Dissociative amnesia is a type of dissociative disorder that involves inability to recall important personal information that would not typically be lost with ordinary forgetting. It is usually caused by trauma or stress. Diagnosis is based on history after ruling out other causes of amnesia. Treatment is psychotherapy, sometimes combined with hypnosis or drug-facilitated interviews.
In dissociative amnesia, the information lost would normally be part of conscious awareness and would be described as autobiographic memory.
Although the forgotten information may be inaccessible to consciousness, it sometimes continues to influence behavior (eg, a woman who was raped in an elevator refuses to ride in elevators even though she cannot recall the rape).
Dissociative amnesia is probably underdetected. Prevalence is not well-established; in one small US community study, the 12-mo prevalence was 1.8% (1% in men; 2.6% in women).
The amnesia appears to be caused by traumatic or stressful experiences endured or witnessed (eg, physical or sexual abuse, rape, combat, genocide, natural disasters, death of a loved one, serious financial troubles) or by tremendous internal conflict (eg, turmoil over guilt-ridden impulses or actions, apparently unresolvable interpersonal difficulties, criminal behaviors).
Dissociative amnesia is one of a group of conditions called dissociative disorders. Dissociative disorders are mental illnesses that involve disruptions or breakdowns of memory, consciousness, awareness, identity, and/or perception. When one or more of these functions is disrupted, symptoms can result. These symptoms can interfere with a person’s general functioning, including social and work activities, and relationships.
Dissociative amnesia occurs when a person blocks out certain information, usually associated with a stressful or traumatic event, leaving him or her unable to remember important personal information. With this disorder, the degree of memory loss goes beyond normal forgetfulness and includes gaps in memory for long periods of time or of memories involving the traumatic event.
Dissociative amnesia is not the same as simple amnesia, which involves a loss of information from memory, usually as the result of disease or injury to the brain. With dissociative amnesia, the memories still exist but are deeply buried within the person’s mind and cannot be recalled. However, the memories might resurface on their own or after being triggered by something in the person’s surroundings.
Dissociative amnesia can be mistaken for other mental illnesses such as dementia or delirium but, in fact, the definition of dissociative amnesia makes it a diagnosis in its own right and it is a dissociative disorder. Dissociative amnesia involves an inability to recall important personal information in a way that is not explained by another illness or everyday forgetfulness. The definition of dissociative amnesia can be found in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, along with all other mental illnesses.
Some people may develop dissociative amnesia as an alternative to suicide. If traumatic memories are recovered in these cases (for example, memories of sexual abuse), without proper treatment these people may be at risk of suicide.
Dissociative amnesia is one of several dissociative disorders that mentally separate a person from some aspect of their self, following some sort of trauma or severe stress. In the case of dissociative amnesia, affected individuals are separated from their memories, suffering abnormal memory loss in ways that significantly affect their lives. They may forget a specific event, or they may forget who they are and everything about themselves and their personal history. The person may or may not be aware of their memory loss though they may appear confused. Unlike those who develop medical amnesia after an injury or stroke, however, someone with dissociative amnesia rarely shows concern about their condition.
Dissociative amnesia is a condition in which a person cannot remember important information about his or her life. This forgetting may be limited to certain specific areas (thematic), or may include much of the person’s life history and/or identity (general).
In some rare cases called dissociative fugue, the person may forget most or all of his personal information (name, personal history, friends), and may sometimes even travel to a different location and adopt a completely new identity. In all cases of dissociative amnesia, the person has a much greater memory loss than would be expected in the course of normal forgetting.
Dissociative amnesia is one of a group of conditions called “dissociative disorders.” Dissociative disorders are mental illnesses in which there is a breakdown of mental functions that normally operate smoothly, such as memory, consciousness or awareness, and identity and/or perception.
Dissociative amnesia is classified by the Diagnostic and Statistical Manual of Mental Disorders , 4th Edition, Text Revision, also known as the DSM-IV-TR as one of the dissociative disorders, which are mental disorders in which the normally well-integrated functions of memory, identity, perception, or consciousness are separated (dissociated). The dissociative disorders are usually associated with trauma in the recent or distant past, or with an intense internal conflict that forces the mind to separate incompatible or unacceptable knowledge, information, or feelings. In dissociative amnesia, the continuity of the patient’s memory is disrupted. Patients with dissociative amnesia have recurrent episodes in which they forget important personal information or events, usually connected with trauma or severe stress . The information that is lost to the patient’s memory is usually too extensive to be attributed to ordinary absentmindedness or forgetfulness related to aging. Dissociative amnesia was formerly called “psychogenic amnesia.”
