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Dissociative amnesia

Amnesia (or amnaesia in Commonwealth English) is a condition in which memory is disturbed. The causes of amnesia are organic or functional. Organic causes include damage to the brain, through trauma or disease, or use of certain (generally sedative) drugs. Functional causes are psychological factors, such as defense mechanisms. Hysterical post-traumatic amnesia is an example of this. Amnesia may also be spontaneous, in the case of transient global amnesia. This global type of amnesia is more common in middle-aged to elderly people, particularly males, and usually lasts less than 24 hours. more...

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Types of amnesia

  • In anterograde amnesia, new events are not transferred to long-term memory, so the sufferer will not be able to remember anything that occurs after the onset of this type of amnesia for more than a few moments. The complement of this is retrograde amnesia, where someone will be unable to recall events that occurred before the onset of amnesia. The terms are used to categorise patterns of symptoms, rather than to indicate a particular cause or etiology. Both categories of amnesia can occur together in the same patient, and commonly result from damage to the brain regions most closely associated with episodic/declarative memory: the medial temporal lobes and especially the hippocampus.
  • Traumatic amnesia is generally due to a head injury (fall, knock on the head). Traumatic amnesia is often transient; the duration of the amnesia is related to the degree of injury and may give an indication of the prognosis for recovery of other functions. Mild trauma, such as a car accident that could result in no more than mild whiplash, might cause the occupant of a car to have no memory of the moments just before the accident due to a brief interruption in the short/long-term memory transfer mechanism. "Traumatic amnesia" is also sometimes used to refer to long-term repressed memory that is the result of psychological trauma.
  • Long-term alcoholism can cause a type of memory loss known as Korsakoff's syndrome. This is caused by brain damage due to a Vitamin B1 deficiency and will be progressive if alcohol intake and nutrition pattern are not modified. It will usually improve little over time even if they are. Other neurological problems are likely to be present.
  • Lacunar amnesia is the loss of memory about one specific event.
  • Fugue state is also known as dissociative fugue. It is caused by psychological trauma and is usually temporary. The Merck Manual defines it as "one or more episodes of amnesia in which the inability to recall some or all of one's past and either the loss of one's identity or the formation of a new identity occur with sudden, unexpected, purposeful travel away from home" .
  • Childhood amnesia (also known as Infantile amnesia) is the common inability to remember events from your own childhood. Whilst Sigmund Freud attributed this to sexual repression, others have theorised that this may be due to language development or immature parts of the brain.
  • Global amnesia is total memory loss. This may be a defence mechanism which occurs after a traumatic event. Post-traumatic stress disorder can also involve the spontaneous, vivid retrieval of unwanted traumatic memories. It is believed that Mauritania's Silent Flute Man suffered from this condition.
  • Posthypnotic amnesia is where events during hypnosis are forgotten, or where past memories are unable to be recalled.
  • Psychogenic amnesia is when one loses the ability to remember who oneself is. It is a common type of amnesia in popular culture; it may or may not be a real phenomenon.
  • Source amnesia is a memory disorder in which someone can recall certain information, but they do not know where or how they obtained it.
  • Memory distrust syndrome is a term invented by the psychologist Gisli Gudjonsson to describe a situation where someone is unable to trust their own memory.


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Dissociative Identity Disorder/Multiple Personality Disorder
From Gale Encyclopedia of Childhood and Adolescence, 4/6/01

Persons with dissociative identity disorder (DID) adopt one or more distinct identities. Each identity or personality is distinct from the other(s) in specific ways. There are cases in which a person will have as many as 100 or more identities, while some people only exhibit the presence of one or two. ("Co-presence" is the term used to describe the situation that exists when two or more personalities are simultaneously present with or without knowledge of each other's existence or current presence.)

Prior to the publication of the Diagnostic and Statistical Manual of Mental Disorder-IV (DSM-IV), dissociative identity disorder was referred to as multiple personality disorder (MPD); the birth personality was referred to as the original personality, and the condition was referred to as "split personality." With the publication of DSM-IV, these terms are now considered imprecise and are no longer used. The DSM-IV lists four criteria for diagnosing someone with dissociative identity disorder:

  • The presence of two or more distinct "identities or personality states;"
  • At least two personalities must take control of the person's identity on a regular basis;
  • Exhibits aspects of amnesia, that is, the person forgets routine personal information;
  • The condition must not have been caused by "direct physiological effects," such as drug abuse or head trauma.

Persons with DID usually have one personality that controls the body and its behavior. Psychiatrists refer to this personality as the "host." This is generally not the person's original personality or birth personality. The host is often initially unaware of the other identities and typically loses time when they appear. The host is the identity that most often initiates treatment, usually after developing symptoms, such as depression. The personality that seeks treatment--whether the host or not--is referred to as the "presenting personality."

The DSM-IV uses the term "alter" to describe the distinct identities or personality states that the client or patient with DID experiences. To be classified as a "personality state," the following conditions must be met: a consistent and ongoing set of response patterns to given stimuli; a significant confluent history; a range of emotions available (anger, sadness, joy, and so on); a range of intensity of affect for each emotion (for example, anger ranging from neutrality to frustration and irritation to anger and rage).

Psychiatrists refer to the phase of transition between alters as the "switch." The number of alters in any given case can vary widely. Alters are often of different genders, i.e., men can have female alters and women can have male. A 1986 study found that in 37% of patients diagnosed with then-MPD, alters demonstrated different handedness from the host. The physical changes that occur in a switch between alters is one of the most difficult aspects of dissociative identity disorder for psychiatrists to understand. People assume whole new physical postures, voices, and vocabularies.

