Cognitive impulsivity and HIV serostatus in substance dependent males

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Abstract
HIV-seropositive (HIV+) drug users show impaired performance on measures of integrity of prefrontal–subcortical systems. The Iowa Gambling Task (GT) is mediated primarily through ventromedial–prefrontal systems, and poor performance on this measure (“cognitive impulsivity”) is common among substance dependent individuals (SDIs) as well as patients with disease involving prefrontal–subcortical systems (e.g., Huntington disease). We hypothesized that HIV+ SDIs might be more vulnerable to cognitive impulsivity when compared with HIV-seronegative (HIV−) SDIs because recent studies report evidence of additive effects of HIV serostatus and drug dependence on cognition. Further, working memory is considered a key component of GT performance and is reliably impaired among HIV+ SDIs compared to controls. We administered the GT to 46 HIV+ and 47 well-matched HIV− males with a past or current history of substance dependence. In addition, we evaluated correlations between subjects' scores on the GT and on a delayed nonmatch to sample (DNMS) task in order to test if working memory deficits accounted for cognitive impulsivity among the HIV+ subjects. The HIV+ subjects performed significantly more poorly on the GT compared to the HIV− group but this effect could not be explained by working memory deficits. Implications of these findings for future basic and applied studies of HIV and substance dependence are discussed. (JINS, 2004, 10, 931–938.)