Double dissociation of HIV and substance use disorders effects on neurocognitive tasks dependent on striatal integrity.

OBJECTIVE: Substance use is common among individuals infected with HIV, yet whether neurocognitive effects of HIV can be distinguished from more nonspecific effects of drug dependence and associated comorbidities is not known.

DESIGN: Cross-sectional observational study of neurocognitive function among HIV-infected and uninfected individuals with and without substance use disorders (SUDs).

METHODS: We compared the performance of 458 (31% HIV-infected) substance dependent individuals (SDIs) and 90 individuals (23% HIV-infected) with no history of substance use disorders (SUDs) on measures of delay discounting and probability learning, tasks which are differentially sensitive to addictive processes and HIV serostatus, respectively.

RESULTS: In factorial analyses of covariance adjusted for age, years of education, and sex, we found that SDIs showed significantly higher rates of delay discounting, regardless of HIV serostatus (P < .05). Conversely, HIV-infected individuals performed significantly more poorly on probability learning compared with uninfected groups, regardless of SUD history (P < .05).

CONCLUSION: Theory-driven cognitive neuropsychological tasks may have the capacity to detect neurocognitive effects of HIV not attributable solely to substance use; evidence from functional neuroimaging studies with more selective neurocognitive probes will be critical for hypothesis testing and mapping underlying brain systems more precisely.