Gender-specific relationship between thigh muscle and fat mass and brain amyloid-beta positivity

Abstract

Background The relationship of specific body composition in the thighs and brain amyloid-beta (A beta) deposition remained unclear, although there were growing evidence that higher muscle and fat mass in thighs had a protective effect against cardiometabolic syndromes. To determine whether muscle mass and fat mass in the thighs affected amyloid-beta (A beta) positivity differently in relation to gender, we investigated the association of muscle mass and fat mass with A beta positivity using positron emission tomography (PET) in individuals without dementia. Methods We recruited 240 participants (134 [55.8%] males, 106 [44.2%] females) without dementia >= 45 years of age who underwent A beta PET, bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DEXA) scans of the hip in the health promotion center at Samsung Medical Center in Seoul, Korea. Lower extremity skeletal muscle mass index (LASMI) was measured using BIA, and gluteofemoral fat percentage (GFFP) was estimated using DEXA scans of the hip. We investigated the associations of LASMI and GFFP with A beta positivity using logistic regression analyses after controlling for age, APOE4 genotype, and cognitive stage. Results Higher muscle mass in the thighs, measured as LASMI (odds ratio [OR]=0.27, 95% confidence interval [CI] 0.08 to 0.84, p=0.031) was associated with a lesser risk of A beta positivity in only females. Higher fat mass in the thighs, measured as GFFP (OR=0.84, 95% CI 0.73 to 0.95, p=0.008) was associated with a lesser risk of A beta positivity in only males. However, the association between LAMSI (p for interaction= 0.810), GFFP (p for interaction= 0.075) and A beta positivity did not significantly differ by gender. Furthermore, LAMSI only negatively correlated with centiloid (CL) values in females (r=-0.205, p=0.037), and GFFP only negatively correlated with CL values only in males (r=-0.253, p=0.004). Conclusions Our findings highlight the importance of recognizing that gender differences exist with respect to the specific body composition to potentially protect against A beta deposition. Therefore, our results may help in designing gender-specific strategies for controlling body composition to prevent A beta deposition.