The Unified Protocol (UP) is a transdiagnostic, emotion-focused, cognitive-behavioral intervention developed to treat emotional disorders. The UP intervenes in the transdiagnostic mechanisms linked to the etiology and maintenance of emotional disorders, promoting adaptive emotional regulation strategies (e.g. conscious awareness of emotions; cognitive flexibility). Originally developed for the in-person and individual format, the UP can be adapted and implemented in the online group format. It offers other advantages, namely reduced waiting lists and treatment costs, an easier implementation and increased access to psychological treatment for the most isolated populations.

This clinical trial aims to implement and evaluate the acceptability, feasibility and effectiveness of UP in an online group format in a clinical population with a primary diagnosis of anxiety disorder and/or mood disorder, compared with UP in an in-person group format. It also aims to explore the psychological processes of therapeutic change (e.g., cognitive flexibility) and their potential mediating role in the response to treatment. Additionally, the study seeks to examine group relationship processes (e.g., group cohesion and therapeutic alliance) and participants' attitudes toward different therapy delivery modalities (online versus in-person), as potential factors influencing treatment engagement and outcomes.

Participants will be recruited through online advertisements, including social media platforms (e.g., Facebook and Instagram), the UpC3 website (https://upc3.pt), referrals from other mental health services, and flyers and posters displayed at the University of Coimbra.

A total of 54 participants with a primary diagnosis of an anxiety disorder and/or mood disorder were randomized (1:1 allocation ratio) to one of two conditions: (1) UP delivered in an online synchronous group format (n = 28) or (2) UP delivered in an in-person group format (n = 26).

In both conditions, participants received 12 weekly 2-hour sessions of the UP in group. Outcomes were assessed at baseline (T0), mid-treatment (T1), post-treatment (T2), and at 3-month (T3) and 6-month (T4) follow-up assessments.