# Differential Patterns of Gut and Oral Microbiomes in Hispanic Individuals with Cognitive Impairment

## TL;DR

This study finds that cognitive impairment in Hispanic individuals is linked to changes in both gut and oral microbiomes, with specific microbes associated with inflammation and periodontal disease.

## Contribution

The study identifies distinct oral and gut microbial patterns in Hispanic individuals with cognitive impairment, highlighting underexplored oral microbiome contributions.

## Key findings

- Cognitive impairment is associated with increased oral genera like Dialister, Fretibacterium, and Mycoplasma.
- Gut genera with anti-inflammatory properties, such as Shuttleworthia and Subdoligranulum, are decreased in cognitive impairment.
- No synergistic effects between oral and gut microbiomes were observed in cognitive impairment.

## Abstract

Alterations in both oral and gut microbiomes have been associated with Alzheimer’s disease and related dementia (ADRD). While extensive research has focused on the role of gut dysbiosis in ADRD, the contribution of the oral microbiome remains relatively understudied. This study aims to evaluate distinct patterns and potential synergistic effects of oral and gut microbiomes in a cohort of predominantly Hispanic individuals with cognitive impairment (CI) and without cognitive impairment (NC). We conducted 16S rRNA gene sequencing on stool and saliva samples from 32 participants (17 CI, 15 NC; 62.5% female, mean age = 70.4 ± 6.2 years) recruited in San Antonio, Texas, USA. Differential abundance analysis evaluated taxa with significant differences between both groups. While diversity metrics showed no significant differences between CI and NC groups, differential abundance analysis revealed an increased presence of oral genera such as Dialister, Fretibacterium, and Mycoplasma in CI participants. Conversely, CI individuals exhibited a decreased abundance of gut genera, including Shuttleworthia, Holdemania, and Subdoligranulum, which are known for their anti-inflammatory properties. No evidence was found for synergistic contributions between oral and gut microbiomes in the context of CI. Our findings suggest that like the gut microbiome, the oral microbiome of CI participants undergoes significant modifications. Notably, the identified oral microbes have been previously associated with periodontal diseases and gingivitis. These results underscore the necessity for further investigations with larger sample sizes to validate our findings and elucidate the complex interplay between oral and gut microbiomes in ADRD pathogenesis.