Neuropsychiatric aspects of Alzheimer's disease: the cholinergic hypothesis revisited.

Altered cholinergic function is a prominent feature of AD. The neuropsychological impairments of AD are attributed, at least partially, to the cholinergic disturbance, and current approaches to treatment of the cognitive abnormalities attempt to enhance cholinergic function. Behavioral changes are common in AD and include psychosis, agitation, depression, anxiety, personality alterations, and neurovegetative changes. The contribution of the cholinergic deficiency to the behavioral alterations has been little explored, but neurochemical, neuroanatomic, pharmacologic, and clinical observations suggest that the cholinergic deficiency contributes importantly to the neuropsychiatric dimension of AD. Investigation of the role of cholinergic dysfunction in the behavioral changes of AD will improve understanding of the pathophysiologic basis of these abnormalities and may lead to new types of therapy for the neuropsychiatric disturbances associated with this common dementing disorder.