Multiple sclerosis (MS) has historically been considered a syndrome that primarily affects White persons of northern European ancestry. This has been strongly disproven in recent decades with prevalence/incidence studies showing that MS impacts individuals from diverse backgrounds. The few studies available investigating clinical characteristics of MS across diverse groups have shown that Hispanic/Latinx/e (Latinx) and non-Hispanic Black/African American (NHB) persons with MS (pwMS) have more severe disease trajectories compared to non-Hispanic Whites (NHW), including an earlier age of disease onset, greater disability, and more severe symptoms overall. Changes in brain structure have been linked outcomes and MS-itself, but what remains understudied is how brain structure differs across race/ethnicity. As such, the current study aims to investigate volumetric brain differences in a diverse sample of pwMS.

The sample (n=79) was compiled from multiple neuroimaging datasets and divided into three groups- Latinx (n=19), NHB (n=29), and NHW (n=32)- based on self-reported race/ethnicity. Participants completed demographic interviews and structural magnetic resonance imaging (MRI) scans. Neuroimaging data was visually inspected and processed in FreeSurfer (7.3.2). Volumetric measures for total gray matter, cortical gray matter, total white matter, and subcortical gray matter were used as the primary outcome measures.

A multivariate general linear model was used to examine volumetric brain differences across groups. Age and total intracranial volume were included as covariates. Results showed a significant effect of race/ethnicity (Pillai’s Trace=0.175, F(6, 148)=2.36, p=.033), indicating significant differences in volumetric brain metrics across race/ethnicity, namely for subcortical gray matter, total gray matter, and total white matter volumes. Post-hoc testing showed the Latinx group to have less subcortical gray matter, total gray matter, and total white matter than NHWs. There was a trend for the NHB versus NHW, with NHBs having less brain volume. No significant differences were observed between the Latinx and NHB groups. Lesion volume and regional gray matter volumes were also examined.

To the authors’ knowledge, this is among the first studies to investigate structural brain differences across race/ethnicity in pwMS. Results point to disparities in brain volume across racial/ethnic groups with MS. These differences may partially underlie the differing trajectories observed in clinical characteristics across race/ethnicity. Future studies should include larger samples of diverse pwMS and examine the intersection of psychosocial and systemic factors (i.e., social determinants of health) and brain metrics to better understand the divergent disease trajectories observed across groups.