Association of the Planetary Health Diet with dementia risk and brain pathology.

BACKGROUND: The Planetary Health Diet (PHD), proposed by the EAT-Lancet Commission, promotes human and environmental health, yet its relevance to dementia and brain pathology remains unclear. METHODS: In the Rush Memory and Aging Project, 926 dementia-free adults (mean age = 79.4) were followed for up to 20 years. Baseline diet was assessed using a >142-item food-frequency questionnaire, and PHD adherence was categorized into tertiles. Dementia and Alzheimer's dementia (AD) were clinically diagnosed. Among 581 decedents, brain autopsies quantified Alzheimer's disease, vascular, and other pathologies. Cognitive function proximate to death was measured via a standardized neuropsychological battery. RESULTS: Over a median 7.5-year follow-up, 317 participants developed dementia. High PHD adherence was associated with lower risks of all-cause dementia (hazard ratio [HR] = 0.71) and AD (HR = 0.70), reduced Alzheimer's disease pathologies, a 2.17-year delay in dementia onset, and better end-of-life cognition. CONCLUSION: High PHD adherence may support healthier brain aging and cognitive resilience.