Dissociative symptoms in patients with substance use disorders

Abstract

Traumatic experiences and their consequences, such as dissociative symptoms and post-traumatic stress disorder (PTSD), often co-occur with substance-related disorders (SUD) such as alcohol and/or drug abuse or dependence. The comorbidity of dissociation, PTSD, and substance-related disorders is often associated with a more severe course of illness and poorer treatment outcomes in affected patients compared to patients with each of these disorders alone. The exact relationship between traumatic experiences, dissociation, PTSD, and addictive disorders is not fully understood, and little research has addressed this complex comorbidity. An open question concerns the prevalence of dissociative symptoms in the subgroup of patients with PTSD and SUD. Most existing studies on this topic are relatively small, use self-report instruments rather than clinical interviews, and include patients who are in early withdrawal or still actively using substances. Further, the relevance of the dissociative subtype of PTSD (D-PTSD), a new diagnostic category in the fifth version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), has hardly been studied in patients with SUD. Another open question concerns approaches to diagnose the full spectrum of dissociative symptoms in SUD patients as a prerequisite for specific treatment. Finally, one of the major challenges in this severely affected patient group is a better understanding of important clinical aspects, such as self-injury and suicidality. Therefore, the aims of this dissertation were 1) to investigate the prevalence of the dissociative subtype of PTSD in patients with SUD, 2) to psychometrically validate a commonly used instrument on dissociative symptoms in this group that also captures somatoform dissociation, and 3) to better understand potential predictors of suicidal behavior in SUD patients with complex trauma as a basis for improved therapeutic interventions. To answer the above questions, latent clinical subtypes, including the dissociative subtype of PTSD, were examined in a large sample of female patients with SUD and PTSD (Study I). In addition, given the importance of the full spectrum of dissociative symptoms also in SUD patients, the factor structure of the extended German version of the Dissociative Experiences Scale (Fragebogen zu Dissoziativen Symptomen, FDS), which also measures somatoform dissociation, was examined in a large sample of SUD patients (Study II). Finally, in our last study (Study III), we examined direct and indirect associations between five different types of childhood trauma (CT), dissociation, and suicidal behaviors, such as suicide attempts (SA) and suicidal ideation (SI), taking into account moderating effects of PTSD. Study I identified a substantial group of patients with the dissociative subtype of PTSD (D-PTSD). Patients with D-PTSD showed more severe psychopathological symptoms than the other patients, indicating increased clinical needs in this vulnerable group. Study II demonstrated that the FDS can be used to reliably screen SUD patients for dissociative psychopathology both within the conceptual framework for these symptoms in the DSM, and in the International Classification of Diseases (ICD). The results of Study III suggest that dissociation directly affects both SI and SA in patients with comorbid SUD and PTSD. In addition, dissociation was found to mediate the relationship between various forms of childhood trauma and suicidal behaviors.