Are Changes in Beliefs About Rumination and in Emotion Regulation Skills Mediators of the Effects of Internet-Delivered Cognitive-Behavioral Therapy for Depression and Anxiety? Results from a Randomized Controlled Trial

Abstract

Background Internet-delivered cognitive behavior therapy (iCBT) is effective in treating anxiety and depression. Research on how these interventions operate is scarce. This study explored whether emotion regulation skills and positive beliefs about rumination were affected by iCBT and if these constructs mediated changes in depression and anxiety. Methods This is a secondary analysis of a pragmatic randomized waitlist-controlled trial testing the effectiveness of supported iCBT. Adults with at least mild symptoms of depression or anxiety were included. Depression (PHQ-9), anxiety (GAD-7), positive beliefs about rumination (PBRS-A) and two emotion regulation skills: cognitive reappraisal (ERQ-A) and expressive suppression (ERQ-S), were measured at baseline and 8-weeks post-treatment. Results The analyses included 358 participants, 71% were female. Median age was 29. Linear mixed models showed statistically significant differences along ERQ-A in favor of the iCBT group ( b \u2009=\u20091.83, SE \u2009=\u20090.82, p \u2009=\u2009.026). Mediation analyses showed reductions in depression ( b \u2009=\u20090.31, SE \u2009=\u20090.15, p \u2009=\u20090.043) and anxiety symptoms ( b \u2009=\u20090.27, SE \u2009=\u20090.14, p \u2009=\u20090.057) were partially mediated by gains in ERQ-A. No effects were observed for PBRS-A and ERQ-S. Conclusions These results align with findings from face-to-face therapy and add to the scarce literature on mediators of effects of iCBT, contributing to the understanding of how these interventions operate. Since mediator and outcome variables were measured at the same time, partial mediation results should be interpreted with caution since the study design did not account for temporality and therefore causality effects cannot be confirmed. Trial Registration ISRCTN91967124.