Ellert R. S. Nijenhuis

The development and psychometric characteristics of the Somatoform Dissociation Questionnaire (SDQ-20).

According to 19th century French psychiatry and contemporary clinical observations, dissociation pertains to both psychological and somatoform components of experience, reactions, and functions. Because such an instrument was lacking, we aimed to develop a self-reporting questionnaire measuring what we propose to call somatoform dissociation. Patients with dissociative disorder and with other DSM-TV psychiatric diagnoses completed a list of 75 items that, according to clinical experience and expert judgment, could reflect instances of somatoform dissociation. Separate logistic analyses and determination of discriminant indices per item revealed 20 items that best discriminated between those with and without dissociative disorders. Mokken analysis showed that these items are strongly scalable on a dimensional latent scale interpreted to measure somatoform dissociation. Reliability of the scale was high. Construct validity was supported by high intercorrelations with the Dissociation Questionnaire, which measures psychological dissociation, and higher scores of patients with dissociative identity disorder compared with patients with dissociative disorders not otherwise specified. In conclusion, the Somatoform Dissociation Questionnaire (SDQ-20) is a scale of good psychometric quality, which measures somatoform dissociation. The symptoms pertain to negative and positive dissociative phenomena, which were well known in 19th century French psychiatry as the mental stigmata and mental accidents of hysteria.

Degree of Somatoform and Psychological Dissociation in Dissociative Disorder Is Correlated with Reported Trauma

In this study, the prevalence and severity of traumatic experiences as reported by patients with dissociative disorders and with other DSM-IV psychiatric diagnoses were compared. Furthermore, the predictive value of emotional, physical, and sexual trauma with respect to somatoform and psychological dissociation was analyzed. In contrast with comparison patients, dissociative disorder patients reported severe and multifaceted traumatization. Physical and sexual trauma predicted somatoform dissociation, sexual trauma predicted psychological dissociation as well. According to the memories of the dissociative disorder patients, this abuse occurred in an emotionally neglectful and abusive social context. Pathological dissociation was best predicted by early onset of reported intense, chronic and multiple traumatization. Methodological limitations restricting causal inferences between reported trauma and dissociation are discussed.

Trauma-related dissociation: conceptual clarity lost and found

OBJECTIVE Imprecise conceptualizations of dissociation hinder understanding of trauma-related dissociation. An heuristic resolution for research and clinical practice is proposed. METHOD Current conceptualizations of dissociation are critically examined. They are compared with a new theory that incorporates classical views on dissociation with other contemporary theories related to traumatization, viewing dissociation as a lack of integration among psychobiological systems that constitute personality, that is, as a structural dissociation of the personality. RESULTS Most current views of dissociation are overinclusive and underinclusive. They embrace non-dissociative phenomena--rigid alterations in the level and field of consciousness--prevalent in non-traumatized populations, and which do not require structural dissociation. These views also largely disregard somatoform and positive symptoms of dissociation and underestimate integrative deficiencies, while emphasizing the psychological defensive function of dissociation. They do not offer a common psychobiological pathway for the spectrum of trauma-related disorders. Structural dissociation of the personality likely involves divisions among at least two psychobiological systems, each including a more or less distinct apperceptive centre, that is, a dissociative part of the personality. Three prototypical levels of structural dissociation are postulated to correlate with particular trauma-related disorders. CONCLUSIONS Limitation of the concept of dissociation to structural dividedness of the personality sets it apart from related but non-dissociative phenomena and provides a taxonomy of dissociative symptoms. It postulates a common psychobiological pathway for all trauma-related disorders. Trauma-related dissociation is maintained by integrative deficits and phobic avoidance. This conceptualization advances diagnosis, classification, treatment and research of trauma-related disorders.

Animal Defensive Reactions as a Model for Trauma-Induced Dissociative Reactions

Patients with complex dissociative disorders remain in alternating psychophysiological states which are discrete, discontinuous, and resistant against integrative tendencies. In this contribution, a parallel is drawn between animal defensive and recuperative states that are evoked in the face of severe threat and the characteristic responses of dissociative disorder patients as displayed in major dissociative states. Empirical data and clinical observations seem to be supportive of the idea that there are similarities between freezing, concomitant development of analgesia and anesthesia, and acute pain in threatened animals and severely traumatized human beings.

One brain, two selves

Having a sense of self is an explicit and high-level functional specialization of the human brain. The anatomical localization of self-awareness and the brain mechanisms involved in consciousness were investigated by functional neuroimaging different emotional mental states of core consciousness in patients with Multiple Personality Disorder (i.e., Dissociative Identity Disorder (DID)). We demonstrate specific changes in localized brain activity consistent with their ability to generate at least two distinct mental states of self-awareness, each with its own access to autobiographical trauma-related memory. Our findings reveal the existence of different regional cerebral blood flow patterns for different senses of self. We present evidence for the medial prefrontal cortex (MPFC) and the posterior associative cortices to have an integral role in conscious experience.

