ATLANTA – Among patients with relapsing-remitting multiple sclerosis, higher body mass index, but not vitamin D status, appears to be related to greater loss of gray matter brain volume over time, results from a 5-year analysis showed.
Dr. Ellen M. Mowry
“We had previously known that obesity is a risk factor for developing MS, and among those who already have the disease, obesity-related comorbidities are associated with increased morbidity and mortality,” lead study author Ellen M. Mowry, MD, said in an interview at the annual meeting of the American Neurological Association. “Loss of brain tissue, especially as measured by reduced volume of gray matter noted on brain MRI, is predictive of long-term disability in MS. While we await the results of confirmatory studies and randomized trials, this study adds to the growing body of evidence suggesting there may be a role for modification of lifestyle factors in mitigating longer-term MS-related disability risk.”
In an effort to determine if body mass index (BMI) or vitamin D status is associated with longer-term MRI measures of neurodegeneration, Dr. Mowry and her colleagues drew from 469 patients participating in a longitudinal MS cohort study at the University of California, San Francisco, known as EPIC. Participants had clinical evaluations, brain MRI, and blood draws annually and were followed for 5 years. The main outcomes of interest were BMI and serum 25-hydroxyvitamin D levels measured over the time period, and their relationship to brain volume.
At baseline, the mean age of patients was 42 years, 70% were female, their mean BMI was 25 kg/m2, and their mean serum vitamin D level was 27.8 ng/mL. Dr. Mowry, a neurologist at Johns Hopkins University, Baltimore, and her colleagues found that over time, each 1-kg/m2 higher BMI was independently associated with reduced gray matter in multivariate models (–1.1 mL; P = .001). In addition, each 1-kg/m2 higher BMI over time was independently associated with greater declines in normalized brain parenchymal brain volume (–1.1 mL; P = .039). Elevated vitamin D levels, however, did not appear to be meaningfully associated with brain volumes.
Dr. Mowry acknowledged certain limitations of the study, including its nonrandomized design. “Such a trial may be warranted but I believe will be challenging to conduct,” she said. “Also, this cohort was designed to assess the association of genes with brain MRI outcomes, and so the people included were racially homogeneous – only Caucasians were included. Since MS risk is especially high among African Americans in recent years, and African Americans appear overall to have a higher risk of long-term disability, it is important to evaluate these and other prognostic factors amongst a more representative group of people with MS.”
The study received funding support from the National Institutes of Health, GlaxoSmithKline, and Biogen. Dr. Mowry disclosed that she has received medication from Teva for use in a clinical trial. In addition, she has been the primary investigator for studies sponsored by Biogen and Sun Pharma, and has conducted investigator-initiated studies sponsored by Genzyme and Biogen.
SOURCE: Ann Neurol. 2018;84[S22]:S206-7. Abstract M250.