Slowed reaction time in asymptomatic HIV-positive patients.

A total of 24 asymptomatic HIV-infected patients (CDC II/III) and 27 HIV-negative controls were tested for speed of reaction and for general neuropsychological functioning. Reaction time was assessed with two computerized tests with differing levels of cognitive complexity. The results show that the asymptomatic HIV-positive patients have a significantly longer mean reaction time to simple and complex stimuli (SRT p < 0.001, CPT p < 0.05), and a significantly greater standard deviation (SD) (SRT-SD p < 0.005). No significant differences were observed on any of the clinical neuropsychological tests, or in the number of false positive (FP) or non-responses to stimuli (NR) from the CPT. The results indicate that asymptomatic HIV-infected patients are slower and have a greater intra-subject variability in speed using a simple test for reaction time. The difference is less pronounced when doing a more demanding cognitive task and not significant in a test of visuo-motor coordination or on other clinical neuropsychological tests. Emotional state or cognitive strategies affecting speed/accuracy trade-off do not account for the findings.