Dissociative Disorders
Types of dissociative disorders according to DSM-IV-TR
- Dissociative amnesia
- Dissociative fugue
- Dissociative identity disorder
- Depersonalization disorder
- Dissociative disorder not otherwise specified
(Reprinted, with permission, from Diagnostic and Statistical Manual of Mental Disorders, 4th edn., Text Revision. Washington DC: American Psychiatric Association, 2000.)
The cardinal feature of the dissociative disorders is an acute or gradual, transient or persistent, disruption of consciousness, perception, memory or awareness, not associated with physical disease or organic brain dysfunction, and severe enough to cause distress or impairment. Four types are described in DSM-IV-TR, and there is a miscellaneous fifth group. The distinction between these types may be blurred, particularly when patients exhibit symptoms from more than one type.
Epidemiologic data on dissociative disorders are patchy. Studies of combat soldiers have found a prevalence of dissociative amnesia of 5–8%. There are no reliable data on dissociative fugue. The prevalence of dissociative identity disorder is disputed but probably low. Case reports suggest a female-to-male ratio of at least 5:1. This ratio might be exaggerated, because males with dissociative disorder, who are likely to be episodically violent, are likely to be directed to the correctional system. Dissociative identity disorder is found in all ethnic groups, though mainly in whites, and in all socioeconomic groups. Depersonalization is a frequent concomitant of anxiety disorders, posttraumatic stress disorder, and severe depression. Up to one half of college students claim to have experienced depersonalization at some time in their lives. It has been reported that 80% of psychiatric inpatients suffer from depersonalization, but in only 12% is the symptom long lasting, and in no case is it the only symptom. The sex ratio is equal.
Normal dissociation is an adaptive defense used to cope with overwhelming psychic trauma. It is commonly encountered during and after civilian disasters, criminal assault, sudden loss, and war. In normal dissociation, the individual’s perception of the traumatic experience is temporarily dulled or dispelled from consciousness. Normal dissociation prevents other vital psychological functions from being overwhelmed by the traumatic experience. The capacity to dissociate, as evidenced by susceptibility to hypnosis, is widely distributed among normal people. However, it is unclear whether pathologic dissociation is an extreme or more enduring form of normal dissociation (i.e., whether there is a continuum of dissociation between normal and abnormal) or whether the pathologic form is distinctive. Recent studies of trauma subjects have found only a low correlation between hypnotizability and measures of dissociation.
Theories concerning the basis of pathologic dissociation can be classified as psychological, neurocognitive, traumagenic, and psychosocial.
Janet postulated that some people have a constitutional “psychological insufficiency” that renders them prone to dissociate in the face of frightening experiences. At that time, memories associated with “vehement emotions” become separated or dissociated from awareness in the form of subconscious fixed ideas, which are not integrated into memory. Rather, they remain latent and are prone to return to consciousness as psychological automatisms such as hysterical paralyses, anesthesias, and somnambulisms (trance states).
Breuer and Freud suggested that hysterical patients harbor inadmissible ideational “complexes” resulting in a splitting of the mind and the emergence of abnormal (hypnoid) states of consciousness. Pathologic associations formed during hypnoid states fail to decay like ordinary memories but reemerge to disrupt somatic processes in the form of hysterical sensorimotor symptoms or disturbances of consciousness. Breuer and Freud disputed Janet’s concept that dissociation is a passive process reflecting a hereditary degeneracy. They introduced the concept of an active defensive process that energetically deflects the conscious mind from disruptive ideas. Out of this theory emerged the later psychoanalytic concepts of repression and ego defense.
Dissociative amnesia and dissociative fugue characteristically arise in a setting of overwhelming stress, particularly in time of war or civilian catastrophe. Murderers, for example, often claim amnesia for the crime long after it would be legally advantageous to do so. Money problems, the impending disclosure of a sexual misdemeanor, marital conflict, or the death of a loved one are the usual precipitants of amnesia and fugue. Sometimes, the dissociative state is precipitated by an intolerable mood, such as severe depression with intense guilt. Dissociation blots out the unendurable memory; and a fugue represents an attempt to get away and start a new life.
