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Higher Body Mass Index Is Associated with Greater Brain Gray Matter Loss in MS

BERLIN—Multiple sclerosis (MS) patients who have a higher body mass index (BMI) are more likely to have reduced brain gray matter volume, researchers reported here at the Congress of the European Committee for Treatment and Research in Multiple Sclerosis.

"The reduction in brain gray matter is relevant since gray matter volume loss portends greater longer-term disability," said Ellen M. Mowry, MD, FAAN, associate professor of neurology at Johns Hopkins University Precision Medicine Center of Excellence for Multiple Sclerosis in Baltimore, in her oral platform presentation.

"Since obesity is modifiable, further studies should explore these relationships in detail. Evaluating the effect of reducing BMI on imaging and clinical outcomes in MS may be warranted," Dr. Mowry said.   

Overall, the longitudinal brain gray matter volume declined from 849 cc3 at baseline to 815 cc3 after year five, Dr. Mowry reported. For every one kilogram increase in BMI, the brain gray matter volume decreased by 1.1 cc3, which was statistically significant (p=0.001), she said.

"Higher BMI is associated longitudinally with lower subsequent normalized gray and brain parenchymal volumes in relapsing-remitting MS and clinically isolated syndrome patients," Dr. Mowry said.

As a companion part of the study, Dr. Mowry looked at whether loss of brain gray matter volume correlated with levels of vitamin D but she found no significant association.

Dr. Mowry and colleagues reviewed data from EPIC, a five-year long study study begun in 2004 at the University of California, San Francisco (UCSF). The researchers enrolled adult patients mostly from the UCSF MS Center with MS and/or clinically isolated syndrome with Expanded Disability Status Scale scores of less than eight. The patients provided a blood sample and had a clinical evaluation and a brain magnetic resonance imaging scan performed annually. Brain volume measures were determined using structural image evaluation.

The study included patients who had relapsing-remitting multiple sclerosis or clinically isolated syndrome with at least one follow-up visit. BMI was calculated from self-reported height; weight was measured at baseline and was subsequently self-reported.

The 469 patients in the study were about 42 years old and 70 percent were women; 5 percent identified as having Hispanic ethnicity; 12 percent were smokers; the mean body mass index was 25 kg/m2 and about 9 percent of the patients said they used vitamin D supplements.

Commenting on the study, Maria Pia Amato, MD, associate professor of neurology at the University of Florence, Italy, and newly elected vice president of ECTRIMS, told Neurology Today Conference Reporter that the change in brain gray matter volume associated with increasing BMI could be related to adipose tissue causing increasing inflammation in the body.

"But really this is all speculation," she said. "We do not know the true mechanism of action," she said, adding that smoking and vitamin D, among other factors, are hypothesized to affect MS.

"We do know that higher BMI in adolescent girls is associated with an increased risk of developing MS," she said.

"What we heard today is that increased BMI may be related to brain atrophy and greater disability," said Dr. Amato, who moderated the oral platform sessions. "I think it is time that we as neurologists inform our patients about the importance of lifestyle factors. We should put more emphasis on the importance of diet as well as weight and physical exercise."

The study was funded by the National Institutes of Health, GlaxoSmithKline, and Biogen Idec. Dr. Mowry reported serving as site principal investigator (PI) for clinical trials and studies sponsored by Biogen and SunPharma. She receives research support from Sanofi Genzyme and Biogen for investigator-initiated trials, receives free medication for a clinical trial, of which she is PI, from Teva Neuroscience, and receives royalties for editorial duties from UpToDate.


ECTRIMS Abstract 169: Mowry E. Azevedo C, McCulloch C, et al. Higher body mass index, but not vitamin D status, is associated with greater subsequent loss of brain gray matter volume in multiple sclerosis.