Do changes in trauma-related beliefs predict PTSD symptom improvement in prolonged exposure and sertraline?

Negative trauma-related belief change has been found to predict subsequent improvement in symptoms of posttraumatic stress disorder (PTSD) in prolonged exposure (PE) and other therapies, consistent with several psychological theories of treatment change (e.g., Foa & Kozak, 1986). However, belief change has not been examined in selective serotonin reuptake inhibitors such as sertraline. We examined processes associated with symptom improvement in 2 treatments for PTSD, hypothesizing that belief change would robustly predict PTSD improvement in patients treated with PE but not those treated with sertraline, reflecting moderation by treatment.

Patients with chronic PTSD (N = 134; 78% women, 71.6% Caucasian, M = 38.1 years, SD = 11.8) received 10 weeks of PE or sertraline in a randomized, controlled trial. Patients reported PTSD and depression symptoms, and trauma-related beliefs (Post-Traumatic Cognitions Inventory; Foa, Ehlers, Clark, D Tolin, & Orsillo, 1999) at pretreatment, every treatment session, and posttreatment.

Using time-lagged mixed regression models, change in trauma-related beliefs predicted subsequent PTSD symptom improvement, an effect moderated by treatment and particularly strong in PE (d = 0.93) compared with sertraline (d = 0.35). Belief change also predicted depressive symptom improvement but more modestly and bidirectionally, with no difference by treatment modality.

Trauma-related belief change precedes PTSD improvement more robustly in PE than in sertraline and with greater specificity compared with depressive symptoms. These findings highlight potentially divergent processes contributing to symptom change in these PTSD treatments, with belief change as a key mechanism of PE. (PsycINFO Database Record