Association of the oral microbiome with cognitive function among older adults: NHANES 2011-2012.

Background: An association between the gut microbiome and cognitive function has been demonstrated in prior studies. However, whether the oral microbiome, the second largest microbial habitant in humans, has a role in cognition remains unclear.
Design, Setting, Participants: Using weighted data from the 2011 to 2012 National Health and Nutrition Examination Survey, we examined the association between oral microbial composition and cognitive function in older adults. The oral microbiome was characterized by 16S ribosomal RNA gene sequencing. Cognitive status was assessed using the Consortium to Establish a Registry for Alzheimer's Disease immediate recall and delayed recall, Animal Fluency Test, and Digit Symbol Substitution Test (DSST). Subjective memory changes over 12 months were also assessed. Linear and logistic regression models were conducted to quantify the association of α-diversity with different cognitive measurements controlling for potential confounding variables. Differences in β-diversity were analyzed using permutational analysis of variance.
Results: A total of 605 participants aged 60-69 years were included in the analysis. Oral microbial α-diversity was significantly and positively correlated with DSST (β, 2.92; 95% CI, 1.01-4.84). Participants with higher oral microbial α-diversity were more likely to have better cognitive performance status based on DSST (adjusted odds ratio, 2.35; 95% CI, 1.28-4.30) and were less likely to experience subjective memory changes (adjusted odds ratio, 0.43; 95% CI, 0.25-0.74). In addition, β-diversity was statistically significant for the cognitive performance status based on DSST (P = 0.031) and subjective memory changes (P = 0.023).
Conclusions: Oral microbial composition was associated with executive function and subjective memory changes among older adults among older U.S. adults in a nationally representative population sample. Oral dysbiosis is a potential biomarker or therapeutic target for cognitive decline. Further work is needed to elucidate the mechanisms underpinning the association between the oral microbiome and cognitive function.
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