We propose an interdisciplinary Center devoted to the study of central and peripheral nervous system and muscle disease associated with infection with Human Immunodeficiency Virus (HIV). This AIDS Dementia Center will combine and integrate clinical and basic science resources of the Medical Center to study the disease in a linear fashion. Center activities will be delineated as follows: 1- A group of HIV infected patients will be identified and evaluated by neurological examination and history, neuropsychological testing, neuroradiological and clinical neurophysiological evaluation. 2- A group of HIV infected hemophiliac children will be evaluated in the same fashion and their course compared with an age-matched uninfected group of hemophiliac children. 3- A series of clinical trials of antiviral agents will be embarked upon, generally as a part of multicenter studies, with emphasis on modification of neurological effects of treatment. 4- Pathological material from these patients and other infected human brains as well as brains from uninfected rats will be examined for the presence of CD4 receptor and possible routes of entry into the nervous system. 5- The same material will be examined for the presence of other possible neuropathic viruses, and the relationship between these and the neuropathic effects of HIV will be assessed. At all stages, emphasis will be on correlation of information from the various sections to give an accurate overall picture of the processes and sequences involved in HIV infection of the nervous system and muscles.