The distinctive neural circuitry of complex posttraumatic stress disorder during threat processing

There is controversy over the extent to which the new International Classification of Diseases (ICD-11) diagnosis of complex posttraumatic stress disorder (CPTSD) is distinct from posttraumatic stress disorder (PTSD). This study aimed to conduct the first investigation of distinctive neural processes during threat processing in CPTSD relative to PTSD.

This cross-sectional functional magnetic resonance study included 99 participants who met criteria for PTSD (PTSD = 32, CPTSD = 28) and 39 trauma-exposed controls. PTSD was assessed with the Clinician-Administered PTSD Scale (CAPS). CPTSD was assessed with an adapted version of the International Trauma Questionnaire. Neural responses were measured across the brain while threat or neutral faces were presented at both supraliminal and subliminal levels.

During supraliminal presentations of threat stimuli, there was greater bilateral insula and right amygdala activation in CPTSD participants relative to PTSD. Reduced supraliminal right dorsolateral prefrontal cortex activation and increased subliminal amygdala and insula activation were observed as common dysfunction for both CPTSD and PTSD groups relative to trauma controls. There were no significant differences in terms of subliminal presentations and no differences in functional connectivity. Dissociative responses were positively associated with right insula activation (r = 0.347, p < 0.01).

These results provide the first evidence of distinct neural profiles of CPTSD and PTSD during threat processing. The observation of increased insula and right amygdala activation in CPTSD accords with the proposal that CPTSD is distinguished from PTSD by disturbances in emotion regulation and self-concept.