The microbial ecosystems within our mouths may affect our cognitive function as we age, according to a UK study.
Researchers at the University of Exeter in England have identified two possible links between the mouth and the mind: pathogenic oral bacteria could enter the bloodstream and move to the brain, or pathogenic oral bacteria could displace nitrate-reducing bacteria, which help create nitric oxide the brain needs for synaptic plasticity and long-term potentiation.
Publishing their findings in PNAS Nexus, the team characterised the oral microbiome of 115 participants, 55 of whom had mild cognitive impairment.
Some participants had the apolipoprotein E4 (APOE4) allele, which increases risk for cognitive decline and Alzheimer’s disease. A high relative abundance of bacteria in the genus Neisseria was associated with better executive function and visual attention within the mild cognitive impairment group.
Among healthy participants, Neisseria correlated with working memory. High prevalence of bacteria in the genus Porphyromonas predicted mild cognitive impairment status, while Prevotella intermedia predicted APOE4-carrier status. According to the authors, diet can affect the oral microbiome, and a nitrate-rich diet (such as the Mediterranean and ‘Dietary Approaches to Stop Hypertension’ diets), favours bacteria associated with good cognitive outcomes.
