Aids 'finds sanctuary from drugs' in brain
By Roger Highfield, Science Editor
(Filed: 11/10/2005)

The Aids virus can continue to damage the brain, attacking regions that control movement, language and feeling, even when patients are receiving the most effective treatment, according to new research.

"Two big surprises came out of this study," explained Dr Paul Thompson, a British researcher at the David Geffen School of Medicine at the University of California, Los Angeles, and the first author of the paper with colleagues the University of Pittsburgh publishes today in the Proceedings of the National Academy of Sciences.

"First, that Aids is selective in how it attacks the brain," he said. "Second, drug therapy does not appear to slow the damage. The brain provides a sanctuary for HIV where most drugs cannot follow."

The researchers were most startled to see no difference in tissue loss between the patients taking highly-active anti-retroviral therapy (HAART) and those who were not. "This was the most terrifying aspect of our findings," said Dr Thompson.

"Even though anti-retroviral drugs rescue the immune system, Aids is still stalking the brain. A protective blood barrier prevents drugs from entering the brain, transforming it into a reservoir where HIV can multiply and attack cells unchecked."

Dr Thompson's laboratory used a new, 3D brain-mapping technique to analyse scans taken by magnetic resonance imaging of 26 people diagnosed with Aids, and then compared the scans to those of 14 HIV-negative people. The brain scans measured the thickness of grey matter in various regions of the cerebral cortex.

The researchers were surprised to discover that Aids consistently injured the brain's motor, language and judgment centres, but left other areas alone.

One in 100 people aged 15 to 49 is infected with HIV, the fourth leading cause of death worldwide. In 2004, 40 million people were living with the disease. Forty percent of Aids patients suffer from progressive neurological symptoms, typically leading to death.

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