The cause of Alzheimer's disease could come from inside your mouth, according to a study

In recent years, more and more scientific studies have confirmed an alarming badumption: Alzheimer's disease is not just a disease, it's an infection.

Although researchers are still trying to isolate the exact mechanisms of this infection, many articles claim that the deadly spread of Alzheimer's disease goes far beyond what we previously thought.

Now, scientists say that they have one of the most decisive tracks so far for a bacterial responsible behind Alzheimer's disease, and that it comes from a neighborhood rather unexpected: the disease of the gums.

In a new article led by lead author Jan Potempa, a microbiologist from the University of Louisville, researchers reported the discovery of Porphyromonas gingivalis – the pathogen causing chronic periodontitis (gum disease) – in the brain of deceased patients of Alzheimer's.

Gingipains of P. gingivalis (red) among brain neurons of a patient with Alzheimer's disease (cortexyma)

This is not the first time that both factors are linked, but the researchers went further.

In separate experiments conducted in mice, an oral infection by the pathogen resulted in colonization of the brain by the bacteria, as well as increased production of beta-amyloid (Aβ), the generally badociated sticky proteins to Alzheimer's disease.

The research team, which is coordinated by the pharmaceutical start-up Cortexme, co-founded by first author Stephen Dominy, does not claim to have discovered definitive evidence of the Alzheimer's cause. Again.

But it is clear that they think we have a solid line of investigation here.

"Infectious agents have already been implicated in the development and progression of Alzheimer's disease, but evidence of causality is not convincing," said Dominy.

"Now, for the first time, we have strong evidence linking the Gram-negative intracellular pathogen, P. gingivalisand the pathogenesis of Alzheimer's ".

In addition, the team identified toxic enzymes called gingipaines secreted by the bacteria in the brain of patients with Alzheimer's disease, which correlated with two distinct markers of the disease: tau protein and a protein label called ubiquitin.

But even more convincingly, the team identified these toxic gingipains in the brains of people who had never been diagnosed with Alzheimer's disease.

This is important because while P. gingivalis and the disease has already been linked, it has never been known – to put it simply – if gum disease is causing Alzheimer's disease or if dementia causes care oral mediocre.

The fact that low levels of gingipain are evident even in people who have never been diagnosed with Alzheimer's disease could be a smoking gun – suggesting that they could have developed the disease they had lived longer.

"Our identification of gingipain antigens in the brains of individuals with AD and also with AD pathology, but without a diagnosis of dementia, argues that the brain infection by P. gingivalis is not the result of poor dental care after the onset of dementia or the consequences of advanced disease, but is an early event that may explain the pathology found in middle-aged individuals before cognitive decline ", write the authors in their article.

In addition, a compound formulated by the company called COR388, which is already the subject of clinical trials on patients with Alzheimer's disease, has shown in experiments on mice that he could reduce the bacterial burden of an already established virus. P. gingivalis brain infection, while also reducing beta-amyloid production and neuroinflammation.

We will have to wait to see what future research will discover on this link – and on the potential benefits of COR388 – but the research community remains cautiously optimistic.

"The drugs targeting the toxic proteins of the bacterium have so far only shown benefits in mice.However, in the absence of new treatments for dementia for over 15 years, it has It is important that we try as many approaches as possible to fight against diseases such as Alzheimer's disease, "said Scientific Director David Reynolds of Alzheimer's Research commented in a statement.

"We will have to see the result of this ongoing trial before learning more about its potential as a treatment for Alzheimer's disease."

The results are reported in Progress of science.