The main purpose of this study is to determine the electrophysiological effects of cholinergic therapy (cholinesterase inhibitors and transdermal nicotine) in Alzheimer disease. The attempt will be to locate electrophysiological markers and predictors of cognitive and clinical treatment response.

Patients diagnosed with mild to moderate probable Alzheimer's disease (mini-mental state exam scores between 15-27), and normal controls (age generally between 60-85). Subjects must either be planning to start daily cholinesterase therapy (e.g. Aricept, Exelon) or willing to try a transdermal nicotine patch for two 8 hour periods.