Each unit increase in dietary inflammatory index scores was associated with a 21% higher risk of dementia over 3 years (HR 1.21, 95% CI 1.03-1.42, P=0.023), reported Nikolaos Scarmeas, MD, PhD, of Columbia University in New York City and the National and Kapodistrian University of Athens Medical School in Greece, and co-authors. https://8ed54231c9291789709f71a7b3ad9aca.safeframe.googlesyndication.com/safeframe/1-0-38/html/container.html
Compared with participants with the lowest inflammatory diet scores, those with the highest scores were three times more likely to develop incident dementia (HR 3.01, 95% CI 1.24-7.26, P=0.014), the researchers wrote in Neurology.
“A diet with a more anti-inflammatory content seems to be related to lower risk for developing dementia within the following 3 years,” Scarmeas told MedPage Today. Available dementia treatments are not very effective, he said — “it’s quite important that we find some measures to partially prevent it.”
“Diet might play a role in combating inflammation, one of the biological pathways contributing to risk for dementia and cognitive impairment later in life,” he added.
Evidence suggests certain foods, nutrients, and non-nutrient food components can modulate inflammatory status acutely and chronically. Earlier prospective research looked at dietary inflammatory potential and cognitive decline only in women, not in both sexes, the researchers noted.
Scarmeas and co-authors analyzed data from 1,059 older adults in the Hellenic Longitudinal Investigation of Aging and Diet (HELIAD), a population-based study that investigates associations between nutrition and age-related cognition in Greece. People with dementia at baseline were excluded from the analysis.
Participants had a mean baseline age of 73.1 and a mean 8.2 years of education; 40.3% were men. Dietary intake was evaluated through a semi-quantitative food frequency questionnaire validated for the Greek population and administered by a trained dietitian.
Foods and nutrients associated with the inflammatory biomarkers interleukin (IL)-1β, IL-4, IL-6, L-10, tumor necrosis factor (TNF)-α, and C-reactive protein in other studies were assigned a value and tallied to obtain a diet inflammatory index score. Higher dietary inflammatory index scores indicated a more inflammatory diet.
People in the first tertile had the lowest scores (-5.83 to -1.76, indicating a more anti-inflammatory diet), which represented about 20 servings of fruit, 19 of vegetables, four of legumes, and 11 of coffee or tea a week, on average. People in the third tertile had the highest scores (0.21 to 6.01) and a more pro-inflammatory diet, with a weekly average of nine servings of fruit, 10 of vegetables, two of legumes, and nine of coffee or tea.
Over an average follow-up of 3.05 years, 62 people were diagnosed with dementia. Higher dietary inflammatory index scores correlated with higher dementia risk. A gradual risk increase across higher tertiles suggested a dose-response relationship between the inflammatory potential of diet and incident dementia, Scarmeas and co-authors observed.
The relatively short follow-up period in this study raised the possibility of reverse causality, but further analysis showed the findings were not moderated by the presence of mild cognitive impairment at baseline.
Food frequency questionnaires may be subject to measurement error, the researchers acknowledged. Data about some dietary components, including eugenol, ginger, onion, turmeric, garlic, oregano, pepper, rosemary, and saffron, were not available. In addition, serum levels of inflammatory biomarkers were not obtained.
“Our results are getting us closer to characterizing and measuring the inflammatory potential of people’s diets,” Scarmeas said. “That, in turn, could help inform more tailored and precise dietary recommendations and other strategies to maintain cognitive health.”