Dietary patterns, obesity and microstructure of the hippocampus in healthy elderly people

Introduction:Dietary habits and obesity have been shown to influence human brain structure and function. It is, however, unclear if diet or obesity, measured using body-mass-index (BMI) and waist- hip ratio (WHR), affects the microstructure of the hippocampus, a key area involved in memory functions. Objectives: This study explored whether dietary patterns are associated with BMI, WHR or hippocampal microstructure, measured by diffusion tensor imaging (DTI) in non-demented elderlies. Method / Design: Dietary patterns were identified using exploratory factor analysis on a food frequency questionnaire in 498 participants aged ≥ 60 years in the ongoing LIFE-study (Leipzig, Germany). Individual hippocampal subfields were segmented on high-resolution 3T-magnetic resonance images in a subgroup (n = 190), using FreeSurfer (www.freesurfer.net). Hippocampal mean diffusivity (MD) of each subfield was extracted on co-registered MD maps derived by DTI, using FSL (www.fmrib.ox.ac.uk/fsl/). Dietary patterns, BMI, WHR and MD were correlated using partial correlations adjusted for important confounders. Results: Factor analysis revealed a ‹red meat and high-sugar› and a ‹fish, fruit and vegetable› pattern. The first pattern correlated to WHR (r=0.30, p<0.01), whereas the second one negatively correlated to WHR (r=-0.37 p<0.01). A higher WHR, but not BMI or dietary patterns, correlated to higher MD, indicative of lower microstructural integrity, on the CA2/3 region of the hippocampus (bilateral, r>0.17, p