Cold sores linked to Alzheimer's: Self-defense?

(CBS) Painful, yes. Embarrassing, maybe. But new research gives scientists a clear picture of how cold sores can lead to a health concern that's a bit more serious:

Alzheimer's disease.

That's right. The same herpes simplex virus type 1 (HSV1) that causes cold sores on the lips, mouth, or gums can contribute to dementia, according to a study published in the March 31 issue of the journal PLoS ONE.

"Herpes infects mucous membranes, such as the lip or eye, and generates viral particles," lead author Dr. Elaine Bearer, a pathology professor at the University of New Mexico School of Medicine, said in a written statement released in conjunction with the study. "These viral particles burst out of the cells of the mucous membrane and enter sensory nerve cells where they travel inside the nerve toward the brain."

By tagging herpesvirus particles with green fluorescent proteins and then looking at them with an electron microscope, scientists were able to watch them affect nerve cells in ways that seem to lead to Alzheimer's.

"It's no longer a matter of determining whether HSV1 is involved in cognitive decline, but rather how significant this involvement is," Bearer said. "We'll need to investigate anti-viral drugs used for acute herpes treatment to determine their ability to slow or prevent cognitive decline."

In the meantime, researchers say it's smart to treat a cold sore as quickly as possible to minimize the amount of time the virus is active. The faster a sore is treated, the faster HSV1 returns to its dormant stage.

Washing blisters with soap and water can help keep them from spreading. In addition, doctors can prescribe antiviral medications like acyclovir, famciclovir, and valacycolvir. They work best when taken just as the virus is starting to "come back."

HSV1 infections are ubiquitous in developed countries like the U.S. About 20 percent of kids are infected by age five, a rate that rises to about 60 percent in the second and third decades of life. Among old people, about 85 percent are affected.

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