EEG changes during mental calculation, reverse recitation and association exercises in patients with dementia of the Alzheimer type

The cerebral functional impairment in dementia of the Alzheimer type (DAT) was a quantitatively assessed using easily repeatable electroencephalographic analysis. Waveform recognition was employed to analyze the EEG (electroencephalogram) changes displayed before and after tasks of mental calculation, reverse recitation and mental association. Marked decrements in the incidence of theta and alpha waves together with decrements of the average amplitude of alpha waves were noted in normal elderly subjects after mental calculation and reverse recitation. In the patients with DAT, mental association tasks evoked pronounced decrements in the average amplitude of theta waves, the average frequency of alpha waves, and both the average frequency and average amplitude of beta waves. These results indicate that analysis of EEG activity responses to mental tasks provides an objective assessment of dementia.