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Alzheimer’s researchers are beginning to think HSV-1 may play a role in dementia

Researchers are taking another look at the cause of Alzheimer’s disease, and some new clues indicate that herpes (specifically HSV-1) may play a role.

How did scientists make the connection between Alzheimer’s and herpes? It wasn’t a clear-cut path, but it started decades ago. When Alzheimer’s researchers found that the brains of Alzheimer’s patients tend to have a large amount of a specific protein called beta amyloid, they assumed a simple connection ⎼ that beta amyloid was a cause of Alzheimer’s disease.

But new research indicates that beta amyloid may not be the problem at all. In 2010, the pharmaceutical company Eli Lilly announced that its experimental drug, semagacestant, didn’t work. While it did succeed in the goal of reducing the body’s production of beta amyloid, it didn’t help patients’ symptoms.

In fact, removal of beta amyloid actually caused Alzheimer’s patients’ dementia to worsen significantly.

So, what is beta amyloid, and why is it found in the brains of Alzheimer’s patients? Harvard researcher Dr. Stephanie Soscia and her colleagues think beta amyloid accumulates because it’s actually helping the brain protect itself from infections. And they think that herpes simplex virus type 1 (or HSV-1, a common cause of cold sores as well as some genital herpes infections) may be at the root of the problem.

It turns out that HSV-1 is particularly high in Alzheimer’s patients. Because of this and other evidence, some Alzheimer’s researchers are beginning to think that HSV-1 may be a cause of Alzheimer’s ⎼ not beta amyloid.

Another research study spearheaded by Professor Ruth Itzhaki, also supports this claim. She found HSV-1 DNA within beta amyloid plaques when she looked at the brains of Alzheimer’s patients.

So what’s next for Alzheimer’s research? Doctors urge caution in interpreting these results ⎼ more than half of Americans have HSV-1 and only a small percentage develop Alzheimer’s ⎼ so there is still a lot to learn. But the seeming connection between HSV-1 and Alzheimer’s disease could mean improved prevention and treatment down the road. According to researchers, preventing Alzheimer’s for some may be as simple as taking antiviral medications for HSV-1 ⎼ like those already used to treat herpes outbreaks. And if so, Alzheimer’s treatment may begin with a simple herpes test.

Photo: Flickr user  by DerrickT, CC 2.0