For people with Alzheimer's disease, having gum disease is tied to faster cognitive decline, according to a new study.
"What we have shown is that regardless of the severity of dementia (within this mild to moderate impaired group) that patients with more severe gum disease are declining more rapidly," said senior author Clive Holmes of the University of Southampton in the UK.
In other studies, Holmes and his coauthors have found that conditions such as chest infections, urinary tract infections, rheumatoid arthritis and diabetes are associated with faster disease progression in Alzheimer's, he said.
"We hadn't previously looked at gum disease because MDs tend to leave this in the hands of dentists but it is an important common low grade chronic infection," Holmes told Reuters Health by email.
The researchers observed 60 people with mild to moderate Alzheimer's disease living at home for six months. The participants did not smoke, had not been treated for gum disease within the previous six months, and had at least 10 teeth.
At the start, each participant completed a cognitive assessment, gave a blood sample, was examined by a dental hygienist and their main caregiver was interviewed to provide a medical and dental history. The same tests and interviews were repeated six months later.
Of the 60 people in the study, 22 had moderate to severe gum disease at the beginning of the study. By six months later, one participant had died, three had withdrawn from the study and three were lost to follow-up.
Cognitive score declined more for those who had periodontitis to begin with than for those who did not, as reported in PLoS One.
According to one theory, cognitive impairment leads to adverse oral health due to inattention to routine oral hygiene and care, said Dr. James M. Noble of the Taub Institute for Research on Alzheimer's Disease and the Aging Brain at Columbia University Medical Center in New York City, who was not part of the new study.
"The second, and the one I'm most intrigued by, is whether or not periodontal disease has an influence on cognitive outcomes of aging, either as an independent risk factor for (new-onset) cognitive impairment including Alzheimer disease, or more rapid decline once (Alzheimer's disease) has been diagnosed, as was suggested by this study," Noble told Reuters Health by email.
Gum disease may cause chronic low-grade inflammation in the rest of the body, and inflammation is associated with changes in the brain, he said.
"It is known that gum disease is associated with increased markers of inflammation," Holmes said.
But the new study indicates a connection between gum disease and cognitive decline, not necessarily that one causes the other, he said. Further studies need to assess whether treating the gum disease would also slow cognitive decline.
"Periodontitis has been associated with heart disease and stroke among other conditions," Noble said.
Based on this and other studies, "it seems to be good advice to brush and floss," Noble said.