Diet Inflammatory Index and Dementia Incidence: A Population-Based Study

Background and objectives: Aging is characterized by a functional shift of the immune system towards a proinflammatory phenotype. This derangement has been associated with cognitive decline and has been implicated in the pathogenesis of dementia. Diet can modulate systemic inflammation; thus, it may be a valuable tool to counteract the associated risks for cognitive impairment and dementia. The present study aimed to explore the associations between the inflammatory potential of diet, assessed using an easily applicable, population-based, biomarker-validated diet inflammatory index (DII), and the risk for dementia in community-dwelling older adults. Methods: Individuals from the Hellenic Longitudinal Investigation of Aging and Diet (HELIAD) were included in the present cohort study. Participants were recruited through random population sampling, and were followed for a mean of 3.05 (SD=0.85) years. Dementia diagnosis was based on standard clinical criteria. Those with baseline dementia and/or missing cognitive follow-up data were excluded from the analyses. The inflammatory potential of diet was assessed through a DII score which considers literature-derived associations of 45 food parameters with levels of pro- and anti-inflammatory cytokines in the blood; higher values indicated a more pro-inflammatory diet. Consumption frequencies were derived from a detailed food frequency questionnaire, and were standardized to representative dietary intake normative data from 11 different countries. Analysis of dementia incidence as a function of baseline DII scores was performed by Cox proportional hazards models. Results: Analyses included 1059 individuals (mean age=73.1 years; 40.3% males; mean education=8.2 years), 62 of whom developed incident dementia. Each additional unit of DII was associated with a 21% increase in the risk for dementia incidence [HR=1.21 (1.03 – 1.42); p=0.023]. Compared to participants in the lowest DII tertile, participants in the highest one (maximal pro-inflammatory diet potential) were 3 [(1.2 – 7.3); p=0.014] times more likely to develop incident dementia. The test for trend was also significant, indicating a potential dose-response relationship (p=0.014). Conclusions: In the present study, higher DII scores (indicating greater pro-inflammatory diet potential) were associated with an increased risk for incident dementia. These findings might avail the development of primary dementia preventive strategies through tailored and precise dietary interventions.