Over the years, researchers are discovering more and more about Alzheimer’s disease. But the reasons for the appearance of this disease remain difficult to define. According to a new study by researchers from Tufts University and the University of Oxford, the varicella-zoster virus can activate herpes simplex (HSV) to trigger the early stages of Alzheimer’s disease. These findings were published in the Journal of Alzheimer’s Disease.
“Our results suggest a pathway to Alzheimer’s disease, caused by a VZV infection which creates inflammatory triggers that wake up HSV in the brain,” said Dana Cairns, GBS12, research associate in the Department of Biomedical Engineering. HSV-1, it is possible that other inflammatory events in the brain may also awaken HSV-1 and lead to Alzheimer’s disease.”
Generally, HSV-1 is in sleep in brain neurons, but when activated, it leads to accumulation of tau and beta-amyloid proteins. These characteristics are generally found in patients with Alzheimer’s disease.
A demonstrated correlation
“We know there is a correlation between HSV-1 and Alzheimer’s disease, and a suggested involvement of VZV, but what we didn’t know was the sequence of events that viruses create to trigger disease. We believe we now have evidence of these events,” said David Kaplan, Stern family professor of engineering and chair of the biomedical engineering department at Tufts’ School of Engineering.
According to the World Health Organization, approximately 3.7 billion people under the age of 50 have been infected with HSV-1, the virus that causes oral herpes. Varicella zoster virus is also extremely common, with about 95% of people who were infected before the age of 20 and get chickenpox. This same virus can be reactivated a few years later in the form of shingles.