Change in negative posttraumatic cognitions is a proposed mechanism through which Prolonged Exposure (PE) leads to symptom reduction of posttraumatic stress disorder (PTSD). A strong case for posttraumatic cognitions as a change mechanism in PTSD treatment can be made by establishing temporal precedence of change in cognitions. The current study examines the temporal relationship between change in posttraumatic cognitions and PTSD symptoms during PE, using the Posttraumatic Cognitions Inventory. Patients with DSM-5 defined PTSD following childhood abuse (N = 83) received a maximum of 14-16 sessions of PE. Clinician-rated PTSD symptom severity and posttraumatic cognitions were assessed at baseline, week 4, 8, and 16 (post-treatment). Using time-lagged mixed effect regression models, we found that posttraumatic cognitions predicted subsequent PTSD symptom improvement. Notably, when using the items of an abbreviated version of the PTCI (PTCI-9), we found a mutual relationship between posttraumatic cognitions and PTSD symptom improvement. Crucially, the effect of change in cognitions on PTSD symptom change was greater than the reverse effect. The current findings corroborate change in posttraumatic cognitions as a change process during PE, but cognitions and symptoms cannot be completely separated. The PTCI-9 is a short instrument that appears suitable to track cognitive change over time.
Keywords: Mechanisms of change; Posttraumatic cognitions; Posttraumatic stress disorder; Prolonged exposure therapy.
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