Could the key to preventing Alzheimer’s be lurking in your mouth? New research from the University of Exeter suggests a surprising link between oral bacteria and brain function as we age. The study, published in PNAS Nexus, reveals that certain bacteria are associated with better memory and attention, while others appear to increase the risk of cognitive decline and even Alzheimer’s disease.
This isn’t just about bad breath. The researchers identified two potential pathways through which oral bacteria could impact brain health. One possibility is that harmful bacteria directly enter the bloodstream, potentially causing damage to the brain. The other involves nitric oxide, a crucial chemical for brain communication and memory formation. An imbalance in oral bacteria can hinder the conversion of nitrate (found in vegetables) to nitric oxide, potentially impacting cognitive function.
The study examined 110 participants over the age of 50, some with no cognitive decline and others exhibiting Mild Cognitive Impairment (MCI). MCI is a decline in mental capabilities greater than expected with normal aging and is considered a significant risk factor for dementia and Alzheimer’s. Participants provided mouth rinse samples, which were then analyzed to identify the types and amounts of bacteria present.
The results were striking. Individuals with higher levels of Neisseria and Haemophilus bacteria showed better performance in memory, attention, and complex tasks. These individuals also had higher levels of nitrite in their mouths, a key component in the production of nitric oxide. Conversely, higher levels of Porphyromonas bacteria were more common in those with memory problems, while Prevotella bacteria were linked to low nitrite levels and were more prevalent in people carrying the APOE4 gene, a known risk factor for Alzheimer’s disease.
“Our findings suggest that some bacteria might be detrimental to brain health as people age,” said Dr. Joanna L’Heureux, lead author of the study from the University of Exeter Medical School. “It raises an interesting idea for performing routine tests as part of dental checkups to measure bacterial levels and detect very early signs of declining brain health.”
This research opens up exciting possibilities for early detection and intervention. Approximately 15% of older adults experience MCI, making it a critical target for preventative measures. If routine dental checkups could identify those at risk based on their oral microbiome, interventions could be implemented earlier, potentially slowing or even preventing the progression to dementia.
The study’s implications extend beyond diagnostics. Professor Anne Corbett, a co-author from the University of Exeter Medical School, suggests that treatments targeting the oral microbiome could be a key to dementia prevention. “If certain bacteria support brain function while others contribute to decline, then treatments that alter the balance of bacteria in the mouth could be part of a solution to prevent dementia. This could be through dietary changes, probiotics, oral hygiene routines, or even targeted treatments.”
While the study provides compelling evidence for the link between oral bacteria and brain health, further research is needed to fully understand the mechanisms involved. The researchers acknowledge that diet was not monitored in this study, and future work will explore the influence of dietary factors on the oral microbiome and its relationship with cognitive function. They also point out that 16S rRNA gene amplicon sequencing, while useful, has limitations in species-level accuracy, and future studies may utilize metagenomics for more precise identification.
The study, titled “Oral microbiome and nitric oxide biomarkers in older people with mild cognitive impairment and APOE4 genotype,” is a significant step forward in our understanding of the complex interplay between oral health and cognitive decline. It offers hope that by understanding and manipulating the bacterial ecosystem in our mouths, we may be able to develop new strategies to combat dementia and preserve cognitive function as we age. The idea that a simple mouth rinse could hold the key to a healthier brain is certainly something to chew on.