The National Neurological AIDS Bank (NNAB), is a longitudinal study of persons with advanced AIDS and other serious diseases. It was first established to better understand how HIV-1 causes neurological disease and gain insight on commorbid conditions. The NNAB was created to respond to researchers, who need well characterized human tissue and fluid samples. The NNAB recruits volunteer subjects with AIDS and HIV-negative subjects with other diseases (such as cancer and ALS) to participate in our longitudinal study. All volunteers agree to donate their tissues and organs at death. The NNAB collaborates with scientists all over the world who are studying neurological diseases, and supplies them with valuable samples. Our participants include men and women, age 18 and older of a variety of ethnicities, racial backgrounds and socioeconomic groups. Complete examinations are conducted in both English and Spanish and participants are compensated for their time.