SEGMENTATION OF THE SPONTANEOUS EEG IN DEMENTIA OF THE ALZHEIMER-TYPE

Studies on EEG data in dementia of the Alzheimer type have mainly inve stigated parameters in the frequency domain. However, the EEG also ref lects the momentary functional state of the brain. The EEG can be part itioned into segments of spatially stationary map landscapes as charac terized by the locations of potential maxima and minima, to study the time domain of the EEG. We calculated the segment structure of 19-chan nel EEG recordings (1-30 Hz) from 10 patients with dementia of the Alz heimer type and 10 sex-matched geriatric controls. The EEG maps corres ponding to global field power peaks were used for analysis. The locati ons of the potential maximum and minimum of the maps were determined o ver the course of 20 s and used for segmentation. The segments of EEG activity were significantly fewer (p < 0.05) and the segments lasted l onger (p < 0.05) in patients compared to controls. This effect could b e observed over the whole period of recording and thus was not caused by only a few long segments. The data may be linked to morphological a nd biochemical findings of neuronal loss and loss of synapses in demen tia of the Alzheimer type.