Dementia is on the rise among the general population, and it is expected to triple by 2050, as people continue to live longer.

Research has focused on modifiable risk factors for dementia and cognitive decline — such as cardiovascular disease, smoking and an unhealthy diet. But healthy teeth and gums may play a role, too.

A team of European researchers reviewed nearly 50 studies on the potential of preventive oral health measures to prevent or slow down cognitive decline. Their findings suggest that poor oral health, such as periodontal or gum disease, increases the risk of cognitive decline and dementia.

Poor periodontal health was associated with a 23 percent increased risk of cognitive decline and a 21 percent increased risk of dementia.

Findings from 47 studies were analyzed for the current review. Poor periodontal health was defined as having periodontitis, or infection of the gums; tooth loss; loss of bone that supports the teeth; and deep pockets or spaces around the teeth caused by swelling or inflammation.

Poor periodontal health was associated with a 23 percent increased risk of cognitive decline and a 21 percent increased risk of dementia. Tooth loss was independently associated with a 23 percent increased risk of cognitive decline and a 13 percent increased risk of dementia.

There are a number of routes by which periodontal disease may lead to cognitive decline and dementia, the study’s lead author, Sam Asher, a junior scientist at the University of Eastern Finland, explained. Periodontal inflammation can increase systemic inflammation, which in turn can increase the risk of neuroinflammation, a known risk factor for dementia. Another possibility is that periodontal bacteria could also affect the brain, and thus affect cognition, through mechanisms that are not yet clear.

Tooth loss can affect the ability to chew food properly, and this could cause nutritional deficits that affect cognition. Finally, poor periodontal health and dementia have several risk factors in common, including cardiovascular and metabolic diseases, and these may also be a way in which gum health affects cognition.

“From a clinical perspective, our findings emphasize the importance of the monitoring and management of periodontal health in the context of dementia prevention,” the researchers write. To get a better picture of the relationship between oral health and cognitive health, longitudinal studies that follow older persons for 10 or more years are needed, along with standardized measures of cognitive function and periodontal health.

“We are currently working on a few longitudinal studies to assess various aspects of the associations between periodontal and cognitive health and account for some of the limitations and gaps in knowledge in the current body of evidence on this novel topic,” Asher told TheDoctor. Further long-term studies would help clarify whether periodontal disease is a risk factor for cognitive decline or dementia or simply a consequence of it.

The review is published in the Journal of the American Geriatrics Society.