Therapist-guided online metacognitive intervention for excessive worry: a randomized controlled trial with mediation...

Previous studies have found an association between excessive worrying and negative beliefs about worry. It is unclear if change in these beliefs mediate worry reduction. This study aimed to examine (1) if a simplified online metacognitive intervention can reduce worry, (2) whether changes in negative beliefs about worry mediate changes in worry severity, and (3) moderated mediation, i.e., if the mediating effect is more pronounced in individuals with a high degree of negative beliefs about worry at baseline. Adult excessive worriers (N = 108) were randomized to 10-weeks of the online metacognitive intervention (MCI) aimed at reducing negative beliefs about worry, or to wait-list (WL). Outcomes, mediation, and moderated mediation were examined via growth curve modelling. Results indicated a significant reduction in the MCI group (d = 1.6). Reductions in negative beliefs about worry and depressive symptoms separately mediated changes in worry severity during the intervention, but in a multivariate test only the former remained significant. Sensitivity analysis indicated that the hypothesized mediation was robust to possible violations of mediator-outcome confounding. The moderated mediation hypothesis was not supported. The results from this randomized trial add to the growing literature suggesting that negative beliefs about worry play a key role in worry-related problems. ClinicalTrials.gov Identifier: NCT03393156.