Neurobiological Underpinnings of Trauma-related Psychopathology
The understanding and treatment of trauma-related psychopathology is a crucial challenge in the field of global mental health today. The etiology and mechanisms of two common trauma-related symptoms – intrusive re-experiencing and dissociative symptomatology – are still not well understood. The pres...
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|The understanding and treatment of trauma-related psychopathology is a crucial challenge in the field of global mental health today. The etiology and mechanisms of two common trauma-related symptoms – intrusive re-experiencing and dissociative symptomatology – are still not well understood. The present work aims to advance the understanding of these phenomena by investigating their neurobiological underpinnings in two disorders: depersonalization/derealization disorder (DPD), in which dissociation depicts the core feature, and the dissociative subtype of posttraumatic stress disorder (PTSD-D), in which dissociative symptomatology and intrusive re-experiencing co-occur and correlate in regard to their severity. Alterations in fiber tract networks in white matter, which are crucial for communicating between brain regions, have not yet been investigated in DPD or PTSD-D. In Study I, white matter network alterations were explored in 23 patients with DPD compared to 23 matched healthy controls. Results yielded relatively lower structural connectivity in left and right temporal regions in DPD, which have previously been associated with dissociative symptomatology in DPD and in other disorders. Furthermore, a trend indicated alterations in a fronto-limbic circuit, which a neurobiological model proposes underlies dissociation in DPD as well as PTSD-D. In Study II, we tested whether fronto-limbic circuits are also altered in PTSD-D (n=23) compared to ‘classic’ PTSD patients (n=19) using the same analysis pipeline as in Study I. No respective white matter changes were detected on a network level in PTSD-D. However, subsequent exploratory analyses revealed alterations in two subcortical networks comprising a limbic-thalamic circuit and low-level motor regions, respectively. The limbic-thalamic network is crucial for declarative and spatial mnemonic processes, which according to dual memory models play a crucial role for the development of intrusive memories. We tested the respective memory model in Study III and confirmed for the first time empirically, that spatial-contextual (allocentric) memory ability is negatively associated with severity of intrusive memories in 33 patients with PTSD. The findings of the present work indicate that (1) dissociation in DPD is underpinned by different alterations in structural connectivity than in PTSD-D and (2) dissociative and intrusive memories are associated with aberrations in similar sub-cortical circuits, supporting the notion that in PTSD-D, a lower state of consciousness exacerbates de-contextualization of the traumatic content, resulting in heightened intrusive symptomatology. Clinical implications of our findings are discussed.