Study finds subtle brain damage in some HIV patients on dr...( ee separate techniques were used to ass...),Health

• Recording of brainwaves during task performance. Researchers recorded subjects' contingent negative variation (CNV), a type of brainwave, while subjects performed a reaction time test. The CNV is considered to be a measure of anticipation and preparation potential as well as an indication of a person' s ability to initiate physical action.

• Neuropsychological testing. Participants performed a battery of tests designed to assess memory and mental agility.

• MRIs. Magnetic resonance imaging was used to measure the size of various parts of the brains of 31 HIV patients and 35 control subjects.

The biggest difference in test results between groups came from the contingent negative variation brainwave recordings. When Chao charted the magnitude of brainwaves during the computer task performance test, she found that while CNV activity among HIV-negative participants surged shortly after appearance of the first image, it remained nearly flat among both the viremic and virally suppressed HIV-positive participants. Lack of CNV response is generally an indication of damage or destruction to brain cells in the basal ganglia, a part of the brain that coordinates motor behavior and one of two brain structures where HIV tends to concentrate.

Chao also found that among control subjects, the stronger their CNV activity, the faster their response time. But there was no correlation between CNV activity and response time among HIV-positive participants. Nevertheless, HIV-positive participants had just as good response times as control subjects. There is a possible explanation, says Chao: the flat CNVs recorded among the HIV-positive participants are possibly an indication that HIV has damaged the normal neurological linkage between a stimulus (for example, a hand touching a hot pan) and a reaction (pulling the hand away). But the fact tha
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Contact: Liese Greensfelder
lgreensfelder@pubaff.ucsf.edu
415-476-2557
University of California - San Francisco
13-Nov-2003