Kaplan & Sadock’s Pocket Handbook of Clinical Psychiatry

16

Dissociative Disorders

Introduction Dissociation is defined as an unconscious defense mechanism involving the seg regation of any group of mental or behavioral processes from the rest of the per son’s psychic activity. This mechanism is central to the pathology of dissociative disorders, which involve a disruption in one or more mental functions, such as memory, identity, perception, consciousness, or motor behavior. The disturbance may be sudden or gradual, transient, or chronic, and the signs and symptoms of the disorder are very often caused by psychological trauma. Unlike trauma- and stressor-related disorders (Chapter 15), traumatic experience is not part of the diagnostic criteria for any dissociative disorders. Within this chapter, there are three specific dissociative disorders: disso ciative amnesia, dissociative identity disorder (DID), and depersonalization/ derealization disorder, as well as a category for other specified or unspecified dissociative disorders. Dissociative fugue , which was included as a major diag nostic category in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) , became a specifier within dissociative amnesia in DSM-5 and DSM-5-TR . Trauma Exposure Unfortunately, exposure to traumatic events is relatively common. Within the United States, 40.8% to 82.7% of individuals are exposed to trauma over the course of their lifetimes though not all populations are affected evenly. Individ uals from resource-poor communities are more likely to experience stress and trauma than individuals who come from more affluent society. Additional factors that can increase one’s risk of exposure to traumatic events are gender, age, race, ethnicity, sexual orientation, marital status, and education level. Dissociative Amnesia Dissociative amnesia occurs when the patient is unable to recall an important memory which is usually traumatic or stressful but retains the capacity to learn new material. The process of dissociation is believed to be a psychological de fense mechanism governed by the limbic system and associated with instances where one “freezes” during a stress response rather than responding with aggres sion (fight), flight, or an attempt to win over a belligerent actor (fawn). There is no medical explanation for the occurrence, nor is the condition caused by a drug. The different types of dissociative amnesia are listed in Table 16-1 .

Dissociative Disorders

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