Relationship between body composition and mortality in older patients with mild cognitive impairment and Alzheimer's disease: NCGG-STORIES

Abstract

Background Although a lower body mass index (BMI) has been identified as a prognostic risk factor among older adults with cognitive impairment, it remains unclear which body composition are associated with prognosis. Objective This study investigated the relationship between body composition and mortality in older adults with mild cognitive impairment (MCI) and Alzheimer's disease (AD). Methods This longitudinal study, using data from a memory clinic in Japan, included patients aged ≥65 years who were clinically diagnosed with MCI or AD. Mortality data (date and cause of death) were obtained using a proxy questionnaire. Body composition (muscle mass, fat-free mass, fat mass, %FM) was measured using bioelectrical impedance analysis, and muscle mass index (MMI), fat-free mass index (FFMI) and fat mass index (FMI) were calculated. Body composition index was divided into tertiles (lowest, middle, and highest). To evaluate associations between body composition and mortality, we conducted survival analyses using Cox proportional hazards model (ref. lowest group). Results A total of 1575 patients were included in the analysis (mean age, 78.2 years; 63.2% women). The highest FMI and %FM groups had a lower risk of mortality than that in the lowest group (hazard ratio [95% confidence interval]: FMI, 0.55 [0.37–0.81]; %FM, 0.49 [0.33–0.71]), and this association was significant in women with MCI and AD. No significant associations were observed between MMI, FFMI, and mortality. Conclusions Lower FM may be a potential risk factor for poor prognosis, emphasizing the need to monitor it from an early stage of cognitive decline.