AIDS dementia complex (ADC) is the most common presenting neurologic manifestation of human immunodeficiency virus (HIV)-1 infection. We report FDG-PET studies in a 39-year-old man who had ADC and completed a 12-wk treatment protocol with 1.2 mg/day of intranasal peptide T, one before and one after 12 wk of treatment with peptide T. Peptide T is an octapeptide under investigation for treatment of ADC patients. Values of rCMRglc were converted to Z scores using the mean and standard deviation of values of rCMRglc in three HIV-seronegative matched controls, each of which was studied twice, at the beginning and end of a 12-wk interval. Thirty-five of 60 regions assayed showed Z scores with absolute values > or = 3 (considered abnormal) in the baseline study. Regions with high absolute values of Z scores were located in subcortical areas and in the limbic system, and to a lesser degree in the frontal, temporal and parietal lobes. Thirty-four of these 35 regions showed remission (decrease in the absolute values of Z scores) after treatment. Only one region showed no improvement in the second study. Three regions with absolute values of Z scores < 3 in the baseline study manifested Z scores with magnitudes > or = 3 in the second study. These preliminary observations suggest that functional neuroimaging techniques provide a useful tool in the evaluation of the response to treatment in ADC patients.