The effects of donepezil on quantitative EEG in patients with Alzheimer's disease.

Donepezil is a cholinesterase inhibitor which has been previously shown to affect the cognitive evoked potentials (EPs) of patients with Alzheimer's Disease (AD) during treatment with the drug. The purpose of this study was to determine the effect of treatment with donepezil 5 mg daily for 1 month on quantitative EEG (QEEG) in patients with AD. Treatment was associated with no significant differences between the pre- and post-treatment QEEGs for (1) absolute power (all four frequency bands), (2) percent relative power (all four frequency bands), (3) total mean frequency, (4) mean frequency for theta and beta, (5) absolute power asymmetry across homologous electrode pairs (all four frequency bands), and (6) interhemispheric coherence across homologous electrode pairs (all four frequency bands). There were significant decreases in mean alpha and delta frequencies that were consistent across broad electrode arrays except for an increase in the delta frequency at T3. The implications of these changes are not yet clear. Studies of QEEG changes with higher doses of donepezil over longer periods of time may yield a better understanding of the neurophysiological effects of the medication.