Multiple sclerosis has traditionally been considered a condition that predominantly affects white people of European ancestry. However, a new analysis conducted by a North American team led by University of Maryland School of Medicine (UMSOM) researchers suggests that the debilitating neurological condition is more prevalent in Black Americans than once thought. It is also far more prevalent in Northern regions of the country including New England, the Dakotas, and the Pacific Northwest.
Findings from the new study were recently published in the journal JAMA Neurology.
“We found a much higher prevalence of multiple sclerosis in Black Americans than previously thought,” said study corresponding author Mitchell Wallin, MD, MPH, Associate Professor of Neurology at UMSOM. “This helps to confirm the profound impact that healthcare inequities and lack of representation in clinical research have had in terms of driving misconceptions about the prevalence of this disease on historically underserved and underrepresented populations.”
Multiple sclerosis (MS) causes the immune system to attack the central nervous system, specifically the protective layer of myelin that insulates nerve fibers. Symptoms include numbness, tingling, mood changes, memory problems, pain, fatigue, and, in severe cases, blindness or paralysis. In 2019, Dr. Wallin led a team that found the prevalence of multiple sclerosis (MS) in the U.S. to be nearly 1 million people, twice as many as previous estimates.
In the current study, he and his colleagues evaluated three years’ worth of de-identified health insurance claims of 96 million adults to locate adults living with multiple sclerosis. They estimated in more detail how many individuals who are age 18 or older are living with MS in various states and the MS prevalence among people of different races or ethnicities living in specific regions.
The study found strong evidence of a higher prevalence of MS in northern regions of the U.S. compared to southern regions. “Although we don’t know for certain why this is the case, it may have something to do with the spread of viruses in colder climates where people remain indoors more or lower vitamin D levels from less sun exposure,” said Dr. Wallin.
Numerous observational studies have linked low vitamin D levels with an increased risk of MS and with more progressive disease. Other landmark research published in Science found that the common Epstein-Barr virus infection greatly increased the risk for developing MS with a new study out this week demonstrating that antibodies made by the body against the virus attack a vital protein in the brain and spinal cord.
In terms of prevalence of MS within certain sub-groups of Americans, the researchers found a higher prevalence of MS in white people, followed by Black people, “other races,” and then people with Hispanic/Latinx ethnicity. MS occurs in about 4 in 1,000 white people, about 3 in 1,000 Black people, about 2 in 1,000 people of “other races” including Asians, Native Americans, Alaska natives and multi-race individuals, and about 1.5 in 1,000 people of Hispanic/Latinx origin.