Multimodal and simultaneous assessments of brain and spinal fluid abnormalities in chronic fatigue syndrome and the effects of psychiatric comorbidity.

The purpose of this study was to investigate whether CFS patients without comorbid psychiatric diagnoses differ from CFS patients with comorbid psychiatric diagnoses and healthy control subjects in neuropsychological performance, the proportion with elevated spinal fluid protein or white cell counts, cerebral blood flow (CBF), brain ventricular lactate and cortical glutathione (GSH). The results of the study did not show any differences in any of the outcome measures between CFS patients with and without psychiatric comorbidity, thus indicating that psychiatric status may not be an exacerbating factor in CFS. Importantly, significant differences were found between the pooled samples of CFS compared to controls. These included lower GSH and CBF and higher ventricular lactate and rates of spinal fluid abnormalities in CFS patients compared to healthy controls. Thirteen of 26 patients had abnormal values on two or more of these 4 brain-related variables. These findings, which replicate the results of several of our prior studies, support the presence of a number of neurobiological and spinal fluid abnormalities in CFS. These results will lead to further investigation into objective biomarkers of the disorder to advance the understanding of CFS.

Elevations of Ventricular Lactate Levels Occur in Both Chronic Fatigue Syndrome and Fibromyalgia.

BACKGROUND: Chronic fatigue syndrome (CFS) and fibromyalgia (FM) frequently have overlapping symptoms, leading to the suggestion that the same disease processes may underpin the two disorders - the unitary hypothesis. However, studies investigating the two disorders have reported substantial clinical and/or biological differences between them, suggesting distinct pathophysiological underpinnings. PURPOSE: The purpose of this study was to further add to the body of evidence favoring different disease processes in CFS and FM by comparing ventricular cerebrospinal fluid lactate levels among patients with CFS alone, FM alone, overlapping CFS and FM symptoms, and healthy control subjects. METHODS: Ventricular lactate was assessed in vivo with proton magnetic resonance spectroscopic imaging (1H MRSI) with the results normed across the 2 studies in which the data were collected. RESULTS: Mean CSF lactate levels in CFS, FM and CFS+FM did not differ among the three groups, but were all significantly higher than the mean values for control subjects. CONCLUSION: While patients with CFS, FM and comorbid CFS and FM can be differentiated from healthy subjects based on measures of CFS lactate, this neuroimaging outcome measure is not a viable biomarker for differentiating CFS from FM or from patients in whom symptoms of the two disorders overlap.