Inflammatory diets may increase risk for incident dementia

Diets with higher inflammatory potential appeared linked to increased risk for incident dementia, according to results of a population-based study published in Neurology.

“We do not well understand the mechanism via which diet may affect brain health,” Nikolaos Scarmeas, MD, PhD, of the 1st department of neurology, Aiginition Hospital, National and Kapodistrian University of Athens Medical School, Greece, told Healio Neurology. “It may have some influence on brain vascular health, on brain oxidative stress, on neurodegenerative changes, etc. The present study provides some evidence that diet may influence cognitive function via inflammation-related mechanisms.”

Scarmeas and colleagues analyzed data from participants of the Hellenic Longitudinal Investigation of Aging and Diet who were recruited via random population sampling and followed for a mean of 3.05 years. Standard clinical criteria were used for dementia diagnosis. Researchers excluded participants with baseline dementia and/or missing cognitive follow-up data. Using a diet inflammatory index (DII) based on literature-derived associations between 45 food parameters with levels of pro- and anti-inflammatory cytokines in the blood, they examined the inflammatory potential of diet. Higher values suggested a diet with more inflammation potential. Further, researchers derived consumptions frequencies via a detailed food frequency questionnaire. They standardized these frequencies to representative dietary intake data from 11 countries. Using Cox proportional hazards models, they conducted analysis of dementia incidence as a function of baseline DII scores.

Among 1,059 individuals (mean age, 73.1 years; 40.3% men) included in the analyses, 62 developed incident dementia. Scarmeas and colleagues noted an association between each additional DII unit and a 21% increased risk for dementia incidence (HR = 1.21; 95% CI, 1.03-1.42). Participants in the higher DII tertile were three times more likely to develop incident dementia compared with those in the lowest tertile. A potential dose-response relationship arose, based on the test for trend being significant.

“People who were eating a more anti-inflammatory diet had lower risk for developing dementia over the course of approximately 3 years,” Scarmeas said. “However, we should note that the study was an observational one, not a clinical trial. Therefore, it does not prove that eating an anti-inflammatory diet prevents brain aging and dementia, it only shows an association.”