Neurobiological and genetic correlates of the dissociative subtype of posttraumatic stress disorder.

Approximately 10%-30% of individuals with posttraumatic stress disorder (PTSD) exhibit a dissociative subtype of the condition defined by symptoms of depersonalization and derealization. This study examined the psychometric evidence for the dissociative subtype of PTSD in a sample of young, primarily male post-9/11-era Veterans ( = 374 at baseline and = 163 at follow-up) and evaluated its biological correlates with respect to resting state functional connectivity (default mode network [DMN]; = 275), brain morphology (hippocampal subfield volume and cortical thickness; = 280), neurocognitive functioning ( = 337), and genetic variation ( = 193). Multivariate analyses of PTSD and dissociation items suggested a class structure was superior to dimensional and hybrid ones, with 7.5% of the sample comprising the dissociative class; this group showed stability over 1.5 years. Covarying for age, sex, and PTSD severity, linear regression models revealed that derealization/depersonalization severity was associated with: decreased DMN connectivity between bilateral posterior cingulate cortex and right isthmus ( = .015; adjusted- [] = .097); increased bilateral whole hippocampal, hippocampal head, and molecular layer head volume ( = .010-.034; = .032-.053); worse self-monitoring ( = .018; = .079); and a candidate genetic variant (rs263232) in the adenylyl cyclase 8 gene ( = .026), previously associated with dissociation. Results converged on biological structures and systems implicated in sensory integration, the neural representation of spatial awareness, and stress-related spatial learning and memory, suggesting possible mechanisms underlying the dissociative subtype of PTSD. (PsycInfo Database Record (c) 2023 APA, all rights reserved).