A study published online in Neurology in July 2022 supports the possibility that oral infections could be a risk factor for dementia. The study, conducted over a 20-year period, followed more than 8,000 individuals around the age of 63 years old. Participants that did not show signs of mild cognitive impairment (MCI) or dementia at baseline were grouped by the severity of their periodontal disease.

Results showed that 14 percent of participants with healthy gums and all their teeth at baseline developed dementia, compared with 18 percent of those with mild periodontal disease and 22 percent that had severe periodontal disease. The highest percentage (23 percent) of participants that developed dementia was found in those that were edentulous (toothless).

While results showed that participants with worse periodontal status were more likely to have risk factors for dementia, such as smoking, hypertension and diabetes, the study was sufficient in suggesting that oral health may be an important factor earlier in aging, in late adulthood.

The association between periodontal disease and MCI or dementia is “rooted in the infection hypothesis, meaning adverse microbial exposures in the mucosal surfaces of the mouth, especially the subgingival space,” says lead author Ryan T. Demmer, Ph.D. 

“One notion is that there could somehow be a direct infection of the brain with oral organisms, which posits that the oral organism could travel to the brain, colonize there and cause damage that impairs cognition,” he adds. Another possible mechanism is that chronic systemic inflammation in response to oral infections can eventually lead to vascular disease which, in turn, is a known risk factor for future dementia, he notes.

Although the study didn’t prove treating periodontal disease can help treat dementia, it does suggest the importance of paying attention to good oral hygiene and visiting dentists when appropriate.