Is there a link between oral health and the rate of cognitive decline?

Better oral hygiene and regular dental visits may play a role in slowing cognitive decline as people age, although evidence is not definitive enough to suggest that one causes the other. The findings, published in the Journal of the American Geriatrics Society, come from the first systematic review of studies focused on oral health and cognition—two important areas of research as the older adult population continues to grow, with some 36% of people over age 70 already living with cognitive impairments.

Researchers have questioned whether an association exists between oral health and cognitive status for older adults. "Clinical evidence suggests that the frequency of oral health problems increases significantly in cognitively impaired older people, particularly those with dementia," said Bei Wu, PhD, of Duke University's School of Nursing in Durham, NC. "In addition, many of the factors associated with poor oral health—such as poor nutrition and systemic diseases like diabetes and cardiovascular disease—are also associated with poor cognitive function."

To look for a link between oral health and cognitive status, Dr. Wu and her colleagues analyzed relevant cross-sectional (data collected at one specific point in time) and longitudinal (data collected over an extended period of time) studies published between 1993 and 2013.

Some studies found that oral health measures such as the number of teeth, the number of cavities, and the presence of periodontal disease (also known as "gum disease") were associated with an increased risk of cognitive decline or dementia, while others studies were unable to confirm any association. Researchers were also quick to note that findings based on the number of teeth or cavities are conflicting, and limited studies suggest that periodontal conditions such as gingivitis are associated with poorer cognitive status or cognitive decline.

"There is not enough evidence to date to conclude that a causal association exists between cognitive function and oral health," said Dr. Wu. "For future research, we recommend that investigators gather data from larger and more population representative samples, use standard cognitive assessments and oral health measures, and use more sophisticated data analyses."