Patients with chronic fatigue syndrome (CFS) are known to have chronic cognitive impairment known as brain fog accompanied by persistent fatigue. To gain insight into how cognitive impairment is produced, EEG was recorded from 19 scalp locations with link-ear reference during a 3-minute, eyes-closed task in 50 patients with CFS and 50 healthy control subjects, matched for age (range 28 to 74 years), gender, and educational level. The Multidimensional Fatigue Inventory (MFI-20) and the Fatigue Severity Scale (FSS) were likewise administered to the same group of patients. Using the EEG data, current densities were localized and computed from 1-30 Hz with exact low-resolution electromagnetic tomography (eLORETA). Non-parametric statistical mapping (SnPM) and linear regression analyses were used to evaluate the differences in current densities in each Brodmann area grouping of cortical grey matter voxels.
Results: Frontal, temporal, parietal, limbic and sub-lobar regions of interest (ROI’s) demonstrated significantly different current densities in CFS patients when compared to healthy controls (HC). Statistically significant differences were found in the delta (1-3 Hz) and in the beta-2 (19-21 Hz) frequency bands in both the left and right hemisphere. Delta sources were found predominately in the frontal and limbic regions of interest (ROI) with beta-2 sources found predominately in central and superior parietal ROIs. Linear regression models, predicting current density from the MFI-20 reduced motivation subscale, found increased delta in the left frontal, temporal, parietal, limbic and sub-lobar ROIs. eLORETA was able to detect evidence of widespread cortical hypoactivation in CFS patients as demonstrated by increased delta and decreased beta-2 sources. Taken together, our findings provide objective quantification of central nervous system dysregulation in CFS sufferers. A model of prolonged subcortical deregulation is hypothesized to explain the results.