Update on cholinergic enhancement therapy for Alzheimer disease.

Although patients with Alzheimer disease have a well-demonstrated deficit in cortical cholinergic markers, treatments designed to enhance cholinergic activity in the central nervous system have not achieved the clinical success of dopamine replacement for Parkinson disease. A brief review of recent clinical reports and some developments in the neurosciences suggests that it may be premature, however, to abandon the search for benefit from cholinergic enhancement therapy in Alzheimer disease.