Subanesthetic effects of the noncompetitive NMDA antagonist, ketamine, in humans. Psychotomimetic, perceptual, cognitive, and neuroendocrine responses

BACKGROUND

To characterize further behavioral, cognitive, neuroendocrine, and physiological effects of subanesthetic doses of ketamine hydrochloride in healthy human subjects. Ketamine, a phencyclidine hydrochloride derivative, is a dissociative anesthetic and a noncompetitive antagonist of the N-methyl-D-aspartate subtype of excitatory amino acid receptor.

METHODS

Nineteen healthy subjects recruited by advertisements from the community participated in this randomized, double-blind, placebo-controlled study. Subjects completed three test days involving the 40-minute intravenous administration of placebo, ketamine hydrochloride (0.1 mg/kg), or ketamine hydrochloride (0.5 mg/kg). Behaviors associated with the positive and negative symptoms of schizophrenia were assessed by using the Brief Psychiatric Rating Scale. Changes in perception and behaviors associated with dissociative states were assessed by the Perceptual Aberration Subscale of the Wisconsin Psychosis Proneness Scale and the Clinician-Administered Dissociative States Scale. Cognitive function was assessed by using the (1) Mini-Mental State Examination; (2) tests sensitive to frontal cortical dysfunction, including a continuous performance vigilance task, a verbal fluency task, and the Wisconsin Card Sorting Test; and (3) tests of immediate and delayed recall. Plasma levels of cortisol, prolactin, homovanillic acid, and 3-methoxy-4-hydroxyphenethyleneglycol were measured.

RESULTS

Ketamine (1) produced behaviors similar to the positive and negative symptoms of schizophrenia; (2) elicited alterations in perception; (3) impaired performance on tests of vigilance, verbal fluency, and the Wisconsin Card Sorting Test; (4) evoked symptoms similar to dissociative states; and (5) preferentially disrupted delayed word recall, sparing immediate recall and postdistraction recall. Ketamine had no significant effect on the Mini-Mental State Examination at the doses studied. Ketamine also had no effect on plasma 3-methoxy-4-hydroxyphenethyleneglycol levels, although it blunted a test day decline in plasma homovanillic acid levels at the higher dose. It also dose dependently increased plasma cortisol and prolactin levels. Ketamine produced small dose-dependent increases in blood pressure.

CONCLUSIONS

These data indicate that N-methyl-D-aspartate antagonists produce a broad range of symptoms, behaviors, and cognitive deficits that resemble aspects of endogenous psychoses, particularly schizophrenia and dissociative states.

Development, reliability, and validity of a dissociation scale

Dissociation is a lack of the normal integration of thoughts, feelings, and experiences into the stream of consciousness and memory. Dissociation occurs to some degree in normal individuals and is thought to be more prevalent in persons with major mental illnesses. The Dissociative Experiences Scale (DES) has been developed to offer a means of reliably measuring dissociation in normal and clinical populations. Scale items were developed using clinical data and interviews, scales involving memory loss, and consultations with experts in dissociation. Pilot testing was performed to refine the wording and format of the scale. The scale is a 28-item self-report questionnaire. Subjects were asked to make slashes on 100-mm lines to indicate where they fall on a continuum for each question. In addition, demographic information (age, sex, occupation, and level of education) was collected so that the connection between these variables and scale scores could be examined. The mean of all item scores ranges from 0 to 100 and is called the DES score. The scale was administered to between 10 and 39 subjects in each of the following populations: normal adults, late adolescent college students, and persons suffering from alcoholism, agoraphobia, phobic-anxious disorders, posttraumatic stress disorder, schizophrenia, and multiple personality disorder. Reliability testing of the scale showed that the scale had good test-retest and good split-half reliability. Item-scale score correlations were all significant, indicating good internal consistency and construct validity. A Kruskal-Wallis test and post hoc comparisons of the scores of the eight populations provided evidence of the scale's criterion-referenced validity.(ABSTRACT TRUNCATED AT 250 WORDS)

