Results from a randomized clinical trial of a digital depression treatment on anxiety symptoms: Empirical support for the generic cognitive model.

The Generic Cognitive Model provides a theoretical framework for understanding common clinical mechanisms in psychopathology. To our knowledge, no research exists on the effects of digital treatments on common clinical mechanisms and outcomes for depressive and anxiety disorders. We analyzed the treatment effects and clinical mechanisms of a text-message delivered major depressive disorder treatment (named CBT-txt, which is efficacious in treating depression) on generalized anxiety disorder symptoms with 103 young adults. Using data from a 3-month randomized clinical trial, a repeated measures ANOVA demonstrated significant differences between CBT-txt and the wait-list control conditions' anxiety symptoms measured by the GAD-7, producing a large treatment effect (Cohen's d = 1.26). Tests of clinical significance showed at 3 months 41.3% of the CBT-txt group moved into the high end-state functioning category (no or minimal anxiety symptoms) producing a Reliable Change Index of 6.20. Mediation analyses testing hypothesized clinical mechanisms showed CBT-txt increased behavioral activation (95% bootstrap, C.I.: -2.55 to -0.40) and reduced perseverative thinking (95% bootstrap, C.I.: -2.53 to -0.46) which in turn, reduced generalized anxiety disorder symptoms. Results suggest that CBT-txt is efficacious in changing common clinical mechanisms and subsequently reducing depressive and anxiety disorder symptoms, providing empirical support for theoretically applying the generic cognitive model for digital treatments.