Plasma Aβ42 correlates positively with increased body fat in healthy individuals

Obesity and overweight, well known risk factors for cardiovascular disease and type 2 diabetes, are now associated with Alzheimer's disease (AD). It remains to be determined if obesity and overweight contribute to the risk of developing AD through modulating levels of amyloid-beta (Aβ), a key molecule in AD pathogenesis. Thus, we investigated whether there were any associations between plasma Aβ levels and body mass index (BMI) or fat mass (FM) in a group of 18 healthy adults. A statistically significant correlation was found between BMI, FM, and plasma levels of Aβ42 (BMI r = 0.602, P = 0.008; FM r = 0.547, P = 0.019), the longer, more pathogenic form of Aβ, but not with plasma levels of the shorter, less pathogenic Aβ40. Although not significant, positive correlations between plasma levels of Aβ42 and levels of insulin and the inflammatory marker C-reactive protein (CRP), along with an inverse trend between plasma Aβ42 levels and levels of high density lipoprotein (HDL) were answered. These results suggest that proteins implicated in inflammation, cardiovascular disease and type 2 diabetes, which in turn are risk factors for AD, may contribute to the associations between BMI/FM and plasma Aβ42 levels. Longitudinal studies involving larger cohorts are required to determine if elevated body fat may predispose individuals to AD through increasing Aβ42 levels throughout early to late adulthood.