International Neurological Study: A Stand Alone Study for Participants of A5175 (A Phase IV, Randomized, Open-Label Evaluation of the Efficacy of Once-Daily Protease Inhibitor and Once-Daily Non-Nucleoside Reverse Transcriptase Inhibitor-Containing Therapy Combination for Initial Treatment of HIV-1 Infected Individuals From Diverse Areas of the World)

Both the central and peripheral nervous systems (CNS and PNS) are affected by HIV; however, the causes of neurotoxicity in HIV infected patients are unknown. Initial data indicate that as many as 40% of patients with HIV develop some form of dementia. Other common neurological problems observed in HIV patients are peripheral neuropathy and opportunistic infections of the CNS. Most antiretroviral drugs used in the treatment of HIV have poor penetration into the CNS, which may explain how HIV persists in the CNS and contributes to the prevalence of dementia and other neurological disorders in HIV infected patients. This study will examine the prevalence of dementia and other neurological disorders in participants in ACTG A5175, "Once-Daily PI/NNRTI Therapy Combinations for Treatment Naive, HIV Infected Patients in Resource-limited Conditions."

The study will last approximately 2.5 to 3 years. Participants will undergo neurological examinations and neuropsychological assessments at entry to both steps of ACTG A5175 and before the administration of the new antiretroviral regimen, then every 24 weeks until they discontinue ACTG A5175. Physicians will make targeted diagnoses at each study visit.