The CHARTER research study is recruiting HIV-infected individuals at varying stages of disease and with differing histories of anti-retroviral treatment for a one time medical and neuropsychological evaluation, which may include a blood draw and lumbar puncture. In addition, a subset of participants will enter a longer term study with assessments every six months which may include a fasting blood draw, MRI, nerve conduction studies, or lumbar puncture. Participants for the long-term study will include persons with neurocognitive impairment that do or do not have high viral loads in the CSF, ARV naive individuals, persons with advanced disease who have either failed or are unable to continue combination therapies, those with peripheral neuropathies, those with lipoatrophy, and persons who develop MRI-detected brain white matter disease despite apparently adequate ARV treatment.