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Ulla Karilampi

Unpublished paper. Presented at the postgraduate course "The psychology of crises and risks", Department of Psychology, University of Göteborg, spring term 1995


Posttraumatic Stress Disorder (PTSD)
Multiple Personality Disorder (MPD)
Dissociative symptoms in PTSD
Posttraumatic symptoms in MPD
Similarities and differences between the two diagnoses



This paper discusses the similarities and differences between the diagnoses of posttraumatic stress disorder (PTSD) and multiple personality disorder (MPD) in order to define their relationship to each other. PTSD is an anxiety disorder that involves impaired functioning following exposure to an event that is outside the range of usual human experiences and that would be disturbing to nearly everyone. Avoidance of painful material is a central mechanism in PTSD. MPD is a dissociative disorder that develops as a reaction to chronic and severe childhood trauma. The core symptom is a fragmentation of the child's identity. Adult patients with MPD experience a complex of symptoms that cause the disorder often to be misdiagnosed and mistreated.

Dissociation is a defense that provides protection against the pain and helplessness caused by immediate traumatic experiences. Traumatic events elicit dissociative symptoms. Several studies have found that the prevalence of dissociative symptoms in PTSD is exceeded only by the dissociative disorders themselves. The severity of the dissociative symptomatology in MPD is closely related to the presence and severity of trauma experienced in childhood, in particular sexual abuse.

Both PTSD and MPD seem to develop as a reaction to severe trauma, but in MPD the stressor is more specific. Other possibly common denominators are chronicity and a high degree of hypnotizability. A person with MPD almost always meets the criteria for PTSD, but a person with PTSD qualifies more seldom as a multiple personality. Still, both PTSD and MPD could be grouped together under a headline of trauma- and stress-related disorders, even though this could cause some problems in differentiating between stressors.

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Both posttraumatic stress disorder (PTSD) and multiple personality disorder (MPD) have found their way into official diagnostic manuals first in recent years, although the symptoms related to both diagnoses have been known since at least a century ago. The validity of both diagnoses have been questioned. Nowadays it seems as if PTSD is generally more easily accepted, probably because the causal connection between disasters, both natural and man-made, and psychological distress is relatively easy to study and to understand. The diagnosis of MPD is not as easily accepted even though it too is related to trauma. But whereas PTSD is related to trauma in adulthood or to single traumatic events in childhood, MPD is a result of exposure to chronic, severe trauma experienced in early childhood. These experiences distort the personality of the growing child in a way that is difficult to understand and to validate. Also, the phenomenon of dissociation itself, which is the main symptom in MPD, is difficult to grasp as it's concept challenges the traditional theories of personality.

Since MPD is a reaction to trauma, some experts prefer to view it as a chronic form of posttraumatic stress reaction. Others claim that the dissociative contribution in PTSD is of such magnitude that PTSD should be listed under the headline of dissociative disorders. The purpose of this paper is to study the similarities and differences between the two diagnoses and to define their relationship to each other.

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Posttraumatic Stress Disorder (PTSD)

Diagnostic and Statistic Manual of Mental Disorders, Third Edition (DSM-III-R) (American Psychiatric Association, 1987) states that posttraumatic stress disorder involves impaired functioning following exposure to an event that is outside the range of usual human experiences and that would be disturbing to nearly everyone, e.g., serious threat to the life of oneself, one's children, spouse or friends, or the sudden destruction of one's home or community. The most distinctive signs of PTSD are:

  • re-experiencing symptoms such as intrusive memories
  • avoidance of stimuli connected with the event
  • a numbing of general responsiveness that may involve loss of ability to have loving feelings
  • heightened bodily arousal
PTSD is classified as an anxiety disorder, but it differs from other anxiety disorders in that it involves a stress-related disorder that follows a traumatic experience.

The most crucial aspect of the PTSD diagnosis is establishing the nature of the traumatic stressor. Peterson, Prout, and Schwarz (1992) state that the sequelae of extreme trauma often includes the survivors' and victims' being ignored, actively avoided and devalued. Frequently family and friends are frightened and do not wish to hear about a disaster. The social demands on survivors to feel and behave in manners not congruent with their inner experience may contribute to their sense of estrangement from others.

