SPECT IMAGING OF THE BRAIN - COMPARISON OF FINDINGS IN PATIENTS WITH CHRONIC FATIGUE SYNDROME, AIDS DEMENTIA COMPLEX, AND MAJOR UNIPOLAR DEPRESSION

OBJECTIVE. Chronic fatigue syndrome is an illness of unknown origin th at begins abruptly with a flulike state and has symptoms suggesting bo th a chronic viral encephalitis and an affective disorder. We compared single-photon emission computed tomography (SPECT) scans of patients with chronic fatigue syndrome with those of patients with AIDS dementi a complex and unipolar depression. SUBJECTS AND METHODS. We used Tc-99 m-hexamethylpropyleneamine oxime to examine 45 patients with chronic f atigue syndrome, 27 patients with AIDS dementia complex, and 14 patien ts with major unipolar depression. Scans of 38 healthy persons were us ed as controls. Comparison of regional defects between groups, as well as midcerebral uptake indexes (an objective measure of global radionu clide uptake), was performed by using analysis of variance with the St udent-Newman-Keuls option. Correlation between the number of regional defects and the midcerebral uptake index was determined by using the S pearman rank-correlation test. RESULTS. Patients with AIDS dementia co mplex had the largest number of defects (9.15 per patient) and healthy patients had the fewest defects (1.66 per patient). Patients with chr onic fatigue syndrome and depression had similar numbers of defects pe r patient (6.53 and 6.43, respectively). In all groups, defects were l ocated predominantly in the frontal and temporal lobes. The midcerebra l uptake index was found to be significantly lower (p < .002) in the p atients with chronic fatigue syndrome (.667) and patients with AIDS de mentia complex (.650) than in patients with major depression (.731) or healthy control subjects (.716). Also, a significant negative correla tion was found between the number of defects and midcerebral uptake in dex in patients with chronic fatigue syndrome and AIDS dementia comple x, but not in depressed patients or control subjects. CONCLUSION. Thes e findings are consistent with the hypothesis that chronic fatigue syn drome may be due to a chronic viral encephalitis; clinical similaritie s between chronic fatigue syndrome and depression may be due to a simi lar distribution and number of defects in the two disorders.