Negative association of fat mass index and Alzheimer’s disease cerebrospinal fluid biomarkers in cognitively impaired patients

INTRODUCTION Alzheimer's disease (AD) is associated with early weight loss, with unclear underlying mechanisms. Using real-world data, we aimed to investigate the links between biological AD profile, body composition, and nutritional status in patients with cognitive impairment. METHODS Cross-sectional study of patients with cognitive decline explored with cerebrospinal fluid (CSF) AD biomarkers and bioelectrical impedance analysis. Nutritional status was assessed using GLIM criteria. Analyses were stratified by sex and adjusted for age, MMSE, comorbidities, and the presence of a caregiver at home. RESULTS Among 420 patients, the fat mass index was positively associated with the Aβ42/40 ratio and negatively with pTau181 levels (p < 0.05). Malnutrition was more frequent in women than men (p = 0.0059). In women, malnutrition was associated with higher t-Tau and pTau181 levels (p < 0.02). In both sexes, pTau181 levels were inversely associated with muscle mass (p = 0.041). CONCLUSION These results suggest possible pathophysiological links between AD CSF biomarkers and nutritional status.