According to Peterson et al (1992), there is increasing evidence that avoidance of painful material is a central mechanism in PTSD. They refer to a study that found that the single best predictor of the diagnosis of PTSD in Vietnam veterans was the strong tendency to terminate the viewing of simulated reenactments of combat material. One of the central principles for treatment across schools of thought is to allow the patient to stop avoiding the painful material in a manner that allows for extinction or mastery of the trauma.

Peterson et al (ibid) make a distinction between what they call "primary" and "secondary" symptoms.
Primary symptoms are those which form the basis for the diagnostic criteria of PTSD according to DSM. Secondary symptoms, or associated features, of PTSD refer to symptoms and symptom clusters which commonly coexist with PTSD, but do not form part of the diagnostic criteria for the disorder. These secondary features of PTSD are depression, anxiety, impulsive behavior, somatization, and substance abuse.

Many of the symptoms of classical traumatic neurosis can be suppressed through alcohol use. Self-medication with alcohol is effective in inducing sleep, reducing anxiety, easing muscle tension, and suppressing REM sleep (with which many posttraumatic nightmares are associated). Initially alcohol use is an effective means of reducing symptoms. However, with continued use, tolerance promotes increased consumption. With time, the use of alcohol becomes less and less effective in reducing the troubling symptoms and may indeed exacerbate them.

Posttraumatic stress disorder in adulthood might in some instances be traced to childhood sexual abuse. In a sample of 105 female psychiatric patients who were sexually abused as children or adolescents and drawn randomly from a number of different state hospitals, 66 % met the criteria for PTSD. None had received that diagnosis.
In another study, the rates of childhood abuse in 38 Vietnam combat veterans seeking treatment for PTSD was compared with 28 veterans who sought treatment for medical disorders not related to PTSD. Those with PTSD had higher rates of childhood sexual abuse than the comparison group (Murray 1993).

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Multiple Personality Disorder (MPD)

Multiple personality disorder is a dissociative disorder. The essential feature of these disorders is a disturbance or alteration in the normally integrative functions of identity, memory, or consciousness. The disturbance or alteration may be sudden or gradual, and transient or chronic. In MPD, the disturbance occurs primarily in identity (American Psychiatric Association, 1987). MPD develops as a reaction to chronic and severe, early childhood trauma such as sexual or physical abuse. The diagnosis is named after it's central feature: the apparent "multiplication" of the personality/identity. But, as Ross (1994) points out, although MPD patients are, by definition, diagnosed as having more than one personality, they, in fact, do not. The different "personalities" are fragmented components of a single personality that are abnormally personified, dissociated from each other, and amnestic for each other. These fragmented components are called "personalities" only by historical convention.

Ross (ibid) illustrates MPD as follows: Multiple personality disorder, he says, is a little girl (or boy) imaging that the abuse is happening to someone else. The imaging is so intense and subjectively compelling, and is reinforced so many times by the ongoing trauma, that the created identities seem to take on a life of their own, though they are all parts of one person. Adult patients with MPD experience a number of core symptoms that include voices in the head and ongoing blank spells or periods of missing time. They also experience numerous other symptoms such as those associated with depression, anxiety, eating disorders, substance abuse, sleep disorders, sexual dysfunctions, and psychosomatic disorders, and symptoms that mimic those of schizophrenia. The complexity of the patients' symptoms often results in misdiagnosis and the institution of treatments that are not effective. But when correctly diagnosed, MPD can be successfully treated with psychotherapy.

Multiple personality disorder is further illustrated by the following case:

Nothing seemed especially unusual about Carrie's case when she first walked through the door. Carrie was deeply troubled, but otherwise seemed quite normal. She came to my office with a history of frequent, severe depressions and mood disorders. For many years she had acted in a manner that her family thought was odd, but they had never paid much attention to her behavior until one New Year's Eve. On that night she failed to show up at a party and her husband, Randolph, discovered her in the apartment of another man.
I still remember the day when I discovered Carrie's real problem. She was very upset when she entered my office. She told me that she liked to walk along the beach by the ocean. Lately when she did this, she would suddenly find herself walking in the water. Often the water was up to her chest or even her chin before she became aware of what was happening. She had to swin back, terrified that she would drown, apparently by her own hand, yet with no knowledge of leaving the beach and wading into the water. Carrie's actions seemed as strange to me as they did to her. In an effort to help Carrie discover why she was walking into the water, I suggested we try hypnosis. I hoped that would force her to concentrate on the incidence and reveal the truth. I assumed that she had been aware of her action at the time and hade willed herself to forget because she was too embarrassed or ashamed about it. I certainly didn't expect to discover what happened next. "She's going to kill me," Carrie said. Her voice was filled with fear as she talked about this unseen but very real person living inside her head. "Who's going to kill you?" I asked. "Wanda. Wanda's going to kill me." "Who is Wanda?" I asked. Perhaps she was paranoid. Perhaps there was a woman named Wanda who Carrie perceived as having a grudge against her. Suddenly Carrie's posture changed. Her beautiful face seemed to harden and distort. Her body tensed, as though braced for a fight. She seemed mad at the world and was totally unlike the Carrie I knew. "I'm Wanda, you fat-headed son of a bitch!"
And then I knew.

