The essential feature of Dissociative Amnesia is an inability to recall important personal information, usually of a traumatic or stressful nature, that is too extensive to be explained by normal forgetfulness (Criterion A). This disorder involves a reversible memory impairment in which memories of personal experience cannot be retrieved in a verbal form (or, if temporarily retrieved, cannot be wholly retained in consciousness). The disturbance does not occur exclusively during the course of Dissociative Identity Disorder, Dissociative Fugue, Posttraumatic Stress Disorder, Acute Stress Disorder, or Somatization Disorder and is not due to the direct physiological effects of a substance or a neurological or other general medical condition (Criterion B). The symptoms must cause clinically significant distress or impairment in social, occupational, or other important areas of functioning (Criterion C).
Dissociative Amnesia most commonly presents as a retrospectively reported gap or series of gaps in recall for aspects of the individual’s life history. These gaps are usually related to traumatic or extremely stressful events. Some individuals may have amnesia for episodes of self-mutilation, violent outbursts, or suicide attempts. Less commonly, Dissociative Amnesia presents as a florid episode with sudden onset. This acute form is more likely to occur during wartime or in response to a natural disaster or other forms of severe trauma.
Several types of memory disturbances have been described in Dissociative Amnesia. In localized amnesia, the individual fails to recall events that occurred during a circumscribed period of time, usually the first few hours following a profoundly disturbing event (e.g., the uninjured survivor of a car accident in which a family member has been killed may not be able to recall anything that happened from the time of the accident until 2 days later). In selective amnesia, the person can recall some, but not all, of the events during a circumscribed period of time (e.g., a combat veteran can recall only some parts of a series of violent combat experiences). Three other types of amnesia—generalized, continuous, and systematized—are less common. In generalized amnesia, failure of recall encompasses the person’s entire life. Individuals with this rare disorder usually present to the police, to emergency rooms, or to general hospital consultation-liaison services. Continuous amnesia is defined as the inability to recall events subsequent to a specific time up to and including the present. Systematized amnesia is loss of memory for certain categories of information, such as all memories relating to one’s family or to a particular person. Individuals who exhibit these latter three types of Dissociative Amnesia may ultimately be diagnosed as having a more complex form of Dissociative Disorder (e.g., Dissociative Identity Disorder).
Associated Features and Disorders
Associated descriptive features and mental disorders. Some individuals with Dissociative Amnesia report depressive symptoms, anxiety, depersonalization, trance states, analgesia, and spontaneous age regression. They may provide approximate inaccurate answers to questions (e.g., “2 plus 2 equals 5”) as in Ganser syndrome. Other problems that sometimes accompany this disorder include sexual dysfunction, impairment in work and interpersonal relationships, self-mutilation, aggressive impulses, and suicidal impulses and acts. Individuals with Dissociative Amnesia may also have symptoms that meet criteria for Conversion Disorder, a Mood Disorder, a Substance-Related Disorder, or a Personality Disorder.
Associated laboratory findings. Individuals with Dissociative Amnesia often display high hypnotizability as measured by standardized testing.
Specific Age Features
Dissociative Amnesia is especially difficult to assess in preadolescent children, because it may be confused with inattention, anxiety, oppositional behavior, Learning Disorders, psychotic disturbances, and developmentally appropriate childhood amnesia (i.e., the decreased recall of autobiographical events that occurred before age 5). Serial observation or evaluations by several different examiners (e.g., teacher, therapist, case worker) may be needed to make an accurate diagnosis of Dissociative Amnesia in children.
In recent years, there has been an increase in reported cases of Dissociative Amnesia that involves previously forgotten early childhood traumas. This increase has been subject to very different interpretations. Some believe that the greater awareness of the diagnosis among mental health professionals has resulted in the identification of cases that were previously undiagnosed. In contrast, others believe that the syndrome has been overdiagnosed in individuals who are highly suggestible.
Dissociative Amnesia can present in any age group, from young children to adults. The main manifestation in most individuals is a retrospective gap in memory. The reported duration of the events for which there is amnesia may be minutes to years. Only a single episode of amnesia may be reported, although two or more episodes are also commonly described. Individuals who have had one episode of Dissociative Amnesia may be predisposed to develop amnesia for subsequent traumatic circumstances. Acute amnesia may resolve spontaneously after the individual is removed from the traumatic circumstances with which the amnesia was associated (e.g., a soldier with localized amnesia after several days of intense combat may spontaneously regain memory of these experiences after being removed from the battlefield). Some individuals with chronic amnesia may gradually begin to recall dissociated memories. Other individuals may develop a chronic form of amnesia.
