Dissociative Identity Disorder (Multiple Personality Disorder)
Dissociative identity disorder is a rare but real disorder that is the most widely discussed of the dissociative disorders. It involves the “presence of two or more distinct identities or personality states (each with its own relatively enduring pattern of perceiving, relat-ing to, and thinking about the environment and self)” (American Psychiatric Association, 2000). The diagnostic criteria also re-quire that “At least two of these identities or personality states recurrently take control of the person’s behavior” (American Psy-chiatric Association, 2000), and that there be amnesia: “Inability to recall important personal information that is too extensive to be explained by ordinary forgetfulness” (American Psychiatric Association, 2000). It is a failure of integration of various aspects of identity and personality structure. Often different relationship styles (dependent versus assertive/aggressive) and mood states (depressed versus hostile) segregate with different identities and personal memories. Such patients may be mystified by events that occurred in another “state”, or by responses of others to them for behavior that occurred in a different “state”. This fragmentation of personality often occurs in response to trauma in childhood, and is perceived by the patient as protective, allowing him or her to tolerate and partially evade chronic abuse. These patients thus view treatment ambivalently as an attempt to deprive them of a defense against attack. They also tend to see others as irrational and unfair, since response to one aspect of their personality fre-quently reflects experience with other aspects. One DID patient (prior to diagnosis) reported puzzlement about accusations by friends and acquaintances that she had made hostile comments for which she had no memory. She would find people angry at her for no reason. Thus their personality fragmentation renders them vulnerable to interpersonal problems yet gives them the belief that they are relatively protected from them.
There are no convincing studies of the absolute prevalence of DID, although there is widespread agreement that the number of diagnosed cases has increased considerably in the USA and some European countries in the past two decades. Two studies have estimated the prevalence as approximately 1% of psychi-atric inpatients (Saxe et al., 1993; Ross et al., 1991). Factors that may account for the increase in the number of true reported cases include 1) more general awareness of the diagnosis among mental health professionals, 2) the availability of specific diagnostic cri-teria starting with DSM-III and 3) reduced misdiagnosis of DID as schizophrenia or borderline personality disorder.
Other authors attribute the increase in reported cases to social contagion, hypnotic suggestion and misdiagnosis Pro-ponents of this point of view argue that these individuals are highly hypnotizable and therefore quite suggestible. They would therefore be especially vulnerable to direct or implicit hypnotic suggestion. They note that not infrequently a few specialist psy-chiatrists make the vast majority of diagnoses. However, it has been observed that the symptoms of patients diagnosed by spe-cialists in dissociation do not differ from those of patients diag-nosed by psychiatrists, psychologists and physicians in more gen-eral practice who diagnose one or two cases a year. Furthermore, such patients have been noted to persist in presenting symptoms for an average of 6.5 years before attaining the diagnosis. They encounter many psychiatrists who are convinced that they do not have DID and that they have some other disorder, such as schizo-phrenia. Were they so easily suggestible, it seems likely that they would accept a suggestion that they have other disorders as well, such as schizophrenia or borderline personality disorder.
Nonetheless, because these patients are indeed highly hypnotizable and therefore suggestible, care must be taken in the manner in which the illness is presented to them. However, it is unlikely that the increased number of cases currently reported is accounted for by suggestion alone. Reduction in previous misdi-agnosis and increased recognition of the prevalence and seque-lae of physical and sexual abuse in childhood are also reasonable explanations.
The disorder is more frequently recognized during childhood but typically emerges between adolescence and the third decade of life; it rarely presents as a new disorder after age 40 years, but there is often considerable delay between initial symptom pres-entation and diagnosis.
Untreated, it is a chronic and recurrent disorder. It rarely remits spontaneously, but the symptoms may not be evident for certain time periods. DID has been called “a disease of hidden-ness” (Schacter, 1995). The dissociation itself hampers self-monitoring and accurate reporting of symptoms and history. Many patients with the disorder are not fully aware of the extent of their dissociative symptoms. They may be reluctant to bring up symptoms because of confusion or shame about the illnessor because they encountered previous skepticism. Furthermore, because the majority of patients report histories of sexual and physical abuse, the shame associated with that and fear of retribu-tion may inhibit reporting of symptoms as well.
The major comorbid psychiatric illnesses are the depressive disorders, substance use disorders and borderline personality disorder. Sexual, eating, and sleep disorders cooccur less com-monly. Such patients frequently display self-mutilative behavior, impulsiveness, and overvaluing and devaluing of relationships. Indeed, approximately a third of patients with DID have symp-toms that fit criteria for borderline personality disorder as well. Such individuals are also more frequently depressed. Conversely, research shows dissociative symptoms in many patients with borderline personality disorder, especially those who report his-tories of physical and sexual abuse. Indeed, the impulsiveness, splitting, hostility and fear of abandonment, frequently seen in certain personality states, are similar to the presentation of many patients with borderline personality disorder. Many such patients also have symptoms that meet criteria for PTSD, with intrusive flashbacks, recurrent dreams of physical and sexual abuse, avoid-ance of and loss of pleasure in usually pleasurable activities, and symptoms of hyperarousal, especially when exposed to remind-ers of childhood trauma.
Thus, comorbidity is a complex issue. In addition, these patients are not infrequently misdiagnosed as having schizophre-nia (Kluft, 1987). This diagnostic confusion is understandable in that they have an apparent delusion that their bodies are occu-pied by more than one person. In addition, they frequently have auditory hallucinations when one personality state speaks to or comments on the activities of another. When misdiagnosed as schizophrenic, patients with DID are frequently given neurolep-tics, which results in a poor therapeutic response and a flattening of affect, which tends to confirm the misdiagnosis (since flat af-fect is characteristic of schizophrenia).
Individuals with DID commonly report somatic or conver-sion symptoms and other psychosomatic symptoms, such as mi-graine headaches. Studies have shown that approximately a third of these patients have complex partial seizures (Schenk and Bear, 1981), although later studies did not show seizure rates that high. Furthermore, the studies did not show substantial elevations in scores on Dissociative Experiences Scale in patients with com-plex partial seizures as compared with those of other neurologi-cal patients (Loewenstein and Putnam, 1988). However, there is sufficient comorbidity that patients recently diagnosed with DID should be evaluated for the possibility of a seizure disorder
The diagnosis can be facilitated by psychological testing. Scales of trait dissociation have been developed (Bernstein and Putnam, 1986; Ross, 1989; Carlson et al., 1993), and patients with DID score extremely high on these scales, in contrast to normal popu-lations and other groups of patients. Those with DID score far higher than normal individuals on standard measures of hypno-tizability, whereas schizophrenic patients tend to have lower than normal scores or the absence of high hypnotizability. Thus, there is comparatively little overlap in the hypnotizability scores of pa-tients with schizophrenia and those with DID. Form level on the Rorschach test is usually within the normal range, but there are frequent emotionally dramatic responses, often involving mutila-tion (especially with the color cards) of a type that is often seen in histrionic personality disorder as well. Form level is an assess-ment of the match between the percept (what the subject reports seeing) and the inkblot structure. Good form level involves rela-tively little distortion of the image to match percept to inkblot. Good form level is useful in distinguishing patients with DID from those with schizophrenia, who have poor form level.