Dissociation in Trauma: A New Definition and Comparison with Previous Formulations

Amid controversy regarding the psychobiological construct of dissociation, efforts to formulate a precise definition of dissociation are rare. Some understandings of dissociation are so broad that a host of common psychobiological phenomena would qualify as dissociative. Overly narrow conceptualizations of dissociation exclude phenomena that originally, and for good reasons, have been regarded as dissociative. A common lack of conceptual distinctions between dissociation as process, organization, deficit, psychological defense, and symptom adds to the current confusion. In previous publications, we criticized many of these perspectives and proposed a detailed psychobiological theory of dissociation in trauma. However, what has remained missing is a precise definition of dissociation in trauma. This article first presents such a definition and elucidates its various components. Next the new definition is compared with several other major definitions of the concept. The strengths of the new formulation are highlighted and discussed.

Somatoform Dissociation: Major Symptoms of Dissociative Disorders

Abstract In most of the recent scientific and clinical literature, dissociation has been equated with dissociative amnesia, depersonalization, derealization, and fragmentation of identity. However, according to Pierre Janet and several World War I psychiatrists, dissociation also pertains to a lack of integration of somatoform components of experience, reactions, and functions. Some clinical observations and contemporary studies have supported this view. Somatoform dissociation, which can be measured with the Somatoform Dissociation Questionnaire (SDQ-20), is highly characteristic of dissociative disorder patients, and a core feature in many patients with somatoform disorders and in a subgroup of patients with eating disorders. It is strongly associated with reported trauma among psychiatric patients and patients with chronic pelvic pain presenting in medical healthcare settings. Motor inhibitions and anesthesia/analgesia are somatoform dissociative symptoms that are similar to animal defensive reactions to major threat and injury. Among a wider range of somatoform dissociative symptoms, these particular symptoms are highly characteristic of patients with dissociative disorders. The empirical findings reviewed in this article should have implications for the contemporary conceptualization and definition of dissociation, as well as the categorization of somatoform disorders in a future version of the DSM.

The development of the somatoform dissociation questionnaire (SDQ-5) as a screening instrument for dissociative disorders.

Using cases of dissociative disorder (n=50) and other DSM‐IV diagnoses (n=50), a somatoform dissociation self‐report questionnaire was developed and its capacity to function as a screening device for dissociative disorders was analysed. A list of 75 items was constructed which, according to clinical experience and expert judgement, could reflect instances of somatoform dissociation. Statistical analyses revealed the 20 best discriminating items. Stepwise forward logistic analysis detected five items which, as a group, provided optimal discrimination between the two groups. At an estimated prevalence rate of dissociative disorders of 10% among psychiatric patients the sensitivity would be 94%, the specificity would be 96%, the positive predictive value would be 72%, and the negative predictive value would be 99%. Cross‐validation in an independent sample (n=33/42) largely corroborated the initial findings. The SDQ‐5 can be used as a brief screening device for dissociative disorders.

Psychometric characteristics of the Somatoform Dissociation Questionnaire: A replication study.

Background: The present study aimed to replicate the results of previous studies concerning the development of two versions of the Somatoform Dissociation Questionnaire. The SDQ-20 evaluates the severity of somatoform dissociative phenomena, and the SDQ-5 is a dissociative disorders screening instrument. Methods: Thirty-one patients with dissociative disorders and 45 consecutive psychiatric outpatients with other DSM-IV diagnoses completed the SDQ-20 and SDQ-5 as well as the Dissociation Questionnaire which measures psychological dissociation. Results: Mokken scale analysis showed that the items of the SDQ-20 are strongly scalable on a latent unidimensional scale. Internal consistency was high. The SDQ-20 convergent validity was supported by high intercorrelations with the DIS-Q. Dissociative patients obtained significantly higher scores than comparison patients. Patients with dissociative identity disorder scored significantly higher compared to patients with dissociative disorder nos. Sensitivity (94%) and specificity (98%) of the SDQ-5 were very satisfactory, as were, at an estimated prevalence rate of dissociative disorders of 10% among psychiatric patients, positive predictive value (84%) and negative predictive value (99%). Conclusions: All results replicated the first findings, and therefore corroborate the conclusion that the SDQ-20 and SDQ-5 are instruments of sound psychometric quality, and that somatoform dissociative phenomena are core symptoms of complex dissociative disorders.

Somatoform dissociative symptoms as related to animal defensive reactions to predatory imminence and injury

: The authors hypothesized that there would be a similarity between animal defensive responses to variable predatory imminence and injury and certain somatoform dissociative symptoms of trauma-reporting patients who have dissociative disorder. As a first test of this hypothesis, 12 somatoform symptom clusters consisting of clinically observed somatoform dissociative phenomena were constructed. All clusters discriminated between patients with dissociative disorders (n = 50) and patients with other psychiatric diagnoses (n = 50). Those expressive of the hypothesized similarity--freezing, anesthesia-analgesia, and disturbed eating--belonged to the 5 most characteristic symptoms of dissociative disorder patients. Anesthesia-analgesia, urogenital pain, and freezing symptom clusters independently contributed to predicted presence of dissociative disorder. Using an independent sample, it appeared that anesthesia-analgesia best predicted presence of dissociative disorder after controlling for symptom severity. The results were largely consistent with the hypothesized similarity.