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Dissociative Amnesia

by Daphne Simeon, MD

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

  • People have gaps in their memory, which may span a few minutes to years.

  • After tests are done to rule out other possible causes, psychologic testing helps identify the disorder.

  • Memory retrieval techniques, including hypnosis and drug-facilitated interviews, are used to fill in the memory gaps.

  • Psychotherapy is needed to help people deal with the experiences that triggered the disorder.

Amnesia is the total or partial inability to recall recent experiences or ones from the distant past. When amnesia is caused by a psychologic rather than a physical disturbance, it is called dissociative amnesia.

In dissociative amnesia, the lost memory usually involves information that is normally part of routine conscious awareness or autobiographic memory—who one is, where one went, to whom one spoke, and what one did, said, thought, and felt. Often, it is information about traumatic or stressful events. Sometimes the information, though forgotten, continues to influence behavior.

The disorder is most common among young adults, usually people who have been involved in wars, accidents, or natural disasters. It may also block memories of sexual abuse during childhood. Dissociative amnesia can persist for some time after a traumatic event. Sometimes, people appear to spontaneously recover memories. Unless confirmed by another person, it is often unclear whether such recovered memories reflect real events from the past.

Symptoms

The most common symptom is memory loss. Shortly after loss of memory, some people seem confused. Many people are somewhat depressed or very distressed by their amnesia. Most people have one or more gaps in their memory. Gaps usually span a few minutes to a few hours or days but may span years or even an entire life. Most people are aware that they have lost some time. However, some become aware of lost time only later, when memories reappear or they are confronted with evidence of things that they have done but do not recall. Some people forget some but not all events over a period of time. Others cannot recall their entire previous life or forget things as they occur.

Did You Know...

  • When doctors use techniques to help people remember, they must be very careful not to do or say anything that could create a false memory.

Diagnosis

Doctors carefully review the person’s symptoms and do a physical examination to exclude physical causes of amnesia. Tests, including magnetic resonance imaging (MRI), electroencephalography (EEG), and blood tests for toxins and drugs, are sometimes needed to exclude physical causes. A psychologic examination is also done. Special psychologic tests often help doctors better characterize and understand the person’s dissociative experiences and thus develop a treatment plan.

Treatment and Prognosis

Doctors begin treatment by helping people 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 a sedative such as a barbiturate or benzodiazepine is given intravenously), doctors question people about the past. Doctors use hypnosis and drug-facilitated interviews to reduce the anxiety associated with the period for which there are gaps in memory and to penetrate or bypass the defenses people have created to protect themselves from recalling painful experiences or conflicts. However, doctors must be careful not to suggest what should be recalled or to cause extreme anxiety. Furthermore, memories recalled through such techniques may not be accurate and may require confirmation from another person or source. Therefore, before hypnosis or a drug-facilitated interview, doctors inform people that memories retrieved with these techniques may or may not be accurate and ask for consent to proceed.

Filling in the memory gap to the greatest extent possible helps restore continuity to personal identity and sense of self. Once amnesia has resolved, continued psychotherapy helps people understand the trauma or conflicts that caused the disorder, find ways to resolve them, and move on with their life.

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.

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