Biologic markers and neurochemical correlates of agitation and psychosis in dementia.

Behavioral and psychiatric symptoms frequently accompany the cognitive deterioration of dementia occurring in up to 80% of both community-based and nursing home patients. In Alzheimer's disease (AD), behavioral complications may develop at any stage of the disease process and tend to follow a more unpredictable course than the core cognitive symptoms. Over the past 15 years, our knowledge of the biologic and neurochemical basis of dementia, and of AD in particular, has increased significantly. Great emphasis has been placed on the cholinergic system abnormalities in the context of the cognitive impairment in AD and on the psychopharmalogic enhancement of cholinergic transmission in AD. However deficits in other neurotransmitter systems, such as the noradrenergic, serotonergic, and dopaminergic systems, also occur and may contribute to the core cognitive symptoms of AD. More recently, there has been increased interest in the biologic and neurochemical basis of behavioral and psychiatric disturbances in dementia. This article reviews the evidence for biologic and neurochemical correlates of psychosis and agitation in dementia, and discusses the treatment implications for these findings.