Terminology of dissociation

Dissociative amnesia, referred to as psychogenic amnesia in DSM-III-R , is one of the dissociative disorders described in DSM-IV . Its diagnostic criteria are:

1) 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;

2) The disturbance does not occur exclusively during the course of another mental disorder, and is not due to the effects of a substance or a neurological and/or other general medical condition.

The symptoms of DID cause clinically significant distress or impairment in functioning. Memory disturbances, collectively known as amnesias, may be localized, selective, generalized, continuous, and/or systematized. For individuals with DID, the existence of amnesia is not necessarily the same in every personality state or personality fragment. For example, when one personality is aware of another but the other has no similar awareness, the condition is described as one-way amnesia. When neither personality is aware of the other, the condition is described as two-way amnesia.

Dissociative fugue (in DSM-III-R, psychogenic fugue) is given these diagnostic criteria in DSM-IV andis usually triggered by traumatic, stressful, or overwhelming life events:

  • Sudden, unexpected travel from home or work, with the inability to recall some or all of one's past;
  • Confusion about personal identity or assumption of a new identity;
  • The disturbance does not occur exclusively during the course of DID and is not due to the effects of a substance or general medical condition;
  • The symptoms cause clinically significant distress or impairment in functioning.

Dissociative disorders in children

There are no reliable figures on the prevalence of this disorder in children, although it has been reported with increased frequency during the 1990s. In diagnosing children, leaders in the field distinguish between children pretending to be other people, or trying out different roles during normal developmental. When behavior in young children becomes intensified, often following a trauma, the result may go beyond the trying out of roles to the creation of alter personality states.

The average age of onset of DID is in early childhood, generally by the age of four. The disorder is far more common among females than males (estimates range as high as 9 to 1). Once established, the disorder will last a lifetime if not treated; even with treatment, the prospects of complete cure are unlikely. According to available statistics, individuals with DID have an average of 15 identities. New identities can accumulate over time as the person faces new types of situations. Switching, the process of changing from one alter to another, may be triggered by outside stimuli such as an event, or by internal stimuli, such as feelings or memories. Switching is usually observable by others, with characteristic changes in posture or facial expression, voice tone or speech patterns, and mood or behavior.

An example of a trigger might be the first experience with sexuality in adolescence. An identity may emerge to deal with this new experience. People with DID tend to have other disorders as well, such as depression,substance abuse, borderline personality disorder and eating disorders. Many individuals with DID also have post-traumatic stress disorder (PTSD); in fact, researchers sometimes describe DID as complex and/or chronic PTSD. (In PSTD by definition, the individual has experienced a traumatic event that involved actual or threatened death or serious injury, or a threat to the physical integrity of self or others, and the person's response involved intense fear, helplessness, or horror.) In nearly every case of DID, horrific instances of physical or sexual child abuse was present. It is believed that young children, faced with abuse and neglect, create a fantasy world in order to escape.

Treatment of dissociative identity disorder is a long and difficult process, and the successful integration of all identities into one is unlikely. A 1990 study of 20 DID clients revealed that only five were successfully treated. Some therapists use a technique of "talking through" to one or more personality states that are not in control. For example, a therapist may address the client's personality states as if they were a group: "I want everyone inside to listen." Treatment also involves having DID clients recall the memories of their childhood, sometimes under hypnosis. This procedure requires skill and caution, however, since the recovered memories may be so traumatic that they cause further harm. The recovery of suppressed memories, a crucial component in DID, is controversial. Many psychologists and psychiatrists with expertise in memory believe that it is unlikely that memories can be recovered for events that occurred before the age of three.

Another cause for the skepticism is the dramatic increase in reports of the disorder since 1980. Eugene Levitt, a psychologist at the Indiana University School of Medicine, noted in an article published in Insight on the News (1993) that "in 1980, the disorder [then known as multiple personality disorder] got its official listing in the DSM, and suddenly thousands of cases are springing up everywhere."

Although there is yet no scientific evidence to support their claim, there are some in the field of psychiatry who feel that DID is an iatrogenic illness, i.e., one that is caused by or aggravated by the actions of a psychotherapist. These researchers contend that the client produces DID symptoms to meet the expectations of a therapist.


Dissociative Experiences Scale (DES)

Developed by Frank W. Putnam and Eve B. Carlson, the Dissociative Experiences Scale (DES) is an assessment instrument that can be completed by a client in about 10 minutes. It asks the respondent to indicate the frequency with which certain dissociative or depersonalization Experiences occur.

Dissociative Disorder Interview Schedule (DDIS)

A structured 30-45 minute interview developed to standardize the diagnosis of DID. The DDIS has shown that DID is a valid diagnosis with a consistent set of features. Developed by Ross, Heber, Norton and Anderson, the DDIS has 'been used in several research studies and has good clinical validity.

Structured Clinical Interview for DSM-IV Dissociative Disorder (SCID-D)

Developed by Marlene Steinberg, this structured interview enables a trained interviewer to assess the nature and severity of dissociative symptoms.


Mapping is a technique used to learn about an individual's internal personality system. The client is asked to draw a map or diagram of his or her personality states. As therapy progresses, the client is asked to update the map. Also known as personality mapping or system mapping.

Further Reading

For Your Information


  • Steinberg, Marlene. Handbook for the Assessment of Dissociation: A Clinical Guide. Washington, DC: American Psychiatric Press, 1995.


  • Arbetter, Sandra. "Multiple Personality Disorder: Someone Else Lives Inside of Me." Current Health November 2, 1992, p. 17.
  • Mesic, Penelope. "Presence of Minds." Chicago, September 1992, p. 100.
  • Sileo, Chi Chi. "Multiple Personalities: The Experts Are Split." Insight on the News , October 25, 1993, p. 18.
  • "When the Body Remembers." Psychology Today , April 1994, p. 9.

Gale Encyclopedia of Childhood & Adolescence. Gale Research, 1998.

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