AbstractThe loss of central nicotinic receptors is a neurochemical hallmark of several degenerative brain disorders, notably Alzheimer's disease (AD) and Parkinson's disease (PD). However, uncertainty has remained about the significance of this loss for the cognitive symptomatology of these disorders. Symptoms of impaired acquisition of information and short‐term storage, impaired memory consolidation, attention, visual perception, and speed may reflect nicotinic lesions. Administration of the nicotinic antagonist mecamylamine in young and elderly humans produces significant dose‐related impairment of new learning, liberalization of response bias, and slowing of reaction time. These results suggest that mecamylamine may in part model the results of nicotinic receptor loss in AD and that nicotinic augmentation of some aspects of cognitive functioning may be a worthwhile strategy to pursue, particularly if agents can be developed that are more selective than nicotine itself. © 1994 Wiley‐Lis