The risk of developing neuromyelitis optica spectrum disorder (NMOSD) is 8 times greater in people of East Asian and Black descent compared to White people, according to a case-control study conducted in Canada and published in the Multiple Sclerosis Journal.

The risk of the disease is also higher in other nonWhite participants, those born outside of Canada, and those with another autoimmune disease, the authors noted.

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However, despite the fact that the disease affects women more than men, the investigation showed no association between the risk of NMOSD and hormonal factors such as reproductive history or age at the first occurrence of menstruation, they added.

“This study illustrates the need for research exploring environmental risk factors for NMOSD,” they wrote.

“We recommend that future studies employ a case–control study design with careful consideration of unique demographic characteristics of the NMOSD population, including female predominance, immigrant composition, and ethnic distribution.”

For the study, the team of researchers led by Ruth Ann Marrie, MD, PhD, from the Departments of Medicine and Community Health Sciences, at Max Rady College of Medicine, Rady Faculty of Health Sciences, the University of Manitoba, in Winnipeg, Canada, used a validated questionnaire and a case-control design to investigate factors associated with the risk of NMOSD.

They recruited 122 patients with aquaporin-4 positive NMOSD through 6 Canadian multiple sclerosis clinics. Of these, the majority (87.7%) were women. They then asked the participants to complete the Environmental Risk Factors in Multiple Sclerosis Study (EnvIMS) questionnaire and compared their answers to those of 956 unaffected people from the Canadian arm of the study.

The results showed that the odds of developing NMOSD were at least 8 times higher in East Asian and Black responders compared to White responders. 

A birthplace outside of Canada and the presence of concomitant autoimmune diseases were also associated with a higher risk of developing the disease.


Rotstein DL, Wolfson C, Carruthers R, et al. A national case-control study investigating demographic and environmental factors associated with NMOSD. Mult Scler. Published online February 18, 2023. doi:10.1177/13524585231151953