Glenn Biggs Institute for Alzheimer’s & Neurodegenerative Diseases at UT Health San Antonio, Boston University School of Medicine and the Framingham Heart Study have found that higher scores on the Dietary Inflammatory Index (DII) are associated with an increased incidence of all-cause dementia and Alzheimer’s disease (AD) dementia.
Dementia is projected to reach 152 million cases by 2050, according to the World Health Organization, placing an increasing strain on caregivers and health care systems. While advancements in drug therapies have improved care and targeted disease mechanisms, preventive measures remain elusive.
Diet has been identified as a potential avenue for reducing dementia risk. Previous observational studies have linked anti-inflammatory diets, such as the Mediterranean and MIND diets, with slower cognitive decline and lower dementia risk.
The DII is a standardized tool that quantifies the inflammatory potential of diets by analyzing nutrients, bioactive compounds, and food components. Prior studies have suggested that higher DII scores are associated with systemic inflammation, which is separately understood to contribute to neurodegenerative processes.
In the study, “Association Between Dietary Inflammatory Index Score and Incident Dementia,” published in Alzheimer’s & Dementia, researchers utilized data from the Framingham Heart Study (FHS) Offspring cohort to analyze dietary data, dementia incidence, and Alzheimer’s disease diagnoses over a median follow-up period of around 13 years.
The study cohort included 1,487 participants aged 60 or older and free of dementia at baseline. Dietary information was obtained from food frequency questionnaires (FFQs) administered during three examination cycles (1991–1995, 1995–1998, and 1998–2001).
DII scores were calculated for 36 dietary components, which were categorized as either anti-inflammatory (e.g., fiber, vitamins A, C, D, E, omega-3 fats) or pro-inflammatory (e.g., saturated fats, total energy intake, and carbohydrates). Higher positive scores indicated more pro-inflammatory diets.
Dementia diagnoses, including Alzheimer’s disease, were ascertained using a combination of neurological evaluations, neuropsychological tests, and medical record reviews. Continuous surveillance ensured the comprehensive capture of dementia cases.
Of the 1,487 participants, 246 developed all-cause dementia, including 187 cases of Alzheimer’s disease. Participants with higher DII scores, indicating pro-inflammatory diets, had significantly increased risks of both all-cause and AD dementia.
For every unit increase in the DII score, the risk of all-cause dementia rose by 21%. A similar increase in DII scores was associated with a 20% higher risk of AD dementia.
When participants were grouped based on their DII scores, those with the most pro-inflammatory diets were 84% more likely to develop all-cause dementia compared to those with the most anti-inflammatory diets.
The association persisted after adjusting for demographic, lifestyle, and clinical factors, including age, sex, education, body mass index, physical activity, smoking, and total energy intake.
Findings support the hypothesis that dietary inflammation contributes to neurodegenerative processes, likely through systemic inflammation pathways. Chronic inflammation, driven by diets high in pro-inflammatory components such as saturated fats and processed carbohydrates, may exacerbate brain inflammation and promote amyloid-beta plaque formation, a hallmark of Alzheimer’s disease.
Anti-inflammatory nutrients, like omega-3 fatty acids and flavonoids, may counteract these effects by reducing cytokine production and supporting brain health. Studies such as the PREDIMED trial have demonstrated that anti-inflammatory diets, like the Mediterranean diet, can improve cognition, likely by reducing systemic inflammation.
As an observational study, there is no way to establish specific causality. The current study’s finding of an 84% risk swing correlation between highest and lowest DII scores is still highly significant.
The results suggest dietary interventions emphasizing anti-inflammatory foods may reduce dementia risk as a long-term strategy. Incorporating DII-type assessments into dietary guidelines could help identify at-risk individuals and develop targeted nutrition strategies at a population level.
