Authenticity as a Mediator of Change in the Unified Protocol for Transdiagnostic Treatment of Depressive and Anxiety Disorders

Objectives Authenticity is defined as awareness of one's internal states and actions that align with personal values, preferences and goals. Research has linked authenticity to wellbeing and lower depression and anxiety symptoms. Although authenticity has been proposed as an important process of change, there is limited empirical research examining the effect of psychotherapy on authenticity and whether changes in authenticity mediate improved mental health outcomes. This study investigated the mediating role of authenticity in psychotherapy. Methods This study is a secondary analysis of a randomized controlled trial including patients with depressive ( n = 52) and anxiety disorders ( n = 52). Multilevel models were used to assess (1) whether the Unified Protocol (UP), a transdiagnostic cognitive‐behavioural treatment, improved subjective sense of authenticity as measured by the Sense of Authenticity Scale, and (2) whether changes in authenticity mediated the treatment effect on depression. Results At post‐treatment, patients who received the UP showed significantly higher levels of self‐reported sense of authenticity compared to waitlist controls (d = 0.97, 95% CI [0.28, 1.65]). This effect was maintained at the six‐month follow‐up. Additionally, authenticity mediated the treatment effect on depression (indirect effect: b = −6.51, SE = 2.89, 95% CI [−14.04, −1.88]), accounting for 22.90% of the total effect. This mediation remained significant when controlling for therapeutic alliance. Conclusions This study provides the first empirical evidence that changes in authenticity mediate outcomes in the UP. These findings suggest that authenticity represents a viable candidate for future research examining the mechanisms of psychotherapy.