EEG changes during long-term treatment with donepezil in Alzheimer's disease patients.

In this pilot study, we examined the long-term treatment effect of donepezil on the quantitative EEG (qEEG) in 12 Alzheimer's disease patients. The qEEGs of the mean absolute and relative amplitudes of betal, alpha, theta and delta activities were obtained at baseline and during donepezil treatment. Comparisons of awake qEEG prior to and during treatment were performed using a 2-way analysis of variance (ANOVA) with repeated measures. In patients with mild dementia (n = 5), the qEEG analysis showed a significant reduction of the mean absolute theta activity (p = 0.05) by donepezil, particularly in frontal and temporo-parietal areas. In patients with moderate/severe dementia (n = 7), a significant decrease in the mean absolute beta 1 activity (p = 0.02), particularly in the frontal and occipital areas may be attributed to disease progression which was not counteracted by the long-term treatment. The differences in qEEG in patients with different stages of dementia under donepezil treatment may be related to different compensatory capacities due to structural and functional brain disturbances.