Higher BMI Associated With Reduced Brain Volume in Multiple Sclerosis

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Investigators sought to determine an association between body mass index or vitamin D status and magnetic resonance imaging measures of neurodegeneration in individuals with relapsing-remitting multiple sclerosis or clinically isolated syndrome.

Increases in body mass index (BMI) appear to be associated with reductions in normalized gray matter (nGMV) and brain parenchymal (nBPV) volume in patients with relapsing-remitting multiple sclerosis (RRMS) and clinically isolated syndrome, according to findings  published in Neurology.

Researchers from the University of California, San Francisco, performed clinical evaluations, brain magnetic resonance imaging (MRI), and blood draws annually in individuals with RRMS or clinically isolated syndrome (n=469). The study was designed to test the association between 25-hydroxyvitamin D levels and BMI with brain volume changes, including changes in nGMV, nBPV, and white matter volumes. Brain volumes were assessed with Normalization of Atrophy-X. Analyses and were adjusted for age, sex, ethnicity, smoking status, and use of multiple sclerosis (MS) treatments.

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According to the Expanded Disability Status Scale, a higher BMI (Expanded Disability Status Scale score 0.13 points higher per 5 kg/m2) was associated with greater clinical disability (95% CI, 0.04-0.22; P =.004). Each 1 kg/m2-higher BMI score was also associated with a significant reduction in nGMV (−1.1 mL; 95% CI, −1.8 to −0.5; P =.001). In addition, a 1 kg/m2-higher BMI score was also associated with significant reductions in nBPV (−1.1 mL; 95% CI, −2.1 to −0.05; P =.039). With regard to vitamin D, there was no meaningful impact on levels of brain volume (nGMV per 10-mL higher vitamin D: −0.4 mL; 95% CI, −2.8 to 2.0; P =.77).

A study limitation was the potential lack of generalizability of the findings across patients with RRMS of other racial groups, as the entire cohort was comprised of white patients with RRMS.

The investigators concluded that additional research “should evaluate how minimizing obesity and related comorbid conditions alters MS-related imaging and clinical outcomes; it may well be that such interventions could be complementary approaches to US Food and Drug Administration-approved MS [disease-modifying therapies] in preventing long-term disability accumulation.”


Mowry EM, Azevedo CJ, McCulloch CE, et al. Body mass index, but not vitamin D status, is associated with brain volume change in MS. Neurology. 2018;91(24):e2256-e2264.