The Los Angeles Times on Monday examined research into the long-term effects of HIV on brain tissue (Brink, Los Angeles Times, 11/7). A study published in October in the Proceedings of the National Academy of Sciences found that HIV can continue to damage some types of brain tissue even when patients are receiving highly active antiretroviral therapy. Paul Thompson, a researcher at the David Geffen School of Medicine at the University of California-Los Angeles, and colleagues from the University of Pittsburgh used a 3D magnetic resonance imaging technique on the brains of 26 people diagnosed with AIDS and 14 HIV-negative people. The researchers found that the brain tissue of AIDS patients was 10% to 15% thinner in regions that control movement, language and feeling than the brain tissue of HIV-positive patients who had not developed AIDS. The tissue loss shown in the brain imaging of the AIDS patients correlated with motor and cognitive defects that the patients showed in multiple brain function tests. The extent of the tissue loss seemed to be related to patients' CD4+ T cell counts. AIDS patients who were taking HAART had no significant difference in tissue loss compared with AIDS patients who were not taking the therapy. "A protective blood barrier prevents drugs from entering the brain, transforming it into a reservoir where HIV can multiply and attack cells unchecked," Thompson said. According to the study, some areas of the brain were not affected by HIV. At least two in five people living with HIV/AIDS are expected to experience HIV-related cognitive injury, ranging from minor impairments to dementia (Kaiser Daily HIV/AIDS Report, 10/12). Researchers are unsure "how great a problem looms," but "even mild to moderate" cognitive impairments among a large percentage of HIV-positive people could become a "public health issue," the Times reports.

Related Study
The National Institute of Mental Health is sponsoring a long-term clinical trial of brain function in HIV-positive people that will eventually include about 1,600 participants. David Clifford, head of the Neurologic AIDS Research Consortium at the Washington University School of Medicine in St. Louis, said that preliminary findings of the study show that about half of the participants have "subnormal performance" indicated by a variety of symptoms, including impaired motor or cognitive abilities. Clifford said, "The biggest concern is that this is the tip of the iceberg. We should not be complacent about the brain in HIV" (Los Angeles Times, 11/7).