Dissociative Amnesia

Overview

Definition

Dissociative amnesia is a potentially reversible memory Memory Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory. Psychiatric Assessment impairment that primarily affects autobiographical information, often following stressful or traumatic events

Types of memory Memory Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory. Psychiatric Assessment

• Autobiographical: details regarding events in person’s life, including events that have happened and their cognitive, emotional, and motivational impact 
• Semantic: memory Memory Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory. Psychiatric Assessment of facts, concepts, objects, words, and definitions
• Episodic: memory Memory Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory. Psychiatric Assessment of specific events  
• Procedural: memory Memory Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory. Psychiatric Assessment of how certain procedures are carried out

Epidemiology

• Lifetime prevalence Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency: approximately 2%–6%
• Higher incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency among women 
• Usually arise in late adolescence and young adulthood
• Comorbid conditions:
  • Substance use disorder
  • History of trauma 
  • Major mood disorders
  • Conversion disorder Conversion disorder Conversion disorder (CD), also called functional neurological symptom disorder, is a psychiatric disorder with prominent motor or sensory impairment which is not compatible with any known neurologic medical condition. The deficits are not consciously produced. Functional Neurological Symptom Disorder (Conversion Disorder)

Pathogenesis

• Environmental factors:
  • Events triggering intolerable and unacceptable emotions
  • Emotions are often triggered by trauma or by betrayal by a trusted person.
  • These triggers are thought to influence how the event is remembered.
• Genetic factors:
  • Genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure and environmental factors that influence their expression (epigenetic model)
  • A stressful or traumatic event Traumatic event An emotionally painful, shocking, stressful, and sometimes life-threatening experience. It can result from witnessing distressing events such as natural disasters, physical or sexual abuse, and terrorism or other acts of violence. Posttraumatic Stress Disorder (PTSD) during childhood or later in life can trigger Trigger The type of signal that initiates the inspiratory phase by the ventilator Invasive Mechanical Ventilation expression of genetic diathesis that otherwise would have been suppressed.
  • 50% of the variance in the development of dissociative symptoms could be accounted for by genetic factors.
• Neurobiologic factors:
  • Temporal, hippocampal, and occipital Occipital Part of the back and base of the cranium that encloses the foramen magnum. Skull: Anatomy areas are associated with autobiographical memory Memory Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory. Psychiatric Assessment.
  • If any of these brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification regions are affected, it can lead to dissociation Dissociation Defense Mechanisms.

Diagnosis and Clinical Features

Diagnosis

Diagnosis is clinical, based on meeting specific criteria:

• Criteria:
  • An impairment in the ability to recall important autobiographical information inconsistent with normal forgetfulness
  • Causes marked distress or impairment in social and occupational functioning.
• Exclusion:
  • Not secondary to substance use or other neurologic/medical conditions
  • Not secondary to other psychiatric disorders.

Clinical features

• Classic presentation:
  • Dissociative symptoms in the setting of extreme trauma
  • Patient cannot recall:
    • Who they are
    • Where they have been
    • What they have done at a specific time
• Types of dissociative amnesia:
  • Localized amnesia: inability to recall autobiographical memory Memory Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory. Psychiatric Assessment of a specific period of time or specific event
  • Selective amnesia: inability to recall parts of an event
  • Systematized: inability to remember certain categories of memory Memory Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory. Psychiatric Assessment (e.g., inability to recall home life during 3rd grade, but able to recall school)
  • Continuous: inability to remember successive events as they occur (anterograde dissociative amnesia).
  • Generalized (global) amnesia: inability to recall the entirety of life history, usually accompanied by loss of person’s identity

Management

• Goal is to restore patient’s lost memories safely (initially, risk of suicide Suicide Suicide is one of the leading causes of death worldwide. Patients with chronic medical conditions or psychiatric disorders are at increased risk of suicidal ideation, attempt, and/or completion. The patient assessment of suicide risk is very important as it may help to prevent a serious suicide attempt, which may result in death. Suicide is increased when patient recalls traumatic events or memories).
• Psychotherapy Psychotherapy Psychotherapy is interpersonal treatment based on the understanding of psychological principles and mechanisms of mental disease. The treatment approach is often individualized, depending on the psychiatric condition(s) or circumstance. Psychotherapy: attempts to identify cognitive distortions based in patient’s history of trauma:
  • 1st-line therapy
  • Examples:
    • Cognitive therapy
    • Hypnosis Hypnosis A state of increased receptivity to suggestion and direction, initially induced by the influence of another person. Anesthesiology: History and Basic Concepts and hypnotherapy
    • Group therapy Group therapy A form of therapy in which two or more patients participate under the guidance of one or more psychotherapists for the purpose of treating emotional disturbances, social maladjustments, and psychotic states. Psychotherapy 
• Pharmacotherapy:
  • Not indicated unless used for treatment of comorbidities Comorbidities The presence of co-existing or additional diseases with reference to an initial diagnosis or with reference to the index condition that is the subject of study. Comorbidity may affect the ability of affected individuals to function and also their survival; it may be used as a prognostic indicator for length of hospital stay, cost factors, and outcome or survival. St. Louis Encephalitis Virus (management of the associated depression with antidepressants) 
  • Drug-assisted interviews:
    • Hypnotic agents ( barbiturates Barbiturates A class of chemicals derived from barbituric acid or thiobarbituric acid. Many of these are gaba modulators used as hypnotics and sedatives, as anesthetics, or as anticonvulsants. Intravenous Anesthetics or benzodiazepines Benzodiazepines Benzodiazepines work on the gamma-aminobutyric acid type A (GABAA) receptor to produce inhibitory effects on the CNS. Benzodiazepines do not mimic GABA, the main inhibitory neurotransmitter in humans, but instead potentiate GABA activity. Benzodiazepines) can help in the retrieval of certain lost memories.
    • Retrieved memories are then reprocessed when the patient is in the usual conscious state.

