The Edinburgh cohort of HIV-positive drug users: auditory event-related potentials show progressive slowing in patients with Centers for Disease Control stage IV disease.

A two-tone auditory event-related potential (AEP) task was used to examine brain function in 206 HIV-positive individuals (infected by intravenous drug use) approximately 6-7 years after initial infection. Multiple regression analysis of AEP latency and amplitude components showed only small effects of past medical and psychiatric history, current symptoms and drug use on electrophysiological responses. HIV-positive patients had longer latency and reduced amplitude of the P300 (P3) component of the AEP compared with a normal control group, but were electrophysiologically similar to a matched control group of HIV-seronegative drug users. However, a lower P3 amplitude was seen in patients in Centers for Disease Control stage IV. One-year follow-up of 103 patients (50%) found significant lengthening of P3 latency in patients with stage IV disease but not in those with stage II or stage III disease. The results suggest that brain involvement in HIV infection can be detected electrophysiologically after the clinical diagnosis of stage IV disease.