The disembodied self:Using an experimental approach to study the neural correlates of dissociation

Peritraumatic dissociation, e.g. an out-of-body experience (OBE) during a traumatic event, is an established risk factor for post-traumatic stress disorder (PTSD). However, its neural basis is not yet well understood. Experimental neuroscience and lesion studies suggest that disrupted brain function in the temporo-parietal junction (TPJ), a critical hub for multisensory integration, is associated with such anomalous bodily experiences. To explore neural markers of disrupted embodiment, we investigated how a transcranial magnetic stimulation (TMS)-induced temporary inhibition of the TPJ affects 1) dissociative experiencing including susceptibility to OBEs, and 2) the brain network of body awareness in healthy participants. First, we tested the paradigm to manipulate bodily self-consciousness called the OBE illusion and threat-evoked changes in heart rate as objective marker of OBEs. Secondly, functional connectivity ! patterns and the OBE paradigm were assessed before and after TMS (n = 26) vs. sham TMS (n = 26). It was expected that a virtual lesion at the TPJ increases self-report dissociation, elicit stronger OBE sensations, and disrupt the brain network of body awareness (e.g. insula, posterior parietal cortex, premotor cortex). Results will be discussed within the framework of dissociative processing

The Clinician-Administered Dissociative States Scale (CADSS):Validation of the German Version

The Clinician-Administered Dissociative States Scale (CADSS) is a structured clinical interview to assess state dissociation rated by clinicians. The current study aimed to validate the German version of CADSS by comparing it to the established self-report measures for dissociation and exploring its underlying factor structure. Severity of within-session state dissociation was assessed directly following a standard psychotherapy session in a trauma-exposed patient sample (N= 105; 81.9% female). Internal consistency, convergent validity with other dissociation measures, and the factorial structure of the instrument were analyzed. The German version exhibited excellent internal consistency (Cronbach's α = .94) and correlated significantly with self-report measures of state dissociation (r = .86) and trait dissociation (r = .77) indicative of high convergent validity. Exploratory factor analysis revealed a three-factor solution with the factors (1) Depersonalization/Derealization, (2) Identity Confusion/Alteration, and (3) Amnesia. Results support the CADSS as a useful instrument to assess state dissociation, conceptualized as a multidimensional construct, in clinical practice

Structural and functional brain alterations in psychiatric patients with dissociative experiences:A systematic review of magnetic resonance imaging studies

Introduction There is currently no general agreement on how to best conceptualize dissociative symptoms and whether they share similar neural underpinnings across dissociative disorders. Neuroimaging data could help elucidate these questions. Objectives The objective of this review is to summarize empirical evidence for neural aberrations observed in patients suffering from dissociative symptoms. Methods A systematic literature review was conducted including patient cohorts diagnosed with primary dissociative disorders, post-traumatic stress disorder (PTSD), or borderline personality disorder. Results Results from MRI studies reporting structural (gray matter and white matter) and functional (during resting-state and task-related activation) brain aberrations were extracted and integrated. In total, 33 articles were included of which 10 pertained to voxel-based morphology, 2 to diffusion tensor imaging, 10 to resting-state fMRI, and 11 to task-related fMRI. Overall findings indicated aberrations spread across diverse brain regions, especially in the temporal and frontal cortices. Patients with dissociative identity disorder and with dissociative PTSD showed more overlap in brain activation than each group showed with depersonalization/derealization disorder. Conclusion In conjunction, the results indicate that dissociative processing cannot be localized to a few distinctive brain regions but rather corresponds to differential neural signatures depending on the symptom constellation

Dissociation and insecure attachment as mediators of the relation between childhood emotional abuse and nonclinical paranoid traits

