Periodontitis may double chances of cognitive decline, study says

Original article was found in the Dental Tribune.

Scientists have frequently linked some forms of periodontal disease with other inflammatory diseases, and now a new study has suggested that poor oral health may also have an impact on brain function. The findings showed that periodontal disease, especially in its more advanced stage, could increase the chance of developing mild cognitive impairment and dementia later in life.

According to the Centers for Disease Control and Prevention, approximately 64.7 million Americans aged 30 or older—the age group that makes up half of the total population—have periodontitis. The disease has been frequently linked with arthritis, diabetes, cancer and cardiovascular disease. Earlier this year, Dental Tribune International reported on a study that suggested that periodontitis may be caused by a parasite, Entamoeba gingivalis, that feeds on the cells of the gingival tissue and eventually destroys it.

In the present study, the researchers included 8,275 participants with an average age of 63 from the Atherosclerosis Risk in Communities Study. None of the participants had dementia at baseline. The researchers assessed the participants for mild cognitive impairment and dementia and performed a full periodontal examination that included measuring periodontal probing depth, bleeding and recession. They were then grouped according to the severity and extent of their periodontal disease and the number of lost teeth (or teeth replaced with implants).

At the start of the study, 22% of the participants had no periodontal disease, 12% had mild periodontal disease, 12% had severe periodontal inflammation and 8% had a low degree of tooth loss. Some of the participants, 12%, had periodontal disease in their molars, 11% had severe tooth loss, 6% had severe periodontal disease and 20% had no teeth at all. At the end of the study, the researchers assessed 4,559 out of 8,275 participants who had been followed for 18 years on average.

“We looked at people’s dental health over a 20-year period and found that people with the most severe gum disease at the start of our study had about twice the risk for mild cognitive impairment or dementia by the end,” co-author Dr. Ryan T. Demmer, associate professor in the Division of Epidemiology and Community Health at the University of Minnesota School of Public Health in Minneapolis, said in a press release. “However, the good news was that people with minimal tooth loss and mild gum disease were no more likely to develop thinking problems or dementia than people with no dental problems,” he added.

The findings showed that, overall, almost one-fifth of the participants, or 1,569 people, developed dementia during the study. This included 14% of the participants with healthy gingivae and a full set of teeth, 18% of those with mild periodontal disease, 22% of the participants who had severe periodontal disease and 23% of the edentulous participants.

The edentulous participants had about twice the risk of mild cognitive impairment and dementia compared with participants with healthy gingivae and a full set of teeth, whereas those with intermediate or severe periodontal disease and with only some teeth had a 20% greater risk of cognitive decline compared with the healthy group. The risks were assessed after the researchers had accounted for other factors that could affect the risk of developing dementia, including diabetes, a high blood cholesterol level and smoking.

“Good dental hygiene is a proven way to keep healthy teeth and gums throughout your lifetime. Our study does not prove that an unhealthy mouth causes dementia and only shows an association. Further study is needed to demonstrate the link between microbes in your mouth and dementia, and to understand if treatment for gum disease can prevent dementia,” Demmer noted.

The researchers cautioned that, since the participants chosen for the study had an average age of 63, their cognitive decline may have preceded periodontal disease and tooth loss.

The study, titled “Periodontal disease and incident dementia: The Atherosclerosis Risk in Communities Study (ARIC),” was published online on July 29, 2020, in Neurology, ahead of inclusion in an issue.