Abstract
Background and objectives: Inhibitory Learning Theory (ILT) framework implies that in-session distress variability may promote extinction learning and thereby enhance exposure therapy efficacy. Thus far, research has mainly focused on in-session distress reduction. The aim of the current study was to assess whether in-session distress variability predicts next session PTSD symptom decline in PTSD patients receiving prolonged exposure (PE). Methods: Eighty-six patients with PTSD received 14 to 16 sessions of PE. Using dynamic panel models, we assessed the temporal relation (i.e., within-persons) between in-session distress variability and PTSD symptom decline. Moreover, we assessed the averaged relation (i.e., between-persons) between in-session distress variability and PTSD symptom decline. Results: Temporal analyses showed that in-session distress variability did not precede PTSD symptom improvement. Averaged analyses showed that distress variability was related to PTSD symptom improvement. Limitation: The operationalization of distress variability appeared to deviate from its theoretical conceptualization. Conclusions: In absence of distress reduction, distress variability can vary. However, our findings suggest that in-session distress variability does not drive symptom reduction during PE. In contrast, averaged over participants, distress variability was related to symptom improvement, suggesting that those with a more variable distress pattern across sessions show better treatment response. More empirical work is needed to shed light on the effect of distress variability during exposure sessions on treatment outcome and to offer grounds for clinical recommendations.