The functions of deliberate self-injury: a review of the evidence

Deliberate self-injury is defined as the intentional, direct injuring of body tissue without suicidal intent. The present article reviews the empirical research on the functions of self-injury. This literature includes self-reports of reasons for self-injuring, descriptions of the phenomenology of self-injury, and laboratory studies examining the effects of self-injury proxies on affect and physiological arousal. Results from 18 studies provide converging evidence for an affect-regulation function. Research indicates that: (a) acute negative affect precedes self-injury, (b) decreased negative affect and relief are present after self-injury, (c) self-injury is most often performed with intent to alleviate negative affect, and (d) negative affect and arousal are reduced by the performance of self-injury proxies in laboratory settings. Studies also provide strong support for a self-punishment function, and modest evidence for anti-dissociation, interpersonal-influence, anti-suicide, sensation-seeking, and interpersonal boundaries functions. The conceptual and empirical relationships among the different functions remain unclear. Future research should address the measurement, co-variation, clinical correlates, and treatment implications of different functions.

Prospective study of posttraumatic stress disorder and depression following trauma

OBJECTIVE

The purpose of this study was to prospectively evaluate the onset, overlap, and course of posttraumatic stress disorder (PTSD) and major depression following traumatic events.

METHOD

The occurrence of PTSD and major depression and the intensity of related symptoms were assessed in 211 trauma survivors recruited from a general hospital's emergency room. Psychometrics and structured clinical interview (the Structured Clinical Interview for DSM-III-R and the Clinician-Administered PTSD Scale) were administered 1 week, 1 month, and 4 months after the traumatic event. Heart rate was assessed upon arrival at the emergency room for subjects with physical injury. Twenty-three subjects with PTSD and 35 matched comparison subjects were followed for 1 year.

RESULTS

Major depression and PTSD occurred early on after trauma; patients with these diagnoses had similar recovery rates: 63 survivors (29.9%) met criteria for PTSD at 1 month, and 37 (17.5%) had PTSD at 4 months. Forty subjects (19.0%) met criteria for major depression at 1 month, and 30 (14.2%) had major depression at 4 months. Comorbid depression occurred in 44.5% of PTSD patients at 1 month and in 43.2% at 4 months. Comorbidity was associated with greater symptom severity and lower levels of functioning. Survivors with PTSD had higher heart rate levels at the emergency room and reported more intrusive symptoms, exaggerated startle, and peritraumatic dissociation than those with major depression. Prior depression was associated with a higher prevalence of major depression and with more reported symptoms.

CONCLUSIONS

Major depression and PTSD are independent sequelae of traumatic events, have similar prognoses, and interact to increase distress and dysfunction. Both should be targeted by early treatment interventions and by neurobiological research.

Measurement of dissociative states with the Clinician-Administered Dissociative States Scale (CADSS)

The purpose of this study was to develop an instrument for the measurement of present-state dissociative symptoms, the Clinician Administered Dissociative States Scale (CADSS). Reported here are interrater reliability and internal consistency of the CADSS, validity as assessed by comparisons with other instruments for the assessment of dissociation, and sensitivity of the CADSS to discriminate patients with dissociative disorders from patients with other psychiatric disorders and healthy subjects. Initial analyses indicated good interrater reliability and construct validity for the CADSS. Scores on the CADSS discriminated patients with dissociative disorders from the other groups.

The Peritraumatic Distress Inventory: a proposed measure of PTSD criterion A2

OBJECTIVE

Meeting criterion A2 for the diagnosis of posttraumatic stress disorder (PTSD) in DSM-IV requires that an individual have high levels of distress during or after the traumatic event. Because of the paucity of valid and reliable instruments for assessing such responses, the authors developed a 13-item self-report measure, the Peritraumatic Distress Inventory, to obtain a quantitative measure of the level of distress experienced during and immediately after a traumatic event.

METHOD

The cross-sectional study group comprised 702 police officers and 301 matched nonpolice comparison subjects varying in ethnicity and gender who were exposed to a wide range of critical incidents.

RESULTS

The Peritraumatic Distress Inventory was found to be internally consistent, with good test-retest reliability and good convergent and divergent validity. Even after controlling for peritraumatic dissociation and for general psychopathology, the authors found that Peritraumatic Distress Inventory scores correlated with two measures of posttraumatic stress symptoms.

CONCLUSIONS

The Peritraumatic Distress Inventory holds promise as a measure of PTSD criterion A2. Future studies should prospectively examine the ability of the Peritraumatic Distress Inventory to predict PTSD and its associated biological and cognitive correlates in other trauma-exposed groups.

