Just like babies, adults can lose their teeth. But unlike babies, the process in older people tends to mark the beginning of a decline in health, particularly in the brain for some.
Now, a new study adds to existing evidence touting a connection between tooth loss and cognitive impairment.
An analysis of about 34,000 adults, more than 4,600 of which had “diminished cognitive function,” found that those with more tooth loss faced a 48% higher risk of cognitive impairment and 28% higher risk of dementia.
And the more teeth a person lost, the greater their risk of cognitive decline, according to the study published July 8 in the journal The Journal of Post-Acute and Long-Term Care Medicine.
The New York University researchers learned that each additional missing tooth was associated with a 1.4% increased risk of cognitive impairment and a 1.1% higher risk of dementia.
But the connection wasn’t significant for those with dentures, suggesting “timely treatment” of oral health may prevent cognitive decline.
“Given the staggering number of people diagnosed with Alzheimer’s disease and dementia each year, and the opportunity to improve oral health across the lifespan, it’s important to gain a deeper understanding of the connection between poor oral health and cognitive decline,” study senior author Dr. Bei Wu, dean’s professor in global health at the NYU Rory Meyers College of Nursing, said in a statement. “Our findings underscore the importance of maintaining good oral health and its role in helping to preserve cognitive function.”
It’s unclear exactly why tooth loss leads to cognitive decline, but scientists have found that missing teeth later in life are more common in people with lower education statuses and higher levels of stress, in which people are either not aware about the importance of or are too busy to maintain oral hygiene.
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Over time, the lack of oral care can lead to cavities, plaque buildup and gum disease. Researchers say missing teeth can also make it hard to chew, contributing to nutritional deficiencies that may lead to changes in brain function.
But it’s periodontitis, or gum disease, that may play the largest role, studies show.
Gum disease is the most common cause of tooth loss in older adults, and is responsible for about 50% of all teeth extractions in people older than 40, leaving up to 30% of adults at high risk of chronic inflammation. Even those who receive treatment for the disease may be left with lingering systemic damage caused by bacteria.
A study published last year found that the bacteria that causes periodontitis was associated with the development of Alzheimer’s disease and other dementias. The researchers say the bacteria and the inflammatory molecules they produce can travel from the mouth through the blood to the brain, resulting in cognitive decline over time.
Another explanation behind the connection between tooth loss and dementia is that people with cognitive problems may be less able to stay on top of their oral care and routine dental visits.
About one quarter of adults aged 65 or older have eight or fewer teeth, according to the Centers for Disease Control and Prevention. And about one in six adults in the same age group have lost all their teeth.