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.
Assuntos
Complexo AIDS Demência/diagnóstico , Complexo AIDS Demência/virologia , Potenciais Evocados P300/fisiologia , HIV-1 , Transtornos Psicomotores/diagnóstico , Transtornos Psicomotores/virologia , Tempo de Reação , Adulto , Eletroencefalografia , Feminino , Humanos , Masculino , Índice de Gravidade de DoençaRESUMO
INTRODUCTION: Reaction time (RT) is thought to be the most suitable measure to detect cognitive deficits in neurologically asymptomatic human immunodeficiency virus type I (HIV-1) infected individual since cognitive slowing is the earliest signal of cognitive-motor disorder related to HIV-1 infection. There is evidence suggesting that the greater the degree of central processing demands required by a task, the more likely that it will be sensitive to the effect of HIV-1 infection. Such statement suggests that the RT deficits exhibited by HIV-1 infected individuals at initial stages could be caused by the slowing of central information processing mechanisms. AIM: To assess the relationships between demands of central information processing and RT in HIV-1 seropositive individuals. SUBJECTS AND METHODS: 50 neurologically asymptomatic HIV-1 individuals were compared with 34 seronegative controls on four discriminative RT tasks of different levels of central processing demands except by the motor response requirements. RESULTS: Seropositive group was slower in RT and performed worse on the higher demanding task. On the lesser demanding tasks no differences in RT nor in accuracy were observed. For the task demanding sensory coding efforts seropositive individual were slower but achieved the same level of accuracy. CONCLUSIONS: Even when these results point to that RT slowing in HIV-1 asymptomatic individuals emerged with the increase in cognitive demands, the fact that RT slowing without accuracy declining can also appear in some tasks demanding sensory processing, preclude ruling out a peripheral deficit as the locus of the RT slowing in these subjects.
Assuntos
Transtornos Cognitivos/virologia , Soropositividade para HIV , HIV-1 , Desempenho Psicomotor , Tempo de Reação/fisiologia , Transtornos Cognitivos/sangue , HIV-1/imunologia , Humanos , Masculino , Doenças do Sistema Nervoso/sangue , Doenças do Sistema Nervoso/virologia , Testes NeuropsicológicosRESUMO
INTRODUCTION: The cognitive effects of long-term exposure to organic solvents could be similar to those triggered by certain neurodegenerative diseases. AIMS: The purpose of this study was to evaluate the effects exerted by accumulated exposure on the cognitive functions. PATIENTS AND METHODS: 105 subjects with an average history of exposure of 19.3 years were evaluated using seven computerised cognitive tasks (CPT, digit-symbol substitution, Stroop, memory span, word learning and recognition, and TRD) and results were later compared with the performance of a non-exposure group and with a normative reference. A study was made of the association between the length of exposure and performance in the variables in which the exposed subjects displayed significantly lower values than control subjects. In order to evaluate the effect exerted by age, regression functions between performance and age were calculated for each group. RESULTS: Only the indicators from the Stroop and digit-symbol tasks correlated with the length of exposure. The regression functions between performance and age for each group showed that the former decreased significantly faster among exposed subjects than among controls. CONCLUSIONS: Findings suggest that, while recent exposure seems to have an effect on a wide range of functions, chronic exposure exerts a selective influence on a smaller group. In this case, only selective attention appears to deteriorate. Similar deficits have been observed in the early stages of patients with Alzheimer's and Parkinson's.