Mature man at dentist

Periodontitis may sound as if it’s strictly an oral health problem, but a study published Jan. 26 in Alzheimer’s & Dementia loosely links it to the risk for Alzheimer’s disease and related dementias and calls for more research into the association.

Researchers conducted oral health exams and took plaque samples from 486 participants over the course of 4.5 years. During that time, the participants also underwent magnetic resonance imaging (MRI) of their brains. Of the people studied, 83.9 were cognitively normal, 14.4% had mild cognitive impairment and 1.7% had dementia at the time of the oral exam. 

During oral exams, the scientists measured clinical attachment level at six sites on each tooth. Clinicians use that to specify the severity of periodontitis; 3 or 4 millimeters is moderate and anything more than 5 is severe. People who had a higher percentage of teeth with CAL at 4 mm or greater had lower entorhinal cortex volume and cortical thinning in regions that are linked to Alzheimer’s disease, the report stated. Having more teeth present was linked to lower odds for infarcts, lower white matter hyperintensity volume, higher entorhinal cortex volume, and less atrophy in regions associated with ADRD.

The researchers say that periodontitis was linked with MRI findings that are related to a person’s risk for Alzheimer’s disease or an associated dementia. Although this can’t prove periodontitis causes the cognitive diseases, the researchers say that their findings should prompt others to investigate that potential relationship.

“Our findings on the association of tooth counts with brain MRI features related to ADRD are in agreement with the literature reporting lower total brain volume or lower regional grey matter volume among participants with severe tooth loss,” the authors wrote.

Not much data exists about the role of microbial features of periodontitis on cognitive outcomes, and even less exists that can link oral profiles to brain MRI features. There is a complete lack of studies associating oral microbial/antibody profiles and brain MRI features. 

The team said that the role of periodontitis in the context of cognitive diseases such as Alzheimer’s disease requires more studies; MRI is just one tool that can explore the relationships. The scientists pointed out, however, that recent studies have shown that brief exposures to severe infection and intense inflammation also are linked to accelerated cognitive aging and elevated Alzheimer’s disease biomarkers.