Understanding the mechanisms driving the reduction of repetitive negative thought

Repetitive negative thought (RNT, worry, rumination) influences the onset and maintenance of anxiety and depression. Reducing RNT is an established active therapeutic ingredient. Although cognitive-behavioural therapy (CBT) targeting RNT is effective, the mechanisms underpinning treatment effects are unknown. Our key goals are to delineate the active therapeutic components and associated mechanisms-of-action of CBT targeting RNT, via experimental manipulation of treatment components within internet-delivered RNT-focused CBT and assessment of mediators in a large-scale factorial trial for individuals with elevated RNT. Combining components in a factorial experiment is more efficient for sample size and resource than conducting separate experiments and better tests the main effects and interactions of each factor than dismantling designs. Hypothesized mechanisms include (i) shifting from overgeneral abstract to specific thinking; (ii) breaking out of RNT-as-a-habit; (iii) replacing self-criticism with self-compassion; (iv) improved present-moment focus; (v) increased patient understanding of difficulties. People with Lived Experience will shape research questions and design: they will guide prioritising which mechanisms-to-study and they will co-design adaptations to existing interventions to better manipulate these mechanisms. This novel project will test these hypotheses experimentally, leading to more potent, economical, and accessible treatments for RNT available via an online platform to transform early intervention.