Can gingivitis cause Alzheimer’s disease? [A Scientific Review]

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Hi, I’m Dr. B, practicing functional dentist for 35 years. I graduated from the Dugoni School of Dentistry in San Francisco, CA in 1987 and am a member of the American Academy of Dental Sleep Medicine (AADSM), Academy of General Dentistry (Chicago, IL), American Academy for Oral Systemic Health (AAOSH), and Dental Board of California. I'm on a mission to empower people everywhere with the same evidence-based, easy-to-understand dental health advice that my patients get. Learn more about Dr. B

Understanding the development of Alzheimer’s disease is a hot topic in today’s health discourse. Science advances have suggested everything from genetics to lifestyle choices as risk factors for this cognitive decline.

Despite consistent investigation and clinical trials, the exact reasons some develop Alzheimer’s are murky. While new research is still emerging, you may want to check your teeth and gums.

When people think of dementia and Alzheimer’s, they don’t first think about gum disease and oral health.

However, research over the last several years suggests that advanced periodontitis (stage IV gum disease) might not just be associated with Alzheimer’s. There’s a chance it could be the root cause.

For years, Alzheimer’s has been discussed as a genetic and lifestyle-based inevitability. But what if it’s an infectious issue instead?

The Problem with Modern Alzheimer’s Treatments

Although Alzheimer’s disease has been researched for years, current treatment methods are shockingly ineffective. Some can even have adverse effects. A staggering 99% of Alzheimer’s disease drugs fail. Clearly, we don’t fully understand the cause of Alzheimer’s just yet.

This lack of efficacy is potentially due to current research looking for links instead of causative factors. Many drugs on the market are created to treat symptoms, not to prevent the disease. At Ask the Dentist, we are all about prevention first. We believe discovering the foundational reasons for Alzheimer’s is better than simply treating its effects.

How Gingivitis Gets to the Brain

Some scientists have begun to investigate a bacteria called Porphyromonas gingivalis (P. gingivalis) as a possible causative agent of Alzheimer’s disease. This pathogen is known to trigger gum disease and cause gingivitis in its early stages.

Doctors have found that Alzheimer’s patients have a much higher rate of gingivitis and advanced periodontal disease than others.

Furthermore, researchers are finding uncommonly high concentrations of proteins produced by P. gingivalis in the brains of people with Alzheimer’s disease.

These proteins react with amyloid beta proteins and toxic enzymes to form amyloid plaques. This insoluble plaque creates inflammation and destroys brain cells. This inflammation and destruction leads to the symptoms of Alzheimer’s.

But how does this bacteria from our teeth get into our brain? It seems that the bacteria that cause gum disease can sneak into spinal fluid, according to the Journal of Science Advances, not to mention the bloodstream. Eventually, they make their way to the brain tissue.

Missing teeth and the holes they leave may be another pathway. In fact, dementia rates rise with the number of teeth lost. Tooth loss is often a result of periodontal disease, seemingly linking infected gums to Alzheimer’s disease.

Evidence for Causation: Gum Disease and Alzheimer’s

While research is years from proving causation beyond a shadow of a doubt, here’s what we know right now:

  • At least one study found that people with the least teeth left were at the greatest risk for dementia.
  • Periodontitis, or gum disease, causes great deals of inflammation. Scientists linked this disease to inflammation of the brain, commonly seen in Alzheimer’s disease.
  • The P. gingivalis, or gum disease bacteria, easily travels to the brain and builds there over time. In mice, this pathogen injures neurons, increases inflammation in the brain. The inflammation in turn causes dementia– and Alzheimer’s-like symptoms.
  • P. gingivalis produces toxins called gingipains. In patients with Alzheimer’s, gingipain levels correlate with the amount of toxic tau tangles within brain cells.
  • Another study found that inhibiting the gingipains in the brains of mice reduced neuroinflammation. Furthermore, it reduced the existing brain infection, and rescued neurons in the hippocampus.

In that last new study, published in January 2019, the scientists proposed a causative link, which is a big deal in the science world. Most health-related science relies on correlations. These predict that with a specific studied behavior, you’re likely to get a certain result.

However, causation is a much more tricky thing to prove. Nevertheless, we’ve found compelling evidence for this bacteria as a cause in the last year. Proposing an actual cause, as opposed to linking the disease to one factor, is unusual. This is an incredibly significant development when it comes to dementia and Alzheimer’s disease.

It tells us that a much bigger emphasis on the prevention and treatment of gum disease may be necessary to help people avoid the tragic pain of age-related brain diseases like these.

While the evidence is far from conclusive, it seems we’ve discovered one previously unknown cause of Alzheimer’s. It’s unlikely that periodontal disease is the only causative factor, but this is one of the most promising findings in recent times. It also has enormous potential to assist in curing, and not just managing, this disease.

