Virus Infections in Early Life Could Set the Stage For Alzheimer’s


Scientists have found that Alzheimer’s could be triggered by viruses that can affect the brain. It’s been years of debate on what causes the disease, and this study sparks the debates with a new way of looking at it.

The study doesn’t prove that Alzheimer’s is caused by viruses or that it’s contagious. It was published in the journal Neuron on 21 June.

Researchers at the Mount Sinai Health System in New York found that some viruses, including two types of the herpes virus, could affect the genes that are involved in Alzheimer’s. The theory was suggested before, but specialists never really embraced this connection.

When the brain’s immune system defends itself from viruses or germs, it can be too aggressive, explains Dr. Rudolph Tanzi (Massachusetts General Hospital). Dr. Tanzi and his Harvard colleague Dr. Robert Moir (unrelated to this study) looked at the sticky beta-amyloid captures that invaded germs and causing the forming of plaque. Dr. Tanzi then had some questions of his own:

“In the Alzheimer brain what are the microbes that matter, what are the microbes that trigger the plaque?”

The First Clues “Came Screaming Out at Us”

To answer this question, a team of researchers at Mount Sinai and Arizona State University found some viral suspects by pure accident. They were looking for new drugs to target Alzheimer’s.

Analyzing genetic data from hundreds of brains at brain banks, they wanted to compare the difference between people that died with Alzheimer’s and the ones without Alzheimer’s.

Mount Sinai geneticist Joel Dudley and senior author of the study said that the clues “came screaming out at us.”

The team found that brains affected by Alzheimer’s had a higher level of viral genetic material, most of them being human herpes viruses, known as HHV6a and HHV7. These viruses often have no symptoms, infect many people in their childhood and will stay dormant in the human body.

But the team continued to see how the viral genes interacted with human genes, said Dudley:

“We’re able to see if viral genes are friending some of the host genes and if they tweet, who tweets back.”

To their surprise, they found many interactions, suggesting that these viruses can switch on or odd the genes related to Alzheimer’s.

Dr. Miroslaw Mackiewicz of NIH’s National Institute on Aging believes that the study can help scientists find new ways of preventing and treating the disease.

Tanzi explains that having a herpes virus “does not mean you’re going to get Alzheimer’s. The Mount Sinai paper tells us the viral side of the story. We still have to work out the microbe side of the story.”


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