Anti-inflammatory diet tied to lower dementia risk

Clinical takeaway: For older patients who already carry Alzheimer or neurodegeneration biomarkers, an anti-inflammatory diet may be the pattern most worth emphasizing; a Mediterranean or heart-healthy diet may still benefit those whose biomarkers remain low.

Healthier diets have long been tied to lower dementia risk, but most studies stop short of asking whether that holds once Alzheimer pathology is already present. A 15-year Swedish cohort study took up that question across three dietary patterns and biomarker strata. The result split around biomarker status: among older adults already showing signs of Alzheimer pathology and neurodegeneration, only a diet low in inflammatory potential tracked with lower dementia risk.

Among participants with elevated biomarkers, each standard-deviation increase in adherence to the anti-inflammatory pattern (the reversed Empirical Dietary Inflammatory Index, rEDII) was linked to lower dementia risk across all three markers: about 29% lower with high p-tau217 (a marker of Alzheimer pathology), 21% lower with high neurofilament light chain (neuronal injury), and 27% lower with high glial fibrillary acidic protein (astrocyte activation).

The other two patterns showed the reverse: higher adherence to the Mediterranean diet and a heart-healthy index (the AHEI) lined up with lower risk only when biomarkers were still in the lower range, not once pathology had set in. Over a mean 8.4 years of follow-up, 240 of 1,865 participants developed dementia.

The cohort study drew on 1,865 dementia-free adults aged 60 and older from the Swedish National Study on Aging and Care in Kungsholmen, followed for up to 15 years. Diet was assessed by repeated food frequency questionnaires and scored against three patterns; baseline blood biomarkers sorted participants into higher- and lower-risk groups. Dementia was identified through clinical exams, medical records, and death certificates.

The split hints at why the patterns diverged. The anti-inflammatory index captures foods tied to lower levels of inflammatory markers like interleukin-6 and tumor necrosis factor, and chronic inflammation is thought to be a key driver of neurodegeneration once pathology takes hold. That may explain why this diet, more than the others, tracked with lower risk in people already carrying the biomarkers. The Mediterranean and heart-healthy diets, oriented toward cardiovascular health, may act earlier, before damage accumulates.

"Phenotyping individuals according to levels of underlying neurodegenerative pathology may aid in identifying those most likely to benefit from specific dietary interventions," wrote Sokratis Charisis, MD, of Massachusetts General Hospital and Harvard Medical School, in an accompanying commentary.

Source: Mrhar A, et al. JAMA Netw Open. 2026 Jun 25. Diet quality and dementia risk in older adults with Alzheimer pathology