June 19, 2019
Good dental health may be important for maintaining good brain health, according to a new report. Researchers found that people who die with Alzheimer’s disease are more likely to have a bacterium linked to gum disease in the brain than those who don’t have Alzheimer’s disease. They also showed the bacterium can find its way from the mouth to the brain in mice.
The bacterium, Porphyromonas gingivalis, is a major cause of periodontitis, the most serious form of gum disease. The findings, presented at the 2019 Experimental biology meeting, add to a growing body of evidence linking poor dental health to Alzheimer’s disease.
“Oral hygiene is very important throughout our life, not only for having a beautiful smile but also to decrease the risk of many serious diseases,” said study author Jan Potempa, a professor at the University of Louisville School of Dentistry and head of the department of microbiology at Jagiellonian University in Krakow, Poland. “People with genetic risk factors that make them susceptible to Alzheimer’s disease should be extremely concerned with preventing gum disease.”
For the study, Dr. Potempa and his colleagues compared brain samples from people with and without Alzheimer’s disease who were roughly the same age when they died. They found P. gingivalis was more common in the brains of those with Alzheimer’s, based on DNA traces of the bacterium and the presence of its main active component, known as gingipains.
In studies using mice, they showed P. gingivalis can move from the mouth to the brain; there is a quite direct route from the nasal cavity to the brain, following the path that nerves involved in smell detection are taking. They also showed that this migration can be blocked by chemicals that interact with gingipains. Researchers are looking at drugs that block these chemicals to see if they may help to stem the onset of Alzheimer’s disease.
P. gingivalis commonly begins to infiltrate the gums during the teenage years. About one in five people under 30 have low levels of the bacterium in their gums. While it is not harmful in most people, if it grows to large numbers the bacteria provoke the body’s immune system to create inflammation, leading to redness, swelling, bleeding and the erosion of gum tissue.
Increasingly, experts think that inflammation may be tied to Alzheimer’s disease and other serious conditions.
The best way to prevent P. gingivalis from growing out of control is by brushing and flossing regularly and visiting a dental hygienist at least once a year, Dr. Potempa said. Smokers and older people are at increased risk for infection. Genetic factors are also thought to play a role in gum disease, but they are not well understood.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Experimental Biology 2019 meeting, April 7, 2019