The Neurobiology of Dissociation in Chronic PTSD

Since the inclusion of the dissociative subtype of PTSD (PTSD+DS) in DSM 5, increasing attention has been given to identifying its unique characteristics. PTSD+DS appears to be characterized by increased complexity and severity of symptoms and trauma history, as well as a wide range of dissociative symptoms beyond just depersonalization and derealization. Here, we explore the etiology of these symptoms through the lens of recent neuroimaging findings. We begin by reviewing the corticolimbic model and the conceptualization of PTSD+DS as a disorder of emotion overmodulation. Next, we conceptualize dissociative symptoms as survival defenses through discussion of the defense cascade model. Finally, we review how such defenses, and the range of present-day symptoms they produce, are enacted in the brain, with particular attention to sensory processing pathways and the emerging conceptualization of PTSD+DS as a disorder of sensory integration. We highlight the clinical relevance of this information with particular attention to emerging clinical interventions.