Enviesamento atencional no abuso de substâncias

Abstract

De acordo com as teorias atuais do comportamento aditivo, os consumidores de heroina e de outras substancias tendem a direcionar a sua atencao para estimulos do ambiente associados ao consumo (substancia), vulgarmente designado de Enviesamento Atencional (EA). Tendo em consideracao a inexistencia de estudos para averiguar o EA em populacoes com historial de dependencias (e.g., heroina), e tendo como referencia a abordagem da carga cognitiva de Lavie (1995), efetuou-se um estudo para avaliar o papel da carga cognitiva no processamento atencional de estimulos motivacionalmente apetitivos, como e o caso das drogas (e.g., heroina) em individuos com registo de dependencia (grupo em tratamento e grupo de altas terapeuticas), comparativamente com individuos nao consumidores. Foi apresentada uma tarefa atencional de discriminacao de letras alvo (X ou N) que poderiam surgir isoladamente (condicao de baixa carga cognitiva) ou apresentadas num conjunto de outras letras (condicao de alta carga cognitiva). A par da apresentacao da letra ou do conjunto de letras poderiam ser apresentados (ƒî14% dos ensaios) estimulos distratores (imagens emocionais ¡V relacionadas com o consumo de heroina, ou imagens neutras). Com base no modelo da carga cognitiva de Lavie (1995), esperavamos que nos grupos de ex. consumidores, comparativamente com individuos sem registo de consumo de drogas, ocorresse um EA apenas na condicao de BCC, i.e., maior interferencia com a tarefa de atencao (tempos de resposta mais longos e maior taxa de erros) quando surgiam estimulos irrelevantes para a tarefa de atencao (discriminacao de letras) mas relacionados com o consumo, comparativamente com estimulos neutros. Esta hipotese nao se verificou, dado que nao foram encontradas diferencas significativas relativamente ao EA perante as imagens relacionadas com o consumo (i.e., imagens emocionais), comparativamente com os estimulos neutros, na condicao de BCC, tal como previa o modelo de Lavie (1995). Os resultados revelaram apenas maior interferencia na tarefa na condicao ACC (TRs mais longos e TA mais baixas), que se verificou independentemente do tipo de estimulo ou do grupo. Foi ainda verificada menor interferencia com a discriminacao de letras nas condicoes em que nao era apresentada qualquer imagem distratora (independentemente do seu conteudo emocional). Por ultimo, os resultados revelaram maior interferencia (TRs mais longos) no grupo de altas terapeuticas, comparativamente com os restantes grupos. Em suma, nao foram encontrados resultados estatisticamente significativos relativamente ao EA entre o grupo tratamento e o grupo de altas terapeuticas, comparativamente com grupo controlo. Estes resultados contrariam grande parte dos estudos efetuados para avaliar a atencao seletiva em populacoes aditas que tem demonstrado consistentemente um EA nesta populacao.

According to current theories related to addictive behavior, heroin and other substances users tend to focus their attention to environmental stimuli associated with the drug use (substance) and commonly referred as Attentional Bias (EA). Given the lack of studies aiming to study the EA in populations with a history of dependencies (e.g., heroin), and taking in knowledge the approach of cognitive load of Lavie (1995), we performed a study to evaluate the role of cognitive load in the attentional processment of stimulus that are motivationally appetitive, such as drugs (e.g., heroin) in subjects with dependency record (treatment group and high therapeutic group) compared to non-consumers subjects. It was presented an attentional task of discrimination of target letters (X or N) that could outcome isolated (low-load cognitive condition) or presented in a set of other letters (high cognitive load condition). Along with the presentation of the letter or the set of letters (~14% of the trials), it could be presented distractor stimuli (emotional images - related to heroin use or neutral pictures). Based on the cognitive load of Lavie (1995) we expected that in the former consumers group, compared to the ones with no history of drug use, should occur a EA inly in the BBC condition, i.e., greater interference with the attention task (longer response times and higher error rate) when irrelevant stimuli appear in the attention task (letter discrimination) but related with the drug use, comparing with neutral stimuli. This hypothesis was not verified since no significant differences were found with regard to EA in front of the images related to drug use (i.e., emotional images), compared to neutral stimuli, in the BBC condition, as the Lavie 81995) model predicted. The results showed only high interference in the ACC task condition (longer TRs and lower TA), which was found apart of the type of stimulus or group. It was also found less interference with letter discrimination in those conditions in which were not presented any distractive image (apart of its emotional content). At last, the results presented higher interference in the high therapeutic group (TR’s longer) compared to other groups. After all, there were no statistically significant results for the EA between the treatment group and the group of high therapeutic, compared with the control group. These results contradict the majority of studies developed to assess selective attention in addicted populations that have consistently shown that exists an EA in this population. Since this is the first study that used the attentional cognitive load paradigm in this type of population, it is important that future studies continue this approach and manipulate the exposure times of the stimuli (and the position of the distractor stimuli in the visual field) emotionally appealing (e.g., heroin) to clarify the stage where the processing at which the EA occurs taking into account different times of abstinence, since these studies are almost nonexistent and EA appears to be an important marker for vulnerability for abstinent consumers to relapse.