It’s a no-brainer that regularly brushing and flossing your teeth, plus regular dental cleanings and treatment, can lead to better oral health; however, a growing amount of research is beginning to uncover a possible association between gum disease and Alzheimer’s disease and dementia.


Alzheimer’s and Oral Health

Before diving into the findings of two recent studies that look at oral bacteria and Alzheimer’s disease, it’s helpful to get a general sense of how Alzheimer’s affects the brain.

In the disease, neurons in the brain stop functioning and communicating with other neurons and eventually die, disrupting the communication, metabolism, and repair processes that are vital to neurons and their networks.

One change that causes cell disruption is the formation of groups of beta-amyloid protein or plaques between neurons. Another is the abnormal accumulation of a protein called tau that collects and branches out inside neurons, blocking the neuron’s transport system.


What the Research is Telling Us

The first study conducted by National Institute on Aging in 2020 seems to support an association between the bacteria that cause gum disease and the development of Alzheimer’s disease and dementias.

Scientists analyzed publicly available data from the Centers for Disease Control’s National Center for Health Statistics to see if gum disease and oral bacterial infections were linked to dementia and death. Data from 6,000 participants of varying age groups, up to a duration of 26 years, was compared.

The bacteria that most commonly causes gum disease was one of the 19 oral bacteria analyzed against antibodies for an association with the diagnosis of Alzheimer’s or dementia and death from Alzheimer’s.

The study found that older adults with signs of gum disease and mouth infections were more likely to develop Alzheimer’s during the study period. Among those 65 years or older, both Alzheimer’s diagnoses and deaths were associated with antibodies against the gum-disease-causing bacteria, which can then cluster with other bacteria to further increase those risks.

A smaller study conducted by New York University College of Dentistry and Weill Cornell Medicine in 2021 found older adults with a higher accumulation of harmful bacteria in the mouth are more likely to have evidence for beta amyloids in the fluid found within the tissue that surrounds the brain and spinal cord.

This appears to indicate that gum disease and other diseases that cause inflammation disrupt the clearance of amyloid from the brain.

While the mouth houses both protective and harmful bacteria, the body’s response to harmful bacteria can cause the chronic inflammation and bleeding of the gums, loosening of teeth, and eventual tooth loss in gum disease. These bacteria and molecules that cause inflammation can enter open blood vessels in wounds or inflamed gum tissue and travel from infections in the mouth through the bloodstream to other regions of the body, including the brain.

In the study, samples of gumline bacteria and fluid from tissue surrounding the spine from 48 cognitively normal adults aged 65 and older were analyzed. While a small sample size, the data showed that individuals with a harmful imbalance in bacteria were more likely to have reduced amyloid levels in the fluid taken from spinal tissue.

This means higher brain amyloid levels, which is what is found in an Alzheimer’s diagnosis.

Since high levels of healthy bacteria are known to help maintain bacterial balance and decrease inflammation in the mouth, there may be a positive relationship between the healthy bacteria and Alzheimer’s disease.

It’s important to note that dementia patients are less likely to be able to brush and floss effectively by themselves, which increases the chances of gum disease and the development of oral infections.

Long-term follow-up studies and clinical trials are being planned to get a better sense of the timing of gum-disease onset in relation to the onset of dementia, and to assess if gum-disease treatment can prevent the development or reduce the symptoms of dementia.


The Oral and Overall Health Connection is Further Reinforced

While further evaluation is needed on the interplay between gum disease and dementia, these findings appear to indicate that taking good and consistent care of your oral health — brushing and flossing at least twice a day, replacing your toothbrush quarterly, consuming less sugary foods and drinks, and visiting your dentist twice a year, for example — could increase the likelihood of maintaining better overall health later in life.


Roosevelt Allen is chief dental officer at United Concordia Dental (, a national dental solutions partner headquartered in Camp Hill, Pa. In his current role, he oversees professional affairs, dental directors, and clinical and dental policy.

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