New research linking gum disease with Alzheimer’s disease will have you reaching for your toothbrush and dental floss.

Let’s dig deeper into the story on this fascinating trigger for Alzheimer’s disease…

Gum disease, or more specifically periodontal disease, is a huge concern for older people. In fact, the Centers for Disease Control (CDC) reports that 70 percent of Americans aged 65 and older have chronic gum disease.1

How does gum disease start?

Like other parts of your body, the mouth is home to harmful bacteria that promote inflammation, as well as healthy, protective bacteria.

According to the CDC, bacteria in the mouth can infect tissue surrounding a tooth, causing inflammation and opening the door to periodontal disease.

When bacteria stay on the teeth long enough, they form a film called plaque, which eventually hardens to tartar. This tartar build-up can spread below the gum line, which makes the teeth harder to clean.

When this occurs, all the fancy toothbrushes and floss can’t do much. At this point, only a dental health professional can remove the tartar and stop the periodontal disease process.

New Study Offers Cautionary Tale

Researchers at the New York University Dentistry School found that folks who have an abundance of harmful bacteria versus healthy bacteria on their gums may be at greater risk for dementia.

That’s because a recent study revealed that they’re more likely to have a protein marker for Alzheimer’s disease, known as amyloid beta, in their cerebrospinal fluid (CSF).

“To our knowledge, this is the first study showing an association between the imbalanced bacterial community found under the gumline and a CSF biomarker of Alzheimer’s disease in cognitively normal older adults,” said lead author Dr. Angela Kamer.2

She added that evidence of amyloid-beta plaque in the brain was also associated with an increase in harmful bacteria and a decrease in beneficial bacteria on the gums.

As you may know, Alzheimer’s is thought to be identified by two brain proteins: amyloid beta plaque and tau.

Amyloid beta lumps together to form plaques, sometimes decades before Alzheimer’s symptoms are detected. Experts believe it’s the first protein deposited in the brain as Alzheimer’s develops. On the other hand, tau builds up in nerve cells and forms tangles.

However, the most recent research shows a stronger case for tau proteins as a factor in Alzheimer’s development than amyloid beta, the latter having been found in the brains of individuals without any form of dementia.

Senior study author Dr. Mony de Leon admits there’s still much more to learn about the origins of this disease.

“The mechanisms by which levels of brain amyloid accumulate and are associated with Alzheimer’s pathology are complex and only partially understood,” Dr. de Leon said.

Connecting Memory Health With Oral Bacteria

Researchers sought to prove the dental-mental wellness connection by taking both gum swabs and spinal tap samples from 48 healthy volunteers over 65 years old.

First, they analyzed the DNA in gum swabs. Then a lumbar puncture was done to obtain cerebrospinal fluid which could be analyzed to determine levels of amyloid beta and tau proteins.

What did they find? Interestingly, the results showed that those people with more healthy bacteria were more likely to have reduced amyloid beta protein levels in their spinal fluid. The investigators suggest this could be because high levels of healthy bacteria help maintain bacterial balance and decrease inflammation, so they may help guard against Alzheimer’s.

Dr. Kramer commented on the significance of the findings.

“Our results show the importance of the overall oral microbiome — not only of the role of ‘bad’ bacteria, but also ‘good’ bacteria — in modulating amyloid levels,” she said.

“These findings suggest that multiple oral bacteria are involved in the expression of amyloid lesions.”

This study was published in the journal Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring.3 But it’s certainly not the first study that found bacteria-causing gingivitis (gum disease) can spread from the mouth to the brain.4

Gingivitis Connected to Memory Loss

A 2019 National Institutes of Health study published in the Journal of Alzheimer’s Disease shows the bacteria that cause gingivitis, the earliest form of periodontal disease, are also connected to several forms of dementia.5

The analysis revealed that older adults with signs of gum disease and mouth infections at baseline were more likely to develop Alzheimer’s during the study period. In fact, among those age 65 years or older, both Alzheimer’s diagnoses and deaths were associated with antibodies against the oral bacterium P. gingivalis.

Will Deep Cleanings Help?

But what happens if one undergoes deep cleaning to remove stubborn deposits of plaque and tartar from under the gumline? Can this prevent Alzheimer’s? The authors say additional long-term study is warranted.

The New York research team is planning another trial to see if this is the case.

Since the cleanings can’t be carried out with a toothbrush, the researchers emphasize the need to visit a dentist or dental hygienist at least once, preferably twice a year to get any benefit.

Meanwhile, it’s still a good idea to brush and floss your teeth as well as use a germ-killing mouthwash. It’s also important to eat foods that support oral health.

The top ten foods include celery, black and green tea, sesame seeds, onions, shiitake mushrooms, raisins, sweet potatoes, kiwis, cheese and water. Avoid foods containing artificial sweeteners and preservatives, colorings, high fructose corn syrup, refined sugar, refined flour and partially hydrogenated oils.


  1. https://www.cdc.gov/oralhealth/conditions/periodontal-disease.html 
  2. https://www.nyu.edu/about/news-publications/news/2021/april/gum-bacteria-alzheimers.html 
  3. https://doi.org/10.1002/dad2.12172 
  4. https://advances.sciencemag.org/content/5/1/eaau3333 
  5. https://www.nia.nih.gov/news/large-study-links-gum-disease-dementia