Dissociative symptoms in relation to childhood physical and sexual abuse

Studies have reported high rates of childhood abuse in people with psychiatric illness. This study examined whether dissociative symptoms are specific to patients with histories of abuse. Ninety-eight female psychiatric inpatients completed self-report instruments that focused on childhood history of trauma, dissociative symptoms, and psychiatric symptoms in general. Sixty-three percent of the subjects reported physical and/or sexual abuse. Eighty-three percent had dissociative symptom scores above the median score of normal adults, and 24% had scores at or above the median score of patients with posttraumatic stress disorder. Subjects with a history of childhood abuse reported higher levels of dissociative symptoms than those who did not.

Peritraumatic dissociation and posttraumatic stress in male Vietnam theater veterans

OBJECTIVE

The aim of this study was to determine the reliability and validity of a proposed measure of peritraumatic dissociation and, as part of that effort, to determine the relationship between dissociative experiences during disturbing combat trauma and the subsequent development of posttraumatic stress disorder (PTSD).

METHOD

A total of 251 male Vietnam theater veterans from the Clinical Examination Component of the National Vietnam Veterans Readjustment Study were examined to determine the relationship of war zone stress exposure, retrospective reports of dissociation during the most disturbing combat trauma events, and general dissociative tendencies with PTSD case determination.

RESULTS

The total score on the Peritraumatic Dissociation Experiences Questionnaire--Rater Version was strongly associated with level of posttraumatic stress symptoms, level of stress exposure, and general dissociative tendencies and weakly associated with general psychopathology scales from the MMPI-2. Logistic regression analyses supported the incremental value of dissociation during trauma, over and above the contributions of level of war zone stress exposure and general dissociative tendencies, in accounting for PTSD case determination.

CONCLUSIONS

These results provide support for the reliability and validity of the Peritraumatic Dissociation Experiences Questionnaire--Rater Version and for a trauma-dissociation linkage hypothesis: the greater the dissociation during traumatic stress exposure, the greater the likelihood of meeting criteria for current PTSD.

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 dissociate disorder and with other DSM-IV 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.

Brain activation during script-driven imagery induced dissociative responses in PTSD: a functional magnetic resonance imaging investigation

BACKGROUND

The goal of this study was to examine the neuronal circuitry underlying dissociative responses to traumatic script-driven imagery in sexual-abuse-related posttraumatic stress disorder (PTSD). Pilot studies in our laboratory have shown that PTSD patients had very different responses to traumatic script-driven imagery. Approximately 70% of patients relived their traumatic experience and showed an increase in heart rate while recalling the traumatic memory. The other 30% of patients had a dissociative response with no concomitant increase in heart rate. This article focuses on the latter group.

METHODS

The neuronal circuitry underlying dissociative responses in PTSD was studied using the traumatic script-driven symptom provocation paradigm adapted to functional magnetic resonance imaging (fMRI) at a 4 Tesla field strength in 7 subjects with sexual-abuse-related PTSD and 10 control subjects.

RESULTS

Compared with control subjects, PTSD patients in a dissociative state showed more activation in the superior and middle temporal gyri (BA 38), the inferior frontal gyrus (BA 47), the occipital lobe (BA 19), the parietal lobe (BA 7), the medial frontal gyrus (BA 10), the medial cortex (BA 9), and the anterior cingulate gyrus (BA 24 and 32).

CONCLUSIONS

These findings suggest that prefrontal and limbic structures underlie dissociative responses in PTSD. Differences observed clinically, psychophysiologically, and neurobiologically between patients who respond to traumatic script-driven imagery with dissociative versus nondissociative responses may suggest different neuronal mechanisms underlying these two distinct reactions.

Are there two qualitatively distinct forms of dissociation? A review and some clinical implications

This review aims to clarify the use of the term 'dissociation' in theory, research and clinical practice. Current psychiatric definitions of dissociation are contrasted with recent conceptualizations that have converged on a dichotomy between two qualitatively different phenomena: 'detachment' and 'compartmentalization'. We review some evidence for this distinction within the domains of phenomenology, factor analysis of self-report scales and experimental research. Available evidence supports the distinction but more controlled evaluations are needed. We conclude with recommendations for future research and clinical practice, proposing that using this dichotomy can lead to clearer case formulation and an improved choice of treatment strategy. Examples are provided within Depersonalization Disorder, Conversion Disorder and Posttraumatic Stress Disorder (PTSD).

