If your gums bled a little this morning when you brushed your teeth, you might want to talk to your dentist about it right away instead of ignoring it because a scary new study has found a potential link between gum disease and the dementia of Alzheimer’s disease.

Researchers found porphyromonas gingivalis, the keystone pathogen in chronic periodontitis, in the brains of Alzheimer’s disease patients. Dr. Steve Dominy, study author and associate professor at University of California, told Newsweek that this could be the “main cause of Alzheimer’s disease.”

The new study, published today in Science Magazine, was sponsored by the biotech startup Cortexyme Inc. of South San Francisco, co-founded by Dominy, who serves as its chief scientific officer. Researchers at the Centre for Brain Research at University of Auckland compared the brain tissue of patients with and without Alzheimer’s disease. They found 96 percent of 53 patients with the condition had the potentially neuro toxic enzyme called arginine gingipain from the bacteria inside their neurons. No less than 91 percent of 54 patients tested positive for a second enzyme from the bacteria known as lysine-gingipain. These were detected at levels higher than the control samples, the scientists said.

The bad news is that experts estimate half of adults have periodontitis, as Newsweek noted. About 10 percent of us experience a severe version of the disease, which erodes the gums and the bones that keep our teeth in place, the scientists said. If the findings are correct, this could help explain why 5.7 million Americans are now living with Alzheimer’s disease.

The good news is that gingipain inhibitors could be valuable for treating P. gingivalis brain colonization and neurodegeneration in Alzheimer’s disease, the researchers said.

However, not all experts are convinced that the connection is a slam dunk.

“I’m fully on board with the idea that this microbe could be a contributing factor. I’m much less convinced that [it] causes Alzheimer’s disease,” neurobiologist Robert Moir of the Harvard University–affiliated Massachusetts General Hospital (MGH) in Boston told Science.

In any case, it sure won’t hurt to do a bit more flossing.