Oral microbiome diversity shapes the association between leisure-time physical activity and cognitive function among older adults

Regular leisure-time physical activity and the composition of the oral microbiome may influence late-life cognition, but their combined effects are unclear. We studied 575 US adults aged 60-69 years from a nationally representative survey with oral microbiome sequencing, self-reported leisure-time physical activity, and four standard cognitive tests of memory, verbal fluency, and processing speed. Higher weekly physical activity and meeting current guideline levels were associated with better memory and processing speed scores after multivariable adjustment. Greater oral microbiome diversity, including higher richness and evenness, was also related to better processing speed. Among participants who met activity guidelines, those with intermediate to high Shannon diversity and a specific community composition profile showed the most favorable verbal fluency and processing speed. These findings suggest that maintaining both regular physical activity and a diverse oral microbiome may jointly support cognitive function in later life and promote healthy aging.