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New research finds a link between tooth loss and dementia. Viktor Pavlenko/EyeEm/Getty Images
  • Around 5 million people aged 65 years or older in the United States have dementia.
  • Researchers have noted a potential relationship between tooth loss and dementia and cognitive decline.
  • In the present study, the researchers conducted a meta-analysis to better understand what the relationship between tooth loss, cognitive decline, and dementia may be.
  • They found a link between more tooth loss and a greater risk of cognitive decline and dementia.

In a new meta-analysis, researchers have identified a connection between tooth loss and a risk of cognitive decline and dementia.

The researchers found that the more teeth a person had lost, the greater their risk of developing dementia or cognitive decline.

The research, published in JAMDA: The Journal of Post-Acute and Long-Term Care Medicine, lays the ground for researchers to determine whether tooth loss causes cognitive decline and dementia, and if so, what accounts for this.

According to the Centers for Disease Control and Prevention (CDC), around 5 million people aged 65 years or older in the United States have dementia.

Dementia refers to a variety of conditions characterized by cognitive issues that affect a person’s everyday life.

The most common cause of dementia is Alzheimer’s disease, accounting for 60–80% of dementia cases. However, it can also be due to a stroke.

Other types of the condition include Lewy body dementia, frontotemporal dementia, and mixed dementia, which can involve multiple types of dementia.

There is no known cure for neurodegenerative dementias, such as Alzheimer’s disease, and clinicians typically manage the symptoms. They also recommend eating a more balanced diet and increasing physical activity to reduce the likelihood of developing some dementias.

In addition to looking for a cure for the most common types of dementia, researchers are interested in identifying any potential risk factors for the condition.

One area of research is the possible connection between tooth loss and dementia.

The Alzheimer’s Association notes that as a person’s Alzheimer’s develops, they may need help remembering to brush their teeth and maintain good dental hygiene.

However, researchers have suggested there may be a causal link between tooth loss and dementia and cognitive decline.

The authors of the present study highlight that current meta-analyses looking at the association between tooth loss, dementia, and cognitive decline have produced mixed results.

To help clarify the connection, they conducted a meta-analysis of longitudinal studies following patients over time, thus aiming to provide contemporary evidence.

Prof. Bei Wu, dean’s professor in Global Health at New York University (NYU) Rory Meyers College of Nursing, co-director of the NYU Aging Incubator, and the study’s senior author, said,

“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.”

The researchers wanted to see whether there is a connection between tooth loss, dementia, and cognitive decline and whether there is any relationship between the number of teeth lost and the risk of developing dementia or cognitive decline.

To do so, the researchers searched six databases for longitudinal studies exploring the association between tooth loss and dementia or cognitive decline up to March 1, 2020.

Studies had to be published in English in peer-reviewed journals, and participants had to be adults in any type of setting.

The meta-analysis covered 34,074 participants, of whom 4,689 had some form of diminished cognitive functioning.

The researchers found that tooth loss was associated with a 1.48 times greater risk of cognitive decline and a 1.28 times greater risk of dementia. This was the case even when other potential confounding factors were accounted for.

Further, the researchers found that for every tooth lost, a person had a 1.1% greater risk of developing dementia and a 1.4% greater risk of experiencing cognitive decline.

According to Xiang Qi, a doctoral candidate from NYU Meyers and the lead author of the paper, “this ‘dose-response’ relationship between the number of missing teeth and risk of diminished cognitive function substantially strengthens the evidence linking tooth loss to cognitive impairment and provides some evidence that tooth loss may predict cognitive decline.”

While the researchers identified an association between tooth loss and dementia and cognitive decline, they also found that wearing dentures significantly reduced the association — a finding supported by previous research.

They note, however, that it is not clear what mechanism is behind the relationship between tooth loss and cognitive decline and dementia.

They suggest this could be due to morphological changes that occur when a person consumes food without teeth, or due to the effects of changed nutritional intake when consuming food without teeth.

According to Prof. Wu, “one possible biological mechanism for the association is suggested by the exposure to pathogenic oral bacteria, such as Porphyromonas gingivalis.”

“This bacterium produces virulent factors, such as endotoxin or gingipains, that exacerbate beta-amyloid deposition and stimulate a neuroinflammatory response in microglia and astrocytes, leading to dementia-related pathological changes.”

Additionally, the researchers point out that the findings could also be accounted for in part by the fact that people with dementia may have difficulty maintaining good dental hygiene.

They also note that socioeconomic factors linked to dementia are linked to tooth loss as well.

Prof. Wu believes further research is necessary to understand the causal mechanism behind the association she and her colleagues have identified. She told Medical News Today:

“In order for us to test a causal relationship, we need randomized clinical trials. However, these studies are difficult to conduct. Moving forward, we need to conduct more longitudinal studies that include comprehensive measures of cognitive function and clinical examination of oral health status.”