Skeletal muscle loss and body composition in progressive supranuclear palsy: A retrospective cross-sectional study

INTRODUCTION: Skeletal muscle mass loss has been associated with decreased physical performance; however, the body composition characteristics in progressive supranuclear palsy (PSP) are not well understood. We investigated body composition parameters, focusing on skeletal muscle mass, in patients with PSP and compared them with those of healthy older adults. METHODS: This retrospective cross-sectional study included 39 patients with PSP and 30 healthy older adults (control group). Using a multi-frequency bioelectrical impedance analysis, we measured the skeletal mass index (SMI), basal metabolism, extracellular water/total body water ratio (ECW/TBW), and body fat percentage and examined the relationship between SMI and age, body mass index (BMI) and other body composition parameters. RESULTS: The PSP group had a higher rate of low muscle mass (56.4%) than the control group (10.0%), although the ages and BMIs were similar. The leg SMI was lower for the PSP group, while the ECW/TBW was higher for the PSP group. The basal metabolism was lower for the PSP group than for the controls but only in the women. The basal metabolism and BMI showed a significant correlation with SMI in the PSP group. There was a significant correlation between SMI and age, ECW/TBW, and body fat percentage in the PSP group but only in the women. CONCLUSION: This study is the first to show that a high proportion of patients with PSP have low muscle mass. We showed differences in terms of sex in muscle mass loss in women with PSP, which was associated with inactivity and aging.