AbstractWe gave scopolamine to patients with Alzheimer's disease (AD) and age‐matched control subjects in order to identify which cognitive functions are affected by blocking muscarinic receptors for acetylcholine (ACh). Both subject groups showed dose‐related impairments in verbal learning, and patients with AD exhibited enhanced vulnerability to effects of scopolamine on attentional vigilance. In the same dose range, scopolamine did not alter retrieval from long‐term lexical‐semantic memory or performance on a test of visual discrimination, suggesting that cholinergic neurotransmission is not critical for these cognitive functions. The importance of cholinergic transmission in learning and attention is confirmed by this study, and the results indicate that both these abilities should be measured in investigations of potential cholinergic treatments