Dissociative amnesia

Definition

The dissociative disorders are a group of mental disorders that were first classified separately in the third edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III) in 1980. DSM-IV (1994) defines the distinctive feature of dissociation as "... a disruption in the usually integrated functions of consciousness, memory, identity, or perception of the environment." All dissociative disorders are defined as causing significant interference with the patient's general functioning, including social relationships and employment.

Description

In order to have a clear picture of these disorders, the reader should first understand dissociation. Dissociation is a mechanism that allows the mind to separate or compartmentalize certain memories or thoughts from normal consciousness. These split-off mental contents are not erased. They may resurface spontaneously or be triggered by objects or events in the person's environment.

Dissociation is a process that occurs along a spectrum of severity. It does not necessarily mean that a person has a dissociative disorder or other mental illness. A mild degree of dissociation occurs with some physical stressors; people who have gone without sleep for a long period of time, have had "laughing gas" for dental surgery, or have been in a minor accident often have brief dissociative experiences. Another commonplace example of dissociation is a person becoming involved in a book or movie so completely that the surroundings or the passage of time are not noticed. Another example might be driving on the highway and taking several exits without noticing or remembering. Dissociation is related to hypnosis in that hypnotic trance also involves a temporarily altered state of consciousness. Most patients with dissociative disorders are highly hypnotizable.

People in other cultures sometimes have dissociative experiences in the course of religious (in certain trance states) or other group activities. These occurrences should not be judged in terms of what is considered "normal" in the United States.

Moderate or severe forms of dissociation are caused by such traumatic experiences as childhood abuse, combat, criminal attacks, brainwashing in hostage situations, or involvement in a natural or transportation disaster. Patients with acute stress disorder, post-traumatic stress disorder (PTSD), or conversion disorder and somatization disorder may develop dissociative symptoms. Recent studies of trauma indicate that the human brain stores traumatic memories in a different way than normal memories. Traumatic memories are not processed or integrated into a person's ongoing life in the same fashion as normal memories. Instead they are dissociated, or "split off," and may erupt into consciousness from time to time without warning. The affected person cannot control or "edit" these memories. Over a period of time, these two sets of memories, the normal and the traumatic, may coexist as parallel sets without being combined or blended. In extreme cases, different sets of dissociated memories may alter subpersonalities of patients with dissociative identity disorder (multiple personality disorder).

The dissociative disorders vary in their severity and the suddenness of onset. It is difficult to give statistics for their frequency in the United States because they are a relatively new category and are often misdiagnosed. And, according to the DSM-IV, criterion for diagnosis require significant impairment in social or vocational functioning.

Dissociative amnesia

Dissociative amnesia is a disorder in which the distinctive feature is the patient's inability to remember important personal information to a degree that cannot be explained by normal forgetfulness. In many cases, it is a reaction to a traumatic accident or witnessing a violent crime. Patients with dissociative amnesia may develop depersonalization or trance states as part of the disorder but they do not experience a change in identity.

Dissociative fugue

Dissociative fugue is a disorder in which a person temporarily loses his or her sense of personal identity and travels to another location where he or she may assume a new identity. Again, this condition usually follows a major stressor or trauma. Apart from inability to recall their past or personal information, patients with dissociative fugue do not behave strangely or appear disturbed to others. Cases of dissociative fugue are more common in wartime or in communities disrupted by a natural disaster.

Depersonalization disorder

Depersonalization disorder is a disturbance in which the patient's primary symptom is a sense of detachment from the self. Depersonalization as a symptom (not as a disorder) is quite common in college-age populations. It is often associated with sleep deprivation or "recreational" drug use. It may be accompanied by "derealization" (where objects in an environment appear altered). Patients sometimes describe depersonalization as feeling like a robot or watching themselves from the outside. Depersonalization disorder may also involve feelings of numbness or loss of emotional "aliveness."

Dissociative identity disorder (DID)

Dissociative identity disorder (DID) is the newer name for multiple personality disorder (MPD). DID is considered the most severe dissociative disorder and involves all of the major dissociative symptoms.

Dissociative disorder not otherwise specified (DDNOS)

DDNOS is a diagnostic category ascribed to patients with dissociative symptoms that do not meet the full criteria for a specific dissociative disorder.

Causes & symptoms

The moderate to severe dissociation that occurs in patients with dissociative disorders is understood to result from a set of causes:

• An innate ability to dissociate easily
• Repeated episodes of severe physical or sexual abuse in childhood
• The lack of a supportive or comforting person to counteract abusive relative(s)
• The influence of other relatives with dissociative symptoms or disorders.

The relationship of dissociative disorders to childhood abuse has led to intense controversy and lawsuits concerning the accuracy of childhood memories. The brain's storage, retrieval, and interpretation of memories are still not fully understood. Controversy also exists regarding how much individuals presenting dissociative disorders have been influenced by books and movies to describe a certain set of symptoms (scripting).

The major dissociative symptoms are:

Amnesia

Amnesia in a dissociative disorder is marked by gaps in a patient's memory for long periods of time or for traumatic events. Doctors can distinguish this type of amnesia from loss of memory caused by head injuries or drug intoxication, because the amnesia is "spotty" and related to highly charged events and feelings.

Depersonalization

Depersonalization is a dissociative symptom in which the patient feels that his or her body is unreal, is changing, or is dissolving. Some patients experience depersonalization as being outside their bodies or watching a movie of themselves.

Derealization

Derealization is a dissociative symptom in which the external environment is perceived as unreal. The patient may see walls, buildings, or other objects as changing in shape, size, or color. In some cases, the patient may feel that other persons are machines or robots, though the patient is able to acknowledge the unreality of this feeling.

