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HIV Infection Linked to Brain Damage
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Researchers at the University of California-San Francisco have found hints that the AIDS virus can cause subtle damage to the brain even if patients are using drugs that suppress the microbe below detectable levels.
Using a battery of tests, including MRI scans of the brain and memory agility tests, the scientists at UCSF's departments of psychiatry and radiology at the Veterans Affairs Medical Center were able to detect evidence of brain damage in some HIV-positive patients who otherwise appeared healthy and fully alert.
The problem of HIV-dementia-- once a common symptom afflicting one in five AIDS patients-- was thought to be largely solved with the use of antiviral drugs that drove down the amount of virus in a patient's blood. But researchers using brain-scanning devices to look for links between the damage caused by alcohol and that caused by the AIDS virus picked up a statistically significant difference in results. The study compared 31 HIV positive patients with 35 uninfected patients who served as controls.
"We've known for 20 years that HIV does really bad things to the brain," said Dr. Michael Weiner, director of the magnetic resonance imaging unit at the VA hospital, and senior investigator in the National Institutes of Health-funded study. "The question was, do people who are HIV positive, and are on drug treatment, have evidence of brain damage? And the answer is yes."
Weiner stressed, however, that the level of damage detected is so low that it can only be spotted with the sophisticated equipment and tests used by his lab.
"Patients do not appear to be clinically affected," Weiner said. "But it does raise concern." He likened it to what happens when an automobile that appears to be functioning well is tested in the shop computer. The computer may detect signs of less-than-peak performance.
It is unknown whether the abnormalities found by the brain scans were caused by the virus or the drugs used to treat it. It is not even clear whether the damage was caused before these patients went on drug therapy. Further study is needed to answer these questions, Weiner said.
One possible explanation for the damage is that the virus continues to thrive in small quantities inside the brain of patients on drug treatment. Although AIDS drugs can virtually eliminate the virus from the bloodstream, some of these medications are unable to pass through the "blood-brain barrier" which protects the brain from all but the smallest particles.
[The San Francisco Chronicle, 11/14/03]
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