For many years, scientists have debated the possible causes of diseases that produce cognitive decline and dementia. A popular theory that the buildup of toxic brain proteins causes Alzheimer’s Disease (AD) hasn’t held up well in clinical efforts. But another hypothesis that focuses on bacterial microbes appears to demonstrate a link between gum disease and dementia. We’ll review the research that supports this more recent theory that connects gum disease and dementia.
Why Do Scientists Believe There’s a Link Between Gum Disease and Dementia?
Throughout the past decade, several studies have shown that a common bacterium that is associated with the development of gum disease was found in the brains of AD patients. The bacterium they identified was Porphyromonas gingivalis. Researchers not only found the presence of the bacterium but also a toxic enzyme it creates called gingipain. Upon discovery, they set out to test the theory that P. gingivalis and gingipain in the mouth could be correlated with cognitive decline. 2
Experiments with Mice Show a Connection Between Oral Bacteria and Cognitive Impairment
A team of university researchers wanted to find out what would happen if they introduced P. gingivalis into the mouths of mice over an extended period. Twenty-two weeks after applying the bacteria, they examined the brains of the experimental mice subjects compared to a control group. They found that the brains of mice given P. gingivalis contained the toxic enzyme gingipain and showed increased levels of neurodegeneration compared to control subjects.1
Following that university study, one of the founders of a biopharmaceutical company that develops therapeutic treatments for degenerative diseases like AD was able to replicate the result of the mice experiment. Then they went a step further to design gingipain inhibitors that worked to reduce its concentration in the brains of the mice test subjects.2
They found that the introduction of these gingipain inhibitors reduced the bacterial load of an established P. gingivalis infection in the brain and reduced neuroinflammation in the test subjects. Further research is indicated, but “data suggest that gingipain inhibitors could be valuable for treating P. gingivalis brain colonization and neurodegeneration in Alzheimer’s disease.” 2
Longitudinal Human Studies Also Show a Link Between Gum Disease and Dementia
Scientists were eager to see if they could prove a link between gum disease and dementia in live human subjects. In the first of these studies, researchers at the University of Leeds sought to use an ongoing longitudinal study of aging to investigate whether or not there was a correlation.
Over a period of twelve years (2002-2014), 4,400 participants in England 50 years of age or older reported information about their oral health. They also took cognitive tests to determine their processing speed, executive function skills, and memory. After analyzing the data, the researchers concluded an association between poor oral health and declining cognitive function.3
A larger longitudinal study based in South Korea collected and analyzed medical records from over 262,000 people. After following the participants from 2005 to 2015, the data showed that chronic periodontitis (severe gum disease) is associated with a higher risk of AD or dementia.4
The most recent study was commissioned by the National Institute on Aging (NIA). The NIA is part of the U.S. Department of Health and Human Services. Using available data from the National Health and Nutrition Examination Survey, the NIA compared the survey data with Medicare records and the National Death Index. Six thousand participants had dental exams and had blood draws to test for antibodies against bacteria associated with periodontal disease. They were looking for a correlation between these markers of periodontal disease and AD and dementia. With 26 years of follow-up data, the research team found that in participants 65 years and older, there was a very strong association between periodontal disease and AD. 5
Assess Your Risk of Gum Disease by Visiting a Periodontist
Sometimes the onset of gum disease isn’t always so obvious. Since gum disease is linked to other systemic diseases – including dementia – it’s wise to let a periodontist assess your current oral health and provide treatment if needed. The board-certified periodontists at Dental Implants & Periodontal Health of Rochester use the most advanced technologies, techniques, and materials to ensure accurate diagnoses and optimal treatments. Be proactive about your health! Call 585-685-2005 to schedule an appointment.
 PLOS ONE: Chronic oral application of periodontal pathogen results in brain inflammation, neurodegeneration and amyloid-beta production in wild type mice, https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0204941
 ScienceAdvances: Porphyromonas gingivalis in Alzheimer’s disease brains: Evidence for disease causation and treatment with small-molecule inhibitors, https://advances.sciencemag.org/content/5/1/eaau3333
 Community Dentistry and Oral Epidemiology: Cognitive function and oral health among ageing adults, https://onlinelibrary.wiley.com/doi/abs/10.1111/cdoe.12452
 Journal of the American Geriatrics Society: Association of Chronic Periodontitis on Alzheimer’s Disease or Vascular Dementia, https://agsjournals.onlinelibrary.wiley.com/doi/full/10.1111/jgs.15828
 Journal of Alzheimer’s Disease: Clinical and Bacterial Markers of Periodontitis and Their Association with Incident All-Cause and Alzheimer’s Disease Dementia in a Large National Survey, https://pubmed.ncbi.nlm.nih.gov/32280099/