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Gum disease bacteria linked to Alzheimer's, study finds

[Dec. 27, 2023: JD Shavit, The Brighter Side of News]

An international team of researchers has unearthed a potential connection between gum disease and Alzheimer's disease. (CREDIT: Creative Commons)

In a groundbreaking study published in the scientific journal Science Advances, an international team of researchers has unearthed a potential connection between gum disease and Alzheimer's disease. The researchers have identified Porphyomonas gingivalis, a type of bacteria commonly associated with gum disease, in the brains of individuals suffering from Alzheimer's.

Additionally, they have demonstrated that treating mice infected with oral P. gingivalis with a drug designed to target the toxic substances released by the bacteria could potentially inhibit the accumulation of amyloid, a hallmark protein associated with Alzheimer's disease.


The findings have ignited both intrigue and caution within the scientific community, as they open up a new avenue for exploring the complex origins of Alzheimer's disease. Dr. David Reynolds, Chief Scientific Officer at Alzheimer's Research UK, commented on the significance of this study. He remarked, "Previously, the P. gingivalis bacteria associated with gum disease has been found in the brains of people with Alzheimer's, but it remains unclear what role, if any, it plays in the development of the disease."

This research presents a promising lead in the ongoing quest to understand Alzheimer's disease better. However, it is essential to view these findings in the context of existing knowledge about the disease's multifaceted nature.


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Alzheimer's is known to arise from various causes, and while bacterial infections may play a role, genetic factors and other influences are undoubtedly central to its development.

The study's methodology involved introducing P. gingivalis into mice, subsequently discovering the bacteria in the brain alongside elevated levels of amyloid, a characteristic protein that forms plaques in the brains of Alzheimer's patients. This observation has sparked interest in exploring the potential links between oral health and cognitive decline. Dr. Reynolds emphasized, "Maintaining good dental health is an important part of a healthy lifestyle, and while we don't yet fully understand the extent to which it can affect our dementia risk, the presence of a single type of bacteria is extremely unlikely to be the only cause of the condition."


To comprehend the implications of this research fully, it is crucial to recognize the complexity of Alzheimer's disease. Multiple factors, including genetics, lifestyle, and environmental influences, contribute to its onset and progression. While the presence of P. gingivalis in the brains of Alzheimer's patients is an intriguing discovery, it does not necessarily indicate a direct causative relationship.

Researcher investigating Porphyomonas gingivalis in the lab. (CREDIT: Creative Commons)

In light of these findings, researchers have shifted their attention to potential treatments. The study demonstrated that targeting the toxic proteins released by P. gingivalis with a specific drug prevented the buildup of amyloid in mice. This promising result raises the possibility of developing new therapeutic strategies for Alzheimer's. However, it is essential to remain cautious and realistic about the potential benefits of such treatments.


Dr. Reynolds elaborated on this point, stating, "Drugs targeting the bacteria's toxic proteins have so far only shown benefit in mice, yet with no new dementia treatments in over 15 years, it's important that we test as many approaches as possible to tackle diseases like Alzheimer's." While the research in mice is encouraging, it is crucial to recognize that translating these findings into effective treatments for humans is a complex and challenging process.

Gingipain IR in brain correlates with AD diagnosis and pathology. (CREDIT: Science Advances)

The drug used in the study is currently undergoing early-phase clinical trials to assess its safety and potential effectiveness in human subjects. This critical step will help determine whether the promising results observed in mice can be replicated in people. Dr. Reynolds emphasized, "We will have to see the outcome of this ongoing trial before we know more about its potential as a treatment for Alzheimer's."


The road to discovering effective treatments for Alzheimer's has been long and arduous. This neurodegenerative disease, which affects millions of individuals worldwide, continues to pose a significant public health challenge. Current treatments can alleviate symptoms temporarily but do not address the underlying causes of the disease. Consequently, there is a pressing need for innovative and effective therapies that can slow or halt its progression.

IHC using RgpB-specific monoclonal antibody 18E6 (representative images from a 63-year-old AD patient). (CREDIT: Science Advances)

The link between gum disease bacteria and Alzheimer's disease, as suggested by this recent study, offers a glimmer of hope in the search for potential treatments. Understanding the role of P. gingivalis in the brain and how it interacts with amyloid could provide valuable insights into the disease's mechanisms.


One possible explanation for the presence of P. gingivalis in the brains of Alzheimer's patients is the existence of a barrier between the mouth and the brain known as the blood-brain barrier. Under normal circumstances, this barrier prevents harmful substances, including bacteria, from entering the brain. However, in certain situations, such as chronic inflammation associated with gum disease, this barrier's integrity may be compromised, allowing bacteria to infiltrate the brain.

Furthermore, chronic inflammation itself has been linked to the development of Alzheimer's disease. The immune system's response to chronic infection or inflammation can lead to the production of harmful molecules that contribute to brain damage. This raises the possibility that P. gingivalis in the brain may trigger or exacerbate inflammation, ultimately contributing to the progression of Alzheimer's.

The relationship between oral health and cognitive function is a topic of increasing interest in scientific research. Previous studies have suggested that poor oral hygiene and gum disease may be associated with a higher risk of cognitive decline in older adults. While these studies do not establish a direct causal link, they underscore the importance of oral health in maintaining overall well-being, particularly as people age.


The ongoing clinical trials of the drug targeting P. gingivalis's toxic proteins will provide critical data on its safety and effectiveness in humans. Regardless of the outcome, this study underscores the importance of maintaining good dental health as part of a healthy lifestyle and emphasizes the need for continued research into Alzheimer's disease to unlock its mysteries and develop effective treatments for those affected by this devastating condition.

For more science and technology stories check out our New Discoveries section at The Brighter Side of News.


Note: Materials provided above by Hiroshima University. Content may be edited for style and length.


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