Changes in Posttraumatic Cognitions Mediate the Effects of Trauma-Focused Therapy on Paranoia

Abstract Background Evidence suggests that in individuals with psychosis, paranoia is reduced after trauma-focused therapy (TFT) aimed at comorbid posttraumatic stress disorder (PTSD). Objective To identify mediators of the effect of TFT on paranoia. Method In a multicenter single-blind randomized controlled trial 155 outpatients in treatment for psychosis were allocated to 8 sessions Prolonged Exposure (PE; n = 53), 8 sessions Eye Movement Desensitization and Reprocessing (EMDR) therapy (n = 55), or a waiting-list condition (WL; n = 47) for treatment of comorbid PTSD. Measures were performed on (1) paranoia (GPTS); (2) DSM-IV-TR PTSD symptom clusters (CAPS-IV; ie, intrusions, avoidance, and hyperarousal); (3) negative posttraumatic cognitions (PTCI; ie, negative self posttraumatic cognitions, negative world posttraumatic cognitions and self-blame); (4) depression (BDI-II); and (5) cognitive biases (ie, jumping to conclusion, attention to threat, belief inflexibility, and external attribution), cognitive limitations (ie, social cognition problems and subjective cognitive problems), and safety behaviors (DACOBS). Outcome in terms of symptoms of paranoia (1) and potential mediators (2–5) were evaluated at posttreatment, controlling for baseline scores. Results The effects of TFT on paranoia were primarily mediated by negative self and negative world posttraumatic cognitions, representing almost 70% of the total indirect effect. Safety behaviors and social cognition problems were involved in the second step mediational pathway models. Conclusions Targeting the cognitive dimension of PTSD in TFT in psychosis could be an effective way to influence paranoia, whereas addressing safety behaviors and social cognition problems might enhance the impact of TFT on paranoia.