Dissociative experiences of Vietnam veterans with chronic posttraumatic stress disorder

Trauma-related dissociation and the autonomic nervous system: a systematic literature review of psychophysiological correlates of dissociative experiencing in PTSD patients

Background: Neurophysiological models link dissociation (e.g. feeling detached during or after a traumatic event) to hypoarousal. It is currently assumed that the initial passive reaction to a threat may coincide with a blunted autonomic response, which constitutes the dissociative subtype of post-traumatic stress disorder (PTSD). Objective: Within this systematic review we summarize research which evaluates autonomic nervous system activation (e.g. heart rate, blood pressure) and dissociation in PTSD patients to discern the validity of current neurophysiological models of trauma-related hypoarousal. Method: Of 553 screened articles, 28 studies (N = 1300 subjects) investigating the physiological response to stress provocation or trauma-related interventions were included in the final analysis. Results: No clear trend exists across all measured physiological markers in trauma-related dissociation. Extracted results are inconsistent, in part due to high heterogeneity in experimental methodology. Conclusion: The current review is unable to provide robust evidence that peri- and post-traumatic dissociation are associated with hypoarousal, questioning the validity of distinct psychophysiological profiles in PTSD.

Biomarkers of Pathological Dissociation: A Systematic Review

Pathological dissociation is a severe, debilitating and transdiagnostic psychiatric symptom. This review identifies biomarkers of pathological dissociation in a transdiagnostic manner to recommend the most promising research and treatment pathways in support of the precision medicine framework. A total of 205 unique studies that met inclusion criteria were included. Studies were divided into four biomarker categories, namely neuroimaging, psychobiological, psychophysiological and genetic biomarkers. The dorsomedial and dorsolateral prefrontal cortex, bilateral superior frontal regions, (anterior) cingulate, posterior association areas and basal ganglia are identified as neurofunctional biomarkers of pathological dissociation and decreased hippocampal, basal ganglia and thalamic volumes as neurostructural biomarkers. Increased oxytocin and prolactin and decreased tumor necrosis factor alpha (TNF-α) are identified as psychobiological markers. Psychophysiological biomarkers, including blood pressure, heart rate and skin conductance, were inconclusive. For the genetic biomarker category studies related to dissociation were limited and no clear directionality of effect was found to warrant identification of a genetic biomarker. Recommendations for future research pathways and possible clinical applicability are provided.

Assessment of dissociation among combat-exposed soldiers with and without posttraumatic stress disorder

BACKGROUND

Dissociation is a disruption of and/or discontinuity in the normal, subjective integration of one or more aspects of psychological functioning, including memory, identity, consciousness, perception, and motor control. A limited number of studies investigated combat-related dissociation.

OBJECTIVE

The primary aim of this study was to evaluate the relationship between dissociative symptoms and combat-related trauma.

METHOD

This study included 184 individuals, including 84 patients who were exposed to combat and diagnosed with posttraumatic stress disorder (PTSD) (Group I), 50 subjects who were exposed to combat but were not diagnosed with PTSD (Group II), and 50 healthy subjects without combat exposure (Group III). The participants were evaluated using the Dissociative Experiences Scale (DES) to determine their total and sub-factor (i.e., amnesia, depersonalization/derealization, and absorption) dissociative symptom levels. In addition, Group I and Group II were compared with respect to the relationship between physical injury and DES scores.

RESULTS

The mean DES scores (i.e., total and sub-factors) of Group I were higher than those of Group II (p<0.001), and Group II's mean DES scores (i.e., total and sub-factors) were higher than those of Group III (p<0.001). Similarly, the number of subjects with high total DES scores (i.e.,>30) was highest in Group I, followed by Group II and Group III. When we compared combat-exposed subjects with high total DES scores, Group I had higher scores than Group II. In contrast, no relationship between the presence of bodily injury and total DES scores could be demonstrated. In addition, our results demonstrated that high depersonalization/derealization factor scores were correlated with bodily injury in PTSD patients. A similar relationship was found between high absorption factor scores and bodily injury for Group II.

CONCLUSIONS

Our results demonstrated that the level of dissociation was significantly higher in subjects with combat-related PTSD than in subjects without combat-related PTSD. In addition, combat-exposed subjects without PTSD also had higher dissociation levels than healthy subjects without combat experience.

The effect of pre-existing vulnerability factors on a laboratory analogue trauma experience

This study examined how pre-existing emotional and personality vulnerability factors affect responses to an analogue trauma experience. Sixty-eight undergraduate participants viewed a distressing film and completed measures of trait anxiety, intelligence, depression, trait dissociation, as well as changes in state anxiety, then recorded intrusions over the following week. Results revealed that trait anxiety, depression, trait dissociation, change in anxiety, and post-state anxiety were associated with intrusion frequency. Post-state anxiety mediated the relationship between trait anxiety, depression and trait dissociation, and intrusions. Implications for PTSD theories and laboratory trauma analogue research examining specific elements of cognitive models of PTSD are discussed.

