Researchers Find Herpes Viruses in Brains Marked by Alzheimer's Disease

A study published in Neuron notes the presence of two common herpes viruses in brain tissue from people with Alzheimer's, reports National Public Radio . The researchers also found evidence suggesting the viruses can interact with brain cells in ways that could accelerate the disease. "The data are very provocative, but fall short of showing a direct causal role," says National Institute on Aging Director Richard Hodes. "And if viral infections are playing a part, they are not the sole actor." The team originally was using genetic data to search for differences between healthy brain tissue and brain tissue from people who died with Alzheimer's, for the purpose of identifying new drug targets. Instead, the team kept finding clues that brain tissue from people with Alzheimer's contained higher levels of viruses. They learned that levels of the HHV-6 and HHV-7 herpes viruses were up to twice as high in brain tissue from people with Alzheimer's. "We mapped out the social network, if you will, of which genes the viruses are friends with and who they're talking to inside the brain," says Mt. Sinai Professor Joel Dudley. The team ascertained that the herpes virus genes were interacting with genes known to elevate the risk for Alzheimer's, and that these risk genes appear to make a person's brain more exposed to infection with the two herpes viruses. Dudley notes once the viruses are activated, they seem to influence the buildup of the plaques and tangles in the brain associated with Alzheimer's.