Alzheimer’s Disease and Its Surprising Link to Gum Disease: What Science Is Revealing

Alzheimer’s disease stands as the most common cause of dementia in the United Kingdom, according to the National Health Service (NHS). It affects millions of individuals and their families, slowly eroding memory, cognitive abilities, and independence. Despite ongoing research, the precise cause of Alzheimer’s remains elusive. However, scientists have identified various potential risk factors that may contribute to its development.

Age is the most significant risk factor. As individuals grow older, the chances of developing Alzheimer’s increase substantially. Beyond age, genetics can also play a crucial role. People with a family history of Alzheimer’s may be more susceptible to the condition. Additionally, untreated mental health issues such as chronic depression, certain lifestyle habits, and cardiovascular-related diseases are all considered contributors.

Over the years, much of the scientific focus has been on genetic and neurological explanations for Alzheimer’s. Yet a growing body of research is now exploring an entirely different angle—the possibility that Alzheimer’s is not merely a degenerative brain disease, but may actually be linked to infection.

This emerging hypothesis has gained traction due to a number of studies indicating a connection between oral health, specifically gum disease, and the onset of Alzheimer’s. One groundbreaking study published in 2019 helped bring this theory into the spotlight. The research was led by Jan Potempa, a microbiologist from the University of Louisville, and it explored the presence of bacteria in the brains of Alzheimer’s patients.

The study revealed that Porphyromonas gingivalis, the same bacterium responsible for chronic periodontitis (a severe form of gum disease), was found in the brain tissue of deceased individuals who had been diagnosed with Alzheimer’s. This discovery was especially striking because it provided biological evidence that an oral infection could potentially contribute to or even trigger neurological decline.

Adding to these findings, earlier experiments conducted by Cortexyme, Inc., a biotech company, showed that infecting mice orally with P. gingivalis led to an increased production of beta-amyloid (Aβ) proteins in their brains. These sticky protein fragments are widely considered hallmarks of Alzheimer’s disease, as they tend to clump together and disrupt communication between brain cells.

According to Dr. Stephen Dominy, a co-founder of Cortexyme, previous research had already suggested the involvement of infectious agents in Alzheimer’s. However, the data had not yet been compelling enough to establish a clear cause-and-effect relationship. The 2019 findings added a new layer of credibility to this line of investigation.

One of the most revealing aspects of the study was the discovery of gingipains—toxic enzymes secreted by P. gingivalis—in the brains of Alzheimer’s patients. These enzymes were closely associated with tau and ubiquitin, two other proteins strongly linked to the onset and progression of Alzheimer’s. Tau, in particular, forms twisted tangles inside neurons, disrupting their function and contributing to cell death.

Interestingly, the researchers also detected these toxic enzymes in the brains of deceased individuals who had not been diagnosed with Alzheimer’s. This observation raised critical questions. Were these individuals in the early, undiagnosed stages of the disease? Or could it be that declining oral hygiene, a common issue in Alzheimer’s patients, led to greater bacterial invasion after cognitive symptoms had already started?

The research paper presented an intriguing interpretation. The scientists proposed that brain infection with P. gingivalis may be an early event, potentially occurring well before clinical symptoms of dementia appear. In other words, the presence of the bacteria and its toxins could be laying the groundwork for cognitive decline long before it becomes noticeable.

To further investigate the therapeutic potential of this discovery, Cortexyme developed a compound known as COR388. This drug was specifically designed to target and neutralize the toxic gingipains produced by P. gingivalis. In the mouse models used during the study, COR388 was able to reduce both the accumulation of beta-amyloid and the inflammation typically associated with neurodegenerative conditions.

While these results are promising, it’s important to remember that success in animal models doesn’t always translate to human treatments. Extensive clinical trials will be required to determine whether COR388 or similar therapies can have a meaningful impact on human patients suffering from Alzheimer’s disease.

As highlighted by David Reynolds, chief scientific officer at Alzheimer’s Research UK, the urgency for new treatments is paramount. “As there haven’t been any new dementia treatments in over 15 years,” he noted, “it’s important that we test as many approaches as possible to tackle diseases like Alzheimer’s.” He added that while the focus on bacterial toxins is a novel approach, evidence in humans is still pending.

The implications of this research go beyond medical science—they highlight the critical importance of oral hygiene as a potential factor in neurological health. Regular dental check-ups, proper brushing and flossing, and treating gum disease early may not only protect your teeth and gums but could also reduce the risk of cognitive decline in the long term.

In the evolving field of Alzheimer’s research, the infection hypothesis is still considered controversial, but it’s gaining momentum. If future studies confirm a definitive link, it could transform the way we think about, prevent, and treat this devastating disease. Rather than focusing solely on genetics and age, intervention strategies might include targeting infectious agents as part of a comprehensive treatment plan.

In conclusion, while we still have much to learn about Alzheimer’s disease, the growing connection between gum disease and cognitive decline offers a new perspective. It reinforces the idea that maintaining overall health, including dental and cardiovascular health, could play a bigger role in brain function than previously believed. As researchers continue to explore this path, there is hope that new, more effective treatments will eventually emerge—perhaps beginning in the most unexpected of places: the mouth.