Mastery and motivational clarification as mediators of cognitive behavioral therapy versus exposure-based cognitive behavioral therapy for depression

<b>ABSTRACT</b><b>Background:</b> With the rising prevalence of major depressive disorder in the general population, understanding the mechanisms through which therapeutic interventions affect treatment outcomes is crucial. This study investigates the roles of mastery and motivational clarification as mediators of the treatment effectiveness of cognitive therapy for depression. <b>Methods:</b> This secondary analysis used data from a randomized controlled effectiveness trial involving 149 participants (<i>M</i> age = 40.7 years, <i>SD</i> = 11.6; 59.6% females, 40.4% males), who received a maximum of 22 sessions of either cognitive behavioral therapy (CBT) or exposure-based cognitive behavioral therapy (EBCT-R). Cross-lagged panel models were used to examine how mastery and motivational clarification mediated changes in depression severity over time. <b>Results:</b> The mediation paths showed a significant positive effect of therapy condition on mastery, with a larger increase for participants in the CBT condition. Mastery had a positive effect on WHO-5 well-being ratings and significantly mediated the treatment effect on well-being. Motivational clarification also had a significant positive effect on WHO-5 ratings, but did not mediate the overall treatment effect. <b>Conclusion:</b> Results suggest that fostering both mastery and motivational clarification within therapeutic interventions can enhance patients' well-being, with mastery specifically mediating the effects of CBT on treatment outcomes.