Separate and combined effects of scopolamine and mecamylamine on human event-related brain potentials

Anticholinergic drugs have been proposed as possible acute model for invest igating geriatric-associated cognitive deficits, but the interactive effect of muscarinic and nicotinic cholinergic blockade on cognitive processes ha s yet to be examined. Behavioural performance and P300 event-related potent ial (ERP) measures were assessed in visual and auditory continuous performa nce (CPT) takes in 10 young adults before and after the double-blind acute administration of a placebo, a centrally acting nicotinic blocker (20 mg me camylamine), a centrally acting muscarinic blocker (0.6 mg scopolamine) and a combination dose of mecamylamine and scopolamine. Relative to placebo, s ingle and combined drug administration failed to alter response accuracy, b ut slowed reaction times in both tasks and decreased subjective alertness. Mecamylamine along significantly reduced P300 amplitudes, but only during t he visual CPT. The results are discussed in relation to cholinergic functio ning in normal and pathological cognition. Copyright (C) 1999 John Wiley & Sons, Ltd.