Dissociative amnesia

Essential Features:

• Inability to recall important autobiographical memories, typically of recent traumatic or stressful events, that is inconsistent with ordinary forgetting.
• The memory loss does not occur exclusively during episodes of Trance Disorder, Possession Trance Disorder, Dissociative Identity Disorder, or Partial Dissociative Identity Disorder and is not better accounted for by another mental disorder (e.g., Post-Traumatic Stress Disorder, Complex Post-Traumatic Stress Disorder, a Neurocognitive Disorder such as Dementia).
• The symptoms are not due to the effects of a substance or medication on the central nervous system (e.g., alcohol), including withdrawal effects, and are not due to a Disease of the Nervous System (e.g., temporal lobe epilepsy), another medical condition (e.g., a brain tumour) or to head trauma.
• The memory loss results in significant impairment in personal, family, social, educational, occupational or other important areas of functioning.

Presence or absence of dissociative fugue:

6B61.0 Dissociative Amnesia with dissociative fugue

• Dissociative amnesia with dissociative fugue is characterized by all of the features of Dissociative Amnesia, accompanied by dissociative fugue, i.e., a loss of a sense of personal identity and sudden travel away from home, work, or significant others for an extended period of time (days or weeks).

6B61.1 Dissociative Amnesia without dissociative fugue

• Dissociative amnesia without dissociative fugue is characterized by all of the features of Dissociative Amnesia occurring in the absence of symptoms of dissociative fugue.

6B61.Z Dissociative Amnesia, unspecified

Additional Clinical Features:

• In rare cases, amnesia may be generalized with regard to identity and life history. However, it is more commonly localized (i.e., failure to recall autobiographical events during a circumscribed period of time) or selective (i.e., failure to recall some but not all of the events during a circumscribed period of time). The extent of amnesia may vary over time.
• Individuals with Dissociative Amnesia may only be partly aware of their memory problems. Those who are aware of their memory problems may minimize the importance of these problems and may become uncomfortable when prompted to address them.
• Dissociative Amnesia is commonly associated with adverse life events, personal or interpersonal conflicts, or stress. The link between the disorder and these events, conflicts, and stressors may not be apparent to the individual. Repeated or long-lasting traumatization, trauma caused by multiple perpetrators, and a close relationship with the perpetrator are associated with more persistent and refractory amnesia.
• Dissociative Amnesia is commonly associated with chronic difficulty in forming and sustaining satisfying interpersonal relationships. The disorder may also be associated with self-harm, suicide attempts and other high-risk behaviours, depressive symptoms, depersonalization, and sexual dysfunctions.

Boundary with Normality (Threshold):

• Mild difficulties remembering autobiographical events are common, especially as a result of normal aging. Forgetting early childhood events is also developmentally typical. However, in contrast to Dissociative Amnesia, normal forgetting: 1) does not typically involve sustained and extensive forgetting of substantial life episodes or significant personal facts; 2) is usually reversed following reminders of forgotten episodes and personal facts; 3) does not have its onset following stressful or traumatic events; and 4) does not result in significant impairment in functioning.

Course Features:

• Onset of Dissociative Amnesia is typically acute, occurring after traumatic or highly stressful events (e.g., war, natural disaster, maltreatment). Onset may occur immediately after the exposure or after a significant delay.
• Although Dissociative Amnesia has been observed across the lifespan, it is most commonly diagnosed in patients between 20 and 40 years of age.
• The interval affected by the memory loss and the duration of a given episode of Dissociative Amnesia are highly variable. In more acute cases, amnesia resolves spontaneously and rapidly (e.g., after a stressor is resolved), whereas in more chronic cases individuals either slowly regain the ability to recall the dissociated memories or never fully do. Dissociative Amnesia with dissociative fugue is associated with a more persistent course.
• Although single episodes of amnesia have been reported, individuals who have had a single episode of Dissociative Amnesia may be predisposed to develop subsequent episodes of amnesia. Most patients experience two or more episodes of Dissociative Amnesia.
• Post-Traumatic Stress Disorder may develop after memories are regained. In such cases, these memories may be experienced in the form of flashbacks.

Developmental Presentations:

• Dissociative Amnesia can be difficult to detect in young children whose symptoms may be misinterpreted as lying, denial, inattention, absorption or developmentally appropriate forgetting. Therefore, assessment of amnesia in children should be based on multiple observations or reports from several individuals and types of observers (e.g., parents, teachers, other caregivers).
• Adults are more likely to experience Dissociative Amnesia with dissociative fugue than children or adolescents.

