If bad breath and tooth decay aren't enough of an incentive to brush your teeth, reducing your risk of dementia might be.
That's right—scientists are increasingly seeing a consistent link between poor oral health and cognitive decline.
Over 5 million American adults over the age of 65 live with dementia, according to 2014 data from the U.S. Centers for Disease Control and Prevention. The condition comes in different forms—the most common of which is Alzheimer's disease—and is characterized by an impaired ability to remember, think and make decisions.
Numerous studies have shown that individuals with poor oral health are more likely to develop this disease, but exactly how they are linked has remained unclear. In a recent umbrella review, published in the journal Aging Research Reviews, researchers from the National Yang-Ming Chiao Tung University in Taiwan gathered data from 28 systemic reviews to clarify which factors were involved in these associations and how they might be used to inform evidence-based clinical advice in the future.
"Most systematic reviews consistently concluded on the role of oral microbiome (the 'ecosystem' of the oral micro-organisms) in dementia," Chia-Shu Lin, a professor in dentistry and lead author on the study, told Newsweek. "The evidence is concluded both from animal and human studies. The association between periodontitis (one of the major gum diseases in adults) and dementia was also consistently reported by previous reviews."
Gum disease is a serious gum infection, marked by chronic inflammation in the oral cavity. Due to its proximity to the brain, scientists think that this inflammation may have adverse effects on the brain, and previous studies have found that gum disease and tooth loss are indeed associated with shrinkage in the hippocampus, the part of the brain involved in learning and memory.
Other studies have shown that the most common microbial culprit of gum disease, Porphyromonas gingivalis, can be found in the brains of people who have died from Alzheimer's. "[These microbes] may invade the brain and damage nerve tissue," Satoshi Yamaguchi, a professor in dentistry at Tohoku University in Japan, previously told Newsweek.
However, while Lin's umbrella review showed a consistent association between dementia risk and oral health, there are some other factors to consider here. "With dementia, patients deteriorate in self-caring ability," Lin said. "For example, patients with Alzheimer's disease would feel difficulty in brushing their teeth, which further exacerbates oral health and cognitive function—such a deterioration in self-caring behavior may induce a 'vicious cycle' that exacerbates one's already poor health in general.
"[Moreover] most studies included in these reviews are observational research, which only depicts the statistical correlation between oral health and cognition, but did not clarify the cause-effect relationship between the factors."
Lin also pointed out that, although the review studies consistently pointed towards this association, they do not indicate that you can prevent dementia by simply brushing your teeth. Even so, this is a significant association, and one that many of us are unaware of.
"The public needs to be more aware of the correlation between oral health and cognitive abilities," Lin said.
Uncommon Knowledge
Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.
Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.
About the writer
Pandora Dewan is a Senior Science Reporter at Newsweek based in London, UK. Her focus is reporting on science, health ... Read more
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