Trauma-Related Negative Cognitions Mediate the Relationship Between Avoidant Personality Beliefs and Impeded Response to Psychotherapy for PTSD

There is strong research evidence for the association of personality pathology and posttraumatic stress disorder (PTSD), as well as trauma-related negative cognitions (TRNC) and PTSD symptoms. However, the relationship between personality pathology and TRNC in the context of PTSD is mostly unknown. In the present study, we aimed to examine whether avoidant and borderline personality beliefs (PB, indicator of personality pathology) could predict therapy outcome in PTSD, and whether the relationship between PB and therapy outcome could be mediated by TRNC. Sixty patients with PTSD were assessed for PB, TRNC and PTSD symptoms at baseline, and for PTSD symptoms at the termination of Prolonged Exposure Therapy. Baseline avoidant PB predicted significant variance in PTSD symptoms at termination over and above baseline PTSD symptoms (16% reduction in treatment effect per SD on avoidant PB). Moreover, TRNC at baseline fully mediated the relationships between baseline avoidant PB and PTSD symptoms at termination. This is the first study to show that avoidant PB predicts treatment response in PTSD, and that patients with avoidant beliefs are more vulnerable to have TRNC, which are associated with impeded therapy response. Our results highlight the importance of targeting both dysfunctional PB and TRNC in PTSD interventions.