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Oral microbiome brain axis and cognitive performance in older adults
Darbaz Adnan1, Phillip A Engen1, Michelle Villanueva1
1Rush Center for Integrated Microbiome and Chronobiology Research, Rush Medical College, Rush University Medical Center, Chicago, IL, USA.
NPJ Dementia
|March 20, 2026
Summary
The oral microbiome composition, particularly lower levels of Gemella and higher levels of anaerobic bacteria, is linked to cognitive function in older adults. These findings suggest the oral microbiome may serve as a biomarker for cognitive health.
Area of Science:
- Microbiology
- Neuroscience
- Gerontology
Background:
- The human oral cavity hosts a complex microbial community, the oral microbiota, with distinct compositions across different niches (saliva, buccal, lingual).
- Alterations in the oral microbiome have been implicated in the increased risk of Alzheimer's disease (AD).
Purpose of the Study:
- To investigate the association between the oral microbiome and cognitive function in older adults.
- To explore niche-specific differences in the oral microbiome related to cognitive performance.
Main Methods:
- Analysis of oral microbiome data from 143 older adults participating in the MIND trial.
- Evaluation of oral niche-specific microbial differences (saliva, buccal, lingual) and microbiome diversity (alpha and beta diversity).
- Correlation of microbial composition with cognitive function scores (Cognitive Z Score).
Main Results:
- Oral microbiome composition, including niche-specific differences and diversity metrics, was associated with cognitive function.
- Lower abundance of *Gemella* and higher abundance of anaerobic pro-inflammatory bacteria (e.g., *Parvimonas*, *Treponema*, *Dialister*) correlated with lower Cognitive Z Scores.
- *Porphyromonas*, previously linked to AD, showed no association with cognitive function in this cohort.
Conclusions:
- The oral microbiota composition may serve as a potential biomarker for cognitive function in older adults.
- Further research is warranted to explore oral microbiota-directed interventions for cognitive decline.
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