- Quantitative EEG (qEEG) was evaluated in Alzheimer's disease (AD) patients and age-matched controls following the administration of a single acute intravenous dose of scopolamine. Eleven AD patients and 8 cognitively intact age-matched controls underwent qEEG in baseline conditions, following double-blind intravenous administration of 0.5 mg scopolamine or placebo. At baseline, AD patients had significantly decreased absolute and relative alpha and increased relative theta amplitudes. In both groups, scopolamine administration was followed by a decrease in absolute and relative alpha amplitude, and increase in the absolute and relative delta activity. The increase in the absolute and relative delta amplitude by scopolamine was significantly more prominent in the controls; the decrease of alpha activity, while larger in controls, was not statistically different from AD. We conclude that scopolamine affects the change in delta amplitude differently in AD patients and controls, probably reflecting the reduced cholinergic tone in AD.