[Neuropathological principles of behavioral disorders in dementia]

Psychotic symptoms, apathy, agitation and aggressiveness are behavioral disorders that occur frequently in patients with Alzheimer's dementia. They cause serious problems for patients, relatives and care-givers. These behavioral disorders are associated with neuropathologic changes and alterations of brain metabolism in specific brain areas. Disturbances in mesotemporal and frontal brain areas seem to be related to psychotic symptoms. Apathy is associated with dysfunction of frontal cortical areas. Agitation and impulsivity appear to result from a hypofunction of the serotonin system in association with a relative hyperfunction of dopaminergic and noradrenergic systems. These dysfunctions are the result of direct neuropathologic changes, but also due to cholinergic deficits that seem to both contribute synergistically to and independently cause behavioral disturbances.