Cognitive mechanisms of switching in HIV-associated category fluency deficits.

HIV infection is associated with deficits in category fluency, but the underlying cognitive mechanisms of such impairments have not been determined. Considering the preferential disruption of the structure and function of frontostriatal circuits in HIV disease, the present study evaluated the hypothesis that HIV-associated category fluency deficits are driven by impaired switching. Study participants were 96 HIV-infected individuals and 43 demographically comparable healthy comparison volunteers who were administered a standard measure of animal fluency and an alternating category fluency task (i.e., fruits and furniture) in a randomized order. Consistent with prior research on letter fluency, HIV infection was associated with greater impairments in switching, but not semantic clustering within the animal fluency task. Moreover, a significant interaction was observed whereby the HIV-associated deficits in switching were exacerbated by the explicit demands of the alternating fluency task. Across both fluency tasks, switching demonstrated generally small correlations with standard clinical measures of executive functions, working memory, and semantic memory. Collectively, these findings suggest that HIV-associated category fluency deficits are driven by switching impairments and related cognitive abilities (e.g., mental flexibility), perhaps reflecting underlying neuropathology within prefrontostriatal networks.