Biology Not Culture Explains Dissociation in Posttraumatic Stress Disorder

Abstract

D issociative symptoms are intriguing phenomena that have often provoked significant controversy in psychiatry (1). Dissociative phenomena evoke the literature about the nature of consciousness and its disruption in psychopathology (2). The proposal of the fifth revision of the DSM to include a dissociative subtype of posttraumatic stress disorder (PTSD) (3) is an important marker of acceptance in the 21st century of the enduring significance and relevance of these dissociative mechanisms in traumatic psychopathology. It is important to acknowledge how clinical interest in dissociation was a major focus in the original formulations of traumatic neurosis and hysteria (4) but that the interest in these phenomena has waxed and waned. Recent neuroimaging studies (5) have provided substantial validity to the centrality of dissociation to the importance on the deficits of affect regulation in PTSD (6). Dissociation is of particular relevance in elucidating the complex phenomenon of numbing that is accompanied by the subjective experience of derealization and depersonalization. The accumulated evidence is that dissociation is a regulatory strategy to deal with the intense hyperarousal that PTSD sufferers experience. The study by Stein et al. (7) utilizing the World Mental Health Survey about the ubiquitous nature of the dissociative type of PTSD across this cohort is an important step forward because it highlights that these phenomena occur across diverse cultures. In particular, it addresses the debate that has existed about the cross-cultural applicability of PTSD (8). The presence of dissociative symptoms across cultures has importance in understanding the origins of dissociative phenomena and argues for further exploration of its underlying neurobiological basis. In essence, depersonalization and derealization are symptoms that reflect a significant disruption of information processing systems and are well documented in traumatized populations. These symptoms cannot simply be dismissed as culture bound phenomena that are driven by suggestion. From an etiologic perspective, the study of Stein et al. (7), by the weight of numbers, adds to a clear relationship between dissociation phenomena and the exposure to prior traumatic events, childhood adversity, and the onset of PTSD in childhood. Also, although child abuse is strongly linked to dissociation, the type of trauma is not the critical issue to a dissociative subtype of PTSD but rather it is the age of trauma exposure and the experience of repeated traumatization that are highly predictive. Victims of child abuse are particularly likely to fall into such a group because of the early age of exposure and the repeated nature of abuse that in turn leads to a further risk of traumatic exposures by lack of protective