Association between visceral fat amount and brain cortical thinning in the community‐dwelling elderly population

Background Despite emerging evidence suggesting that visceral fat may play a major role in the neurotoxic effect of obesity, no study has investigated the association between visceral fat amount and cortical thickness in the elderly. We examined the association of abdominal fat amount with cortical thickness and subcortical structures in the elderly. Method Community‐dwelling individuals (≥60 years of age) without known neurological diseases (n=316) were included. Areas of subcutaneous fat and visceral fat were estimated from computed tomography scan. Regional cortical thicknesses and subcortical volumes were obtained by analyzing brain 3T magnetic resonance imaging. A generalized additive model was built to explore non‐linearity between abdominal fat amount and cortical thickness. A generalized linear model was used to explore the brain imaging markers associated with an increase in abdominal fat amount (quintiles used for cortical thickness). Result There were inverted U‐shape relationships of visceral fat amount with global (p=0.02), frontal (p=0.02), temporal (p=0.02), and parietal thicknesses (p<0.001). The quintile 5 (the highest) group had significantly thinner cortices compared with the quintile 3 group in the global (β=‐0.04, p=0.004), parietal (β=‐0.04, p=0.01), temporal lobes (β=‐0.05, p=0.002), cingulate (β=‐0.06, p=0.01), and insula (β=‐0.06, p=0.02). The higher amount of visceral fat was significantly associated with the smaller volume of the pallium (β=‐0.66, p=0.01) and putamen (β=‐1.36, p=0.03). Most of the associations between subcutaneous fat amount and the brain imaging markers were not significant. Conclusion We found an inverted U shaped relationship between visceral fat amount and cortical thickness in elderly individuals. Future studies are needed to elucidate causal relationships and explore other factors which may be confounders.