Differential Diagnosis

• Nonpathologic dissociation Nonpathologic dissociation Depersonalization/Derealization Disorder: dissociation Dissociation Defense Mechanisms normally experienced during daily activities (i.e., arriving at a destination in your vehicle without recalling the details of the drive). Nonpathologic dissociation Nonpathologic dissociation Depersonalization/Derealization Disorder is distinguished from dissociative amnesia because the patient does not experience feelings of distress or functional impairment.
• Transient global amnesia: form of temporary anterograde amnesia Anterograde amnesia Loss of the ability to form new memories beyond a certain point in time. This condition may be organic or psychogenic in origin. Organically induced anterograde amnesia may follow craniocerebral trauma; seizures; anoxia; and other conditions which adversely affect neural structures associated with memory formation (e.g., the hippocampus; fornix (brain); mammillary bodies; and anterior thalamic nuclei). Wernicke Encephalopathy and Korsakoff Syndrome with sudden onset often triggered by highly stressful events. This impairment is associated with disorientation Disorientation St. Louis Encephalitis Virus, but patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship do not lose awareness of self. The symptoms resolve without any intervention and without any lasting neurologic deficits Neurologic Deficits High-Risk Headaches. The distinguishing features between this diagnosis and dissociative amnesia is the age at onset (usually ≥ 50 years for transient global amnesia) as well as preservation of personal memories.
• Dementia Dementia Major neurocognitive disorders (NCD), also known as dementia, are a group of diseases characterized by decline in a person’s memory and executive function. These disorders are progressive and persistent diseases that are the leading cause of disability among elderly people worldwide. Major Neurocognitive Disorders: group of chronic disorders of the mental processes caused by brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification disease or injury, marked by memory Memory Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory. Psychiatric Assessment disorders, personality changes, and impaired reasoning Reasoning Decision-making Capacity and Legal Competence. The patient with dementia Dementia Major neurocognitive disorders (NCD), also known as dementia, are a group of diseases characterized by decline in a person’s memory and executive function. These disorders are progressive and persistent diseases that are the leading cause of disability among elderly people worldwide. Major Neurocognitive Disorders is upset by memory Memory Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory. Psychiatric Assessment loss and tries to recall memories, whereas the patient with dissociative amnesia is not upset and is not trying to recall memories. Dementia Dementia Major neurocognitive disorders (NCD), also known as dementia, are a group of diseases characterized by decline in a person’s memory and executive function. These disorders are progressive and persistent diseases that are the leading cause of disability among elderly people worldwide. Major Neurocognitive Disorders usually is prevalent in populations that are much older than those with dissociative amnesia. 
• Dissociative identity disorder Dissociative identity disorder Dissociative identity disorder (DID) is a psychiatric condition marked by the presence of ≥ 2 distinct personality identities in a patient, with each personality having their own memories. The patient switches between personalities rapidly, especially under stress. It is associated with a history of childhood trauma or abuse. Dissociative Identity Disorder (DID): disorder marked by the presence of ≥ 2 distinct personality identities in the patient, with each personality having their own memories. The patient switches between personalities rapidly, especially under stress. Dissociative identity disorder Dissociative identity disorder Dissociative identity disorder (DID) is a psychiatric condition marked by the presence of ≥ 2 distinct personality identities in a patient, with each personality having their own memories. The patient switches between personalities rapidly, especially under stress. It is associated with a history of childhood trauma or abuse. Dissociative Identity Disorder is associated with a history of childhood trauma or abuse similar to those with dissociative amnesia. Unlike dissociative amnesia, memory Memory Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory. Psychiatric Assessment impairments in DID include amnesia for normal everyday events or recurrent blackouts. 
• Acute stress disorder Acute stress disorder Acute stress disorder describes stress reactions displayed after an individual has experienced a traumatic event. Symptoms last more than 3 days but less than 1 month and include re-experiencing the event as flashbacks or nightmares, avoidance of reminders of the event, irritability, hyperarousal, and poor memory and concentration. Acute Stress Disorder: stress reactions displayed after an individual has experienced a traumatic event Traumatic event An emotionally painful, shocking, stressful, and sometimes life-threatening experience. It can result from witnessing distressing events such as natural disasters, physical or sexual abuse, and terrorism or other acts of violence. Posttraumatic Stress Disorder (PTSD). Symptoms last > 3 days, but < 1 month and include reexperiencing the event as flashbacks or nightmares, avoidance of reminders of the event, irritability, hyperarousal, and poor memory Memory Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory. Psychiatric Assessment and concentration. When a patient exhibits amnesia that extends beyond the time frame of the event, the diagnosis of dissociative amnesia can be made.