Association between dietary inflammatory index score and incident dementia: results from the Framingham heart Study offspring cohort

BackgroundThe Dietary Inflammatory Index (DII), has been specifically designed to capture the inflammatory content of diet and has shown association with neurodegenerative disease related outcomes. But literature is limited on the role of diet-driven inflammation measured by the DII on incident all-cause dementia and Alzheimers disease dementia (AD). ObjectiveWe evaluated whether higher DII scores were associated with increased incidence of all-cause dementia and AD over 22.3 years of follow-up in the community-based Framingham Heart Study (FHS) Offspring cohort. Design, Setting, and ParticipantsObservational longitudinal study in the FHS Offspring cohort. Dementia surveillance for present study: until 2020. Data were analyzed from December 2020 to June 2022. Participants completed a validated 126-item food frequency questionnaires (FFQ), administered at FHS examination cycle 7 (1998-2001) and examination cycle 5 (1991-1995), and/or 6 (1995-1998). Individuals aged <60 years, with prevalent dementia, no dementia follow-up, other relevant neurological diseases, and/or no FFQ data were excluded. ExposureA DII score (based on the published method by Shivappa et al. 2014) was created based on previous studies linking individual dietary factors to six inflammatory markers (i.e. C-reactive protein, interleukin (IL)-1{beta}, IL-4, IL-6, IL-10, and tumor necrosis factor-alpha), consisting of 36 components. A cumulative DII score was calculated by averaging across a maximum of three FFQs. Main outcomes and measuresIncident all-cause dementia and AD. ResultsWe included 1487 participants (mean{+/-}SD, age in years 69 {+/-} 6; 53{middle dot}2% women; 31{middle dot}6% college graduates]). 246 participants developed all-cause dementia (including AD n=187) over a median follow up time of 13{middle dot}1 years. Higher DII scores were associated with an increased incidence of all-cause dementia and AD following adjustment for age and sex (Hazard ratio (HR) 1{middle dot}16, 95% confidence interval (CI) 1{middle dot}07 to 1{middle dot}25, p<.001; HR 1{middle dot}16, 95% CI 1{middle dot}06 to 1{middle dot}26, p=.001). The relationships remained after additional adjustment for demographic, lifestyle, and clinical covariates (HR 1{middle dot}21, 95% CI 1{middle dot}10 to 1{middle dot}33, p<0.001; HR1{middle dot}20, 95% CI1{middle dot}07 to 1{middle dot}35, p=.001). Conclusion and relevanceHigher DII scores were associated with a higher risk of incident all-cause dementia and AD. Although these promising findings need to be replicated and further validated, our results suggest that diets which correlate with low DII scores may prevent late-life dementia.