Section 7. Mental Health Disorders

Chapter 106. Amnesia and Related Disorders

Topics: Introduction | Dissociative Amnesia | Dissociative Fugue | Dissociative Identity Disorder | Depersonalization Disorder

Dissociative Amnesia

Dissociative amnesia is a type of amnesia caused by trauma or stress resulting in an inability to recall important personal information.

Dissociative amnesia is one type of amnesia. Amnesia is the total or partial inability to recall recent or remote experiences (see Section 6, Chapter 82). When amnesia is caused by a psychologic rather than a physical disturbance, it is called dissociative amnesia. Amnesia may also be a symptom of other disorders, such as acute stress disorder, posttraumatic stress disorder, or somatization disorder.

In dissociative amnesia, the lost memory usually involves information that is normally part of routine conscious awareness or "autobiographical" memory--who one is; what one did; where one went; to whom one spoke; what was said, thought, and felt; and so on. Sometimes the information, though forgotten, continues to influence the person's behavior.

People with dissociative amnesia usually have one or more memory gaps spanning a few minutes to a few hours or days. However, memory gaps spanning years or even a person's entire life may occur. Most people with dissociative amnesia are aware that they have "lost some time," but some become aware of time loss only when they realize or are confronted with evidence that they have done things that they do not recall. Some people with dissociative amnesia forget some but not all events over a period of time; others cannot recall their entire previous life or forget things as they occur.

The disorder is most common among young adults, more commonly among people who have been involved in wars, accidents, or natural disasters. It may also block memories of childhood sexual abuse, later recalled in adulthood. Dissociative amnesia can occur for some time after a traumatic event. Whether such recovered memories reflect real events in the person's past remains unknown, unless confirmed by another person.

Symptoms and Diagnosis

The most common symptom of dissociative amnesia is memory loss. Shortly after becoming amnesic, a person may seem confused. Many people with dissociative amnesia are somewhat depressed or very distressed by their amnesia.

To make the diagnosis, the doctor carefully reviews the person's symptoms and performs a physical examination to exclude physical causes of amnesia. Tests, including electroencephalography and blood testing for toxins and drugs, are sometimes needed to exclude physical causes. A psychologic examination is also performed. Special psychologic tests often help the doctor better characterize and understand the person's dissociative experiences to develop a treatment plan.

Treatment and Prognosis

A doctor begins treatment by helping the person to feel safe and secure. If the missing memories are not spontaneously recalled, or if the need to recall the memories is urgent, memory retrieval techniques are often successful. Using hypnosis or drug-facilitated interviews (interviews conducted after the person is calmed and sedated with an intravenous drug such as amobarbital or midazolam), the doctor questions the amnesic person about the past.

A doctor uses hypnosis and drug-facilitated interviews to reduce anxiety associated with the period for which there is amnesia, and to penetrate or bypass the defenses the amnesic person has created for protection from recalling painful experiences or conflicts. The doctor must be careful not to suggest what should be recalled or stimulate extreme anxiety. Memories recalled through such techniques may not be accurate and may require external corroboration. Therefore, before hypnosis or a drug-facilitated interview is performed, the doctor informs the amnesic person that memories retrieved with these techniques may or may not be accurate and obtains the person's consent to proceed.

Filling in the memory gap to the greatest extent possible helps restore continuity to the person's identity and sense of self. Once the amnesia has disappeared, continued psychotherapy helps the person understand the trauma or conflicts that caused the disorder and find ways to resolve them.

Most people recover what appears to be their missing memories and resolve the conflicts that caused the amnesia. However, some people never break through the barriers that prevent them from reconstructing their missing past.