Mediterranean-type diet and brain structural change from 73 to 76 years in a Scottish cohort

Objective: To assess the association between Mediterranean-type Diet (MeDi) and the change in brain MRI volumetric measures and mean cortical thickness across a three year period in older age (73 to 76 years). Methods: We focussed on two longitudinal brain volumes (total and grey matter; N = 401 and 398, respectively) plus a longitudinal measurement of cortical thickness (N = 323), for which the previous cross-sectional evidence of an association with the MeDi was strongest. Adherence to the MeDi was calculated from data gathered from a food frequency questionnaire at age 70, three years prior to the baseline imaging data collection. Results: In regression models adjusting for relevant demographic and physical health indicators, we found that lower adherence to the MeDi was associated with greater three-year reduction in total brain volume (explaining 0.5% of variance, p<0.05). This effect was half the size of the largest covariate effect (i.e., age). Cross-sectional associations between MeDi and baseline MRI measures in 562 participants were not significant. Targeted analyses of meat and fish consumption did not replicate previous associations with total brain volume or total grey matter volume. Conclusions: Lower adherence to the MeDi in an older Scottish cohort is predictive of total brain atrophy over a three-year interval. Fish and meat consumption does not drive this change, suggesting that other components of the MeDi or, possibly, all of its components in combination are responsible for the association.