Dissociative amnesia is amnesia (memory loss) 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 decades.
After tests are done to rule out other possible causes, doctors diagnose the disorder based on symptoms.
Memory-retrieval techniques, including hypnosis and medication-facilitated interviews, are used to fill in the memory gaps.
Psychotherapy is needed to help people deal with the experiences that triggered the disorder.
(See also Overview of Dissociative Disorders and Memory Loss.)
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 general medical disorder, 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
What one did, said, thought, and felt
Often, the lost memory is information about traumatic or stressful events, such as childhood abuse. Sometimes the information, though forgotten, continues to influence behavior. For example, even though a woman who was raped in an elevator cannot recall any details of the assault, she nonetheless avoids elevators and is unwilling to enter them.
Dissociative amnesia is probably underreported, so accurate statistics on its prevalence are not available. It does, however, seem to be more common among women than men and usually occurs in people who have experienced or witnessed traumatic events, such as physical or sexual abuse, rape, wars, genocide, accidents, natural disasters, or death of a loved one. It may also result from concern about serious financial troubles or tremendous internal conflict (such as feelings of guilt about certain impulses or actions, apparently unresolvable interpersonal difficulties, or crimes committed).
Dissociative amnesia can persist for some time after a traumatic event. Sometimes people appear to spontaneously recover memories.
Unless confirmed by another person or other evidence, how closely and accurately such recovered memories reflect real events from the past may be unclear.
Symptoms of Dissociative Amnesia
The most common symptom of dissociative amnesia is memory loss.
Memory loss may involve any of the following:
A specific event or events or a specific period of time, such as the months or years of being abused as a child or the days spent in intense combat (localized amnesia)
Only certain aspects of an event or only certain events during a period of time (selective amnesia)
Personal identity and entire life story, sometimes including well-learned skills and information about the world (generalized amnesia)
Information in a specific category, such as all information about a particular person or about their family (systematized amnesia)
Each new event as it occurs (continuous amnesia)
Generalized amnesia is rare. It is more common among combat veterans, people who have been sexually assaulted, and people experiencing extreme stress or conflict. It usually begins suddenly.
Amnesia may not appear immediately after a traumatic or stressful event. It may take hours, days, or longer to appear.
Shortly after loss of memory, some people seem confused. Some are very distressed. Others are strangely indifferent.
Most people with dissociative amnesia have one or more gaps in their memory. Gaps usually span a few minutes to a few hours or days but may span years, decades, or even an entire life. Most people are unaware or only partly aware that they have gaps in their memory. They become aware only later, when memories reappear or they are confronted with evidence of things that they have done but do not recall.
Affected people have difficulty forming and maintaining relationships.
Some people have flashbacks, as occur in posttraumatic stress disorder (PTSD). That is, they relive events as if they were actually happening, and they are unaware of their subsequent personal history—for example, that they survived the trauma. Flashbacks may alternate with amnesia for what happened during the flashback. Some people with dissociative amnesia develop PTSD later, especially when they become aware of the traumatic or stressful events that triggered their amnesia.
People may also have vague symptoms, such as fatigue, weakness, or problems sleeping. Depression and suicidal and other self-destructive behaviors (such as substance misuse and reckless sexual behavior) are common. Risk of suicidal behaviors may be increased when amnesia resolves suddenly and people are overwhelmed by traumatic memories.
Rarely, people with an extreme form of dissociative amnesia suddenly travel from their home for a period of time. During this time, they do not remember some or all of their past life, including who they are (their identity). These episodes are called dissociative fugues.
Diagnosis of Dissociative Amnesia
A doctor's evaluation, based on specific diagnostic criteria from the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR)
Sometimes tests to rule out other possible causes
Doctors diagnose dissociative amnesia based on the person’s symptoms:
People cannot recall important personal information (usually related to the trauma or stress) that would not typically be forgotten.
They are very distressed by their symptoms, or their symptoms make them unable to function in social situations or at work.
Doctors also do a physical examination to exclude neurologic causes of amnesia such as dementia.
Tests are sometimes needed to exclude other causes of amnesia. Tests include the following:
Magnetic resonance imaging (MRI) or computed tomography (CT) to rule out brain tumors and other structural brain disorders
Electroencephalography (EEG) to rule out a seizure disorder
Blood or urine tests for toxins and drugs
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 of Dissociative Amnesia
A supportive environment
Sometimes memory-retrieval techniques (such as hypnosis)
Psychotherapy
Supportive environment
Doctors begin treatment by helping people feel safe and secure—for example, by helping them to avoid further traumatization. If people have no apparent urgent reason to recover the memory of a painful event, this supportive treatment may be all that is needed. People may gradually recall the missing memories. When a supportive environment does not improve matters or when the need to recover memories is urgent, doctors may use hypnosis or medication-facilitated interviews.
Memory-retrieval techniques
If the missing memories are not recalled or if the need to recall the memories is urgent, memory-retrieval techniques are often successful. They include
Hypnosis
Medication-facilitated interviews (interviews conducted after a sedative, such as a barbiturate or benzodiazepine, is given intravenously)
Doctors use hypnosis and medication-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 are careful not to suggest what should be recalled (and thus create a false memory) or to cause extreme anxiety. Recalling the traumatic circumstances that stimulated memory loss is often very upsetting.
Furthermore, memories recalled through such techniques may not be accurate and may require confirmation from another person or source. Therefore, before hypnosis or a medication-facilitated interview, doctors inform people that memories retrieved with these techniques may or may not be accurate and ask for consent to proceed.
Also, doctors try to reassure people with dissociative amnesia that they want to help. People who were abused, especially during childhood, are sometimes suspicious of therapists and may expect the therapist to exploit or abuse them and to impose uncomfortable memories rather than help them recover real memories.
Filling in the memory gap to the greatest extent possible helps restore continuity to personal identity and sense of self.
Psychotherapy
Once amnesia has resolved, continued psychotherapy helps people do the following:
Understand the trauma or conflicts that caused the disorder
Find ways to resolve them
Avoid future traumatization if possible
Return to normal functioning
Prognosis for Dissociative Amnesia
Sometimes memories return quickly, as can happen when people are taken out of the traumatic or stressful situation (such as combat). In other cases, amnesia, particularly in people with dissociative fugue, persists for a long time. Symptoms may decrease as people age.
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.
