"We found prominent roles for Roseoloviruses HHV-6A and HHV-7, both implicated across multiple domains, and 3 independent cohorts", the team writes.
HAMILTON: It's not clear exactly how virus genes interact with Alzheimer's genes, but Dudley says it is clear that the same genes that make some brains more susceptible to Alzheimer's also seem to make them prone to infection with these herpes viruses. "Viruses were the last thing we were looking for", Dudley says.
The nature and significance of viruses and other pathogens in the brain are now hot topics in neuroscience, though the exploration is still in its early stages.
"We saw a key virus, HHV-6A, regulating the expression of quite a few Alzheimer's risk genes and genes known to regulate the processing of amyloid, a key ingredient in Alzheimer's neuropathology". "This research reinforces the complexity of AD, creates opportunities to explore Alzheimer's more thoroughly, and highlights the importance of sharing data freely and widely with the research community".
Childhood viruses that infect nearly everyone and lie dormant in the body for life might be involved in Alzheimer's disease, researchers reported Thursday. They designed their study to map and compare biological networks underlying Alzheimer's disease. It's been overshadowed by the prevailing theory that Alzheimer's stems from sticky plaques that clog the brain.
The study found that herpes viruses were involved in networks that regulate amyloid precursor proteins.
They argue, however, that their work shouldn't make anyone anxious.
While the current findings are more specific, they do not provide evidence to change how risk and susceptibility are assessed, nor the diagnosis and treatment of Alzheimer's, the authors said.
HHV-6 and HHV-7 cause roseola, a very common childhood disease that usually infects babies and toddlers. "It was really striking", says Sam Gandy, a co-author who is a Mount Sinai neurologist and amyloid expert.
Keith Fargo, the Alzheimer's Association's director of scientific programs and outreach, said that more research will need to be done to prove that there is a connection between herpes viruses and Alzheimer's. "We didn't have a horse in this virus race whatsoever. But it would be negligent for us to ignore these results until the next study reports back, which will take several years".
"And now, not only is the viral hypothesis resurrected: it has specific testable pathways and networks and interactions that can be explored and reconciled with the rest of the work emerging in Alzheimer's". "We are excited about the chance to capitalize on this approach to help in the scientific understanding, treatment and prevention of Alzheimer's and other neurodegenerative diseases". They were then able to incorporate additional data from the Emory Alzheimer's Disease Research Center to understand viral impacts on protein abundance.
The new research is the fruitful result of close working relationships among researchers from Arizona State University, Banner, Mount Sinai and other research organizations, as well as public-private partnerships in AMP-AD. The research, published June 21 in Neuron, found convincing signs that certain types of herpes virus may promote the complex process that leads to the disease that afflicts some 5.7 million Americans.
The nature and significance of viruses and other pathogens in the brain are now hot topics in neuroscience, though the exploration is still in its early stages. Each patient had undergone clinical evaluation to follow the course of their disease before death and neuropathological evaluation to evaluate factors, including the degree of amyloid plaque formation. "What I believe is that in genetically or physiological susceptible individuals, the virus is acting as an agonist of the disease", Dudley says-a number of processes likely participate, with viruses being just one piece of the puzzle.