Effects of Antiretroviral CNS Penetration on Procedural Learning Task Performance in HIV+ Drug Users

The CNS may act as a reservoir for HIV despite systemic viral suppression. Combination antiretroviral therapy (cART) regimens with a high capacity to penetrate the blood-brain barrier (CNS Penetration Effectiveness, CPE) are associated with lower levels of CNS viral load and improved cognitive performance in several HIV+ samples. We tested HIV- and HIV+ substance dependent individuals (SDIs) on motor and cognitive procedural learning (PL) tasks previously used to detect HIV-associated deficits and a control task of sustained attention. We hypothesized that HIV- subjects would show superior performance to HIV+ subjects, while HIV+ subjects prescribed high CPE cART would perform better than HIV+ subjects prescribed low CPE cART. We found no differences in PL task performance between HIV+ subjects as a function of cART CPE ranking. Contrary to expectation, only the High CPE subjects performed significantly worse than the HIV- group. No group differences were observed on the control task. The negative association between CPE ranking and PL performance may indicate possible neurotoxic effects of High CPE cART within an HIV+ SDI sample, although these data are not conclusive. Findings of HIV-associated deficits on PL task performance within SDIs are consistent with previous findings from our laboratory. The lack of group differences on the control task suggests that observed deficits cannot be attributed to global neurocognitive impairment.