Phase II Study of the Efficacy of Peptide T in HIV-Positive Individuals With Cognitive Impairment.

Inclusion Criteria: * Patients must have: 1. Cognitive dysfunction on neuropsychological testing. 2. HIV antibody positivity. 3. Expected survival of 6 months. 4. EITHER no use of an antiretroviral within the past 4 weeks OR use of approved regimens of AZT, ddI, or ddC. 5. Medically stable EKG and urinalysis. 6. Given informed, written consent to participate. * Allowed: 1. Inhaled aerosolized pentamidine for Pneumocystis carinii pneumonia prophylaxis, dapsone, cotrimoxazole, topical antifungal agents, nystatin or ketoconazole, acyclovir. 2. Amitriptyline (up to 50 mg/day) or an equivalent dose of another antidepressant for relief of peripheral neuropathy that is expected to remain unchanged throughout the first 6 months of the study. * Abstinence or agree to use barrier methods of birth control / contraception during the study * Negative pregnancy test within 30 days of study entry * Bilirubin \<= 3 * CD4 (Must be \<= 500 cells/mm3 if patient is without non-cognitive HIV-related symptoms. CD4 count \> 500 cells/mm3 allowed if patient has other (non-cognitive) HIV-related symptoms. ( 0 - 100 - 200 - 300 - 400 - 500 - 600 - 700 - 800 plus.) * Creatinine \<= 1.5 mg/dl * Granulocytes \>= 750 * Hemoglobin \> 8 g/dl (No more than two transfusions per month permitted.) * Other Lab Values Prothrombin time \> 70 percent of control. * Platelet Count \>= 75000 /mm3 * SGOT(AST) \< 5 x ULN (ULN = upper limit of normal). Exclusion Criteria: * Patients with the following are excluded: 1. History of mental retardation or learning disability. 2. Evidence of current DSM-III-R Axis I disorder within 3 months prior to study entry or past history of psychotic disorder or bipolar mania. 3. History of neurologic disorder not secondary to HIV infection (e.g., head trauma requiring medical observation or hospitalization, seizure disorder). * Patients with the following symptoms or conditions are excluded: 1. Kaposi's sarcoma or other malignancy likely to require chemotherapy during the first 6 months of the study. 2. Serious underlying medical problems that may complicate interpretation of the treatment results, including unstable diabetes mellitus, severe arteriosclerotic heart disease, uncontrolled hypertension, or hepatic or renal failure. 3. Non-HIV related condition that is likely to interfere with interpretation of neuropsychologic test results. 4. Inability to participate in neuropsychologic testing or unable to comply with intranasal study medication administration. * Excluded within 4 weeks prior to study entry: 1. Antiretrovirals except as allowed in the Patient Inclusion Criteria. 2. Psychoactive agents (e.g., benzodiazepines, antidepressants, antipsychotics, amphetamines) Excluded within 8 weeks prior to study entry: Long-acting psychoactive agents (e.g., Prozac). * Active alcohol abuse in the past 3 months, or abuse judged by the investigators as likely to interfere with the analyses of neuropsychologic function. Abuse of cocaine, marijuana, heroin or other opiates (including methadone), barbiturates, amphetamines or other substances within the past 3 months, judged by the investigators as likely to interfere with the analyses of neuropsychologic tests. * Positive pregnancy test within 30 days of study entry * No abstinence or no agreement to use barrier methods of birth control / contraception during the study