Structure of ICD-11 complex PTSD and relationship with psychoform and somatoform dissociation

The structure of the relationship between ICD-11 Complex Post-traumatic Stress Disorder (C-PTSD) and dissociative symptoms requires more extensive research, especially with respect to the empirical support for a DSM-5 dissociative subtype of PTSD. The present study sought to examine 1) the structural validity of ICD-11 C-PTSD, 2) the association between latent C-PTSD factors and features of dissociation, and 3) whether patients with C-PTSD show elevated levels of dissociation when compared to PTSD and no ICD-11 PTSD disorder. A sample of traumatized psychiatric outpatients (N = 114) were diagnosed with a structured interview and subsequently administered the International Trauma Questionnaire (ITQ), the Dissociative Symptom Scale (DSS), and the Somatoform Dissociation Questionnaire, 5-items (SDQ). We used Confirmatory Factor Analysis (CFA) to replicate the established structure of C-PTSD as operationalized with the ITQ. Subsequently, a structural equation model (SEM) approach was employed to examine associations of ITQ with psychoform and somatoform dissociation as measured with the DSS and SDQ. The expected factorial structure of C-PTSD was replicated in the present sample, and the domains PTSD and disturbances in self-organization were found to be related but distinct constructs. All ICD-11 C-PTSD latent factors were associated with dissociative experiences. The strongest effects were found for the symptom clusters Affective Dysregulation, Disturbances in Relationship, and Re-Experiencing. However, dissociative Gaps in Awareness and Memory and Sensory Misperception were not predicted by any ICD-11 C-PTSD latent factors. Cumulative levels of dissociative experiences appeared to differentiate ICD-11 PTSD and C-PTSD with significantly higher levels for C-PTSD. ICD-11 C-PTSD is strongly associated with dissociative phenomena in complex ways. Somatoform and psychoform manifestations of dissociation should be routinely assessed in patients with ICD-11 C-PTSD because such expressions may cover intense affects and painful relationship experiences. Future studies are needed to substantiate the causal and predictive relationship between ICD-11 C-PTSD and dissociation.