Determinants Of Bone Mineral Density In Persons With Multiple Sclerosis

Abstract

Persons with multiple sclerosis (MS), including men and premenopausal women, have significantly increased risk of reduced bone mineral density (BMD). Therapeutic glucocorticoid use in MS does not appear to consistently result in this reduced BMD. There is evidence that low vitamin D ((25(OH)D) and the suggestion that reduced physical activity negatively affects BMD in MS. In addition, depression and elevated cortisol are known to be associated with decreased BMD and are also common in MS. PURPOSE: The overall aim of this study was to determine associations of 25(OH)D, physical activity, endogenous cortisol, and depression, to BMD in persons with MS. METHODS: We tested 7 persons with MS (5 Female, 2 Male; Md EDSS = 2) and 11 control (C) subjects (10 Female, 1 Male). Depression (Beck Depression Inventory) and the Multiple Sclerosis Functional Composite score (MSFC) was obtained from all subjects as were the following measures: Bone mineral density (BMD) of the lumbar spine (L2-L4) and femoral neck (mean left and right) was measured with dual X-ray absorptiometry. Vitamin D (25(OH)D) was measured from serum and cortisol from a nighttime salivary sample (11:00PM, EIA). Physical activity was indicated by accelerometers worn for 7 days around the waist and recorded as raw acceleration units. Analysis was by unpaired t-tests and Pearson correlations. Data are Mean (SE). Significance was p≤0.05. RESULTS: MS subjects compared to C reported greater depression (MS = 7(3), C = 3(0.5), p = 0.001), and had lower MSFC (MS = 2.2, C = 2.8). There were no differences between groups in BMD, 25(OH)D, cortisol, or physical activity. Despite the lack of difference between groups, physical activity was strongly correlated to femoral neck BMD in the MS group (r = 0.77, p =0.04) but not control (r = -0.07, p = 0.87). Neither 25(OH)D, cortisol, or depression was correlated to BMD in MS or C. CONCLUSIONS: In MS subjects with normal BMD and replete 25(OH)D, physical activity but not cortisol or depression, contributes to BMD. This study was Supported by NMSS grant PP1509