It is unclear whether depersonalization represents a minor variant of global dissociation or a different process. In depersonalization, affect and the sense of being connected is split off from the individual’s sense of self and perception of the outside world, giving rise to the feeling of being detached, like a robot or in a dream. Depersonalization may be the subjective component of a biological mechanism that allows an animal to function in a terrifying situation, whereas dissociation is represented by the freezing behavior that enables hunted animals to escape detection. These extreme survival maneuvers are subject to overload. Learned helplessness in animals, for example, may represent a breakdown of those neural circuits that modulate the sensitivity of the brain to incoming stimuli.
Episodic memory is a form of explicit memory involving the storage of events, which then have access to conscious awareness. Episodic memory is usually recounted in words, as a narrative. If significant enough, episodic memories become part of autobiographical memory, the history of the self. The medial temporal lobe, particularly the hippocampus, is essential to the encoding, storage, and retrieval of episodic memory. Dissociation may represent an interference with the encoding, storage, or retrieval in narrative form of traumatic episodic memories.
The locus coeruleus is an important source of noradrenergic fibers that project to the cerebral cortex, hypothalamus, hippocampus, and amygdala. The amygdala and orbitofrontal cortex select out those stimuli that have been primary reinforcers in the past. The amygdala projects to the hippocampus (via the entorhinal cortex), to the sensory association cortex, and to the hypothalamus and brain stem, coordinating a central alarm apparatus that scans sensory input for stimuli the animal has learned to fear, and sounds an alert when such stimuli are encountered. Evidence indicates that serotonin acts postsynaptically in the amygdala to provoke the synthesis of enkephalins, which modulate or dampen the affect associated with fearful experience and may interfere with the consolidation of traumatic memories. If the amygdaloid alarm system becomes overloaded and breaks down, the animal will be at the mercy of raw fear. Thus, whenever reminders of trauma are perceived in the environment, or whenever fragments of traumatic episodic memory threaten to emerge into awareness, an alarm is sounded and the fail-safe, last-resort defense of dissociation must be invoked.
Traumatic memories are stored in two systems: (1) the hippocampal explicit episodic memory system and (2) the amygdaloid implicit alarm system. The amygdaloid system can disrupt storage and retrieval via the hippocampal system. Research suggests that immature animals exposed to early inescapable stress or gross deprivation of cospecies contact are particularly vulnerable to subsequent trauma. In primates, morphine decreases (and naloxone increases) the amount of affiliative calling of an animal separated from its mother, whereas diazepam reduces freezing and hostile gestures in reaction to direct threat, probably through the prefrontal cortex. Animal research has suggested that high circulating corticosteroid levels in stressed juveniles are associated with a reduction in the population of glucocorticoid receptors in the hippocampus. Furthermore, neuroimaging studies of veterans with chronic posttraumatic stress disorder have demonstrated an apparent shrinkage in hippocampal volume.
Clinical evidence for the linkage between emotional trauma and dissociation is derived from the following observations: (1) the high prevalence of histories of childhood trauma reported by patients with dissociative disorder; (2) elevated levels of dissociation in people who report child abuse; (3) elevated levels of dissociation in combat veterans with posttraumatic stress disorder; (4) the prevalence of acute dissociative reactions in war or disaster; and (5) the observation that marked dissociation during a traumatic experience predicts subsequent posttraumatic stress disorder. Almost all adults with dissociative identity disorder report significant trauma in childhood, particularly incest, physical abuse, and emotional abuse. These patients commonly report repeated abuse, sometimes of an extremely sadistic, bizarre nature.
The difficulty of corroborating retrospective accounts of abuse has provoked much controversy. Are these reports false, unwittingly created by clinical interest and the recent explosion of coverage in the media? The possibility of iatrogenic facilitation cannot be excluded. The more dramatic forms of dissociative disorder—particularly fugue and multiple identity—may represent, at least in part, forms of abnormal illness behavior, distorted attempts by emotionally needy patients to elicit care and protection from therapist-parent surrogates, or bids to retain the interest of therapists in the context of an intense transference relationship. Traumagenic and psychosocial theories are not necessarily mutually exclusive.
Dissociative Amnesia & Dissociative Fugue
DSM-IV-TR Diagnostic Criteria
Dissociative Amnesia
The predominant disturbance is one or more episodes of inability to recall important personal information, usually of a traumatic or stressful nature, that is too extensive to be explained by ordinary forgetfulness.
