A new study published in PNAS Nexus found that our mouth microbiome can help identify early signs of cognitive decline. The researchers determined that specific kinds of oral bacteria are associated with cognitive impairment, specifically memory decline and Alzheimer’s disease. By analyzing the oral microbiome, dentists can potentially offer a unique and non-invasive method for assessing the risk of developing this debilitating condition.
The new study analyzed the oral microbiome of 110 people over the age of 50 in the U.K., according to Women's Health. One group had no decline in brain function while the second group had mild cognitive impairment. The group with good memory function had large amounts of the bacteria Neisseria and Haemophilus in their mouths. The second group had higher levels of the bacteria Porphyromonas, common in periodontal disease, and were more likely to suffer memory problems. The researchers noted that the bacteria Prevotella, which is also commonly found in periodontal disease, is also associated with individuals who have the APOE4 gene, which is linked to Alzheimer’s disease.
Scientists theorize that bacteria in the mouth can trigger inflammation, which then travels to the brain, causing dementia. Another possibility is that when the bacteria is imbalanced, it can impact the formation of nitric acid from the nitrate found in the diet from sources such as vegetables. Nitric acid helps boost memory and communication in the brain.
Experts say it’s too soon to establish a cause-and-effect relationship between oral microbiome and Alzheimer’s, but other researchers believe it’s possible. A study conducted by a team from the Columbia College of Dental Medicine found a “clear link between poor periodontal health and brain magnetic resonance imaging (MRI) markers of Alzheimer’s disease and cognitive aging.”
Jennifer Bramen, a senior research scientist and director of neuroimaging at the Pacific Neuroscience Institute in Santa Monica, suggests that eating nitrate-rich foods like vegetables can “benefit the oral microbiome by promoting bacteria associated with better oral and cognitive health outcomes.”
Top researcher Panos N. Papapanou, a professor of dental medicine, who was one of the scientists who found the link between periodontal health and Alzheimer’s disease biomarkers, warns that periodontitis is highly prevalent among elderly Americans, and especially among those who have limited access to oral healthcare.
“There are data that demonstrate that people who take care of their oral health have lower general health care expenditures,” he says. “Taking care of your mouth is important for your oral health and function, but also an integral part of general wellbeing as people age.”