Scientists have discovered that the mix of bacteria in your mouth could serve as an early warning system for cognitive decline, with specific bacterial communities linked to both better and worse brain function. The research, published in PNAS Nexus, reveals how different oral bacteria interact with memory and thinking abilities in older adults.
The study, involving 120 participants over age 50, identified specific groups of oral bacteria that appear to influence cognitive health, particularly in people with mild cognitive impairment (MCI) – a condition that often precedes dementia.
The Good, The Bad, and The Bacterial
Two bacterial groups emerged as key players. The researchers found that higher levels of bacteria called Neisseria and Haemophilus were associated with better performance on cognitive tests measuring memory, executive function, and visual attention in people with MCI. These beneficial bacteria also showed links to higher levels of nitrite, a molecule important for brain health.
Conversely, different bacteria – particularly one species called Prevotella intermedia – were more common in people carrying the APOE4 gene, a known genetic risk factor for Alzheimer’s disease. The study found that Porphyromonas bacteria were also more abundant in people with mild cognitive impairment compared to healthy controls.
A Window Into Brain Health
The research provides new insights into how oral health might influence cognitive decline. The team analyzed oral samples from 60 healthy participants and 55 individuals with MCI, looking at both bacterial communities and chemical markers of nitric oxide, a molecule crucial for brain function.
“The findings underscore the delicate balance between different groups of oral bacteria and their potential influence on brain health,” notes the research team. The study suggests that certain bacteria may help maintain healthy brain function by producing beneficial compounds, while others might contribute to cognitive decline.
Early Warning System
Particularly intriguing was the discovery that specific bacterial patterns could identify people carrying the APOE4 gene variant, which increases Alzheimer’s risk. This finding suggests that oral bacteria profiles might serve as early indicators of dementia risk, potentially before traditional symptoms appear.
Future Implications
The research opens new possibilities for early intervention and prevention. By understanding how oral bacteria influence brain health, scientists might develop new approaches to support cognitive function as people age – potentially through targeted probiotics or dietary interventions.
The findings are particularly relevant for individuals at higher genetic risk for dementia, suggesting that maintaining oral health might be especially crucial for these populations.
Looking Ahead
While more research is needed to fully understand these connections, the study provides compelling evidence that the mouth-brain connection may be more important than previously thought. The research team emphasizes that future studies should explore whether influencing these bacterial communities could help prevent or delay cognitive decline.
The research was conducted at the University of Exeter and funded by the National Institute for Health and Care Research, the Medical Research Council, and the Wellcome Trust. The study involved 120 participants from the PROTECT study, an online aging cohort tracking cognitive health in older UK adults.
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