Cognitive Impairment Is Associated with Alterations in Diet Quality and Inflammatory Biomarkers in Older Adults: A Cross-Sectional Analysis of Data Collected from the Microbiome in Aging Gut and Brain (MiaGB) Consortium Cohort.

Background: Research suggests that gut inflammation and alterations in intestinal barrier function may be important mechanisms linking diet, systemic inflammation, and cognitive outcomes.

Objectives: The objective of this study was to explore the relationship between diet, cognitive health, and inflammatory markers in older adults. It was hypothesized that cognitive impairment would be associated with lower diet quality and higher levels of inflammatory markers.

Methods: A cross-sectional analysis was conducted using data from the microbiome in aging gut and brain consortium cohort. Participants aged 60 y and older were assessed for cognitive status using the Montreal Cognitive Assessment (MoCA), diet quality using the Healthy Eating Index-2020 (HEI-2020), and dietary inflammatory potential using the dietary inflammatory index (DII). Inflammatory biomarkers were measured in plasma and stool samples, including interleukin (IL)-6, IL-1β, lipopolysaccharide-binding protein (LBP), toll-like receptor 4 (TLR4), and zonula occludens-1 (ZO-1).

Results: Among 217 participants, 33.6% presented with cognitive impairment based on MoCA scores. There were no differences in DII and HEI-2020 scores between participants with and without cognitive impairment. The only significant finding related to the components of the HEI was a higher adequacy of dairy intake in those without cognitive impairment (54.8%) compared with those with cognitive impairment (44.4%, P = 0.035). Key inflammatory markers, including IL-6, IL-1β, LBP, and TLR4, were elevated in those with cognitive impairment, whereas plasma ZO-1 levels were reduced. Stool calprotectin levels were notably higher in those with cognitive impairment, suggesting increased intestinal inflammation. There was a weak but significant correlation between stool calprotectin and DII score (r_s = 0.283, P = 0.046).

Conclusions: The findings suggest that elevated inflammatory markers and disrupted intestinal barrier integrity may contribute to cognitive decline. These results highlight the need to develop dietary interventions to mitigate cognitive impairment through modulation of inflammation.