Severe Periodontal Disease linked to increased dementia risk: Study

A total of 4,559 people was assessed at the end of the study, when they had been followed for an average of 18 years.

Overall, 1,569 people developed dementia during the study, or 19%. This was the equivalent of 11.8 cases per every 1,000 person-years. The study found that of the people who had healthy gums and all their teeth at the start of the study, 264 out of 1,826, or 14%, developed dementia by the end of the study. For those with mild gum disease, 623 out of 3,470, or 18%, developed dementia. For participants with severe gum disease, 306 out of 1,368, or 22%, developed dementia. And 376 out of 1,611, or 23%, developed dementia in the group that had no teeth. This was equal to a rate of 16.9 cases per 1,000 person-years.

When looking at both mild cognitive impairment and dementia, the group with no teeth had about twice the risk compared to participants with healthy gums and all their teeth. People with intermediate or severe gum disease, but who still had some teeth, had a 20% greater risk of developing mild cognitive impairment or dementia compared to the healthy group. These risks were after researchers accounted for other factors that could affect dementia risk, such as diabetes, high cholesterol 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 said.

A limitation of the study is the fact that initial gum examinations were made when the participants had an average age of 63, and it is possible that cognitive decline might have been begun before the start of gum disease and tooth loss.