Abstract
Background
Cortical thinning occurs with advancing age, with global thinning apparent by middle age. Specifically in Alzheimer's disease (AD), there is a distinct pattern of thinning of the cortical ribbon. While there is no cure or effective treatment currently available for AD, early intervention prevention programs hold considerable promise. Following particular dietary patterns represents one potential intervention strategy accessible to all, with adherence to healthy dietary patterns, such as the Mediterranean Diet (MeDi), proposed to be associated with improved brain health; however, the relationship of MeDi adherence to cortical thinning has not been thoroughly characterised.
Methods
Cognitively normal participants of the Australian Imaging, Biomarkers and Lifestyle study (n=269; mean age 71.74 ± 7.0; 43% male), completed the Cancer Council of Victoria food frequency questionnaire at baseline, from which a MeDi score was computed, and underwent MRI at baseline, and at least one other timepoint over a six year period, to determine cortical thickness. Linear mixed models assessed baseline cortical thickness and trajectories of cortical thinning dependent on MeDi adherence. All models included age, gender, body mass index, years of education, APOE ɛ4 allele carrier status and energy intake, with p-values false discovery rate adjusted.
Results
Cross-sectional analysis showed cortical thickness at baseline did not differ depending on MeDi adherence. However, longitudinally, higher MeDi score was associated with less decline in cortical thickness both globally and for multiple regions of interest (ROI): these ROI included frontal, occipital, parietal and temporal lobe structures (p<0.05; Cohen's f ranging from 0.18 to 0.34).
Conclusions
Attenuated cortical thinning seen in those with higher MeDi adherence suggests this diet may exert a protective effect with regards to cortical integrity. These findings are in agreement with our published work whereby MeDi adherence was associated with less cognitive decline over time. The results of the current study may inform the development of non-pharmacological interventions for maintaining cortical thickness and thereby reducing the risk of cognitive impairment and AD.