Adiposity is inversely associated with hippocampal volume in African Americans and European Americans with diabetes

Aims To assess associations between body mass index (BMI), waist circumference (WC), and computed tomography-determined volumes of pericardial, visceral, and subcutaneous adipose tissue with magnetic resonance imaging-(MRI) based cerebral structure and cognitive performance in individuals with type 2 diabetes (T2D). Methods This study was performed in 348 African Americans (AAs) and 256 European Americans (EAs) with T2D. Associations between adiposity measures with cerebral volumes of white matter (WMV), gray matter (GMV), white matter lesions, hippocampal GMV, and hippocampal WMV, cognitive performance and depression were examined using marginal models incorporating generalized estimating equations. All models were adjusted for age, sex, education, smoking, HbA1c, hypertension, statins, cardiovascular disease, MRI scanner (MRI outcomes only), and time between scans; some neuroimaging measures were additionally adjusted for intracranial volume. Results Participants were 59.9% female with mean (SD) age 57.7(9.3) years, diabetes duration 9.6(6.8) years, and HbA1c 7.8(1.9)%. In AAs, inverse associations were detected between hippocampal GMV and both BMI (β [95% CI] − 0.18 [− 0.30, − 0.07], P = 0.0018) and WC (− 0.23 [− 0.35, − 0.12], P = 0.0001). In the full bi-ethnic sample, inverse associations were detected between hippocampal WMV and WC (P ≤ 0.0001). Positive relationships were observed between BMI (P = 0.0007) and WC (P < 0.0001) with depression in EAs. Conclusions In patients with T2D, adiposity is inversely associated with hippocampal gray and white matter volumes.