This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purpose of this research study is to compare the frequency, nature and severity of cognitive impairment (e.g., memory;attention);neurocognitive disorders;and functional status between younger (18-39 years) and older (50 years and older) individuals infected with HIV (Human Immunodeficiency Virus) in its symptomatic stages. The relationship of aging to plasma viral load and to immunological decrements over time will also be assessed.