Tooth loss caused by periodontal disease, which affects approximately 19% of the world’s adult population, can lead to Alzheimer’s disease. Several studies have shown that bacteria and inflammation in the mouth contribute to brain degeneration.

According to the American Dental Association, if you don’t brush and floss your teeth, after a few days a thin sticky film (plaque) forms that contains more than 500 types of bacteria. These bacteria produce acids after you eat or drink something, especially if those foods contain sugar. And acids attack tooth enamel and can lead to serious problems for dental health, as well as for general health.

If plaque is not removed, it can harden on the teeth and turn into tartar. This buildup of plaque and tartar on the teeth can cause inflammation of the gums, which is an early stage of gingivitis or periodontal disease.

If gingivitis is not treated, the inflammation becomes chronic, the gums begin to recede, giving way to more bacteria, until the immune system, trying to eliminate the infection, rejects the tooth, which eventually weakens and falls out. .

From periodontitis to Alzheimer’s disease

However, inflammation is not localized in the oral cavity, but can spread to other parts of the body. Chronic inflammation in the body can, in turn, lead to chronic neuroinflammation in the brain, causing neurodegeneration and playing a key role in the development of Alzheimer’s disease.

According to a 2022 World Health Organization report, severe periodontal disease—chronic inflammation and destruction of the gums and bone that supports the teeth—affects approximately 19 percent of adults, or more than 1 billion people worldwide. Although more research is needed, recent studies have suggested that oral health may be a modifiable risk factor for Alzheimer’s disease, the most common type of dementia.

One of the first studies to document a link between periodontal disease, tooth loss, and Alzheimer’s disease focused on a cohort of elderly nuns participating in a larger study of aging. After studying data from 144 nuns, researchers found that severe tooth loss was associated with a 6.4 times greater risk of dementia compared to people with optimal oral health.

Recent studies have also shown that a higher rate of tooth loss was associated with a decline in cognitive function. In a small 2016 study of 60 patients with mild to moderate dementia, periodontitis was associated with a sixfold increase in cognitive ability.

Another 2017 study of nearly 28,000 Taiwanese patients found that those with chronic periodontal disease for 10 years or more were 1.7 times more likely to develop Alzheimer’s disease.

A 2022 meta-analysis of 47 studies found that tooth loss and poor oral health are associated with both cognitive decline and dementia.

Tooth loss, cause or effect of neurodegeneration?

However, there are several factors that create confusion and prevent researchers from drawing definitive conclusions about the cause-and-effect relationship between poor oral health and Alzheimer’s disease.

One could be that higher rates of dental problems in patients with dementia may be a symptom rather than a cause of cognitive decline. People with dementia have difficulty maintaining oral hygiene and are at increased risk of developing periodontal disease, meaning that the relationship between oral health and cognitive health may be bidirectional.

Other known risk factors for dementia, such as smoking and low levels of education, are also associated with poor oral health. In addition, tooth loss can prevent people from eating as well as they should, and the lack of certain nutrients can affect general health and cognitive function. “People should know that oral health is extremely important. Although we cannot tell patients with gum disease that they will definitely get Alzheimer’s disease, we do know that severe periodontitis increases the risk of dementia,” said Dr. Anita Visser, professor of geriatric dentistry at the University of Groningen in the Netherlands.

Gum bacteria found in the brains of patients with Alzheimer’s disease

Research has shown that bacteria that normally live in the mouth can also infect the brain and contribute to the neurodegeneration typical of Alzheimer’s disease.

A 2019 study published in Science Advances found that DNA from the bacterium P. gingivalis, the main cause of periodontal disease, was found in the brains of Alzheimer’s patients at autopsies. Bacterial DNA has also been found in the cerebrospinal fluid of people diagnosed with Alzheimer’s disease.

In summary, although studies have shown a link between poor oral health and the risk of developing Alzheimer’s disease, the exact mechanisms by which periodontal bacteria can affect the central nervous system remain unknown.

How to avoid severe periodontal diseases

In most cases, the development of periodontitis begins with the formation of bacterial plaque. To prevent the formation of dental plaque and, eventually, tartar, it is important to:

– brush your teeth properly at least twice a day;

– you use dental floss every day,

– limit the use of sweet foods and drinks or brush your teeth immediately after eating sweet foods;

– visit a dentist every 6 months for a routine check-up and hygiene.

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