CHAPTER 7 - Delirium and Dementia (Organic Brain Syndromes)

Abstract

Medical disorders frequently present with neuropsychiatric manifestations. This chapter focuses on a select group of neuropsychiatric disorders referred to as organic mental disorders. The essential feature of these disorders is a psychological or behavioral abnormality associated with transient or permanent dysfunction of the brain. Organic mental disorders tend to present as one or more organic brain syndromes, for example, as a particular constellation of psychological or behavioral signs and symptoms that tend to occur together. The third edition of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-III) defines seven purely descriptive organic brain syndromes in three groups: (1) organic brain syndromes with global cognitive impairment such as delirium and dementia, (2) organic brain syndromes with selective psychological impairment such as amnestic syndrome and organic hallucinosis, and (3) organic brain syndromes predominantly manifested by personality dis-turbance or that closely resemble some of the functional mental disorders such as organic affective syndrome and organic delusional syndrome. The organic brain syndromes are a heterogeneous group of disorders with vastly different clinical presentations. The occurrence, type, severity, course, and outcome of an organic brain syndrome are influenced to a varying degree by several factors. The differential diagnosis of the organic brain syndromes depends on the predominant clinical features present as outlined in the decision tree from DSM-UI. The focus of treatment of an organic brain syndrome is identification and treatment of the underlying brain disorder.