Dissociative Amnesia must be distinguished from Amnestic Disorder Due to a General Medical Condition, in which the amnesia is judged to be the direct physiological consequence of a specific neurological or other general medical condition (e.g., head trauma, epilepsy). This determination is based on history, laboratory findings, or physical examination. In Amnestic Disorder Due to a Brain Injury, the disturbance of recall, though circumscribed, is often both retrograde (i.e., encompassing a period of time before the head trauma) and anterograde (i.e., for events after the trauma), and there is usually a history of a clear-cut physical trauma, a period of unconsciousness, or clinical evidence of brain injury. In contrast, in Dissociative Amnesia, the disturbance of recall is almost always anterograde (i.e., memory loss is restricted to the period after the trauma), and there are typically no problems with learning new information. The rare case of Dissociative Amnesia with retrograde amnesia can be distinguished by the diagnostic use of hypnosis; the prompt recovery of the lost memories suggests a dissociative basis for the disturbance. In seizure disorders, the memory impairment is sudden in onset, motor abnormalities may be present, and repeated EEGs reveal typical abnormalities. In delirium and dementia, the memory loss for personal information is embedded in a far more extensive set of cognitive, linguistic, affective, attentional, perceptual, and behavioral disturbances. In contrast, in Dissociative Amnesia, the memory loss is primarily for autobiographical information and cognitive abilities generally are preserved. The amnesia associated with a general medical condition usually cannot be reversed.
Memory loss associated with the use of substances or medications must be distinguished from Dissociative Amnesia. Substance-Induced Persisting Amnestic Disorder should be diagnosed if it is judged that there is a persistent loss of memory that is related to the direct physiological effects of a substance (e.g., a drug of abuse or a medication). Whereas the ability to lay down new memories is preserved in Dissociative Amnesia, in Substance-Induced Persisting Amnestic Disorder, short-term memory is impaired (i.e., events may be recalled immediately after they occur, but not after a few minutes have passed). Memory loss associated with Substance Intoxication (e.g., “blackouts”) can be distinguished from Dissociative Amnesia by the association of the memory loss with heavy substance use and the fact that the amnesia usually cannot be reversed.
The dissociative symptom of amnesia is a characteristic feature of both Dissociative Fugue and Dissociative Identity Disorder. Therefore, if the dissociative amnesia occurs exclusively during the course of Dissociative Fugue or Dissociative Identity Disorder, a separate diagnosis of Dissociative Amnesia is not made. Because depersonalization is an associated feature of Dissociative Amnesia, depersonalization that occurs only during Dissociative Amnesia should not be diagnosed separately as Depersonalization Disorder.
In Posttraumatic Stress Disorder and Acute Stress Disorder, there can be amnesia for the traumatic event. Similarly, dissociative symptoms such as amnesia are included in the criteria set for Somatization Disorder. Dissociative Amnesia is not diagnosed if it occurs exclusively during the course of these disorders.
Malingered amnesia is most common in individuals presenting with acute, florid symptoms in a context in which potential secondary gain is evident—for example, financial or legal problems or the desire to avoid combat, although true amnesia may also be associated with such stressors. Furthermore, individuals with true Dissociative Amnesia usually score high on standard measures of hypnotizability and dissociative capacity.
Care must be exercised in evaluating the accuracy of retrieved memories. There has been considerable controversy concerning amnesia related to reported physical or sexual abuse, particularly when abuse is alleged to have occurred during early childhood. Some clinicians believe that there has been an underreporting of such events, especially because the victims are often children and perpetrators are inclined to deny or distort their actions. However, other clinicians are concerned that there may be overreporting, particularly given the unreliability of childhood memories. There is currently no method for establishing with certainty the accuracy of such retrieved memories in the absence of corroborative evidence.
Dissociative Amnesia must also be differentiated from memory loss related to Age-Related Cognitive Decline and nonpathological forms of amnesia including everyday memory loss, posthypnotic amnesia, infantile and childhood amnesia, and amnesia for sleep and dreaming. Dissociative Amnesia can be distinguished from normal gaps in memory by the extensive and involuntary nature of the inability to recall the content of the lost memory (i.e., memories of a traumatic nature) and by the presence of significant distress or impairment.
Diagnostic criteria for 300.12 Dissociative Amnesia
A. The predominant disturbance is one or more episodes of inability to recall important personal information, usually of a traumatic or stressful nature, that is too extensive to be explained by ordinary forgetfulness.
B. The disturbance does not occur exclusively during the course of Dissociative Identity Disorder, Dissociative Fugue, Posttraumatic Stress Disorder, Acute Stress Disorder, or Somatization Disorder and is not due to the direct physiological effects of a substance (e.g., a drug of abuse, a medication) or a neurological or other general medical condition (e.g., Amnestic Disorder Due to Head Trauma).
C. The symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.