Higher Diet Inflammatory Index Associated With Increased Dementia Risk

Nikolaos Scarmeas, MD, MS

An increased risk of dementia was found to be associated with higher diet inflammatory index (DII) scores, suggesting greater pro-inflammatory diet potential, data from a recent study published in Neurology suggest. 

A total of 1059 patients with an average age of 73.1 years (standard deviation [SD], 5) were included in analyses from the Hellenic Longitudinal Investigation of Aging and Diet study, a population-based, multidisciplinary study estimating epidemiology of dementia and other neuropsychiatric conditions in the aging Greek population. Sixty-two of the 1059 participants developed incident dementia over a mean follow-up period of 3.05 years (SD, 0.85; range, 6.08), with 53 developing Alzheimer disease (AD), 5 developing vascular dementia, 3 developing Lewy body dementia, and 1 developing dementia due to an underlying psychiatric disorder. 

Investigators found a 21% increase in the risk for dementia incidence with each additional unit of DII (HR, 1.21 [95% CI, 1.03-1.42]; P = .023). Participants in the highest DII tertile, defined as those who had the maximal pro-inflammatory diet potential, were 3 times more likely to develop incident dementia, compared with those in the lowest DII tertile (95% CI, 1.2-7.3; P = .014). When testing for trend, the relationship was also significant, with the positively for a dose-response relationship (P = .014). 

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“In the present study, we were able to demonstrate that the inflammatory potential of diet, assessed using an easily applicable tool, was positively associated with the risk for dementia in community-dwelling non-demented older adults,” corresponding author Nikolaos Scarmeas, MD, MS, associate professor of clinical neurology; and adjunct associate research scientist, Taub Institute for Research in Alzheimer’s Disease and the Aging Brain, the Gertrude H. Sergievsky Center, Columbia University, et al wrote. “Although the validity and reproducibility of these associations need to be ascertained by further studies, they contribute substantial information to the present literature and might assist the efforts for the development of population-level dietary guidelines and effective healthy aging strategies.”

Participants were community-dwelling older adults who had no baseline dementia, were available for follow-up data, and had available baseline dietary information. DII score assessed the inflammatory potential of diet, considering literature-derived associations of 45 food parameters. Levels included pro- and anti-inflammatory cytokines in the blood, and higher values indicated a more pro-inflammatory diet. 

A detailed, semiquantitative food frequency questionnaire (FFQ) had information on all main food groups consumed over the last month, administered to patients by a trained dietitian. Investigators then used the USDA food composition tables to classify certain foods into macro- and micro-nutrient intakes, selecting foods that most appropriately matched those consumed in Greece. 

The study was limited due to the loss of several patients to follow-up (n = 689), potentially creating a threat to the study’s internal validity in introducing informative censoring. Additionally, dementia diagnosis was based solely on clinical criteria, introducing the possibility of disease misclassification bias. Reverse causality was also a concern due to the relatively short follow-up period, which had a mean of 3.05 years (SD, 0.85). Another potential limitation noted was the possibility of measurement error for dietary intake via the FFQ.

Social and lifestyle factors can impact patients’ risk of developing AD specifically. James E. Galvin, MD, recently sat down with NeurologyLive® to discuss this importance of considering these aspects, as there has been growing evidence over the past decade that specific choices can play a significant role in the risk of this disease. Among them include dieting and exercising properly, lowering smoking and alcohol intake, and engagement in late-life cognitive activities that keep the mind active. Hear more about what he had to say in the video below. 

REFERENCE

Sokratis C, Ntanasi E, Yannakoulia M, et al. Diet inflammatory index and dementia incidence: A population-based study. Neurology. Published online November 10, 2021. doi:10.1212/WNL.0000000000012973