A pathogen that is causing gum disease might also be the culprit behind Alzheimer's, a condition afflicting millions around the world and, to this day, still has no cure.

A new study published on Wednesday, Jan. 23, linked Porphyromonas gingivalis (Pg), the bacteria behind chronic periodontitis (gum disease) to the neurodegenerative disease. According to the authors, the bacteria were found in the brains of deceased patients who had been diagnosed with Alzheimer's.

Gum Disease Linked To Alzheimer's

This is not the first time that the bacteria have been linked to Alzheimer's but in their study, the researchers further investigated how it plays a role in the development of the disease.

In mouse models, the researchers found that oral infection led to brain colonization of the bacteria and increased production of amyloid beta, the protein associated with Alzheimer's. Moreover, they detected gingipains, the toxic enzymes secreted by the bacteria, in the brains of patients who have been diagnosed with Alzheimer's, correlating to two markers: the tau protein and the protein tag ubiquitin.

"Infectious agents have been implicated in the development and progression of Alzheimer's disease before, but the evidence of causation hasn't been convincing," stated Stephen Dominy, lead author of the study. "Now, for the first time, we have solid evidence connecting the intracellular, Gram-negative pathogen, Pg, and Alzheimer's pathogenesis."

A Cure For Alzheimer's

The study, which is coordinated by the pharmaceutical startup Cortexyme and co-founded by Dominy, developed a series of molecule therapies that target Pg gingipains. A compound called COR388, which was formulated by the start-up, reduced bacterial load of an established Pg brain infection, blocked the production of amyloid-beta, reduced neuroinflammation, and protected the neurons in the hippocampus.

The COR388 is currently going through clinical trials with patients diagnosed with Alzheimer's.

David Reynolds, the chief scientific officer of the Alzheimer's Research UK, commented that Alzheimer's is a complex disease that might have several different causes, not just bacterial infection. He cited previous research that proved other factors are also responsible for the development of the disease.

"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," he said in a statement.

"It's important we carefully assess all new potential treatments, and this drug is currently in an early phase clinical trial to establish if it is safe for people. 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 research was published in the journal Science Advances on Wednesday, Jan. 23.