Deficits in Complex Motor Functions, Despite No Evidence of Procedural Learning Deficits, Among HIV+ Individuals With History of Substance Dependence

Department of Psychiatry, University of Illinois-Chicago, USA.
Neuropsychology (Impact Factor: 3.27). 12/2008; 22(6):776-86. DOI: 10.1037/a0013404
Source: PubMed


Human immunodeficiency virus (HIV) and drugs of abuse affect common neural systems underlying procedural memory, including the striatum. The authors compared performance of 48 HIV seropositive (HIV+) and 48 HIV seronegative (HIV-) participants with history of cocaine and/or heroin dependence across multiple Trial Blocks of three procedural learning (PL) tasks: Rotary Pursuit (RP), Mirror Star Tracing (MST), and Weather Prediction (WP). Groups were well matched on demographic, psychiatric, and substance use parameters, and all participants were verified abstinent from drugs. Mixed model analyses of variance revealed that the individuals in the HIV+ group performed more poorly across all tasks, with a significant main effect of HIV serostatus observed on the Mirror Star Tracing and a trend toward significance obtained for the Rotary Pursuit task. No significant differences were observed on the Weather Prediction task. Both groups demonstrated significant improvements in performance across all three procedural learning tasks. It is important to note that no significant Serostatus x Trial Block interactions were observed on any task. Thus, the individuals in the HIV+ group tended to perform worse than those in the HIV- group across all trial blocks of procedural learning tasks with motor demands, but showed no differences in their rate of improvement across all tasks. These findings are consistent with HIV--associated deficits in complex motor skills, but not in procedural learning.

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    • "It has been hypothesized that this shift depends primarily on implicit mechanisms (Brand et al., 2007), which are gradually superseded by executive (Brand et al., 2007) or declarative memory processes (Gupta et al., 2009). We have previously reported variable implicit learning performance among HIV+ compared with HIV– SDIs (Gonzalez et al., 2008; Martin, Gonzalez, Vassileva, & Maki, 2011). These prompted the question of whether serostatus effects on IGT performance among SDIs might be more prominent during the first three trial blocks—for example , that HIV+ SDIs' decision making might be more susceptible initially to ambiguity but eventually improved to the HIV– drug users' level of advantageous decision making. "
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    • "In 1993, Martin and colleagues suggested that HAND may be associated with impaired motor skill learning, which Kalechstein et al. (1998) later showed may be exacerbated in individuals with comorbid depression. However, a larger and more comprehensive study of substance abusers by Gonzalez et al. (2008) revealed that, although HIV infection was associated with slowed complex motor skills (e.g., rotary pursuit), there was no evidence of impaired procedural learning per se. Although perceptual priming appears to be spared in HIV infection, HAND is nevertheless associated with deficits in semantic priming (e.g., Nielsen- Bohlman et al. 1997). "
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    • "Surprisingly few studies have investigated the effects of either a positive HIV serostatus or substance abuse on these functions, despite their common effects on striatum (cf. A. Martin et al. 1993; van Gorp et al. 1999). Recently we reported evidence of additive effects of HIV on SDIs' performance of two motor skill learning tasks, the Pursuit Rotor and the Star Mirror Tracing Task (Gonzalez et al. 2008). This initial investigation found no evidence of impairment of probabilistic learning measured by the Weather Prediction Task (Knowlton et al. 1996), however the study sample was primarily male; follow up analyses have indicated possible gender effects on vulnerability to impaired performance on this cognitive procedural learning task (Martin, unpublished data 2008). "
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