Obesity Affects Disease Activity and Progression, Cognitive Functioning, and Quality of Life in People With Multiple Sclerosis.

Background and objectives: While obesity is a known risk factor of the development of multiple sclerosis (MS), its impact on MS disease progression remains unclear. We aimed to investigate the influence of body mass index (BMI) on disease activity and progression, cognitive performance, and health-related quality of life in patients with MS.

Methods: Patients from an incident population-based case-control study (n = 3,249) were categorized based on BMI status at diagnosis and followed up after diagnosis through the Swedish MS registry. Outcomes included changes in the Expanded Disability Status Scale (EDSS), Multiple Sclerosis Impact Scale 29, and Symbol Digit Modalities Test. The mean follow-up time was 10.6 years (SD 6.1). Linear mixed models were used to analyze long-term changes while Cox regression models assessed the risk of 24-week confirmed disability worsening, time to reach EDSS score 3 and EDSS score 4, the appearance of new lesions on MRI, patient-reported physical and psychological worsening, and processing speed worsening.

Results: Obesity, compared with healthy weight, was associated with a 0.02-point faster annual increase in the EDSS score (β for EDSS score x time 0.02, 95% CI 0.00-0.04). In addition, obesity was linked to a higher risk of reaching EDSS score 3 (HR 1.43, 95% CI 1.17-1.75) and EDSS score 4 (HR 1.40, 95% CI 1.07-1.73) and an increased risk of physical and psychological worsening. New lesions on MRI were more frequent among those with overweight and obesity, compared with those with healthy weight (HR 1.21, 95% CI 1.02-1.44 and HR 1.29, 95% CI 1.03-1.62, respectively). Among those who had not changed BMI group during follow-up, the associations between obesity and unfavorable outcomes became more pronounced, and the HR of cognitive disability worsening was 1.51 (95% CI 1.09-2.09) among those with obesity, compared with nonobese participants.

Discussion: In participants with MS, obesity was associated with faster disease progression, poorer health-related quality of life, and more rapid cognitive decline. Both overweight and obesity were associated with higher MRI activity.