Syndromes of brain dysfunction presenting with cognitive impairment or behavioral disturbance: Delirium, dementia, and mental disorders caused by a general medical condition

Abstract

The disorders under consideration are the result of identifiable conditions. Historically, an arbitrary distinction has been made between organic conditions, associated with a presumably clear pathological basis, and functional conditions, or psychiatric disorders that lacked obvious disease processes. Delirium, however, is a disorder of cognitive dysfunction that lacks a well-understood pathophysiology despite unequivocal association with multiple and various medical conditions. More generally, delirium and dementia are frequently complicated by psychopathology (for example, delusions or changes in mood) traditionally associated with so-called functional disorders (schizophrenia and affective disorders, respectively). The organic/functional distinction obscured the propensity of medical conditions (e.g., thyroid dysfunction) to present with psychiatric symptoms that resolved after effective treatment of the nonpsychiatric condition. The nosological conventions of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) (1) allow recognition of syndromes of disseminated cognitive dysfunction, such as delirium and dementia, as well as the psychopathology that is the product of various and multiple medical conditions without obscuring the need to consider these entities in the differential diagnosis of functional symptomatology. Regardless of the evolution of diagnostic convention, the illnesses described in this chapter can present to the psychiatrist as a mental condition or present to other medical specialists as medical conditions. © 2008 Humana Press, a part of Springer Science+Business Media, LLC.