A memory-based model of posttraumatic stress disorder: evaluating basic assumptions underlying the PTSD diagnosis

In the mnemonic model of posttraumatic stress disorder (PTSD), the current memory of a negative event, not the event itself, determines symptoms. The model is an alternative to the current event-based etiology of PTSD represented in the Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; American Psychiatric Association, 2000). The model accounts for important and reliable findings that are often inconsistent with the current diagnostic view and that have been neglected by theoretical accounts of the disorder, including the following observations. The diagnosis needs objective information about the trauma and peritraumatic emotions but uses retrospective memory reports that can have substantial biases. Negative events and emotions that do not satisfy the current diagnostic criteria for a trauma can be followed by symptoms that would otherwise qualify for PTSD. Predisposing factors that affect the current memory have large effects on symptoms. The inability-to-recall-an-important-aspect-of-the-trauma symptom does not correlate with other symptoms. Loss or enhancement of the trauma memory affects PTSD symptoms in predictable ways. Special mechanisms that apply only to traumatic memories are not needed, increasing parsimony and the knowledge that can be applied to understanding PTSD.

Psychodynamics and psychiatric diagnoses of pseudoseizure subjects

OBJECTIVE

The goal of this study was to determine current and lifetime rates of DSM-III-R disorders in patients with pseudoseizures and to ascertain whether trauma is associated with the occurrence of pseudoseizures.

METHODS

Adult pseudoseizure patients (N = 45) were interviewed regarding seizure course and life events, and they were given the Structured Clinical Interview for DSM-III-R--Patient Version, the Structured Clinical Interview for DSM-III-R Dissociative Disorders, the Dissociative Experiences Scale, and the Personality Diagnostic Questionnaire--Revised. The pseudoseizures were diagnosed in a tertiary-care video-EEG facility. Most of the subjects (78%) were female, and the mean age of the overall patient group was 37.5 years (SD = 9.7).

RESULTS

The mean duration of the subjects' seizure history was 8.3 years (SD = 8.0). Common current psychiatric diagnoses included somatoform disorders (89%), dissociative disorders (91%), affective disorders (64%), personality disorders (62%), posttraumatic stress disorder (PTSD) (49%), and other anxiety disorders (47%). The lifetime occurrence of nonseizure conversion disorders was 82%. The mean Dissociative Experiences Scale score was 20.2 (SD = 18.2). Trauma was reported by 84% of the subjects: sexual abuse by 67%, physical abuse by 67%, and other traumas by 73%.

CONCLUSIONS

Pseudoseizure subjects have high rates of the psychiatric disorders found in traumatized groups; they closely resemble patients with dissociative disorders. Reclassification of conversion seizures with the dissociative disorders should be considered. Pseudoseizures often appear to express distress related to abuse reports. Clinicians should screen pseudoseizure patients for adult and childhood trauma, dissociative disorders, depression, and PTSD.

Acute stress disorder, posttraumatic stress disorder, and depression in disaster or rescue workers

OBJECTIVE

The events of Sept. 11, 2001, highlighted the importance of understanding the effects of trauma on disaster workers. To better plan for the health care of disaster workers, this study examined acute stress disorder, posttraumatic stress disorder (PTSD), early dissociative symptoms, depression, and health care utilization in disaster workers.

METHOD

Exposed disaster workers (N=207) and unexposed comparison subjects (N=421) were examined at 2, 7, and 13 months after an airplane crash.

RESULTS

Exposed disaster workers had significantly higher rates of acute stress disorder, PTSD at 13 months, depression at 7 months, and depression at 13 months than comparison subjects. Those who were younger and single were more likely to develop acute stress disorder. Exposed disaster workers with acute stress disorder were 3.93 times more likely to be depressed at 7 months. Those with high exposure and previous disaster experience or who had acute stress disorder were more likely to develop PTSD. Similarly, those who were depressed at 7 months were 9.5 times more likely to have PTSD. Those who were depressed at 13 months were 7.96 times more likely to also meet PTSD criteria. More exposed disaster workers than comparison subjects obtained medical care for emotional problems at 2, 7, and 13 months. Overall, 40.5% of exposed disaster workers versus 20.4% of comparison subjects had acute stress disorder, depression at 13 months, or PTSD.

CONCLUSIONS

Exposed disaster workers are at increased risk of acute stress disorder, depression, or PTSD and seek care for emotional problems at an increased rate.

