Abstract
We report on brain SPECT analysis of regional cerebral blood flow (rCBF) in late life chronic fatigue syndrome (CFS) patients and compare their results with patients with late life depression and elderly normal controls 45 years and older. We attempted to distinguish CFS from normals and patients with depression and applied the findings to understand the pathophysiology of the illness. We studied 33 patients with CFS (55 ± 10 years), 26 patients with late life depression (62 ± 8 years), and 19 normal controls (66 ± 8 years); 43 other normal controls had only ¹³³Xe rCBF measurements (66 ± 8 years). We evaluated rCBF quantitatively with ¹³³Xe images and qualitatively with high resolution imaging using 99mTc-HMPAO. We found that rCBF in CFS measured by ¹³³Xe varied between 35 and 41 ml/min/l00g in both hemispheres, p < 0.0001 and 0.05; similar findings were observed in depression. In CFS 99mTc-HMPAO imagain demonstrated right orbitofrontal and marked right dorsofrontal hypoperfusion at 58% to 66% of the maximal activity in the brain, p , 0.001. In late life depression, hypoperfusion was primarily limited to the right orbitofrontal lobe, 42% and 57%, p , 0.001. In depression, the abnormalities were most striking in the left temporal lobe and particularly in the left anterior frontal lobes. CFS patients with major depressive disorder by DMS-III-R criteria did not differ in regional cerebral hypoperfusion from those without major depression. The pathophysiology of the illness may involve the dysregulation of a neural network which includes circuits between the hippocampus (located in the anterior temporal lobe) and the dorsolateral prefrontal cortex.