AIDS Causes Brain Damage

For the first time, new imaging research demonstrates the selective pattern of injury inflicted by AIDS on brain areas that regulate motor, language, and sensory functions. High-resolution three-dimensional (3D) color scans created from magnetic resonance images (MRI) brilliantly illustrate the damage.

The study, performed by scientists from the University of California, Los Angeles (UCLA, USA) and the University of Pittsburgh (PA, USA), was published October 10, 2005, on the online website of the Proceedings of the [U.S.] National Academy of Sciences. The study presented a new method to measure the impact of AIDS on the living brain, and reveals that the brain is still susceptible to infection when patients are receiving highly active antiretroviral therapy (HAART).

"Two big surprises came out of this study,” explained Paul Thompson, Ph.D., first author and associate professor of neurology at the David Geffen School of Medicine at UCLA. "First, that AIDS is selective in how it attacks the brain. Second, drug therapy does not appear to slow the damage. The brain provides a sanctuary for HIV where most drugs cannot follow.”

Dr. Thompson's laboratory utilized a new 3D brain-mapping technique developed at UCLA to analyze the MRI scans 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 gray matter in various regions of the cerebral cortex. Scientists diagnosed and scanned the AIDS patients; all 26 individuals had lost at least half of their T-cells, the immune cells targeted by HIV. None had experienced AIDS-related dementia, and 13 were on HAART.

The striking differences between the AIDS patients' and the control individuals' brain scans were easy to see on the detailed 3D images. Regions of tissue loss shone red and yellow, whereas intact areas glowed blue and green. The researchers were also surprised to discover that AIDS consistently injured the brain's motor, judgment, and language centers, but left other areas alone. Specific patterns of tissue damage directly correlated with patients' mental and physical symptoms, including impaired motor coordination and slowed reflexes.

The UCLA group also tied thinning of the language cortex and reasoning center to depletion of T-cells from the immune system. This discovery may provide insights into why AIDS is often accompanied by mild vocabulary loss, judgment problems, and difficulty planning. As the disease progresses, these symptoms can deteriorate into memory loss and dementia similar to Alzheimer's disease.




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University of California, Los Angeles
University of Pittsburgh