This study was a secondary analysis of LaFreniere and Newman (2016), a randomized controlled trial comparing two ecological momentary interventions (EMIs) for generalized anxiety disorder (GAD): The worry outcome joumal (WOJ) and thought log (TL). We predicted that higher thought-related distress would be a mediator by which higher uncontrollability beliefs (UB) would hinder the efficacy of the WOJ, but not the TL. Fifty-one undergraduates who met GAD criteria underwent one of the EMIs for 10 days. WOJ users tracked worries, associated distress, interference, expected outcome probabilities, and whether their worries came true four times/day. TL users tracked general thoughts, associated distress, and interference four times/day. Bootstrapping path analysis was used to analyze moderated mediation models. Higher UB predicted higher thought-related distress for both EMIs. Higher UB also predicted reduced efficacy of the WOJ at post-trial and of both EMIs at 30-day follow-up. However, for WOJ users, when higher initial UB levels predicted higher thought related distress early in treatment, participants reported greater levels of worry at post-trial and follow-up. In contrast, UB's effect on the TL group at post-trial and follow-up was not mediated by early distress. Thought related distress appears to be a mechanism by which UB impedes the WOJ intervention.
