HIV Delivers 'Double Whammy' to Brain

Virus doesn't just destroy neurons, it prevents new ones from forming, study finds.

By Randy Dotinga
HealthDay Reporter
Wednesday, August 15, 2007; 12:00 AM

Copyright © 2007 ScoutNews, LLC. All rights reserved.

WEDNESDAY, Aug. 15 (HealthDay News) -- HIV, the virus that causes AIDS, often infiltrates the brains of infected patients, causing everything from cognitive decline to death.

Now, new research in mice suggests the virus doesn't just kill brain cells but also prevents replacement cells from developing.

This "double whammy" explains why HIV is so devastating to the brain, but it could also point the way to new treatments, said study co-author Dr. Stuart Lipton, a neurologist and researcher with the Burnham Institute for Medical Research and the University of California at San Diego.

According to Lipton, HIV infection has become the leading cause of dementia in people under the age of 40. In some cases, "you can't work, you can't concentrate or pay attention, you can't move properly," he said.

His team published its findings in the August issue of Cell Stem Cell.

Brain problems are on the rise as HIV-infected patients live long enough to develop related health problems, he said. Still, the brain illnesses that afflict these patients "may be the best-kept secret of AIDS in the world."

The challenge for doctors is figuring out how to treat brain symptoms when the most powerful antiretroviral drugs cannot pass the natural barrier that protects the brain. HIV, however, can make its way into the brain and remains there even when the level of virus in the blood approaches zero during treatment.

In the new study, researchers genetically engineered mice to have higher levels of a protein called HIV/gp120, which is thought to contribute to the deterioration of the brain in HIV-infected patients.

Lipton and his colleagues found that the protein disrupts stem cells in the brain that are supposed to turn into new brain cells when needed. As a result, it becomes difficult for HIV-infected brains to create new cells when old ones are injured or killed off by the virus.

"Most people would not think that AIDS has anything to do with stem cells," Lipton said. "But it has the ability to stop stem cells from dividing."