Multiple sclerosis (MS) has long been thought to be most prevalent among white people, but a new study suggests that the prevalence of the illness is high in both white and Black people compared with Latinos and Asians.

The prevalence of MS in Black people has been vastly understudied, according to the study’s author, Annette Langer-Gould, MD, PhD, of Kaiser Permanente Southern California in Los Angeles in a news release.

Published in Neurology, a medical journal of the American Academy of Neurology, of which Langer-Gould is a member, the study findings are significant because they indicate that MS has “affected Black and white adults at similar rates for decades.”

“The belief that MS is rare in Black people has been based on a history of problematic evidence, including a 1950s study of veterans that found white men more likely than Black men to receive services through the Veterans Administration for MS,” Langer-Gould said. “That study did not consider the barriers and disparities Black men faced in receiving services and that they were less likely to be measured accurately.”

This new study examined more than 2.6 million adults living in Southern California and determined how many people had a MS diagnosis in 2010. Of the patients, 3,863 people had MS with a median age of 52; 77% were women.

MS prevalence per 100,000 people was 226 among Black people and 238 among white people. The prevalence among Latino and Asian people was 70 per 100,000 people and 23 per 100,000 people, respectively.

Among Black and Asian people, women had a higher prevalence of MS. Of Black patients with MS, 82% were women; of Asian patients, 84% were women. Women made up 76% of white people with MS and 75% of Latino people.

Langer-Gould noted that the terms used in current research, including Hispanic, Asian, Black, and white, are socially constructed  and do not dictate uniform biological or cultural differences. Therefore, updated research is required to address systemic bias in medical research.

“Understanding MS prevalence in all people has important implications when it comes to making sure people are properly screened and treated for this disease,” said Langer-Gould.

To learn more about MS in Black patients, click here.