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Could Herpesvirus help cause Alzheimer's?



FRIDAY, October 19, 2018 (HealthDay News) – There is increasing evidence that herpes virus, which is responsible for cold sores, can also cause Alzheimer's, says a new research paper.

It has long been known that herpes simplex virus 1 (HSV1) can be found in the brains of older people with Alzheimer's disease, and research has shown that herpes increases Alzheimer's risk in people genetically predisposed to dementia said researcher Ruth Itzhaki.

Recent data suggest that treating people with antiviral medications "I could protect them from dementia," said Itzhaki, a professor of neuroscience at Manchester University in England.

"We found that the antiviral anti-herpes drug acyclovir blocks HSV1

DNA replication and lowers beta-amyloid and P-tau levels caused by HSV1 infection from cell cultures," said Itzhaki. Beta-amyloid plaques and tangles of tau proteins are two of the hallmarks found in the brains of Alzheimer's patients.

But the effect of herpes on the brain is not fully understood yet, and it is unlikely that the virus alone can explain all cases of Alzheimer's disease, said James Hendrix, director of global scientific initiatives for the Alzheimer's Society.

Hendrix noted that half of all adults carry the herpes simplex 1 virus.

"We know that 50 percent of the population are not getting Alzheimer's disease, so it's not a 1-to-1 correlation," said Hendrix. "If we took the recommendation of the author of this paper and gave everyone over 55 antiviral drugs, I do not think we would quench Alzheimer's disease, we could lower it a bit, but I do not think we would eliminate it Alzheimer's Disease. "

Herpes simplex virus 1 infects most people in infancy and henceforth remains inactive in the peripheral nervous system, Itzhaki said. Stress can cause the virus to be reactivated and cause cold sores in some people.

Itzhaki and her colleagues believe that herpes contributes to Alzheimer's disease by migrating into the brains of older people as their immune system naturally abates

it has infected the brain, Itzhaki argues, causing HSV1 damage and inflammation in brain cells whenever it is reactivated by events such as stress, immunosuppression or infection by other microbes.

This damage is particularly poor in humans with the APOE4 gene (19659002) "The likelihood of developing Alzheimer's is 12 times higher in APOE4 carriers that have HSV1 [the herpes virus] in the brain those with no factor, "said Itzhaki [19659002]" We suggest that repeated activation causes cumulative damage that eventually leads to Alzheimer's disease in people with an APOE4 allele, "Itzhaki continued. "Presumably, Alzheimer's disease develops in APOE4 carriers in the brain due to increased HSV1-induced toxic product formation or less damage repair."

Dr. Sam Gandy is Deputy Director of the Mount Sinai Alzheimer Research Center in New York City. He said there is evidence that viruses can affect other brain and nervous system disorders, in particular Lou Gehrig's Disease or Amyotrophic Lateral Sclerosis (ALS).

"Probably the best evidence that viruses can contribute to severe brain disease comes from ALS, where they did not find a herpes virus, but a retrovirus," Gandy said. "The peptides of the virus appeared in the cerebrospinal fluid of patients with ALS, and when they treated these patients with antiretroviral drugs, they appeared to stabilize clinically."

Itzhaki said that a recent study from Taiwan indicates that this frees the body from herpes through antiviral drugs could reduce Alzheimer's risk.

The Taiwanese results showed that the risk of dementia was infected in people with herpes, and that treatment with antiviral drugs caused a dramatic decrease in the number of people with severe HSV1. Later Itzhaki said

Hendrix said that Taiwanese results can be explained in other ways. For example, it may not be the anti-viral drugs that reduced the rate of dementia, but the fact that these specific patients received better overall medical care.

"We know that better health care leads to lower rates of dementia". Hendrix said

Gandy said that while the link between herpes and Alzheimer's is promising, clinical trials would be needed to show that antiviral treatment can effectively combat dementia in humans.

"There is much circumstantial evidence Evidence requires finding living people who have the virus and the symptoms of dementia, giving them the antiviral substance and showing that their symptoms are stabilizing or improving," Gandy said.

New research tools are needed, including a brain scan that can specifically detect herpes in the brain, he added.

"We need to be able to find the virus as a warning flag, to tell ourselves that we should start treatment and then see if that impacts on progress," Gandy said.

The new paper was published online October 19 in the journal Frontiers in Aging Neuroscience .

More information

The World Health Organization has more on herpes simplex virus 1.

SOURCES: Ruth Itzhaki, Ph.D., Professor of Neuroscience, University of Manchester, United Kingdom; James Hendrix, Ph.D., director of global scientific initiatives, Alzheimer's Association; Sam Gandy, M.D., Ph.D., Deputy Director of the Mount Sinai Alzheimer Research Center, New York City; 19 Oct. 2018, Frontiers in Aging Neuroscience online


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