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WASHINGTON – Viruses that sneak into the brain could play a role in Alzheimer's disease, scientists recently reported in a provocative study that promises to revive some long-debated theories about what triggers the disease that steal the mind.
However, a team led by researchers at Mount Sinai Health System in New York found that some viruses – including two extremely common herpes viruses – affect the behavior of the genes involved. In Alzheimer's.
The idea that infections earlier in life could somehow pave the way for decades of later Alzheimer's simmered at the cutting edge of traditional medicine for years. It has been overshadowed by the prevailing theory that Alzheimer's disease comes from sticky plates that obstruct the brain.
Thursday's study even has some specialists who have never kissed the infection link, saying it's time to take a closer look. "With such a terrible disease, we can not afford to reject all scientific possibilities," said Dr. John Morris, who heads the Alzheimer's Research Center at the School of Medicine at the University of Toronto. 39, University of Washington at St. Louis. He did not participate in the new research, but qualified it impressively.
The study also demonstrates that the brain's immune system defends itself against viruses or other germs, which can be more risky than a real infection. Rudolph Tanzi of Massachusetts General Hospital. With a Harvard colleague, Dr. Robert Moir, Tanzi has performed experiments showing that sticky beta-amyloid captures invading germs by engulfing them – and that is why plaque starts to form in the first place.
brain, what are the microbes that matter, what are the microbes that trigger the plaque? ", says Tanzi, who also did not play a part in the new research.
The Mount Sinai team and Arizona State University found viral suspects by accident. The study, funded by the National Institutes of Health, was not the virus hunt, but was looking for new drug targets for Alzheimer's disease.The researchers were using complex genetic data from hundreds of brains in several brain banks to compare the differences between people dying with Alzheimer's disease and normally cognitive people.
The first clues that viruses were circulating "were screaming at us" Mount Sinai geneticist, Joel Dudley, lead author of the research published Thursday in the journal Neuron
The team found viral genetic material at much higher levels in Alzheimer's brains than in the brain. The most common were two human herpes viruses, known as HHV6a and HHV7, which infect most people during childhood, often without symptoms, and then remain dormant in the body.
This was not unusual. Since 1980, other researchers have linked a variety of bacteria and viruses, including another type of herpes that causes cold sores, to an increased risk of Alzheimer's. The new study went one step further: researchers used computer models to test how viral genes interacted with human genes, proteins, and accumulation of amyloids, almost like viruses. "We are able to see if the viral genes are friends with some of the host genes and they tweet, which tweets back," says Dudley.
They found a lot of interactions, suggesting that viruses could even turn on and off genes linked to Alzheimer's disease. To see if these interactions mattered, the researchers raised mice devoid of a molecule that herpes seemed to deplete. Indeed, the animals have developed more of these amyloid plaques.
"I'm looking at this document and it makes me sit down and say," Wow, "said Scientific Program Director of the Alzheimer's Association Keith Fargo.Search makes a much more likely viral connection, but warned that the study will not affect how today 's patients are treated.
If the results show, they could change the way scientists look for new ways to treat or treat Preventing Alzheimer's Disease Miroslaw Mackiewicz of the NIH's National Institute on Aging Already, the NIH is funding a first-stage study to see if an antiviral drug is beneficial for people who have both Alzheimer's disease and various herpes viruses
Tanzi from the general pointed out.It may not even have penetrated into the brain.
But in another study soon published, Tanzi showed biologically as HHV6 and cold sores causing cold sores could trigger or "seed" the formation of amyloid plaques, supporting Mount Sinai discoveries. Yet he does not think viruses are the only suspects.
"The Mount Sinai document tells us the viral side of the story.We still have to work on the microbe side of history," said Tanzi, who is looking for bacteria and d & # 39; other bugs in what is called the Brain Microbiome Project. "The brain has always been considered a sterile place. This is absolutely not true.
Editor's note: The Associated Press's Department of Health and Science is receiving support from the Howard Hughes Medical Institute's Department of Science Education. AP is solely responsible for all content.
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