The Impact of Dietary Patterns on Cognitive Function and Dementia Risk in Older Adults

Abstract

Dietary patterns are increasingly recognized as modifiable determinants of late-life cognitive health. This review synthesizes evidence from prospective cohorts, randomized trials, and mechanistic studies linking whole-diet approaches—particularly Mediterranean, DASH, and MIND patterns—to cognitive trajectories and dementia risk in older adults. We summarize biological pathways (vascular, metabolic, inflammatory, oxidative, and microbiome-gut–brain axes), evaluate study quality and heterogeneity, and contrast diet-only versus multi-domain lifestyle interventions. Overall, adherence to Mediterranean-style and MIND dietary patterns is consistently associated with slower cognitive decline and lower incidence of Alzheimer’s disease (AD) and all-cause dementia, with supportive (though mixed) findings from trials. Evidence points to benefits mediated by improved cardiometabolic profiles, reduced neuroinflammation, enhanced cerebrovascular health, and neurotrophic signaling. Research gaps include long-duration trials with incident dementia outcomes, culturally adapted diet indices, and biomarker-anchored adherence measures. We propose a practice-oriented framework for clinical and public-health translation, emphasizing feasible dietary targets, equity, and implementation science.