Alzheimer's 'may be caused by a virus'

Prof Riona Mulcahy and Prof John Nolan

Prof Riona Mulcahy and Prof John Nolan

This particular set of herpes viruses is common. The research doesn't prove anything just yet, but it's an interesting theory and one that many experts have been talking about for some time. Researchers funded by the National Institute on Aging (NIA), part of the National Institutes of Health, made the discovery by harnessing data from brain banks and cohort studies participating in the Accelerating Medicines Partnership - Alzheimer's Disease (AMP-AD) consortium. HHV six and seven are fairly common in young kids and can cause what's known as sixth disease with a fever and rash.

New research by a team of scientists in Waterford has identified a unique combination of nutrients that they say slows the progression of Alzheimer's disease.

"The integrated findings of this study suggest that AD biology is impacted by a complex constellation of viral and host factors acting across different timescales and physiological systems", the researchers wrote.

They found that human herpesvirus 6A and 7 were up to twice as abundant in Alzheimer's disease samples than non-Alzheimer's ones.

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. "This research reinforces the complexity of Alzheimer's disease, creates opportunities to explore Alzheimer's more thoroughly, and highlights the importance of sharing data freely and widely with the research community".

In this study, researchers initially performed RNA sequencing on more than 600 samples of postmortem tissue of people with and without Alzheimer's, looking to quantify which genes were present in the brain and whether any were associated with the development of the disease. Instead, what ultimately stood out to them were not any particular human genes but in fact an abundance of genes related to two particular strains of herpes virus. It seems feasible that amyloid is not the cause of disease in many cases.

"We're able to see if viral genes are friending some of the host genes and if they tweet, who tweets back", Dudley said.

"It's conceivable there are ways in which viruses interact that we haven't really taken very seriously before, in terms of provoking the pathology or the expression of disease", senior author Sam Gandy, MD, PhD, told MedPage Today. Their data analyses and subsequent studies in experimental mice found that the HHV-6A virus effectively suppressed miR-155, leading to altered levels of Aβ and amyloid plaque density in vivo.

Childhood viruses that infect nearly everyone and lie dormant in the body for life might be involved in Alzheimer's disease, researchers reported Thursday.

"We didn't go looking for viruses, but viruses sort of screamed out at us", said lead author Ben Readhead, of Arizona State University. "When we built those network models, we found that the virus/host interaction contained many known Alzheimer's genes", he said. Antiviral drugs could also be explored as a potential preventive treatment.

Although the hypothesis that viruses play a part in brain disease isn't new, "this is the first study to provide strong evidence based on unbiased approaches and large datasets that lends support to this line of inquiry", comments NIA director Richard J. Hodes, M.D. Ruth Itzhaki, a neurobiologist at the University of Manchester in the United Kingdom, who has led numerous studies linking HSV-1 with Alzheimer's, says she has suffered "derision and vituperative hostility" for pursuing this line of inquiry. According to the so-called pathogen hypothesis of AD, the brain reacts to infection by engulfing viruses with the protein amyloid beta (Aβ), sequestering the invaders and preventing them from binding with cell surfaces and inserting their viral genetic payload into healthy cells.

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