TUESDAY, Jan. 4 (HealthDay News) -- Elderly people who lose their teeth may be at increased risk for dementia, researchers have found.

The new study included more than 4,000 Japanese participants, 65 and older, who underwent a dental examination and a psychiatric assessment. Compared with participants who still had many of their natural teeth, those with fewer or no teeth were much more likely to have experienced some memory loss or have early-stage Alzheimer's disease.

The findings were published online Dec. 31 in Behavioral and Brain Functions.

Participants with symptoms of memory loss tended to report that they had visited the dentist rarely, if at all. Dr. Nozomi Okamoto, the study's principal investigator, said that this may be one explanation for the study's findings but suggested that there may be other links between tooth loss and memory problems.

"Infections in the gums that can lead to tooth loss may release inflammatory substances, which in turn will enhance the brain inflammation that cause neuronal death and hasten memory loss," she said in a news release from the journal's publisher. "The loss of sensory receptors around the teeth is linked to some of the dying neurons."

This may lead to a vicious cycle, Okamoto explained. The loss of these brain connections can cause more teeth to fall out, further contributing to cognitive decline.

More information

The U.S. National Institute of Neurological Disorders and Stroke has more about dementia.