Dietary diversity is associated with longitudinal changes in hippocampal volume among Japanese community dwellers

Background/Objectives: Dietary habits are known to affect health, including the rate of brain ageing and susceptibility to diseases. This study examines the longitudinal relationship between dietary diversity and hippocampal volume, a key structure of memory processing known to be impaired in dementia. Subjects/Methods: Community-dwelling adults aged 40–89 years (n=1683; men: 50.6%) from the National Institute for Longevity Sciences-Longitudinal Study of Aging were followed for 2 years. Dietary intake was assessed by 3-day dietary records, and dietary diversity at baseline was quantified using the Quantitative Index for Dietary Diversity (QUANTIDD). Longitudinal changes in hippocampal and total grey matter volumes were measured with T1-weighted MRI and FreeSurfer. Associations between dietary diversity quintiles and brain volume changes were examined with general linear models adjusted for age, sex, education, smoking, alcohol intake, physical activity, and comorbidities. Results: Mean (±SD) percent decreases over 2 years were 1.00% (±2.27%) for hippocampal volume and 0.78% (±1.83%) for total grey matter. Greater dietary diversity was associated with smaller decreases in total grey matter (p=0.065; trend p=0.017) and more strongly with smaller decreases in hippocampal volume: estimated mean (±SE) percent decreases were 1.31% (±0.12%), 1.07% (±0.12%), 0.98% (±0.12%), 0.81% (±0.12%), and 0.85% (±0.12%) across ascending dietary diversity quintiles (p=0.030; trend p=0.003). Conclusions: Among community dwellers, increased dietary diversity may be a nutritional strategy to prevent hippocampal atrophy.

Rei Otsuka, Yukiko Nishita, Akinori Nakamura, Takashi Kato, Kaori Iwata, Chikako Tange, Makiko Tomida, Kaori Kinoshita, Takeshi Nakagawa, Fujiko Ando, Hiroshi Shimokata, Hidenori Arai