Amnesia is a symptom of other medical and mental disorders; however, the patterns of amnesia are different, depending on the cause of the disorder. Amnesia associated with head trauma is typically both retrograde (the patient has no memory of events shortly before the head injury) and anterograde (the patient has no memory of events after the injury). The amnesia that is associated with seizure disorders is sudden onset. Amnesia in patients suffering from delirium or dementia occurs in the context of extensive disturbances of the patient’s cognition (knowing), speech, perceptions, emotions, and behaviors. Amnesia associated with substance abuse, which is sometimes called “blackouts” typically affects only short-term memory and is irreversible. In dissociative amnesia, in contrast to these other conditions, the patient’s memory loss is almost always anterograde, which means that it is limited to the period following the traumatic event(s). In addition, patients with dissociative amnesia do not have problems learning new information.
Dissociative amnesia as a symptom occurs in patients diagnosed with dissociative fugue and dissociative identity disorder . If the patient’s episodes of dissociative amnesia occur only in the context of these disorders, a separate diagnosis of dissociative amnesia is not made.
Dissociative symptoms can be mild, but they can also be so severe that they keep the person from being able to function, and can also affect relationships and work activities.
What are the symptoms of dissociative amnesia?
There are three types, or patterns, of dissociative amnesia:
Localized: Memory loss affects specific areas of knowledge or parts of a person’s life, such as a certain period during childhood, or anything about a friend or coworker. Often the memory loss focuses on a specific trauma. For example, a crime victim may have no memory of being robbed at gunpoint, but can recall details from the rest of that day.
Generalized: Memory loss affects major parts of a person’s life and/or identity, such as a young woman being unable to recognize her name, job, family, and friends.
Fugue: With dissociative fugue, the person has generalized amnesia and adopts a new identity. For example, one middle manager was passed over for promotion. He did not come home from work and was reported as missing by his family. He was found a week later, 600 miles away, living under a different name, working as a short-order cook. When found by the police, he could not recognize any family member, friend, or coworker, and he could not say who he was or explain his lack of identification.
Dissociative amnesia is different from amnesia caused by medical problems, such as illnesses, strokes, or brain injuries. In medically caused amnesia, recovering memories is rare and generally a slow and gradual process.
Most cases of dissociative amnesia are relatively short. Often, when memories return, they do so suddenly and completely. Memory recovery may happen on its own, after being triggered by something in the person’s surroundings, or in therapy.
Another difference is that people who suffer medical amnesia are quite upset by their memory loss, whereas most people with dissociative amnesia seem to have surprisingly little concern over their amnesia.
Symptoms and Signs
The main symptom of dissociative amnesia is memory loss that is inconsistent with normal forgetfulness. The amnesia may be
- Rarely, dissociative amnesia is accompanied by purposeful travel or bewildered wandering, called fugue (from the Latin word fugere “to flee”).
Localized amnesia involves being unable to recall a specific event or events or a specific period of time; these gaps in memory are usually related to trauma or stress. For example, patients may forget the months or years of being abused as a child or the days spent in intense combat. The amnesia may not manifest for hours, days, or longer after the traumatic period. Usually, the forgotten time period, which can range from minutes to decades, is clearly demarcated. Typically, patients experience one or more episodes of memory loss.
Selective amnesia involves forgetting only some of the events during a certain period of time or only part of a traumatic event. Patients may have both localized and selective amnesia.
In generalized amnesia, patients forget their identify and life history—eg, who they are, where they went, to whom they spoke, and what they did, said, thought, experienced, and felt. Some patients can no longer access well-learned skills and lose formerly known information about the world. Generalized dissociative amnesia is rare; it is more common among combat veterans, people who have been sexually assaulted, and people experiencing extreme stress or conflict. Onset is usually sudden.
In systematized amnesia, patients forget information in a specific category, such as all information about a particular person or about their family.
In continuous amnesia, patients forget each new event as it occurs.
Most patients are partly or completely unaware that they have gaps in their memory. They become aware only when personal identity is lost or when circumstances make them aware—eg, when others tell them or ask them about events they cannot remember.
Patients seen shortly after they become amnestic may appear confused. Some are very distressed; others are indifferent. If those who are unaware of their amnesia present for psychiatric help, they may do so for other reasons.
Patients have difficulty forming and maintaining relationships.
Some patients report flashbacks, as occur in posttraumatic stress disorder (PTSD); flashbacks may alternate with amnesia for the contents of the flashbacks. Some patients develop PTSD later, especially when they become aware of the traumatic or stressful events that triggered their amnesia.
Depressive and functional neurologic symptoms are common, as are suicidal and other self-destructive behaviors. Risk of suicidal behaviors may be increased when amnesia resolves suddenly and patients are overwhelmed by the traumatic memories.
• To recover memory, a supportive environment and sometimes hypnosis or a drug-induced semihypnotic state
• Psychotherapy to deal with issues associated with recovered memories of traumatic or stressful events
If memory of only a very short time period is lost, supportive treatment of dissociative amnesia is usually adequate, especially if patients have no apparent need to recover the memory of some painful event.