Prevent Gum Disease for Your Brain

Tests in the aforementioned January 2019 study found that medications that stop gingipains toxic effects within the brain might help to stop P. gingivalis from bioaccumulating. With or without medication, taking preventative measures against gum disease is always the right decision.

Chronic periodontitis can lead to tooth loss and worse. Now, knowing that it might lead to a healthier, happier old age, it’s more important than ever before.

Beyond ramping up your oral hygiene, you can implement a gum disease diet. Be proactive, and even if you haven’t been diagnosed, tell your dentist about any bleeding in your gums. It doesn’t take long for gum damage to become irreversible, so I recommend communicating immediately about any changes in gum health.

If you’re currently battling gingivitis, no shame here. Bleeding gums are reversible, and three out of four Americans will experience it at some point in their lives.

No matter what state your gums are in, it’s crucial to take intentional care of them, for your health and for your future. As you have read, dental hygiene is a major health concern.

You can improve gum health by reducing stress, a known contributor to gum disease. Also, I advise upping your vitamin C intake, cutting down on smoking, and staying hydrated.

The effects on your overall health can’t be overstated, as gum disease has been linked to breast cancer and other major diseases. To read up on my recommendations for handling chronic gum disease, take a look at my in-depth article.

As this science emerges, a pharmaceutical company in California called Cortexyme is working on a new drug. It aims to stop the production of amyloid beta and inhibit gingipains. This article will be updated as news continues about this exciting research.

Key Takeaways: Can gingivitis cause Alzheimer’s disease?

  • It seems that poor oral hygiene can lead to not only gingivitis, but perhaps eventually to Alzheimer’s disease. The mouth-body connection is of vital importance to overall health.
  • The bacteria that cause periodontal disease may increase the risk of Alzheimer’s. It is found more frequently in Alzheimer’s patients’ brains than their peers.
  • Emerging research continues to support the link between unhealthy gums and plaque buildup in the brain.
  • Maintaining oral health has many benefits. These range from possibly preventing Alzheimer’s disease and tooth loss to guarding against breast cancer and cardiovascular issues.
  • If you have periodontal disease or gingivitis, taking steps to treat this issue can have major benefits for your future and your mind.
Learn More: Gum Disease: Stages, Prevention, and Treatment

11 References

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  3. Dominy, S. S., Lynch, C., Ermini, F., Benedyk, M., Marczyk, A., Konradi, A., … & Holsinger, L. J. (2019). Porphyromonas gingivalis in Alzheimer’s disease brains: Evidence for disease causation and treatment with small-molecule inhibitors. Science advances, 5(1), eaau3333. Full text:
  4. Horliana, A. C. R. T., Chambrone, L., Foz, A. M., Artese, H. P. C., de Sousa Rabelo, M., Pannuti, C. M., & Romito, G. A. (2014). Dissemination of periodontal pathogens in the bloodstream after periodontal procedures: a systematic review. PLoS One, 9(5), e98271. Full text:
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  7. Poole, S., Singhrao, S. K., Chukkapalli, S., Rivera, M., Velsko, I., Kesavalu, L., & Crean, S. (2015). Active invasion of Porphyromonas gingivalis and infection-induced complement activation in ApoE-/-mice brains. Journal of Alzheimer’s Disease, 43(1), 67-80. Abstract:
  8. Poole, S., Singhrao, S. K., Chukkapalli, S., Rivera, M., Velsko, I., Kesavalu, L., & Crean, S. (2015). Active invasion of Porphyromonas gingivalis and infection-induced complement activation in ApoE-/-mice brains. Journal of Alzheimer’s Disease, 43(1), 67-80. Abstract:
  9. Ilievski, V., Zuchowska, P. K., Green, S. J., Toth, P. T., Ragozzino, M. E., Le, K., … & Watanabe, K. (2018). Chronic oral application of a periodontal pathogen results in brain inflammation, neurodegeneration and amyloid beta production in wild type mice. PloS one, 13(10), e0204941. Full text:
  10. Ishida, N., Ishihara, Y., Ishida, K., Tada, H., Funaki-Kato, Y., Hagiwara, M., … & Matsushita, K. (2017). Periodontitis induced by bacterial infection exacerbates features of Alzheimer’s disease in transgenic mice. NPJ aging and mechanisms of disease, 3(1), 15. Full text:
  11. Freestone, P. P., Sandrini, S. M., Haigh, R. D., & Lyte, M. (2008). Microbial endocrinology: how stress influences susceptibility to infection. Trends in microbiology, 16(2), 55-64. Abstract: