Dental appointments are seldom appropriate occasions for deep conversations about scientific breakthroughs — or anything else, for that matter. So, I decided not to interrupt my dentist the other day while she was working on one of my troublesome molars to ask her whether she thinks the bacteria in my mouth may cause Alzheimer’s.
She was kind of busy, after all. And I found it difficult to enunciate.
Under different circumstances, I might have mentioned that neurological experts have been studying the connection between the microbial mix in our mouths and our cognitive function for quite some time now. And I might have briefly described the results of a study published last month in the journal PNAS Nexus that identified the specific bacteria and the possible mechanism involved.
Joanna L’Heureux, PhD, and her team of researchers at the University of Exeter recruited 110 participants 50 years old and older from the PROTECT brain health study and split them into two groups: one displaying mild cognitive impairment and the other exhibiting no brain dysfunction. Members of each group submitted mouth-rinse samples, which researchers analyzed for bacterial population.
Participants whose samples contained ample clusters of two bacteria groups — Neisseria and Haemophilus — performed better on memory tests than their counterparts who lacked sufficient quantities of these microbes. Those memory-challenged individuals tended to be saddled with excessive amounts of Porphyromonas. And among those who were genetically predisposed to developing Alzheimer’s, Prevotella was the dominant bacteria.
Researchers suggest that these bugs could affect the brain in a couple of different ways: Harmful bacteria may enter the bloodstream and trigger neuroinflammation. Also, an imbalanced microbial mix could inhibit the conversion of nitrate (which we get from eating veggies) to nitric oxide, which is key to the brain’s ability to communicate between its various sectors and form memories.
“Our findings suggest that some bacteria might be detrimental to brain health as people age,” L’Heureux says. “It raises an interesting idea for performing routine tests as part of dental checkups to measure bacterial levels and detect very early signs of declining brain health.”
And it could lead to a variety of interventions, such as dietary changes, a course of probiotics, or specific oral hygiene routines, adds coauthor Anne Corbett, PhD. “If certain bacteria support brain function while others contribute to decline, then treatments that alter the balance of bacteria in the mouth could be part of a solution to prevent dementia.”
“If certain bacteria support brain function while others contribute to decline, then treatments that alter the balance of bacteria in the mouth could be part of a solution to prevent dementia.”
A cursory online search revealed a sprinkling of dental practices around the country that claim to offer dental bacteria testing (mine doesn’t), which I suppose is good news for seniors living in those locales who are fortunate enough to afford such specialized care. Unfortunately, a wide swath of the Medicare set can’t even afford to get their teeth cleaned.
Only about half of U.S. seniors who lacked dental insurance visited a dentist in 2022, according to a 2024 report from the Centers for Disease Control and Prevention. And even among those with insurance, more than 30 percent stayed away from the chair. That’s despite the widespread availability of Medicare Advantage (MA) plans that offer some level of dental coverage.
The coverage those plans offer, however, is typically limited to preventive services and requires a copay or coinsurance. Only about 4 percent of the 27 million Medicare Advantage beneficiaries highlighted in a 2024 JAMA research letter were enrolled in a comprehensive dental plan. And not all dental practices accept Medicare payments (mine doesn’t).
“Policies such as additional premiums for dental services, limiting coverage to only some procedures, or high coinsurance may prevent beneficiaries from using dental services despite being enrolled in an MA plan that offers a dental benefit — even if a dental benefit was one of the incentives for enrolling in that plan,” notes Lisa Simon, MD, DMD, who authored the JAMA letter. “These results might explain why, despite having widespread access to dental coverage, only about half of MA beneficiaries visit a dentist annually.”
I’m fortunate to currently find myself among that portion of the Medicare set that manages to see a dentist on a regular basis. But that’s not due to some extraordinary benefits in my MA plan; it’s because I remain gainfully employed and my employer offers dental coverage my dentist will accept. I can thank them both for my newly repaired molar, though it seems I’ll have to look elsewhere for help should Alzheimer’s come calling.
This Post Has 0 Comments