As they explain in their paper neurological magazine "Neuron", they studied the brains of almost 1,000 people dead and found increased presence -up doubled two herpesviruses (of HHV-6A and HHV-7) in people with Alzheimer's neuropathology, compared to those without had Alzheimer's when they died. The research team created computer models that mapped the genes that were disrupted or activated during the progression of Alzheimer's. Readhead said the connection between finding the virus in the blood and it activating the Alzheimer's genes and triggering the disease is still not understood well.
A new study from the Icahn School of Medicine at Mount Sinai, published in the journal Neuron, has reignited a controversial theory about what causes the neurodegenerative disease by studying the brains of people from three different brain banks. The viruses remain dormant however within the body. Scientists, however, state that it cannot yet be said with certainty that, in fact, herpes can cause or exacerbate the now incurable neurodegenerative disease.
They examined the influence of each virus on specific genes and proteins in brain cells, and identified associations between specific viruses and amyloid plaques, neurofibrillary tangles, and clinical dementia severity.
Alzheimer's disease is an irreversible, progressive brain disorder that slowly destroys memory and thinking skills and, eventually, the ability to carry out simple tasks. "I think they're like gas on the flames of some pathology that may be immune-driven".
Readhead says around 90 percent of children in the USA and the United Kingdom are exposed to these viruses in the first few years of life.The findings don't prove the viruses cause Alzheimer's, nor do they suggest it's contagious.
Leah Rosenbaum at ScienceNews reports that there is more recent support for this theory. As with any complex set of findings, they will need to be confirmed in additional patient cohorts, and further studies to specifically address a causal role for viruses are now being conducted by the research team.
According to one of the study's senior authors, Sam Gandy, although viral and genetic causes are often seen separately, it is possible that the viral protein acts as transcription factors that turn on the Alzheimer's disease genes.
This study has been enabled by the extensive molecular profiling of several large patient cohorts, generated in the course of the National Institute on Aging (NIA) Accelerating Medicines Partnership-Alzheimer's Disease (AMP-AD). Researchers have been down this road before.
More than a century after Alzheimer's discovery, there is still no effective prevention or cure for the disease, not even clear justification.
Alzheimer's remains a mystery, but researchers are confident the new study opens up avenues for finding the cause. That's unlikely to be the end of the story.
Doctors don't know what causes Alzheimer's disease or the best way to treat it, but they have new evidence to suggest that a common virus may play a role in who develops the condition.