Herpes virus has role in development of Alzheimer's disease : Study

Viruses could play a key role in the development of Alzheimer's disease(AD), according to a new study published in the journal Neuron. Researchers found strong evidence to suggest that two strains of the human herpesvirus HHV-6A and HHV-7 may contribute to the disease that impairs memory and cognitive functions.

Herpes viruses 6 and 7 are widely present in humans but is not well understood. They infect nearly every human, typically during infancy, and are closely linked to the childhood rash called roseola, according to the HHV-6 Foundation.

Ben Readhead and his associates designed the study to map and compare biological networks underlying two distinct Alzheimer's disease-associated phenotypes using multiple independent datasets collected from human subjects. The authors initiated with a computational network characterization of a specific endophenotype of the AD: brains meeting neuropathological criteria for the Alzheimer's disease from individuals who were cognitively intact at the time of death which is referred as “preclinical AD”.

The researchers in the new study looked at data on 622 brains from people who had had signs of the disease and 322 from people who did not seem to be affected by it. The brains with Alzheimer's had levels of the herpes virus that were up to twice as high as in people who did not have the disease.

“This study presents novel evidence linking the activity of specific viruses with an Alzheimer's disease. This has been enabled by comprehensive molecular profiling of large patient cohorts, facilitating the integration of diverse biomedical data types into an expansive view spanning multiple disease stages, brain regions, and omic domain.” said the authors.

“Our results offer evidence of complex viral activity in the aging brain, including changes specific to AD, particularly implicating Herpesviridae, HHV-6, and HHV-7. These data provide compelling evidence that specific viral species contribute to the development of neuropathology and AD.” they added.

However, if viruses or other infections are confirmed to have roles in the AD, it may enable researchers to find new antiviral or immune therapies to treat or prevent the disease," said Fargo, the Alzheimer's Association's director of scientific programs and outreach. "The Alzheimer's Association welcomes new ideas in the Alzheimer's field and new avenues to pursue potential treatments and prevention strategies," he added.

The researchers observed the presence of many viral species in the aging brain and linked multiple viral species with Alzheimer's disease biology, including regulation of AD genetic risk networks, AD gene expression changes, and association with clinical dementia rating and neuropathology burden. Prominent roles for Roseoloviruses HHV-6A and HHV-7, which implicated across multiple domains, and in 3 independent cohorts were found.

The study concluded that evidence has been found that links the activity of specific viral species with molecular, genetic, clinical, and neuropathological aspects of the AD.

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https://www.cell.com/neuron/fulltext/S0896-6273(18)30421-5