A Multicenter Placebo-Controlled Double-Blind Trial to Evaluate Azidothymidine (AZT) Treatment of the AIDS Dementia Complex and Central Nervous System (CNS) Human Immunodeficiency Virus (HIV) Infection

Inclusion Criteria Concurrent Medication: Allowed: * Aspirin, in modest doses. * Ibuprofen, in modest doses. * Maintenance antibiotic therapy posttherapy for an AIDS-defining opportunistic infection. Concurrent Treatment: Allowed: * Blood transfusion if cardiovascular status is compromised. Exclusion Criteria * Active substance abuse. Co-existing Condition: Patients with the following conditions will be excluded: * Concurrent or previous central nervous system infections or neoplasms. * Active AIDS-defining opportunistic infection. * Severe premorbid psychiatric illness. * Confounding neurological disease. * Concurrent neoplasms. Concurrent Medication: Excluded: * Maintenance methadone or naltrexone. * Acetaminophen. * Mood- or central nervous system-altering drugs. * Zidovudine for Pneumocystis carinii pneumonia (PCP). * Acyclovir. * Rifampin or derivatives. * Drugs with antiretroviral activity. * Experimental agents. The following patients will be excluded from the study: * Patients requiring ongoing therapy for an AIDS-defining opportunistic infection. * Patients with a history of Mycobacterium avium intracellulare infection. * Patients with a history of Pneumocystis carinii pneumonia infection. * Patients with a daily temperature of 38 degrees C or more for 1 month. Prior Medication: Excluded: * Zidovudine (AZT). * Excluded within 14 days of study entry: * Systemic anti-infectives. * Excluded within 30 days of study entry: * Immunomodulators and biologic response modifiers. * Any investigational agent. * Cytotoxic chemotherapy for Kaposi's sarcoma. Prior Treatment: Excluded: * Radiation therapy. Patients must demonstrate the following clinical and laboratory findings: * No currently active AIDS-defining opportunistic infections. * One negative blood culture for Mycobacterium avium intracellulare within 4-6 weeks prior to study entry. * Constitutionally well without persistent fever. * Less than 25 Kaposi's sarcoma lesions and less than 10 new lesions during the 30 days prior to study entry. Patients may have stable or indolently progressive mucocutaneous Kaposi's sarcoma. * Characteristic clinical symptoms and signs of AIDS dementia complex. * Abnormalities on 2 or more of 7 neuropsychological motor tests in the Neurological Screening Battery. * Estimated premorbid IQ equal to or greater than 70 (+ or - 5), which is consistent with completion of sixth grade.