And now to what we don’t know: More research is needed to determine if these differences are because of biological or genetic reasons, says Dorlan J. Kimbrough, M.D., a board-certified neurologist at Duke Neurological Disorders Clinic and assistant professor of neurology at Duke University School of Medicine in Durham, NC. Other causes may also be in play. A look at a few of them:
Environmental Factors
Cigarette smoking, Epstein Barr Virus infection, and vitamin D levels have all been linked to developing MS, says Dr. Kimbrough. But while some of these factors differ between white and Black populations—for instance, research has shown that Black people have significantly lower levels of total 25-hydroxyvitamin D (25OHD) than white people—other research has also found that having higher serum levels of 25OHD was associated with a lower risk of MS for white patients, and no association in Hispanic or Black patients.
Social Determinants of Health
These are considered the conditions that people live in that can alter their lives, including their health, Dr. Williams says. For communities of color with MS, this can mean access to care issues, socioeconomic conditions that affect receiving diagnosis and early treatment, and being under- or uninsured. Here, too, more research is needed—many of the studies that have been performed in MS on these communities have been “really very limited,” points out Kalina M. Sanders, M.D., a board-certified neurologist specializing in MS at Baptist Health in Jacksonville, FL. “These studies … are oftentimes retrospective studies. They are registry-based studies. So there is some limitation in really what the data means,” she explains.
Study Selection Bias
Dr. Kimbrough says it’s possible that patients of color included in MS studies have had severe cases (of note, patients recruited into studies are vetted for their diagnosis). Backing that possibility up, one study suggests that minority populations studied may be “skewed” toward MS patients with more severe symptoms if those minority patients are being referred to tertiary centers (where research often occurs) while milder patients are managed by community neurologists (and often aren’t included in research studies).
Differences in Treatment Response
Disease-modifying therapies (DMTs) are the go-to medication for multiple sclerosis, but one study, comparing treatment with different forms of interferon β-1a, found that 36 Black patients experienced more relapses and were less likely to remain relapse-free and achieve no evidence of disease activity (NEDA) than 616 white patients. Another retrospective review found that Black MS patients on DMTs showed signs of “greater disability progression over a shorter period and a poorer response to these DMTs,” according to an article by Dr. Kimbrough and Petra Brayo, M.D.
In short, doctors don’t have a lot of data on the efficacy of DMTs for BIPOC, says Dr. Williams, who is part of an ongoing, five-year, multinational, prospective study called ESTEEM, looking at the impact of a specific medication on MS disease activity in African Americans.
Bottom line, says Dr. Williams: There is a real need for patients of color to take part in research—both for accuracy of the findings and to help raise awareness that MS can happen in Black people and other people of color.