Poor oral hygiene is associated with an increased risk of numerous health problems, including heart disease, diabetes, cancer, rheumatoid arthritis and premature death, reports The Washington Post.
Emerging evidence suggests that what happens to our teeth and gums can affect what happens in our brains – and potentially even increase the risk of dementia.
“People should be really aware that oral health is very important,” said Anita Visser, professor of geriatric dentistry at the University of Groningen in the Netherlands.
Severe periodontal disease — the chronic inflammation and deterioration of the gums and bones that support the teeth — affects about 19 percent of people over the age of 15, or more than 1 billion people worldwide, according to a 2022 report by the World Health Organization. More research is needed, but recent observational studies have suggested that oral health may be a modifiable risk factor for Alzheimer’s, the most common type of dementia.
Scientists are still working to find out if and how the health of the oral cavity and our minds are connected, but they have identified two potential culprits that could explain how gum disease could lead to Alzheimer’s disease: bacteria and inflammation.
Connecting dental health and mental health
One of the first studies to document the link between gum disease, tooth loss and Alzheimer’s focused on a cohort of elderly nuns who were part of a larger study on aging. Researchers followed 144 of the nuns and found that severe tooth loss was associated with up to 6.4 times greater risk of dementia than those who lost fewer teeth.
More recent longitudinal studies also found that a higher incidence of tooth loss was associated with cognitive decline. In a small 2016 study of 60 patients with mild to moderate dementia, periodontitis was associated with a sixfold increase in cognitive decline.
Another 2017 study of nearly 28,000 Taiwanese patients reported that having chronic periodontal disease for 10 or more years corresponded to a 1.7-fold increase in the risk of Alzheimer’s disease. A 2022 meta-analysis of 47 longitudinal studies reported that tooth loss and poor oral health are associated with both cognitive decline and dementia.
This research outlines an emerging picture of an association between poor oral health and dementia, but there are a number of confounding factors that prevent researchers from drawing conclusions. Research has found that bacteria that normally live in the mouth can also infect the brain and contribute to neurodegeneration in Alzheimer’s disease.
A 2019 study published in Science Advances showed that the DNA of the bacterium P. gingivalis, a key pathogen in gum disease, could be found in the brain autopsies of Alzheimer’s patients. Bacterial DNA has also been detected in the cerebrospinal fluid of people living with a probable diagnosis of Alzheimer’s disease.
Toxic enzymes of the bacterium P. gingivalis were also found in the brains of Alzheimer’s patients and were correlated with the amount of tau protein pathology, a hallmark of the disease.
Oral infection of mice with the bacterium led to the presence of P. gingivalis DNA, as well as the accumulation of amyloid β cellular debris – a hallmark of Alzheimer’s disease – in their brains.
The researchers were able to inhibit bacterial enzymes in mice infected with P. gingivalis, which reduced amyloid β production and neuroinflammation. (However, a recent clinical trial targeting these bacterial enzymes failed, and the Food and Drug Administration has put future testing on hold).
“The mechanisms by which periodontal bacteria can gain access to the central nervous system remain unknown,” but they could reach the brain through circulation in the blood or along peripheral nerves, wrote Dioguardi, who co-authored a recent review on the role of which play gingival diseases and oral bacteria in Alzheimer’s.
Inflammation of the mouth can affect the brain
If we do not brush our teeth for several days, each tooth develops a thin biofilm called dental plaque, which abounds in acid-producing bacteria.
“Your body doesn’t like these bacteria,” Visser said. “They are on the edge of the teeth and on the edge of the gum.”
Along with the accumulation of dental plaque comes the inflammation of the gums, because our immune system tries to fight against the infection. Gingivitis, the mildest form of periodontal disease, is still reversible; brushing and removing plaque build-up will allow your gums to heal.
But a more severe gum disease, or periodontitis, can follow if the gingivitis is not treated.
“The whole body is fighting this bacteria,” Visser said. “The immune system is really challenged and alert and working hard against these bacteria.”
This chronic inflammation becomes a vicious circle: inflammation of the gums increases the space between the teeth and the gums, allowing more bacteria to enter, which can lead to inflammation not
not only of the gums, but also of the underlying bone. Continuing unabated, the body will reject the tooth, causing it to weaken and eventually lose the tooth.
This chronic inflammation can spill over from the mouth to the rest of the body. Gum disease is linked to an increase in pro-inflammatory molecules in the blood, Dioguardi said.
Chronic inflammation in the body can, in turn, lead to chronic neuroinflammation in the brain, which induces neurodegeneration and plays a key role in Alzheimer’s disease.
Oral health and dementia
Visser is conducting a longitudinal study that collects oral health data—dental X-rays and bacterial samples—from several hundred cognitively impaired patients to learn more about how their oral health affects their cognitive risk.
The challenge of unraveling the relationships between our lifestyle, our teeth and our brain remains. “There are so many confounding factors, lifestyle, smoking, education level, diet,” Visser said. “So it’s very difficult to do this research.”
Until more is known, the researchers emphasize that oral hygiene remains one of the simplest and most important ways you can take care of yourself.
“Awareness among the population regarding the increased risk of Alzheimer’s associated with tooth loss and periodontitis can lead to increased attention to oral health”, declared Dioguardi.
For better health – and possibly for a healthier brain – keep brushing your teeth.
2023-09-23 10:37:12
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