Dissociation, somatization, and affect dysregulation: the complexity of adaptation of trauma

OBJECTIVE

A century of clinical research has noted a range of trauma-related psychological problems that are not captured in the DSM-IV framework of posttraumatic stress disorder (PTSD). This study investigated the relationships between exposure to extreme stress, the emergence of PTSD, and symptoms traditionally associated with "hysteria," which can be understood as problems with stimulus discrimination, self-regulation, and cognitive integration of experience.

METHOD

The DSM-IV field trial for PTSD studied 395 traumatized treatment-seeking subjects and 125 non-treatment-seeking subjects who had also been exposed to traumatic experiences. Data on age at onset, the nature of the trauma, PTSD, dissociation, somatization, and affect dysregulation were collected.

RESULTS

PTSD, dissociation, somatization, and affect dysregulation were highly interrelated. The subjects meeting the criteria for lifetime (but not current) PTSD scored significantly lower on these disorders than those with current PTSD, but significantly higher than those who never had PTSD. Subjects who developed PTSD after interpersonal trauma as adults had significantly fewer symptoms than those with childhood trauma, but significantly more than victims of disasters.

CONCLUSIONS

PTSD, dissociation, somatization, and affect dysregulation represent a spectrum of adaptations to trauma. They often occur together, but traumatized individuals may suffer from various combinations of symptoms over time. In treating these patients, it is critical to attend to the relative contributions of loss of stimulus discrimination, self-regulation, and cognitive integration of experience to overall impairment and provide systematic treatment that addresses both unbidden intrusive recollections and these other symptoms associated with having been overwhelmed by exposure to traumatic experiences.

The relationship between acute stress disorder and posttraumatic stress disorder: a prospective evaluation of motor vehicle accident survivors

Motor vehicle accident survivors (n = 92) were assessed for acute stress disorder (ASD) within 1 month of the trauma and reassessed (n = 71) for posttraumatic stress disorder (PTSD) 6 months posttrauma. ASD was diagnosed in 13% of participants, and a further 21% had subclinical levels of ASD. At follow-up, 78% of ASD participants and 60% of subclinical ASD participants met criteria for PTSD. The strong predictive power of acute numbing, depersonalization, a sense of relieving the trauma, and motor restlessness, in contrast to the low to moderate predictive power of other symptoms, indicates that only a subset of ASD symptoms is strongly related to the development of chronic PTSD. Although these findings support the use of the ASD diagnosis, they suggest that the dissociative and arousal clusters may require revision.

Predictors of posttraumatic stress symptoms among survivors of the Oakland/Berkeley, Calif., firestorm

OBJECTIVE

The purpose of this study was to examine factors predicting the development of posttraumatic stress symptoms after a traumatic event, the 1991 Oakland/Berkeley firestorm. The major predictive factors of interest were dissociative, anxiety, and loss of personal autonomy symptoms reported in the immediate aftermath of the fire; contact with the fire; and life stressors before and after the fire.

METHOD

Subjects were recruited from several sources so that they would vary in their extent of contact with the fire. Of 187 participants who completed self-report measures about their experiences in the aftermath of the firestorm, 154 completed a follow-up assessment. Of these 154 subjects, 97% completed the follow-up questionnaires 7-9 months after the fire. The questionnaires included measures of posttraumatic stress and life events since the fire.

RESULTS

Dissociative and loss of personal autonomy symptoms experienced in the fire's immediate aftermath, as well as stressful life experiences occurring later, significantly predicted posttraumatic stress symptoms measured 7-9 months after the firestorm by a civilian version of the Mississippi Scale for Combat-Related Posttraumatic Stress Disorder and the Impact of Event Scale. Dissociative symptoms more strongly predicted posttraumatic symptoms than did anxiety and loss of personal autonomy symptoms. Intrusive thinking differs from other kinds of posttraumatic symptoms in being related directly to the trauma and previous stressful life events.

CONCLUSIONS

These findings suggest that dissociative symptoms experienced in the immediate aftermath of a traumatic experience and subsequent stressful experiences are indicative of risk for the later development of posttraumatic stress symptoms. Such measures may be useful as screening procedures for identifying those most likely to need clinical care to help them work through their reactions to the traumatic event and to subsequent stressful experiences.

