ACTG 5199 

Study Objective: To estimate the prevalence and incidence of primary HIV neurological disease and CNS opportunisitic infections, and changes in neurocognitive functioning with antiretroviral treatment in international resource-limited settings.

ACTG 5271

Study Objective: To collect comparative neuropsychological data in healthy controls to aid in the interpretation of neuropsychological tests in resource-limited settings.

START Neurology Substudy

Study Objective: To determine whether immediate initiation of ART in ART-naive persons with CD4+ count > 500 cells/mm³ is superior with respect to neurocognitive function to deferring ART initiation until CD4+ counts decline to below 350 cells/mm³.