Add risk of developing memory problems later in life to the list of consequences linked to poor oral health.
Not taking care of your mouth and teeth has already been associated with heart disease, diabetes, certain cancers and preterm birth. Now, a new study finds that folks with gum disease or tooth loss have evidence of shrinkage within the hippocampus, a brain area essential for memory.
"Retaining more healthy teeth without periodontal disease may help to protect brain health," said study author Dr. Satoshi Yamaguchi, an associate professor at Tohoku University Graduate School of Dentistry in Sendai, Japan.
The new study was not designed to say how, or even if, the number of healthy teeth or gum disease status causes dementia or memory problems, but previous research suggests that simmering inflammation may be a smoking gun.
"It has also been suggested that the pathogen of periodontal disease itself may invade the brain and damage nerve tissue," Yamaguchi said. "Fewer teeth reduce chewing stimulation, which can also lead to brain atrophy."
The new study included 172 people (average age: 67) with no memory problems at the outset. Participants had dental exams and took memory tests when the study started. They also had brain scans to measure the volume of the hippocampus at outset and again, four years later. Researchers also counted the number of teeth and checked for gum disease.
People with mild gum disease who had fewer healthy teeth and those with severe gum disease who had more healthy teeth showed a faster rate of shrinkage in the left hippocampus.
The increase in the rate of brain shrinkage due to one less tooth was equivalent to nearly one year of brain aging for people with mild gum disease, the study found.
Among folks with severe gum disease, an increase in brain shrinkage due to one more tooth was equivalent to 1.3 years of brain aging.
"It is important to retain more teeth, but retaining more teeth with severe periodontal disease may be detrimental to the brain," Yamaguchi said.
"Regular dental visits are important to control the progression of periodontal disease, and teeth with severe periodontal disease may need to be extracted and replaced with appropriate dentures," he said.
The study was published online July 5 in Neurology.
The message is clear: Take care of your oral health, said Dr. Saul Pressner, a dentist in private practice in New York City who reviewed the findings.
"Generally, good oral hygiene, flossing daily, using a water flosser, and regular twice-yearly dental checkups can all help prevent the onset and progression of periodontal disease," Pressner said.
Percy Griffin, director of scientific engagement at Alzheimer's Association, also reviewed the findings.
"This research adds to existing evidence connecting oral health and cognition," Griffin said. "We've previously seen some data to date linking periodontal diseases and cognitive decline, but this research looks specifically at the number of teeth."
Still, more research is needed in larger and more diverse groups of people to draw any definitive conclusions, Griffin said.
"We don't know at this time whether things like brushing your teeth will reduce your risk of developing cognitive decline as you age," he said. "What we can say is good oral hygiene is important for overall health and healthy aging."
Griffin noted that there are several other modifiable lifestyle risk factors, including exercise and diet, that can reduce your risk for thinking and memory problems as you age.
Learn more about what you can do to protect your brain health as you age at the Alzheimer's Association.
SOURCES: Satoshi Yamaguchi, PhD, DDS, associate professor, Tohoku University Graduate School of Dentistry, Sendai, Japan; Saul Pressner, DMD, dentist, New York City; Percy Griffin, PhD, director, scientific engagement, Alzheimer's Association, Chicago; Neurology, July 5, 2023