Validity of the Dissociative Experiences Scale in screening for multiple personality disorder: a multicenter study

OBJECTIVE

The Dissociative Experiences Scale has proved a reliable and valid instrument to measure dissociation in many groups, but its capacity to distinguish patients with multiple personality disorder from patients with other psychiatric disorders has not yet been conclusively tested.

METHOD

A discriminant analysis was performed to classify 1,051 subjects as having or not having multiple personality disorder. Another discriminant analysis was performed on a subgroup of 883 subjects more closely representing patients in a typical psychiatric facility in terms of base rates of dissociative disorders. A cutoff score of 30 was also used to classify subjects, and Bayes's theorem, which allows for the calculation of the positive predictive value and the negative predictive value of a screening test, was applied.

RESULTS

According to discriminant analysis of the total study group, the scale's sensitivity was 76% and its specificity was also 76%; according to discriminant analysis of the more representative subgroup, the scale's sensitivity was 76% and its specificity was 85%. Use of the cutoff score of 30 produced similar results. Results of the application of Bayes's theorem showed that 17% of the subjects scoring 30 or higher would actually have multiple personality disorder and 99% of those scoring less than 30 would not have multiple personality disorder.

CONCLUSIONS

These results indicate that the Dissociative Experiences Scale performs quite well as a screening instrument to identify subjects with multiple personality disorder. In addition, the consistency of responses to scale items across centers indicates that the symptoms reported by patients with multiple personality disorder are highly similar across diverse geographic centers. This consistency supports the reliability and validity of the diagnosis of multiple personality disorder across centers.

Disintegrated experience: The dissociative disorders revisited

We present proposed changes to the dissociative disorders section of the 4th edition of the Diagnostic and Statistical Manual of Mental Disorders and review the concept of pathological and nonpathological dissociation, including empirical findings on the relations between trauma and dissociative phenomenology and between dissociation and hypnosis. The most important proposals include the creation of two new diagnostic entities, brief reactive dissociative disorder and transient dissociative disturbance, and the readoption of the criterion of amnesia for a multiple personality disorder diagnosis. We conclude that further work on dissociative processes will provide an important link between clinical and experimental approaches to human cognition, emotion, and personality.

Objective assessment of peritraumatic dissociation: psychophysiological indicators

OBJECTIVE

The aims of this study were to investigate psychophysiological changes associated with peritraumatic dissociation in female victims of recent rape and to assess the relation between these changes and symptoms of posttraumatic stress disorder (PTSD).

METHOD

Eighty-five rape victims were examined in a laboratory setting within 2 weeks after the rape, and measures of heart rate, skin conductance, and nonspecific movement were collected. Self-report indexes of reactions to the trauma and interviews to assess PTSD symptoms and peritraumatic dissociation were also completed. On the basis of their scores on the Peritraumatic Dissociation Index, the subjects were classified as having low or high levels of dissociation.

RESULTS

Items from the index exhibited good internal consistency, and scores were approximately normally distributed. Individuals in the high peritraumatic dissociation group showed a significantly different pattern of physiological responses from those of the low dissociation group. In general, there was a suppression of autonomic physiological responses in the high dissociation group. This group also contained a larger proportion of subjects (94%) identified as meeting PTSD symptom criteria. Also, among the high dissociation subjects there was a discrepancy between self-reports of distress and objective physiological indicators of distress in the laboratory setting.

CONCLUSIONS

The results provide preliminary support for the idea that there is a dissociative subtype of persons with PTSD symptoms who exhibit diminished physiological reactivity. The results also underscore the importance of assessing dissociative symptoms in trauma survivors.

Development and validation of a measure of adolescent dissociation: the Adolescent Dissociative Experiences Scale

This study describes the initial reliability and validity data on the Adolescent Dissociative Experiences Scale (A-DES), a screening measure for pathological dissociation during adolescence. The A-DES showed good scale and subscale reliability, and, as hypothesized, increased scores were associated with reported trauma in a patient population. A-DES scores were able to distinguish dissociative disordered adolescents from a normal sample and from a patient sample with a variety of diagnoses.

Dissociation in posttraumatic stress disorder: evidence from the world mental health surveys

BACKGROUND

Although the proposal for a dissociative subtype of posttraumatic stress disorder (PTSD) in DSM-5 is supported by considerable clinical and neurobiological evidence, this evidence comes mostly from referred samples in Western countries. Cross-national population epidemiologic surveys were analyzed to evaluate generalizability of the subtype in more diverse samples.

