Cognitive Behavioural Therapy (CBT) has been extensively studied in the treatment of depression and anxiety disorders and related conditions. While traditional CBT assessment tends to focus on symptom reduction at pre-treatment and post-treatment points, the ways in which psychological recovery occurs across the course of therapy are under-understood and in need of further investigation. The current process-based investigation conceptualizes recovery in CBT as a sequential recalibration of cognitive restructuring, behavioural activation, emotional regulation, therapeutic collaboration, self-efficacy and consolidation of adaptive coping response. Systematic reviews, meta-analyses and quantitative research examining the efficacy and mechanisms of change in CBT were compiled and synthesized. Special focus was placed on cognitive restructuring, behavioural activation, treatment processes, therapeutic alliance, and the time course of process variables and clinical outcomes. Results of quantitative analyses suggest significant effects of CBT compared to inactive control groups in the areas of major depressive disorder and anxiety disorders, while effect sizes are smaller when compared to active interventions. The effects were reported as g = 0.75 for major depressive disorder and g = 0.88 for social anxiety disorder compared to control conditions, in a meta-analysis of 144 trials, and more recently, primary-care evidence reported g = 0.44 when comparing CBT, cognitive therapy, and behavioural activation to inactive control conditions. Three network meta-analyses have been conducted, with standardized mean differences of 0.57 for cognitive restructuring, 0.52 for behavioural activation and 0.44 for CBT compared to usual care. Regarding specific mechanisms, an association of r = .35 between cognitive restructuring and psychotherapy outcome is seen, while behavioural activation shows effects in depression, anxiety and activation outcome, according to evidence. This process model identifies symptom reduction as the downstream outcome of changes in cognitive appraisal, behavioural engagement, emotional regulation and perceived competence. The results endorse a process-oriented interpretation that posits that psychological recovery occurs via interrelated cognitive and behavioural changes that are not just based on symptom reduction. Additionally, methodological weaknesses such as heterogenous outcome measures, lack of adequate temporal measurement, use of self-report measures, and limited evidence for individual mechanisms are identified. Intensive longitudinal designs, process measurement at a session level, mediation analyses, and randomized trials on mechanisms are needed for future research.

Keywords: Cognitive Behavioural Therapy; psychological recovery; cognitive restructuring; behavioural activation; mechanisms of change; psychotherapy process; emotional regulation; self-efficacy; therapeutic alliance; depression; anxiety; cognitive change