Treatment for more severe memory loss begins with creation of a safe and supportive environment. This measure alone frequently leads to gradual recovery of missing memories. When it does not or when the need to recover memories is urgent, questioning patients while they are under hypnosis or, rarely, in a drug-induced (barbiturate or benzodiazepine) semihypnotic state can be successful. These strategies must be done gently because the traumatic circumstances that stimulated memory loss are likely to be recalled and to be very upsetting. The questioner must carefully phrase questions so as not to suggest the existence of an event and risk creating a false memory. Patients who were abused, especially during childhood, are likely to expect therapists to exploit or abuse them and to impose uncomfortable memories rather than help them recall real memories (traumatic transference).
The accuracy of memories recovered with such strategies can be determined only by external corroboration. However, regardless of the degree of historical accuracy, filling in the gap as much as possible is often therapeutically useful in restoring continuity to the patient’s identity and sense of self and in creating a cohesive life narrative.
Once the amnesia is lifted, treatment helps with the following:
• Giving meaning to the underlying trauma or conflict
• Resolving problems associated with the amnestic episode
• Enabling patients to move on with their life
If patients have experienced dissociative fugue, psychotherapy, sometimes combined with hypnosis or drug-facilitated interviews, may be used to try to restore memory; these efforts are often unsuccessful. Regardless, a psychiatrist can help patients explore how they handle the types of situations, conflicts, and emotions that precipitated the fugue and thus develop better responses to those events and help prevent fugue from recurring.
Treatment for Dissociative Amnesia
Some cases of dissociative amnesia require treatment in a hospital. These are cases in which the person is a clear and present danger to him or herself or others, when a definitive diagnosis has not been made or when medication effects need professional monitoring. Hospitalization for dissociative amnesia is particularly helpful for patients experiencing current abuse. Dissociative amnesia may spontaneously resolve when a person is removed from a traumatic situation.
Outside of hospitalization, treatment for dissociative amnesia tends to involve psychotherapy. Psychotherapy may be augmented by the use of hypnosis or a drug-facilitated interview to allow a person to be in a state of enhanced calm in which to discuss or discover deeply buried memories.
People with dissociative amnesia also commonly suffer from comorbid (co-occurring) disorders like depression or posttraumatic stress disorder and these disorders, or their symptoms, are typically treated with antidepressants, antipsychotics or anticonvulsants (mood stabilizers).
Treatment of dissociative amnesia usually requires two distinct periods or phases.
Psychotherapy for dissociative amnesia is supportive in its initial phase. It begins with creating an atmosphere of safety in the treatment room. Very often, patients gradually regain their memories when they feel safe with and supported by the therapist. This rapport does not mean that they necessarily recover their memories during therapy sessions; one study of 90 patients with dissociative amnesia found that most of them had their memories return while they were at home alone or with family or close friends. The patients denied that their memories were derived from a therapist’s suggestions, and a majority of them were able to find independent evidence or corroboration of their childhood abuse.
If the memories do not return spontaneously, hypnosis or sodium amytal (a drug that induces a semi-hypnotic state) may be used to help recover them.
After the patient has recalled enough of the missing past to acquire a stronger sense of self and continuity in their life history, the second phase of psychotherapy commences. During this phase, the patient deals more directly with the traumatic episode(s), and recovery from its aftereffects. Studies of the treatments for dissociative amnesia in combat veterans of World War I (1914–1918) found that recovery and cognitive integration of dissociated traumatic memories within the patient’s overall personality were more effective than treatment methods that focused solely on releasing feelings.
At present, there are no therapeutic agents that prevent amnestic episodes or that cure dissociative amnesia itself. Patients may, however, be given antidepressants or other appropriate medications for treatment of the depression, anxiety, insomnia , or other symptoms that may accompany dissociative amnesia.
Dissociative amnesia poses a number of complex issues for the legal profession. The disorder has been cited by plaintiffs in cases of recovered memories of abuse leading to lawsuits against the perpetrators of the abuse. Dissociative amnesia has also been cited as a defense in cases of murder of adults as well as in cases of neonatricide (murder of an infant shortly after birth). Part of the problem is the adversarial nature of courtroom procedure in the U.S., but it is generally agreed that judges and attorneys need better guidelines regarding dissociative amnesia in defendants and plaintiffs.
The prognosis for recovery from dissociative amnesia is generally good. The majority of patients eventually recover the missing parts of their past, either by spontaneous re-emergence of the memories or through hypnosis and similar techniques. A minority of patients, however, are never able to reconstruct their past; they develop a chronic form of dissociative amnesia. The prognosis for a specific patient depends on a combination of his or her present life circumstances; the presence of other mental disorders; and the severity of stresses or conflicts associated with the amnesia.
Strategies for the prevention of child abuse might lower the incidence of dissociative amnesia in the general population. There are no effective preventive strategies for dissociative amnesia caused by traumatic experiences in adult life in patients without a history of childhood abuse.
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.