Could Alzheimer’s Begin in the Mouth?
In recent years, a wave of scientific discoveries has begun to challenge the way we think about Alzheimer’s disease. Long seen as an inevitable consequence of aging, Alzheimer’s may in fact be triggered—or at least accelerated—by something far more unexpected: infection.
A landmark study published in 2019 provided one of the strongest clues yet, pointing to an unlikely suspect—gum disease.
Researchers led by microbiologist Jan Potempa at the University of Louisville found traces of Porphyromonas gingivalis—the bacterium responsible for chronic periodontitis—in the brains of patients who had died from Alzheimer’s. The finding, reported in ScienceAlert, was striking: a common oral pathogen present where it shouldn’t be—the brain.
The Gum Disease–Alzheimer’s Connection
This was not the first time gum disease and Alzheimer’s had been linked, but the research went a step further. In mouse experiments, oral infection with P. gingivalis led to brain colonization and a rise in beta-amyloid (Aβ), the sticky protein long recognized as a hallmark of Alzheimer’s.
The team behind the study included the biotech company Cortexyme, co-founded by Stephen Dominy, the paper’s first author. While they stopped short of claiming proof that gum disease causes Alzheimer’s, the results opened a bold new direction in understanding the illness.
“Infectious agents have previously been implicated in Alzheimer’s, but the causal evidence was weak. Now, for the first time, we have a solid link between the pathogen P. gingivalis and the disease’s progression,” Dominy explained.
The researchers also identified toxic enzymes called gingipains—secreted by the bacteria—inside Alzheimer’s patients’ brains. These enzymes were closely associated with two other disease markers: tau protein and ubiquitin.
A New Avenue for Treatment
Even more surprising, gingipains were detected in the brains of people who had died without an Alzheimer’s diagnosis. This suggests that gum infections could silently set the stage for the disease years—or even decades—before symptoms appear.
If true, this would mean that P. gingivalis isn’t just a byproduct of poor oral health in older adults with dementia, but potentially an early, causal factor in the disease itself.
Encouragingly, the study also pointed toward a possible intervention. Cortexyme developed a compound called COR388, which reduced bacterial load in the brains of infected mice, while also lowering beta-amyloid production and brain inflammation. Though still in the early stages and limited to animal studies, this line of research could open the door to innovative treatments.
The findings, published in Science Advances, suggest a radical shift in how we think about Alzheimer’s: not just as a disease of age and genetics, but one that might begin in something as ordinary—and treatable—as gum disease.
