January 03, 2007
Herpes Virus And ApoE Gene Cause Alzheimer's RIsk

The ApoE-4 version of the ApoE gene which is associated with a higher Alzheimer's Disease risk probably increase the risk of Alzheimer's by doing a poorer job of suppressing the Herpes virus that causes cold sores.

A gene known to be a major risk factor for Alzheimer's disease puts out the welcome mat for the virus that causes cold sores, allowing the virus to be more active in the brain compared to other forms of the gene. The new findings, published online in the journal Neurobiology of Aging, add some scientific heft to the idea, long suspected by some scientists, that herpes somehow plays a role in bringing about Alzheimer's disease.

The work links a form of the ApoE gene known as ApoE-4, which after advanced age is the leading known risk factor for getting Alzheimer's disease, with the form of herpes herpes simplex 1 or HSV that infects more than 80 percent of Americans and causes cold sores around the mouth. The findings from a group at the University of Rochester Medical Center show that the particular form of the gene that puts people at risk also creates a fertile environment for herpes in the brain, allowing the virus to be more active than other forms of the ApoE gene permit.

We need vaccines that will prevent Herpes virus infections. We also need drugs or perhaps gene therapies that'll suppress or kill Herpes in the brain and peripheral nerves.

Scientists have known for more than 15 years that the ApoE-4 gene is a player in Alzheimer's disease, but the idea that it works in concert with the herpes virus is new.

Note how we've known about the ApoE-4 link to Alzheimer's for 15 years without being able to do anything about it. That's true with many other genetic variations which have known roles in causing diseases. We lack the gene therapy technologies to intervene. Though the knowledge that specific genes play roles in development of diseases does allow many scientists to focus their attention on how those those operate and how their role may help cause diseases.

Different lines of evidence point toward an Apo-E4 plus Herpes connection with Alzheimer's.

Ruth Itzhaki of the University of Manchester has led the way with several studies showing a correlation between herpes and Alzheimer's. She has shown that Alzheimer's patients who have the ApoE-4 form of the gene have more herpes DNA in the brain regions that are affected by Alzheimer's, compared to Alzheimer's patients who also have herpes but who have a different form of the ApoE gene. And she has shown that people with the ApoE-4 version of the gene who are infected with herpes are more likely to get Alzheimer's disease than people infected with herpes who have a different form of the ApoE gene, or than people who have the ApoE-4 gene but who don't have herpes.

Other scientists have found that a herpes infection is active more often causing the tell-tale cold sores around the mouth in the 25 percent of people who have a copy of the ApoE-4 gene. In other words, people who are frequently troubled by cold sores are more likely to have the gene that makes them more vulnerable to Alzheimer's disease.

Every time you get a cold sore do you suffer mild brain damage? Seems plausible at least.

ApoE-4 does not increase the odds of infection but it does increase the amount of time time the virus is active.

The team found that the virus infiltrates brain cells about the same no matter which gene is involved. But they found that the subsequent activity level of the virus generally mirrored the disease-causing potential of the gene. They found that in animals with the ApoE-4 gene, the virus is less likely to be in the quiet, latent stage of its life cycle, suggesting it has more of an opportunity to replicate. In animals with the ApoE-2 gene, the virus was less active.

Brain aging is the form of aging I most want to slow down and delay. How to rejuvenate the 100 billion neurons in the brain is the hardest task facing rejuvenation medicine. We'll be able to reverse the aging of the rest of the body before we develop the ability to make the brain youthful once again. Therefore any treatments we can come up with to slow brain aging will provide great benefits and give us more time to develop brain rejuvenation therapies.

Share |      Randall Parker, 2007 January 03 09:59 PM  Brain Alzheimers Disease

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