• Posted January 8, 2025

More Evidence Bolsters the Oral Herpes and Alzheimer’s Link

That cold sore on your lip might be painful and unsightly, but it could also be a harbinger of debilitating brain aging.

The oral herpes virus appears to be linked with Alzheimer’s disease, suggesting that the common infection might play a role in the disease, a new study published in the journal Cell Reports says.

Herpes simplex virus 1 -- the virus behind oral herpes -- appears to trigger the appearance of tau protein in the brain, researchers say.

This tau might initially protect the brain from the virus, but contribute to brain damage later.

“Our study challenges the conventional view of tau as solely harmful, showing that it may initially act as part of the brain’s immune defense,” senior researcher Or Shemesh, an assistant professor of ophthalmology with the University of Pittsburgh, said in a news release from the college.

Between 50% to 80% of U.S. adults have oral herpes, according to Johns Hopkins Medicine. About 90% of adults have been exposed to the HSV-1 virus by age 50.

For this study, researchers identified HSV-1-related proteins in samples taken from the brains of Alzheimer’s patients.

They found greater amounts of HSV-1 proteins among tau tangles, the clotted twists of tau protein which are known as one of the hallmarks of Alzheimer’s disease.

Doctors then created miniature cell models of human brains in Petri dishes, to study the effect of the virus on brain cells.

The results indicated that an HSV-1 infection can affect levels of tau protein in the brain, with tau acting to protect nerve cells from dying as a result of the infection.

“These findings emphasize the complex interplay between infections, immune responses and neurodegeneration, offering a fresh perspective and potential new targets for therapeutic development,” Shemesh concluded.

However, it’s still not clear how herpes virus influences tau protein, and why tau can turn from protective to destructive in some brains, researchers noted.

The research team plans to test drugs that target viruses or fine-tune the brain’s immune response, to see whether they can lower risk of Alzheimer’s or other degenerative brain disorders like Parkinson’s disease or ALS.

More information

Johns Hopkins Medicine has more on oral herpes.

SOURCE: University of Pittsburgh, news release, Jan. 2, 2025