RESUMO
INTRODUCTION: Reaction time (RT) deficit exhibited by HIV-1 asymptomatic seropositive individuals cannot always be explained by the effect of a cognitive slowing single factor. Evidence exists that decisional and peripheral components of RT may have differential slowing. OBJECTIVES: To assess the hypothesis of a cognitive slowing single factor as the main responsible for RT slowing in these subjects. METHODOLOGY: Thirty two (32) HIV-1 neurologically asymptomatic seropositive individuals were compared to 29 seronegative controls in two discriminative reaction time tasks (DRT) having increased cognitive difficulty but equal motor response demands. P300 component of the event-related potential was recorded simultaneously. RT, PPI, errors, and P300 latency were assessed using ANOVA. RESULTS: Seropositives were slower than controls in RT, made more errors and showed delayed latencies of P300 in both tasks. However, while the increase of RT from the easier to the more difficult task was additive, the increase of P300 latencies was multiplicative. CONCLUSIONS: These results reveal differences in patterns of slowing between central and motor information processing mechanisms. Such results suggest that a single common factor is not enough to explain cognitive slowing in HIV-1 seropositive subjects.