Body composition and disability in people with multiple sclerosis: A dual-energy x-ray absorptiometry study

Introduction: Body composition refers to the relative distribution of different tissue types within the body, including fat, lean, and bone tissues. There is evidence for associations between body composition and the development of multiple sclerosis (MS). The relationship between body composition and disease progression and disability accumulation, however, is unclear. Objectives: To examine: a) differences in overall and regional body composition by disability status in persons with multiple sclerosis (MS); and b) the relationship between body composition and other outcomes reflecting impairments and limitations due to MS. Methods: Cross-sectional investigation of 47 ambulatory persons with relapsing remitting MS who were grouped by Expanded Disability Status Scale (EDSS) scores as having mild (1.0-4.0; n = 26) or moderate (4.5-6.5; n = 21) disability. Main outcome measures were whole-body and regional soft tissue composition (%body fat (BF), fat mass (FM), and fat-free soft tissue mass (FFM)), bone mineral content (BMC), and bone mineral density (BMD) determined from dual-energy X-ray absorptiometry (DXA). Other outcomes included physical fitness, mobility, cognitive processing speed, symptoms, and health-related quality of life (HRQOL). Results: Whole-body and regional %BF and FM were significantly higher, and whole-body and appendicular BMC and BMD were significantly lower in participants with moderate disability than those with mild disability (all p < .05). There were no significant differences in whole-body or regional FFM by disability status. In the overall sample, body fat correlated significantly with cardiorespiratory fitness (pr(s) = -.52 to -.56), pain symptoms (pr(s) = .32), and psychological HRQOL (pr(s) = .34). FFM (pr(s) = .38-.48) and BMC (pr(s) = .53-.69) correlated primarily with measures of muscular strength. Conclusions: Persons with MS who have greater disability present with higher body fat and lower bone tissue content and density than those with mild disability. These findings highlight the need for strategies that address potential changes in body composition with disability accumulation.