(Allison & Schwarz, 1992)

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Dissociative symptoms in PTSD

Dissociation as a reaction to trauma
In 1896, William James hade already described traumatic amnesia (a dissociative reaction) among village inhabitants exposed to two catastrophic landslides. More recent work supports earlier observations that traumatic events elicit dissociative symptoms.
There seems to be three frequent types of dissociative alterations in conscious experience following disasters:

  1. experiences of unreality or detachment from the self and the physical and social environments
  2. alterations in perceptual experience
  3. memory disturbances

In an article from 1993, Cardeña and Spiegel systematically evaluated the psychological reactions of a nonclinical population to the October 1989 earthquake in the San Fransisco Bay Area within one week of the earthquake and four months later. The vast majority of the respondents had experienced only slight personal damage or loss of property or none at all. Still, 44,5 % had experienced alterations in time perception, 34 % alterations in memory, 32,8 % had experienced derealization and 25 % depersonalization. The early reactions of the respondents were similar to those of other groups studied. At the follow-up study four months later, the dissociative symptoms had decreased significantly. Still, this study suggests that extreme stress can bring about at least transient dissociative phenomena among nonclinical populations.

The incidence of pscyhogenic amnesia and fugue states are said to increase significantly in wartime and during natural disasters. Putnam (1985) writes that 5 to 20 % of veterans report amnesia for their combat experiences. Another study that he refers to showed a 35 % incidence of amnesic syndromes among soldiers who had experienced prolonged marching and fighting under heavy enemy fire. Soldiers who only experienced periodic bombings or fighting sustained a 13 % incidence, and those exposed only to the normal life of a base camp without combat exposure suffered a 6 % incidence of amnesia. An overall incidence of 1.3 % for dissociative reactions in a peacetime military setting was calculated.
In the case of the wartime amnesic syndromes, the precipitating trauma was primarily combat-related and involved either direct physical threats or witnessing of the violent death of friends. During peacetime, the same types of amnesic syndromes had the loss of a loved one, a financial reverse, or difficulties in an important relationship as the precipitating trauma.

Dissociation and hypnotizability in PTSD
According to Spiegel, Hunt and Dondershine (1988), hypnotizability is the fundamental capacity to experience dissociation in a structured setting. Thus, hypnotizability should be high if extreme dissociative symptoms occur.

The literature suggests that spontaneous dissociation, imagery, and hypnotizability are important components of PTSD symptoms. In one study, 26 Vietnam combat veterans were divided into high and low symptom groups on the basis of posttraumatic symptoms, and those with high symptoms were found to be significantly more hypnotizable. Spiegel et al (ibid) compared the hypnotizability of 65 Vietnam veteran patients with PTSD to that of a normal control group and four patient samples. The patients with PTSD had significantly higher hypnotizability scores than other patient groups and the control sample.
The authors conclude that most of the symptoms associated with posttraumatic stress disorder have a flavor of dissociation:

  • reexperiencing the event through intrusive recollections, nightmares, flashbacks
  • emotional numbing with feelings of detachment or isolation
  • stimulus sensitivity with the avoidance of environmental cues that are associated with recollections of the traumatic events
  • difficulty concentrating
The phenomenon of dissociation implies an isolated set of interacting affects and memories that can be reactivated. They come as a unit, consistent with the evidence in cognitive psychology for state-dependent memory.

Testing for dissociative symptoms
In 1986, the Dissociative Experiences Scale (DES) was created. DES is a brief, self-report measure of the frequency of dissociative experiences in the daily life, meant to use for adult clinical populations.

