Oral microbiome brain axis and cognitive performance in older adults

The human oral microbiota is a community of microorganisms that reside in the oral cavity, including lingual, buccal, and saliva, each niche with a distinct microbial composition. Alterations in oral microbiota have been associated with an increased risk of Alzheimer's disease (AD). This study used data from 143 older adults in the MIND trial to evaluate the association between oral microbiome and cognitive function. Oral niche-specific differences (saliva, buccal, and lingual), as well as the microbiome composition differences (α and β diversity), were associated with cognitive function. A lower abundance of Gemella and a higher abundance of anaerobic pro-inflammatory bacteria (e.g., Parvimonas, Treponema, Dialister) were linked to a lower Cognitive Z Score. Porphyromonas, previously linked to AD, was not associated with cognition. The outcomes suggest that oral microbiota may be a biomarker for cognitive function. Further research is required to assess whether oral microbiota-directed strategies can positively impact cognitive decline.