Alzheimer’s and Gum Disease: Can One Bacterium Cause Both?

Gum problems affect more than half of the world’s population, but most people choose to ignore their oral health - a decision that can have dire consequences, as it turns out. An increasing number of scientific findings point out how gum disease causing bacteria can spread and affect the entire body, even your brain. In a previous article, we’ve discussed how poor oral health can contribute to heart disease and problems with episodic memory, but an even more worrying finding has been made in 2019, suggesting that a strain of bacteria that is typically involved in gum disease called Porphyromonas gingivalis may be the cause of Alzheimer’s disease.

The Science Behind Alzheimer’s Disease
For decades, beta-amyloid plaques and TAU tangles have been considered the cause of Alzheimer’s disease. These plaques and tangles bunch together causing clumps in the brain tissue that interfere with the function of our brain cells. As a result, certain brain functions, such as short term memory, executive functioning, and even emotional perception, just to name a few, become affected, making Alzheimer’s sufferers progressively less and less independent and capable of living life at its fullest.
Indeed, beta-amyloid plaques and TAU tangles are a unique and frequent finding in post-mortem studies in Alzheimer’s patients, and for decades, the reason behind their development was a mystery. One of the major hypotheses was that the cause may be due to an infection, and once again, post-mortem research suggested that it might be a strain of the herpes virus or even a fungus that trigger the condition.

However, these studies were small, and their results too unconvincing for the global medical community to recognize that infections cause the neurodegenerative condition, especially since other factors, such as genetics and age are known risk factors of Alzheimer’s.

The Link Between Gum Disease and Alzheimer’s
In 2019, a new study was published in the Science Advances journal finding a bacterium typically associated with gum disease in the brains of Alzheimer’s patients. But the researchers didn’t stop there and did a follow-up study in an attempt to find not only a cause but also a cure for the condition.

The scientists suggested that toxins called gingipains produced by Porphyromonas gingivalis bacteria were to blame for the creation of plaques and tangles, and they developed a drug they called COR388 that blocks these gingipains. During this second experiment, mice were exposed to the Porphyromonas gingivalis bacteria, and after 6 weeks, the bacteria already appeared in their brain and started causing plaques.

Then, the mice were treated with the drug the researchers had developed, which resulted in a significant reduction of plaques in the mice’s brains and halted neurodegeneration. The researchers conclude that Alzheimer’s disease is caused by the Porphyromonas gingivalis bacterium, and they are already in the process of conducting clinical trials on human subjects to test the efficacy of the experimental drug.

In an interview with the New Scientist in December of 2019, one of the leading authors of the study Steve Dominy revealed that 570 people with mild to moderate Alzheimer’s from 95 health centers across the US and Europe were enrolled in the clinical trial, and we should expect the results in 2021.
A Critical View

While the gum disease study definitely uncovered one way the beta-amyloid plaques and TAU tangles characteristic of Alzheimer’s can occur, many leading scientists in the field point out that we should look at the bigger picture instead of stating that Porphyromonas gingivalis is the exclusive cause of Alzheimer’s, as any other microorganism could likewise be responsible for the formation of plaques and tangles.

Still, the research is exemplary, as it makes us reimagine what the plaques and tangles found in Alzheimer's patients' brains really are - a symptom of the disease, instead of its definitive cause. The study also managed to show how an infection considered relatively harmless managed to contribute to the development of the most widespread neurodegenerative condition - Alzheimer’s disease.

The lesson here is clear: good overall health, including dental hygiene and oral health, as well as a timely treatment of any infections, even seemingly minor one, is key in preventing serious future health issues.