Culture-Related Features:

• In cultures with strictly defined social role expectations, Dissociative Amnesia may be associated with severe psychological stresses or conflicts (e.g., marital conflict, other family disturbances, attachment problems, conflicts due to restriction or oppression) rather than with traumatic exposures such as physical or sexual abuse.
• Amnesia reported after culturally accepted religious activities involving dissociative trance or possession should not be diagnosed as Dissociative Amnesia unless it is in excess of what is considered culturally normative and is associated with functional impairment.

Sex- and/or Gender-Related Features:

• The prevalence of Dissociative Amnesia is similar in males and females.

Boundaries with Other Disorders and Conditions (Differential Diagnosis):

• Boundary with Acute Stress Reaction: Acute Stress Reaction is a response to an event or situation of an extremely threatening or horrific nature that is considered to be normal given the severity of the stressor. Symptoms of Acute Stress Reaction may include transient amnesia for the immediate period and the event(s) of the stressor. Acute Stress Reaction begins to subside within a few days after the event or following removal from the threatening situation. Dissociative Amnesia should be considered as a diagnosis when the amnesia includes autobiographical information not directly related to the stressor or when the amnestic episode lasts longer than the immediate aftermath of the stressor (i.e., from several hours to several days).
• Boundary with memory deficits in Dissociative Neurological Symptom Disorder: Dissociative Neurological Symptom Disorder may include a variety of cognitive symptoms that are not due to the direct effects of a substance or a Disease of the Nervous System. If cognitive symptoms are focused exclusively on autobiographical memory, Dissociative Amnesia is the more appropriate diagnosis.
• Boundary with Possession Trance Disorder: Amnesia may occur in Possession Trance Disorder. However, amnesia in Possession Trance Disorder is related to episodes experienced as involving the intrusion of a new identity attributed to a spirit, power, deity, or other spiritual entity. Possession Trance Disorder also involves behaviours or movements that are experienced as being controlled by the possessing agent, symptoms that are not typically present in Dissociative Amnesia.
• Boundary with Dissociative Identity Disorder and Partial Dissociative Identity Disorder: Episodes of amnesia are common in Dissociative Identity Disorder and may also occur in Partial Dissociative Identity Disorder. However, amnesia in Partial Dissociative Identity Disorder is usually brief and restricted to extreme emotional states or episodes of self-harm. Moreover, Dissociative Amnesia is not characterized by the experience of two or more distinct, alternate personality states, as is the case in Dissociative Identity Disorder and Partial Dissociative Identity Disorder. In Dissociative Amnesia with dissociative fugue, the individual is typically confused about their identity. If two or more distinct personality states recurrently take executive control of the individual’s consciousness and functioning, which may include episodes of amnesia, Dissociative Identity Disorder is the more appropriate diagnosis.
• Boundary with Post-Traumatic Stress Disorder and Complex Post-Traumatic Stress Disorder: In Post-Traumatic Stress Disorder and Complex Post-Traumatic Stress Disorder, memories of the traumatic event(s) may be fragmented, disorganized, or incomplete. When the amnesia is more pervasive and also involves autobiographical memories that are not related to the traumatic event(s) and the diagnostic requirements of both disorders are met, an additional diagnosis of Dissociative Amnesia may be assigned.
• Boundary with Disorders Due to Substance Use: Amnesia is common in Disorders Due to Substance Use, particularly alcohol-related disorders (e.g., ‘alcohol blackouts’). If amnesia occurs exclusively in the context of alcohol or drug use, a diagnosis of Dissociative Amnesia is not warranted. However, differential diagnosis may be complicated in cases in which an individual with a history of dissociative amnestic episodes also uses alcohol or other substances.
• Boundary with memory deficits in Neurocognitive Disorders, head trauma, and medical conditions classified elsewhere: Neurocognitive Disorders—including Delirium, Amnestic Disorder, and Dementia—are characterized by primary acquired clinical deficits in cognitive functioning, frequently including significant and pervasive memory impairment. In Neurocognitive Disorders, a specific aetiological factor or underlying disease process can often be identified. Memory loss may also occur as a result of a brain injury or as an effect of some Diseases of the Nervous System or medical conditions classified elsewhere (e.g., a brain tumour). In Dissociative Amnesia, memory loss is primarily for autobiographical memories, and no underlying disease process or injury that represents a potential aetiology for the memory impairment can be identified.