The scale is a 28-item questionnaire and screening instrument in which the subject is asked to mark what percentage of the time (from 0 to 100 %) the described experience has happened to him or her. Some of the questions ask about amnestic dissociation (e.g., item 25: "Some people find evidence that they have done things that they do not remember doing"), some about absorption and imaginative involvement (e.g., item 17: "Some people find that when they are watching television or a movie they become so absorbed in the story that they are unware of other events happening around them"), some about depersonalization or derealization (e.g., item 13: "Some people have the experience of feeling that their body does not belong to them"), or other types of dissociative experiences (e.g., item 21: "Some people find that when they are alone they talk out loud to themselves"). The total DES score can range between 0 and 100. Subjects who score over 25 should be interviewed further in order to detect possible cases of a dissociative disorder.

Several studies using DES have found high rates of dissociative symptoms in samples of subjects with PTSD. In fact, PTSD scores the third highest mean/median score on DES (31.10), exceeded only by MPD (48.16) and dissociative disorders not otherwise specified (36.30). Thus, PTSD shows the highest occurrence of dissociative symptoms outside the group of dissociative disorders (Bernstein Carlson & Putnam 1993).

The Structured Clinical Interview for DSM-III-R Dissociative Disorders (SCID-D) is a semistructured diagnostic interview that systematically assesses the severity of five dissociative symptoms (amnesia, depersonalization, derealization, identity confusion, and identity alteration) in all psychiatric patients, and diagnoses the dissociative disorders according to DSM-III-R criteria. The five SCID-D symptoms are scored on a four-point scale, and the main criteria are frequency and persistence of the symptoms. The total SCID-D score can range between 5 and 20. In 1993, Bremner et al. compared dissociative symptom areas in Vietnam veterans with and without PTSD. The PTSD patients had more severe dissociative symptoms in each of the five symptom areas of the SCID-D and higher total symptom scores (16.98) at a level similar to that in dissociative disorders (17.28) and MPD (18.17). Symptom severity in the area of amnesia appeared to be particularly prominent.

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Posttraumatic symptoms in MPD

Dissociation is believed to be a defense mobilized against the pain and helplessness caused by traumatic experiences such as rape, incest and combat. It provides protection from immediate experiences rather than unconscious memories or wishes.

This definition has been empirically tested by Boon and Draijer (1993). They analysed the trauma histories of 146 patients: 82 patients with a dissociative disorder and 64 patients with other psychiatric disorders. Boon and Draijer found that childhood traumatic experiences are not specific to the background of dissociative disorder patients, but that traumatic experiences, particularly physical abuse and sexual abuse, were significantly more prevalent in the childhood of dissociative disorder patients than in that of psychiatric control patients without a dissociative disorder. There was also a significant difference in severity of both physical abuse and sexual abuse between the dissociative patients and other psychiatric patients: patients with a dissociative disorder reported the most severe abuse histories, and were repeatedly traumatized. Also, the dissociative disorder patients differed significantly from the other psychiatric patients in the age at which physical and sexual abuse had started. The abuse histories of dissociative disorder patients had started at an early age (before age 6), while trauma histories of the other patients had begun mostly at an older age (after age 6 and up to early adolescence).

Boon and Draijer came to the conclusion that the severity of the dissociative symptomatology is closely related to the presence and severity of trauma experienced in childhood, in particular sexual abuse. They believe that MPD can be considered to be a specific and complicated posttraumatic disorder which develops in early childhood in response to severe and chronic abuse.

Spiegel (cited in Peterson et al 1992) states that given the evidence that more than 90 % of patients who present with the symptoms of MPD have histories of severe physical and sexual abuse, it makes sense to conceptualize this syndrome as a chronic PTSD.

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Similarites and differences between the two diagnoses

Both posttraumatic stress disorder and multiple personality disorder seem to develop as a reaction to severe trauma, but in MPD the stressor is more specific. For example, natural disasters may lead to a dissociative reaction, but not to the extent of fragmenting the personality (except temporarily, as sometimes in psychogenic fugue). MPD is created by means of repeated dissociations that occur under extreme stress of childhood abuse in combination with other factors such as psychosocial influence, family dynamics, and individual characteristics (Braun, 1988). The exact mechanisms of MPD are not known. Neither is the relationship between childhood abuse and PTSD. It might be that the onset of an overt manifestation of posttraumatic symptoms could in some cases be delayed for years, or that childhood trauma sensitizes the individual to stressful events later in life. Also, the roll of hypnotizability is unclear, though it has been demonstrated that a high level of symptoms of either PTSD or MPD are related to a high degree of hypnotizability.