An analogue study of intrusions

According to cognitive theorists, intrusive trauma memories have their origin in how information during the event is processed. Two studies investigated functional cognitive strategies during medical crises that might protect against intrusions. In Study 1, interviews with health-care professionals were used to identify cognitive strategies judged to be effective in controlling emotions and dealing with medical crises. Study 2 systematically manipulated the use of those strategies in a trauma analogue film paradigm. Experimental participants reported fewer intrusions, and less fear and avoidance of film-related stimuli during the subsequent week than controls. The manipulation did not affect anxiety during the film or memory disorganization. Implications for cognitive theories of intrusion development are discussed.

A cluster analysis of symptom patterns and adjustment in Vietnam combat veterans with chronic posttraumatic stress disorder

This study investigated whether a subgroup of veterans with malignant posttraumatic stress syndrome, as described by Rosenheck (1985) and Lambert et al. (1996), could be identified via cluster analysis within two samples of Vietnam veterans with combat-related posttraumatic stress disorder (PTSD). In the initial subsample (n = 157), four clusters were identified, including a subgroup that scored consistently higher on measures of interpersonal violence and current physical problems. Similar results were found in the cross-validation subsample (n = 156). These results provide support for the theoretical concept of malignant PTSD and suggest that veterans with chronic PTSD are not homogenous. Whereas some manifest extreme levels of both functional impairment and PTSD symptomatology, others exhibit markedly less functional impairment despite manifesting clinically significant levels of PTSD. Clinicians can consider this heterogeneity in their treatment decisions.

Psychometric properties of the Stanford Acute Stress Reaction Questionnaire (SASRQ): a valid and reliable measure of acute stress

A reliable and valid measure is needed for assessing the psychological symptoms experienced in the aftermath of a traumatic event. Previous research suggests that trauma victims typically experience dissociative, anxiety and other symptoms, during or shortly after a traumatic event. Although some of these symptoms may protect the trauma victim from pain, they may also lead to acute stress, posttraumatic stress, or other disorders. The Stanford Acute Stress Reaction Questionnaire (SASRQ) was developed to evaluate anxiety and dissociation symptoms in the aftermath of traumatic events, following DSM-IV criteria for acute stress disorder. We present data from multiple datasets and analyses supporting the reliability and construct, convergent, discriminant, and predictive validity of the SASRQ.

Hypnosis in the treatment of trauma: a promising, but not fully supported, efficacious intervention

Hypnotic techniques for the treatment of posttraumatic conditions were often used by the clinical pioneers of the end of the 19th century and by military therapists treating soldiers during the 20th century's conflagrations. More recently, hypnosis has also been used with survivors of sexual assault, accidents, and other traumas, and with various groups, including children and ethnic minorities. Nonetheless, there have been almost no systematic studies on the efficacy of hypnosis for posttraumatic disorders. This state of affairs is especially disappointing considering that: hypnosis can be easily integrated into therapies that are commonly used with traumatized clients; a number of PTSD individuals have shown high hypnotizability in various studies; hypnosis can be used for symptoms associated with PTSD; and hypnosis may help modulate and integrate memories of trauma. Hypnotic techniques may indeed be efficacious for posttraumatic conditions, but systematic group or single-case studies need to be conducted before reaching that conclusion.

Dissociative processes and symptoms of posttraumatic stress in Vietnam veterans

The diagnostic taxonomy of posttraumatic stress disorder (PTSD) is a contentious issue. Commentators are divided as to whether PTSD should remain grouped with the anxiety disorders or conceptualized as a dissociative disorder. This study sought to clarify the issue by investigating the extent to which anxiety and dissociative processes differentially predict the severity of each of the three symptoms clusters in PTSD. Seventy-four Australian veterans of the Vietnam War were assessed on measures of dissociation, trait anxiety, and posttraumatic stress symptomatology. Multiple regression analyses showed that all three symptoms clusters were predicted by anxiety, but the clusters differed in the pattern of their relationship with dissociation variables. The failure of pathological dissociation to predict PTSD symptoms prompts a reconsideration of the point at which dissociative mechanisms may impact on this disorder. The findings are consistent with current classification of combat-related PTSD as an anxiety disorder.

Patterns of dissociation in clinical and nonclinical samples

Research has consistently found elevated mean dissociation scores in particular diagnostic groups. In this study, we explored whether mean dissociation scores for different diagnostic groups resulted from uniform distributions of scores within the group or were a function of the proportion of highly dissociative patients that the diagnostic group contained. A total of 1566 subjects who were psychiatric patients, neurological patients, normal adolescents, or normal adult subjects completed the Dissociative Experience Scale (DES). An analysis of the percentage of subjects with high DES scores in each diagnostic group indicated that the diagnostic group's mean DES scores were a function of the proportion of subjects within the group who were high dissociators. The results contradict a continuum model of dissociation but are consistent with the existence of distinct dissociative types.

Post traumatic stress disorder: an evolving concept

This inductive inquiry used Rodgers' evolutionary view of concept analysis to define the concept post-traumatic stress disorder (PTSD). Medline, a computerized database, was used to generate the literature sample. Based on the analysis, PTSD was defined as a complex varying psychological and biological response to an acute stressor experienced directly or indirectly, or to chronic stress. PTSD is detrimental to normal functioning of individuals. People who had prolonged exposure to a stressor, who felt guilt for their own actions, and who had a less adequate support system had more severe symptoms. Future research is needed to find ways to prevent or minimize development of PTSD.