Neural and behavioral correlates of peritraumatic dissociation in an acutely traumatized sample

Peritraumatic dissociative responses have been identified as strong predictors of subsequent posttraumatic stress disorder development. We aimed to clarify the mechanism by which peritraumatic dissociation is related to PTSD development by exploring the neural correlates of peritraumatic dissociation during posttraumatic adjustment.

We combined a prospective questionnaire study with a neuroimaging paradigm in an acutely traumatized sample recruited from the emergency department from 2004 until 2009. 121 acutely traumatized subjects were assessed for acute stress disorder, PTSD, and dissociative symptoms at 3 time points within the first 3 months post trauma. A subsample of 21 subjects underwent a script-driven 4-Tesla functional magnetic resonance imaging scan 2 to 4 months post trauma.

Peritraumatic dissociation predicted PTSD diagnostic status at 5-6 weeks and 3 months over and above childhood trauma (Wald = 4.035, P = .045; Wald = 4.793, P = .029, respectively). Peritraumatic dissociation scores were positively correlated with activation in the right occipital lobe, ie, the lingual (Brodmann area [BA] 18, z = 3.37), fusiform (BA 19, z = 3.64), and parahippocampal (BA 19, z = 3.25) gyri. After covariation of dissociation at the time of the scan, peritraumatic dissociation remained positively correlated with activation in the right lingual (BA 18, z = 3.21) and fusiform (BA 19, z = 3.55) gyri.

The neuroimaging findings indicate that peritraumatic dissociation is associated with greater activation of the right occipital lobe (BAs 18 and 19), a region previously implicated in vivid autobiographical memory recall of highly emotional events. These results suggest that peritraumatic dissociation directly leads to the formation of intrusive memories. Peritraumatic dissociation and childhood trauma emerged as valuable predictors of PTSD development and therefore can guide the identification of individuals at risk.