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MS Society funded study explores the effects of cannabis on cognition in men and women with MS

  • Canadian Study
  • MS Society Funded
Background:

Nearly 20% of individuals with multiple sclerosis (MS) use cannabis (also known as marijuana) to help them manage symptoms such as pain. In MS, men experience greater cognitive dysfunction than women. Recent research has discovered that cannabis contributes to cognitive dysfunction, however the link between cannabis use and cognitive impairment in men compared to women is unknown.

A recently published article in the Multiple Sclerosis Journal-Experimental, Translation, Clinical, co-authored by MS Society-funded researcher and neuropsychiatrist Dr. Anthony Feinstein from the University of Toronto, evaluates if there is an interaction between gender and cannabis in terms of cognitive impairment for individuals living with MS.

The Study:

Data from 140 individuals with MS who participated in a psychological study, testing if distraction adds to cognitive burden in MS, was used to determine cannabis use (e.g. monthly, more frequently, or no use). The individuals participated in cognitive assessments that tested their information processing speed, memory and executive function (attention control, planning abilities). The results of these tests were analyzed to determine if there was a correlation between cognition and cannabis use, and whether differences in the effects between males and females exist.

Results:

Of the 140 individuals who participated in the study, 33 people used cannabis regularly. Of the 33 users that used cannabis, 14 were men and 19 were women. Irrespective of gender, cannabis users had lower processing speed compared to non-cannabis users. Interestingly, the researchers identified that men performed worse compared to women on visual and verbal memory functions as measured using the California Verbal Learning Test-II.

Comment:

Overall, the study found that cannabis use among people with MS can have impacts on cognitive functioning, specially a negative effect on memory. This is particularly true for men as was found using certain tests of memory. There limitations of this study were that there were only 33 individuals who were sampled, which limited the comparison to 14 men and 19 women, and there was no information on the frequency of cannabis use (e.g. how many times per week, month, etc.) so it is unknown if greater or lesser use of cannabis impacts any of the cognitive assessments.

The MS Society advocates for all safe and efficacious treatment options to be available to people living with MS, and supports high quality research such as Dr. Feinstein’s work which provides valuable information about medical marijuana that help patients, their families, and healthcare teams make appropriate treatment decisions.

Source:

Patel V & Feinstein A. (2017) Cannabis and cognitive functioning in multiple sclerosis: The role of gender. Mult Scler J Exp Transl Clin. 3(2): 2055217317713027.