Identity disturbances

Patients with dissociative fugue, DDNOS, or DID often experience confusion about their identities or even assume new identities. Identity disturbances result from the patient having split off entire personality traits or characteristics as well as memories. When a stressful or traumatic experience triggers the reemergence of these dissociated parts, the patient may act differently, answer to a different name, or appear confused by his or her surroundings.

Diagnosis

When a doctor is evaluating a patient with dissociative symptoms, he or she will first rule out physical conditions that sometimes produce amnesia, depersonalization, or derealization. These physical conditions include epilepsy, head injuries, brain disease, side effects of medications, substance abuse or intoxication, AIDS dementia complex, or recent periods of extreme physical stress and sleeplessness. In some cases, the doctor may give the patient an electroencephalogram (EEG) to exclude epilepsy or other seizure disorders.

If the patient appears to be physically normal, the doctor will rule out psychotic disturbances, including schizophrenia. In addition, doctors can use some psychological tests to narrow the diagnosis. One is a screener, the Dissociative Experiences Scale (DES). If the patient has a high score on this test, he or she can be evaluated further with the Dissociative Disorders Interview Schedule (DDIS) or the Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D). It is also possible for doctors to measure a patient's hypnotizability as part of a diagnostic evaluation.

Treatment

Treatment of the dissociative disorders often combines several methods.

Psychotherapy

Patients with dissociative disorders often require treatment by a therapist with some specialized understanding of dissociation. This background is particularly important if the patient's symptoms include identity problems. Many patients with dissociative disorders are helped by group as well as individual treatment.

Medications

Some doctors will prescribe tranquilizers or antidepressants for the anxiety and/or depression that often accompany dissociative disorders. Patients with dissociative disorders are, however, at risk for abusing or becoming dependent on medications. As of 1998, there is no drug that can reliably counteract dissociation itself.

Hypnosis

Hypnosis is frequently recommended as a method of treatment for dissociative disorders, partly because hypnosis is related to the process of dissociation. Hypnosis may help patients recover repressed ideas and memories. Therapists treating patients with DID sometimes use hypnosis in the process of "fusing" the patient's alternate personalities.

Prognosis

Prognoses for dissociative disorders vary. Recovery from dissociative fugue is usually rapid. Dissociative amnesia may resolve quickly, but can become a chronic disorder in some patients. Depersonalization disorder, DDNOS, and DID are usually chronic conditions. DID usually requires five or more years of treatment for recovery.

Prevention

Since the primary cause of dissociative disorders is thought to involve extended periods of humanly inflicted trauma, prevention depends on the elimination of child abuse and psychological abuse of adult prisoners or hostages.

Key Terms

Amnesia

A general medical term for loss of memory that is not due to ordinary forgetfulness. Amnesia can be caused by head injuries, brain disease, or epilepsy, as well as by dissociation.

Depersonalization

A dissociative symptom in which the patient feels that his or her body is unreal, is changing, or is dissolving.

Derealization

A dissociative symptom in which the external environment is perceived as unreal.

Dissociation

A psychological mechanism that allows the mind to split off traumatic memories or disturbing ideas from conscious awareness.

Fugue

A dissociative experience during which a person travels away from home, has amnesia for their past, and may be confused about their identity but otherwise appear normal.

Hypnosis

The means by which a state of extreme relaxation and suggestibility is induced: used to treat amnesia and identity disturbances that occur in dissociative disorders.

Multiple personality disorder (MPD)

An older term for dissociative identity disorder (DID).

Trauma

A disastrous or life-threatening event that can cause severe emotional distress, including dissociative symptoms and disorders.

Further Reading

For Your Information

Books

• "Dissociative Disorders." In Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. (DSM-IV) Washington, DC: The American Psychiatric Association, 1994.
• Eisendrath, Stuart J. "Psychiatric Disorders." In Current Medical Diagnosis & Treatment 1998, edited by Lawrence M. Tierney, Jr., et al. Stamford, CT: Appleton & Lange, 1997.
• Kolb, Lawrence C., and H. Keith H. Brodie. Modern Clinical Psychiatry. Philadelphia: W. B. Saunders Company, 1982.
• Napier, Nancy J. Getting Through The Day: Strategies for Adults Hurt as Children. New York and London: W. W. Norton & Company, 1994.
• Nemiah, John C. "Psychoneurotic Disorders." In The New Harvard Guide to Psychiatry, edited by Armand M. Nicholi, Jr. Cambridge, MA, and London, UK: The Belknap Press of Harvard University Press, 1988.
• Noll, Richard. The Encyclopedia of Schizophrenia and the Psychotic Disorders. New York and Oxford, UK: Facts On File, 1992.
• Pascuzzi, Robert M. and Mary C. Weber. "Conversion Disorders, Malingering, and Dissociative Disorders." In Current Diagnosis 9, edited by Rex B. Conn, et al. Philadelphia: W. B. Saunders Company, 1997.
• "Psychiatric Disorders: Hysterical Neurosis." In The Merck Manual of Diagnosis and Therapy, vol. I, edited by Robert Berkow, et al. Rahway, NJ: Merck Research Laboratories, 1992.
• van der Kolk, Bessel A., and Onno van der Hart. "The Intrusive Past: The Flexibility of Memory and the Engraving of Trauma." In Trauma: Explorations in Memory, edited by Cathy Caruth. Baltimore and London: The Johns Hopkins University Press, 1995.

Gale Encyclopedia of Medicine. Gale Research, 1999.