[Show abstract][Hide abstract] ABSTRACT: The construct of "prospective memory" (PM) refers to a type of episodic memory for a future intention or "remembering what one must do." This function has been proposed as a candidate mechanism underlying behaviors of critical importance in HIV disease, including adherence with medication regimens and continued engagement in risk behavior. We administered tasks of time-based and event-based prospective memory and control tasks of retrospective and working memory to 31 HIV-seropositive and 35 HIV-seronegative substance-dependent individuals (SDIs). We found that compared with HIV- controls HIV+ participants showed deficits in time-based but not event-based PM. Retrospective, but not working, memory performance correlated significantly with time-based PM performance. In addition, performance on the time-based PM task was a significant predictor of scores on a self-report measure of risky sexual and injection practices. These preliminary data provide new and unique findings regarding the components of executive function mediated by prefrontal cortical systems that are impaired among HIV+ SDIs and their relevance to "real-world" behaviors.
Full-text · Article · Aug 2007 · Journal of Clinical and Experimental Neuropsychology
[Show abstract][Hide abstract] 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.
Full-text · Article · Dec 2004 · Journal of the International Neuropsychological Society