EEG correlates of acute nicotinic and muscarinic cholinergic blockade: separate and combined administration of mecamylamine and scopolamine in normal human subjects

Anticholinergic drugs have been proposed as a possible acute model for human electroencephalographic (EEG) studies focused on dementia but the interactive effects of muscarinic and nicotinic cholinergic receptor system blockade on the regulation of electrocortical activity has yet to be examined. EEG recordings were carried out in 15 normal subjects before and after the double-blind acute administration of a placebo, a centrally acting nicotinic blocker (20 mg of mecamylamine), a centrally acting muscarinic blocker (0·6 mg of scopolamine) and a combination dose of mecamylamine and scopolamine. Mecamylamine decreased absolute and relative beta power and increased relative theta power. Scopolamine increased relative power in both theta and beta frequency bands. Mecamylamine produced greater theta increments than scopolamine, while combined administration of the two central blockers induced changes similar to that observed with mecamylamine administered alone. Results are discussed in relation to electrocerebral activity in normal and pathological aging. © 1997 John Wiley & Sons, Ltd.