A New Model of Dissociative Identity Disorder

The Scope of Dissociative Disorders: An International Perspective


Vedat Sar, MD

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Clinical Psychotherapy Unit and Dissociative Disorders Program, Medical Faculty of Istanbul, Istanbul University, 34390 Capa, Istanbul, Turkey

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PII S0193-953X(05)00090-0

In contrast to the meaning that the unfortunate term “posttraumatic stress disorder” imposes, trauma is not identical with a noxious event [1]. It is a complex sociopsychologic process with subjective and objective components following traumatic experience that is embedded in past, present, and future. A comprehensive definition of psychic trauma is the loss of cohesion in internal world, in external reality, and between them; creating loss of psychic harmony in a given time point and across the life span. In that sense, trauma and dissociation are concepts that dissolve in each other [2]. An approach to trauma without understanding dissociation remains meaningless from both psychiatric and sociopsychologic point of views. Extracting dissociation from concepts and adaptations of everyday life or from general psychopathology empties its content and marginalizes it (ie, it is a disservice to both the traumatized person and the professional who wants to help them).

This issue includes a special article about culture-bound aspects of dissociation (see the article by Somer elsewhere in this issue). This article is concerned mainly with the documentation of the universality of dissociative disorders as presented by empirical studies conducted in various countries using standardized assessment instruments. The similarities between dissociative patients in various cultures are obvious ^{[3], [4]}. Cultural differences between perceptions and conceptualizations of researchers and mental health professionals in psychiatry are higher than those in any other medical specialty. This seems to be the main reason why dissociative disorders have been considered by some authors as culture bound syndromes; somewhat paradoxically, either as a merely North American disorder or a premodern phenomenon seen in exotic cultures, primitive societies, or mystic-religious communities. Modern pioneers of the field initiated a rising wave of dissociation studies in North America in the 1980s, to be slowed down in 1990s by the so-called “backlash” movement, which has been balanced by a steadily enlarging and emerging international research. Large-scale systematic studies on dissociative disorders in this initial period of international research flourished mainly in The Netherlands [3], Turkey [4], and Germany [5]. Case series also have been published from Switzerland [6] and Australia [7]. Case presentations and many other contributions continue to come from many countries throughout the world. This article does not claim to be an exhaustive one. Rather, to elucidate the way for future research, it tries to evaluate the key aspects of this mosaic of clinical and scientific endeavors.

EPIDEMIOLOGY OF DISSOCIATION: A COMMON PSYCHIATRIC DISORDER

Most of the screening studies on dissociative disorders have been conducted in clinical settings (Table 1). Studies on dissociative disorders in Istanbul, Turkey, yielded prevalence slightly above 10% among psychiatric inpatients and outpatients ^{[8], [9], [10]}. Although still considerable, these rates were lower in The Netherlands [11], Germany [5], and Switzerland [6] among inpatients (between 4.3% and 8%). A Finnish study [12] reported higher rates for psychiatric outpatients (14%) and inpatients (21%). A study conducted among emergency admissions in Istanbul yielded the highest rate (35.7%) [13].

Two large-scale studies conducted in the general population of Sivas, Turkey, provided detailed information about the prevalence of all dissociative disorders in the community. The first one was conducted on a representative sample of 994 participants from both genders [14]. Although there was no difference in average Dissociative Experiences Scale (DES) scores between genders, there were two times more women than men among high scorers. The second study was conducted on a representative female sample of 648 participants in the same city using a structured diagnostic interview (ie, the Dissociative Disorders Interview Schedule) [15]. The overall prevalence of dissociative disorders was 18.3%. The largest group was Dissociative Disorder not Otherwise Specified (DDNOS) (8.3%). A total of 7.3% of the population reported having had dissociative amnesia at least once throughout their life. The prevalence of depersonalization disorder was 1.4%, whereas 1.1% of the population had Dissociative Identity Disorder (DID). Conditions based primarily on presence of distinct personality states (ie, DID and allied forms of DDNOS) together built up a prevalence of 5.2%. Only one proband (0.2%) had dissociative fugue as a solitary phenomenon; when present it was usually part of a more complex dissociative disorder (DID or DDNOS).

In The Netherlands, 378 subjects from a nonclinical population were screened using the Dissociation Questionnaire, a self-rating scale of European origin ^{[16], [17]}. A total of 2.1% of the participants had a score above the cutoff point (score of 2.5), and 0.5% had a score comparable with those of patients with dissociative disorders (scores of 3 or higher). Of the eight high scorers, seven were women. A total of 2.9% of the women and 0.7% men had scores above the 2.5 cutoff, a ratio of 4 to 1. In a large general psychiatric population in Germany [18], there were no significant gender differences in the distribution of high dissociators.

In Germany, a screening study was conducted on 51 male criminal offenders admitted to a medicolegal institution by the court so as to understand diminished or lack of responsibility for the offense because of psychiatric disorder, including a large group of persons with substance-use disorders [19]. Using the Structured Clinical Interview for Diagnostic and Statistical Manual (DSM)-IV Dissociative Disorders [20], a high prevalence of dissociative symptoms and disorders (23.5%), mostly DDNOS, were demonstrated. A total of 22.6% of the group had a DES score 20 or higher. In Turkey [21] 26.8% of 108 male prisoners in a regular correctional center had a DES score 20 or above. This rate was 18.5% for DES scores 30 or above. According to the Structured Clinical Interview for DSM-IV Dissociative Disorders, 15.7% of the subjects had a dissociative disorder, either DDNOS (N = 10) or dissociative amnesia (N = 7). Interestingly, only 2.8% of the prisoners fit the DSM-III-R borderline personality disorder criteria, whereas this rate was 28% for antisocial personality disorder and 66.4% for lifetime posttraumatic stress disorder diagnosis [21].

Overall, independent studies from various countries clearly demonstrate that dissociative disorders constitute a common mental health problem not only in clinical practice but also in the community. The lack of dissociative disorder sections in commonly used general psychiatric screening instruments has led to the omission of dissociative disorders in large-scale epidemiologic studies. Although studies using specific instruments have began to correct this perception, the inclusion of dissociative disorders in general psychiatric screening studies will help to gather detailed information about comorbidity issues (see the article by Sar and Ross elsewhere in this issue). Differences between rates obtained in various settings may be related to differences in treatment-seeking behavior and in mental health delivery systems. In particular, the relatively high prevalence of DDNOS both in clinical settings and in the community points to the necessity for a thorough revision in the DSM-IV dissociative disorders section.