The Effect of Body Mass Index on Brain Volume and Cognitive Function in Relapsing-Remitting Multiple sclerosis: A CombiRx Secondary Analysis

Background

Multiple sclerosis (MS) is an autoimmune disease leading to physical, emotional and cognitive disability. High body mass index (BMI) may impact cognitive function and brain volume in MS. Yet, there is paucity of evidence addressing the impact of BMI on cognitive function and brain volume in MS.

Objectives

The purpose of this study was to examine the effects of BMI on normal appearing brain volume and cognitive function in patients with relapsing–remitting MS.

Methods

A secondary data analysis of the NIH CombiRx study was conducted. Multivariate regression and mixed model analyses were executed to analyze the effect of BMI on brain volume and cognitive function.

Results

The mean baseline age of the 768 participants was 38.2(SD = 9.4) years. 73% were female and 88.8% were Caucasian. The mean BMI was 28.8 kg/m²(SD = 6.7). The multivariate regression and mixed model analyses failed to show a clinical effect of BMI on brain volume and cognitive function.

Conclusion

BMI did not show an effect on cognitive function and brain volume among MS patients. Although there is increased interest in the effects of modifiable factors on the course of MS, the effects of BMI on brain volume and cognitive function are debatable and warrant further research.

ClinicalTrials.gov NCT00211887

Does obesity exacerbate brain lesion volume and atrophy in patients with multiple sclerosis?

BACKGROUND

Obesity is common among patients with multiple sclerosis (pwMS) and has been shown to exacerbate central inflammation, a key factor in disease progression. The purpose of this cross-sectional study is to examine the possible relationships between obesity, as measured by body mass index (BMI), and MS-related brain changes in atrophy and lesion volume, as measured from MRI, in a large, representative sample of pwMS.

METHODS

BMI and MRI data, along with demographic and disease variables, were acquired from the Multiple Sclerosis Partners Advancing Technology and Health Solutions (MS PATHS) registry. Unadjusted and adjusted partial correlations, controlling for gender, race, age, education level, MS phenotype, disability and disease duration, examined the associations between BMI and MRI outcomes, which included brain parenchymal fraction, white matter fraction, gray matter fraction, thalamic volume, and T2 lesion volume.

RESULTS

The sample consisted of 3,046 pwMS. Unadjusted and adjusted BMI-MRI correlations accounted for between 0.4% and 2.0% of shared variance (R²). When considering the relationship between MRI outcomes and BMI category (normal weight, overweight, obese), multiple regression analyses continued to show minimal association, with BMI category accounting for no more than 1.5% of shared variance.

CONCLUSIONS

No clinically meaningful associations were found between BMI and MRI outcomes in this large, representative sample of MS patients, regardless of demographics and disease variables. These unexpected negative results will require replication with a longitudinal design using more precise measures of obesity.