The secondary symptoms in both disorders are quite the same, but in MPD the symptom is often associated with only a part of the personality, so that a particular state-dependent identity manifestation may for example be depressed, while another one is not. Both PTSD and MPD are chronic unless treated.

A person with MPD almost always meets the criteria for PTSD, but a person with PTSD qualifies more seldom as a multiple personality. Peterson et al. (1992) state that dissociative phenomena are a more dramatic and serious manifestation of the intrusion of thoughts, affect, images, and memories. They appear to be more highly correlated with experiences of multiple traumas. Although PTSD has features of a dissociative disorder, PTSD does not manifest the repeated state dependent disruption and association seen in MPD.

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Should posttraumatic stress disorder be classified as a variant of dissociative disorders, or should multiple personality disorder be viewed as a special type of posttraumatic disorder? (PTSD is currently classified as an anxiety disorder in DSM-III-R, and MPD as a dissociative disorder.) I think both should rather be grouped together under the headline of trauma- and stress-related disorders, together with the other dissociative disorders. Even other disorders with stress or trauma etiology could be transfered here.

Until the 1987 revision of DSM, there was not a single mention of any type of trauma-related disorder in this diagnostic manual. Peterson et al (1992) say that there appears to have been a great deal of resistance to the concept of psychological problems coming from physical trauma. In fact, one of the problems has been the denial that certain traumas even occur.

This proposed change in classification could turn out to be a problem in those cases where the causality between trauma and a pscyhiatric disorder is only partial. For example, some substance abusers may have been molested or raped in their youth, while others break under the accumulated weight of everyday problems. Also, in the end, we might find that all psychiatric problems are, at least to some degree, caused by trauma or stress. This would cause trouble trying to differentiate between different types of stressors.

Maybe one ought to follow the device "when in doubt, do nothing." Only time and further research will give us a clue as to which direction we should take.

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Allison, R., Schwarz, T. (1992) Minds in many pieces. Ann Arbor: University Microfilms International.

American Psychiatric Association (1987) Diagnostic and Statistical Manual of Mental Disorders, 3rd edition-revised (DSM-III-R). Washington, D.C.: American Psychiatric Association.

Bernstein Carlson, E., Putnam, F.W. (1993) An update on the Dissociative Experiences Scale. Dissociation, VI, 1, 16-27.

Boon, S., Draijer, N. (1993) Multiple personality disorder in the Netherlands: a study on reliability and validity of the diagnosis. Amsterdam/Lisse: Swetz & Zeitlinger B.V.

Braun, B.G. (1988) The BASK model of dissociation. Dissociation, 1, 1, 4-23.

Bremner, J.D., Steinberg, M, Southwick, S.M., et al. (1993) Use of the Structured Clinical Interview for DSM-IV dissociative disorders for systematic assessment of dissociative symptoms in posttraumatic stress disorder. American Journal of Psychiatry, 150, 7, 1011-1014.

Cardeña, E., Spiegel, D. (1993) Dissociative reactions to the San Fransisco Bay Area earthquake of 1989. American Journal of Psychiatry, 150, 3, 474-478.

Murray, J.B. (1993) Relationship of childhood sexual abuse to borderline personality disorder, posttraumatic disorder, and multiple personality disorder. Journal of Psychology, 127, 6, 657-676.

Peterson, K.C., Prout, M.F., Schwarz, R.A. (1992) Post-traumatic stress disorder: a clinician's guide. New York/London: Plenum Press.

Putnam, F.W. (1985) Dissociation as a response to extreme trauma. In: Kluft, R.P. (Ed.) Childhood antecedents of multiple personality. Washington, D.C.: American Psychiatric Press, 65-98.

Ross, C.A. (1994) The Osiris complex: case-studies in multiple personality disorder. Toronto: University of Toronto Press.

Spiegel, D., Hunt, T., Dondershine, H.E. (1988) Dissociation and hypnotizability in posttraumatic stress disorder. American Journal of Psychiatry, 145, 3, 301-305.


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