Background: Research suggests dissociation and insecure attachment serve as explanatory mechanisms in the pathway from childhood trauma to paranoia. However, past work has not examined these mechanisms concurrently in nonclinical populations. Objective: The current study sought to examine dissociation and insecure attachment as parallel mediators of the association between childhood emotional abuse and paranoid traits. Furthermore, a serial mediation model with insecure attachment preceding dissociation in the explanatory pathway was explored. Methods: Eighty-nine nonclinically ascertained young adults were assessed for childhood emotional abuse, dissociation, attachment styles, and paranoid traits. Parallel and serial mediation models were tested. Results: The association of childhood emotional abuse with both interview-based and self-reported paranoid traits was significantly mediated by dissociation and preoccupied attachment. Fearful attachment was a significant mediator in the model for self-reported paranoid traits. No evidence for a serial mediation effect was found. Conclusions: The present findings extend support for dissociation and attachment insecurity as mechanisms underlying the link between childhood emotional maltreatment and paranoid traits. Longitudinal research is needed to inform whether insecure attachment contributes to dissociation along the pathways to paranoid traits

Neural correlates of acute post-traumatic dissociation:a functional neuroimaging script-driven imagery study

Background: Current neurobiological models of post-traumatic stress disorder (PTSD) assume excessive medial frontal activation and hypoactivation of cortico-limbic regions as neural markers of post-traumatic dissociation. Script-driven imagery is an established experimental paradigm that is used to study acute dissociative reactions during trauma exposure. However, there is a scarcity of experimental research investigating neural markers of dissociation; findings from existing script-driven neuroimaging studies are inconsistent and based on small sample sizes. Aims: The current aim was to identify the neural correlates of acute post-traumatic dissociation by employing the script-driven imagery paradigm in combination with functional magnetic resonance imaging. Method: Functional neuroimaging data was acquired in 51 female patients with PTSD with a history of interpersonal childhood trauma. Blood-oxygen-level-dependent response during the traumatic (versus neutral) autobiographical memory recall was analysed, and the derived activation clusters were correlated with dissociation measures. Results: During trauma recall, enhanced activation in the cerebellum, occipital gyri, supramarginal gyrus and amygdala was identified. None of the derived clusters correlated significantly with dissociative symptoms, although patients reported increased levels of acute dissociation following the paradigm. Conclusions: The present study is one of the largest functional magnetic resonance imaging investigations of dissociative neural biomarkers in patients with PTSD undergoing experimentally induced trauma confrontation to elicit symptom-specific brain reactivity. In light of the current reproducibility crisis prominent in neuroimaging research owing to costly and time-consuming data acquisition, the current (null) findings highlight the difficulty of extracting reliable neurobiological biomarkers for complex subjective experiences such as dissociation

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

Latent classes of DSM-5 acute stress disorder symptoms in children after single-incident trauma: findings from an international data archive

Background: After a potentially traumatic event (PTE), children often show symptoms of acute stress disorder (ASD), which may evolve into posttraumatic stress (PTS) disorder. A growing body of literature has employed latent class analysis (LCA) to disentangle the complex structure underlying PTS symptomatology, distinguishing between homogeneous subgroups based on PTS presentations. So far, little is known about subgroups or classes of ASD reactions in trauma-exposed children. Objective: Our study aimed to identify latent classes of ASD symptoms in children exposed to a single-incident PTE and to identify predictors of class membership (gender, age, cultural background, parental education, trauma type, and trauma history). Method: A sample of 2287 children and adolescents (5–18 years) was derived from the Prospective studies of Acute Child Trauma and Recovery (PACT/R) Data Archive, an international archive including studies from the USA, UK, Australia, and Switzerland. LCA was used to determine distinct subgroups based on ASD symptoms. Predictors of class membership were examined using a three-step approach. Results: Our LCA yielded a three-class solution: low (42%), intermediate (43%) and high (15%) ASD symptom severity that differed in terms of impairment and number of endorsed ASD symptoms. Compared to the low symptoms class, children in the intermediate or high severity class were more likely to be of female gender, be younger of age, have parents who had not completed secondary education, and be exposed to a road traffic accident or interpersonal violence (vs. an unintentional injury). Conclusions: These findings provide new information on children at risk for ASD after single-incident trauma,