Associations of Diet Quality with Midlife Brain Volume: Findings from the UK Biobank Cohort Study

Background: Higher quality diets may be related to lower dementia rates. Midlife is emerging as a critical life stage for a number of dementia risk factors. Objective: This study examines whether diet quality is related to brain structure during midlife, and if this differs by sex. Methods: This study used data from 19184 UK Biobank participants aged 40–65 years. Diet quality was assessed using three dietary indices including the Mediterranean Diet Score (MDS), Healthy Diet Score (HDS), and Recommended Food Score (RFS). MRI brain measures included total, grey, white and hippocampal volume. Linear regression examined associations between diet quality and brain volume, controlling for potential confounders. Results: Better quality diet across all indices was significantly related to larger grey matter volume: MDS β= 429.7 (95%CI: 65.2, 794.2); HDS β= 700.1 (348.0, 1052.1); and RFS β= 317.1 (106.8, 527.3). Higher diet scores were associated with greater total volume: HDS β= 879.32 (286.13, 1472.50); RFS β= 563.37 (209.10, 917.65); and white matter volume: RFS β= 246.31 (20.56, 472.05), with the exception of Mediterranean diet adherence. Healthy eating guidelines and dietary variety associations with total and grey matter volume were more prominent in men. Conclusion: Findings suggest that diet quality is associated with brain structure during midlife, potentially decades prior to the onset of dementia.