METHODS

Interviews were administered to 25,018 respondents in 16 countries in the World Health Organization World Mental Health Surveys. The Composite International Diagnostic Interview was used to assess 12-month DSM-IV PTSD and other common DSM-IV disorders. Items from a checklist of past-month nonspecific psychological distress were used to assess dissociative symptoms of depersonalization and derealization. Differences between PTSD with and without these dissociative symptoms were examined across a variety of domains, including index trauma characteristics, prior trauma history, childhood adversity, sociodemographic characteristics, psychiatric comorbidity, functional impairment, and treatment seeking.

RESULTS

Dissociative symptoms were present in 14.4% of respondents with 12-month DSM-IV/Composite International Diagnostic Interview PTSD and did not differ between high and low/middle income countries. Symptoms of dissociation in PTSD were associated with high counts of re-experiencing symptoms and net of these symptom counts with male sex, childhood onset of PTSD, high exposure to prior (to the onset of PTSD) traumatic events and childhood adversities, prior histories of separation anxiety disorder and specific phobia, severe role impairment, and suicidality.

CONCLUSION

These results provide community epidemiologic data documenting the value of the dissociative subtype in distinguishing a meaningful proportion of severe and impairing cases of PTSD that have distinct correlates across a diverse set of countries.

A polysomnographic and clinical report on sleep-related injury in 100 adult patients

In 100 consecutive adults who came to a sleep disorders center complaining of repeated nocturnal injury, polysomnographic study identified five disorders: night terrors/sleepwalking (N = 54), REM sleep behavior disorder (N = 36), dissociative disorders (N = 7), nocturnal seizures (N = 2), and sleep apnea (N = 1). Ninety-five patients sustained ecchymoses, 30 had lacerations, and nine had fractures. DSM-III axis I disorders (past or current) were found in 48.1% of the group with night terrors/sleepwalking and in 30.6% of the group with REM sleep behavior disorder; these were mainly affective disorders. In these two groups, clonazepam controlled the symptoms of 51 of the 61 patients to whom it was given.

Dissociation and posttraumatic stress disorder in Vietnam combat veterans

OBJECTIVE

This study compared current dissociative symptoms and dissociation at the time of specific traumatic events in Vietnam combat veterans with posttraumatic stress disorder (PTSD) and Vietnam combat veterans without PTSD.

METHOD

Vietnam combat veterans who sought treatment for PTSD (N = 53) were compared to Vietnam combat veterans without PTSD (N = 32) who sought treatment for medical problems. Dissociative symptoms were evaluated with the Dissociative Experiences Scale. Dissociation at the time of a combat-related traumatic event was evaluated retrospectively with the modified Dissociative Experiences Questionnaire. The Combat Exposure Scale was used to measure level of combat exposure.

RESULTS

There was a significantly higher level of dissociative symptoms, as measured by the Dissociative Experiences Scale, in patients with PTSD (mean = 27.0, SD = 18.0) than in patients without PTSD (mean = 13.7, SD = 16.0). This difference persisted when the difference in level of combat exposure was controlled with analysis of covariance. PTSD patients also reported more dissociative symptoms at the time of combat trauma, as measured retrospectively by the Dissociative Experiences Questionnaire (mean = 11.5, SD = 1.6) than non-PTSD patients (mean = 1.8, SD = 2.1).

CONCLUSIONS

Dissociative symptoms are an important element of the long-term psychopathological response to trauma.

Auditory hallucinations: a comparison between patients and nonpatients

The form and the content of chronic auditory hallucinations were compared in three cohorts, namely patients with schizophrenia, patients with a dissociative disorder, and nonpatient voice-hearers. The form of the hallucinatory experiences was not significantly different between the three groups. The subjects in the nonpatient group, unlike those in the patient groups, perceived their voices as predominantly positive: they were not alarmed or upset by their voices and felt in control of the experience. In most patients, the onset of auditory hallucinations was preceded by either a traumatic event or an event that activated the memory of earlier trauma. The significance of this study is that it presents evidence that the form of the hallucinations experienced by both patient and nonpatient groups is similar, irrespective of diagnosis. Differences between groups were predominantly related to the content, emotional quality, and locus of control of the voices. In this study the disability incurred by hearing voices is associated with (the reactivation of) previous trauma and abuse.