This CNS HIV Antiretroviral Therapy Effects Research Extension (CHARTER Extension) is a continuation of the epidemiological longitudinal study of the participants being studied under the existing award, N01MH22005, entitled, [unreadable]CNS HIV Antiretroviral Therapy Effects Research (CHARTER)[unreadable], which was awarded to the University of California at San Diego (UCSD) in September 2002. This contract is due to expire on August 31, 2010. This follow-on study to CHARTER is expected to collect valuable research data over the course of the next 5 years, such as neuromedical characterization, neuropsychological functioning, psychiatric and drug abuse variables, treatment data, various brain imaging results, and viral and host genetics information from specific groups of subjects. This data will ultimately be included with the accumulated clinical and research data stored.