The disturbance does not occur exclusively during the course of dissociative identity disorder, dissociative fugue, posttraumatic stress disorder, acute stress disorder, or somatization disorder and is not due to the direct physiological effects of a substance (e.g., a drug of abuse, a medication) or a neurological or other general medical condition (e.g., amnestic disorder due to head trauma).
The symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.
DSM-IV-TR Diagnostic Criteria Dissociative Fugue
The predominant disturbance is sudden, unexpected travel away from home or one’s customary place of work, with inability to recall one’s past.
Confusion about personal identity or assumption of a new identity (partial or complete).
The disturbance does not occur exclusively during the course of dissociative identity disorder and is not due to the direct physiological effects of a substance (e.g., a drug of abuse, a medication) or a general medical condition (e.g., temporal lobe epilepsy).
The symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.
(Reprinted, with permission, from Diagnostic and Statistical Manual of Mental Disorders, 4th edn., Text Revision. Washington DC: American Psychiatric Association, 2000.)
The amnesia for distressing events can be localized (i.e., complete amnesia for events during a circumscribed period of time), selective (i.e., failure to remember some but not all events during a circumscribed period of time), generalized (i.e., affecting an entire period of life), or continuous (i.e., failure to remember anything after a particular date). Patchy amnesia is prevalent among people exposed to military or civilian trauma. A common sequence is for the patient to progress from a first stage, characterized by an acute altered state of consciousness (mental confusion, headache, and preoccupation with a single idea or emotion), to a second stage in which he or she loses the sense of personal identity. At this point the patient may be found wandering in a fugue state, unable to give an account of himself or herself. Rarely, the patient enters a third stage in which he or she assumes a new identity, usually one more gregarious and uninhibited than previously. The diagnostic separation of amnesia from fugue may be illusory, because the two conditions are probably on a continuum. During the first stage of confusion and altered consciousness, some patients report audiovisual hallucinations and a preoccupation with quasidelusional ideas. This condition, originally known as hysterical twilight state, lacks the disorganization of thought processes and affective incongruity found in schizophrenia. The patient operates at a higher level of consciousness than is associated with epilepsy or other organic brain dysfunctions.
Table 24–1 lists tests that are useful screens in the diagnosis of dissociative disorders.
Test | Description |
|---|---|
Dissociative Disorders Interview Schedule (DDIS) | A structured interview that examines for dissociative disorder, somatoform disorder, depression, borderline personality disorder, substance abuse, and physical and sexual abuse |
Structured Clinical Interview for the DSM-IV Dissociative Disorders (SCID-D) | A semistructured interview derived from the SCID |
Dissociative Experiences Scale (DES) | A 28-item self-report questionnaire that screens for dissociative symptoms in adults (age 18 years and older) |
Adolescent Dissociative Experiences Scale (A-DES) | A 30-item self-report screening questionnaire for adolescents (age 12–20 years) |
Child Dissociative Checklist (CDC) | A 20-item screening checklist to be completed on children (age 5–12 years) by a parent or adult observer |
Structured Interview for Reported Symptoms (SIRS) | A structured interview designed to detect the malingering of psychosis |
Dissociative amnesia and dissociative fugue must be differentiated from delirium or dementia. The clinician must exclude amnestic disorders due to such medical conditions as vitamin deficiency, head trauma, carbon monoxide poisoning, and herpes encephalitis as well as amnestic disorders secondary to alcoholism (Korsakoff syndrome); to anxiolytic, anticonvulsant, sedative, and hypnotic drugs; and to steroids, lithium, or β-blockers. The clinician must also distinguish other organic disorders such as the retrograde amnesia of head injury, seizure disorder (particularly the dreamy state of temporal lobe epilepsy), and transient global amnesia due to cerebral vascular insufficiency.
Differential diagnosis is based on a full history, a detailed mental status examination, physical and neurologic examination, and when appropriate, special investigations such as a toxicology screen, laboratory testing, electroencephalography, brain imaging, and neuropsychological testing. The most difficult diagnostic problems arise when dissociation is superimposed on organic disease (e.g., pseudoseizures coexisting with epilepsy). The differentiation of dissociative disorders from malingering is discussed later in this chapter.
