Electroencephalogram variability in dementia with lewy bodies, Alzheimer's disease and controls.
Dementia with Lewy bodies (DLB) is probably still underdiagnosed in the clinical setting. Previous studies have suggested a relationship between fluctuations in attention and electroencephalogram (EEG) measures. Since fluctuation in attention is a core symptom of DLB, we sought to further explore whether EEG measures could help differentiate DLB from Alzheimer's disease (AD) and healthy controls. The EEGs of 20 patients with DLB, 64 patients with AD and 54 elderly controls were assessed in regard to frequencies, coherence, and variability. Greater variability was seen in delta-band power over 2-second intervals in parietal electrodes of DLB patients. The DLB group had a higher degree of overall coherence in the delta band and a lower degree of overall coherence in the alpha band than the other groups. Finally, EEG measures could distinguish DLB patients from AD patients and controls with areas under the receiver operating characteristic curves ranging between 0.75 and 0.80 and between 0.91 and 0.97, respectively. We suggest that the difference in variability may be associated with the fluctuating cognition seen in DLB. This might have clinical implications as guidance in the diagnosis of DLB. The EEG analysis is simple enough to be possible to apply in clinical practice.