Apathy

Deficits in motivated behavior are a very common sequela of most neuropsychiatric disorders, a source of significant disability to the individual, and a source of great frustration to their caregivers. Well-intentioned attempts to encourage certain activities in the apathetic patient often precipitate aggressive, dyscontrolled behavior. The psychopharmacologic approach to motivated behavior deficits is informed by the study of the components, circuitry, and neurochemistry of motivated behavior in animals and humans. This article selectively reviews this literature. The circuitry of motivated behavior involves a combination of behavior specific regions in the hypothalamus as well as a general reward system running from midbrain to forebrain and including important components of several frontal-subcortical circuits. Catecholaminergic systems, particularly the mesolimbic dopaminergic system, are key modulators of motivated behaviors. Treatment thus involves the use of catecholaminergic agents.