Our second key finding: Gray matter integrity measures in these regions were significantly associated with lower general cognitive ability after adjustment for age, sex, and education.

Our first key finding: Higher CSVD burden was linked to widespread, regionally specific gray matter abnormalities. These included altered diffusivity, tissue integrity, and thickness in the cingulate, insular, and temporal cortices, as well as the hippocampus.

We analyzed neuroimaging and cognitive data from 2,603 participants of the population-based Hamburg City Health Study. Using multi-modal MRI we derived a composite CSVD burden score and assessed regional gray matter micro- and macrostructure.

In participant subgroups with a higher abundance of periodontitis-related taxa, we observed poorer cognitive performance, reduced cortical thickness/subcortical volumes, and elevated leukocyte counts, even after adjusting for covariates.

Leveraging this network, we systematically examined associations between periodontal microbiome profiles and 37 brain health-related phenotypes, including cognitive function, brain structure, mental health, inflammatory biomarkers, diet, vascular risk factors, and demographics.

This “microbiome similarity network” exhibited a continuous pathogenicity gradient: bacterial taxa linked to periodontitis were more abundant in participants on one end, whereas bacteria associated with health or other oral conditions were more predominant on the opposite end.

Topological data analysis revealed a network grouping participants based on their similarity of oral microbiome profiles.

Using 16S rRNA sequencing data of 1,026 Hamburg City Health Study participants paired with topological data analysis (Mapper & SAFE), we integrated microbiome abundance with clinical oral health, neuroimaging, cognitive tests, inflammatory markers, diet, and vascular risk factors.