COVID-19 pandemic disrupted trial recruitment in 2020-2022. Cooperating healthcare centers lacked resources, and funding was exhausted, necessitating trial termination.

Cognitive Behavioral Therapy (CBT) is the most prestigious psychological treatment for depression. However, not only do we need to increase its efficacy but also to widen the repertoire of evidence-based psychotherapeutic interventions. The importance of the patient's engagement in treatment is highlighted in the literature as a key factor for a good therapeutic outcome over and above the type of therapy. In this sense, personal construct therapy (PCT), with some promising supporting evidence, is particularly suited to fit the personal values and attitudes of each patient. In contrast to CBT, PCT does not educate patients about depression and give them directions on the changes to be made in their dysfunctional behaviors or cognitions. Rather, PCT explores their coherence with respect to the person's sense of identity, their construction of self and others, and works with the conflicts or dilemmas that appear during this conjoint exploration using the Repertory Grid Technique (RGT). In this project, for the first time, the RGT will be implemented using Virtual Reality (VR). This format could be highly appealing for young people, thus facilitating their involvement in therapy. The efficacy of this innovative application of PCT using VR (PCT-VR) will be compared to usual PCT, and to CBT in a randomized clinical trial. The Beck Depression Inventory-II is the primary outcome measure for calculating both statistical and clinical significance, but other measures will also be used at pre-, post-therapy and six-month follow up. The trial will be done in a natural health context, mostly the usual primary care center of each patient, with those who consult during the active period of the study.

Our research group has been working on both depression and personal construct theory for more than two decades (this includes our previous funded projects), particularly with a dilemma-focused intervention aimed to resolve the cognitive conflicts detected with the RGT. By fostering a technological innovation with VR, it is expected to boost the current efficacy of psychotherapy by increasing the engagement of young people and obtaining better outcomes. If these goals are met, a pathological evolution of the patient with its associated personal, health and social costs could be avoided.

This project will allow to test the hypothesis that a novel brief psychotherapeutic intervention, personal construct therapy with virtual reality (PCT-VR) will be more efficacious in the treatment of mild-to-moderate depression of young adults than current treatments such as the well-established Cognitive Behavioral Therapy (CBT), and the promissory personal construct therapy (PCT). It is expected that the enhancement of a current psychotherapy with VR, based on the immersive exploration of the patient's self-identity, will increase the positive effects of existing psychological therapies (at least the other therapies included in the study) in terms of symptom reduction of depressive symptoms (primary outcome), and bettering of psychological functioning, wellbeing and satisfaction. It is assumed that the use of the VR device created for this study, will make the treatment more attractive for young adults, this increasing their engagement in the therapy process. It is hypothesized that an immersive exploration of the personal constructs used to perceive self and others will facilitate self-understanding and change. As a secondary hypothesis, it is expected that PCT, thanks to its personalized and non-prescriptive nature, will be more efficacious than CBT. Also, as reflected in the literature, it is expected that the quality of the therapeutic alliance will be associated to outcome, but whether this association varies in its intensity across therapy modalities will be also explored.

General objectives With this project, it is pursued the goal of increasing the efficacy of psychological therapies for mild-to-moderate depression in young adults. It is expected to obtain better clinical results with the promissory and novel treatment modalities (PCT and PCT-VR) than with the current most prestigious CBT. By obtaining supporting evidence for these therapies, the range of psychotherapeutic alternatives for depression will be increased and this will benefit the potential for adapting the interventions to the personal styles, characteristics and preferences of each patient. An optimal personalization of the treatment favors the patient engagement in therapy and strengthens the therapeutic alliance which, in turn, should be reflected in a facilitation of the change process.

Specific objectives

1. To assess the efficacy of an innovative VR-enhanced treatment modality of psychotherapy (PCT-VR) which has never been tested before. Differential outcomes will be considered not only in terms of statistical but also clinical significance and remission rates. In addition to the reduction of depressive symptoms our study is aimed also to better psychological functioning, wellbeing and satisfaction with the services provided.

2- To evaluate the efficacy for mild-to-moderate depression in young adults of PCT, a psychotherapeutic approach with some supporting evidence for a variety of disorders and conditions but still insufficient to be considered efficacious for depression.

3- To verify the good levels of efficacy shown by CBT in the treatment of depression, mostly in international studies.

4- To identify baseline variables predicting differential outcome such as symptom severity (also comparing mild with moderate depression), and characteristics of the personal construct system such as the level of cognitive conflict.

5- To gauge the significance of the therapeutic alliance in the different treatment modalities of the study and its influence in the therapeutic outcomes measured.

6- To explore the personal views of patients with respect to the therapy process that they will have experienced as a way to advance our knowledge of the therapy process (including potential adverse effects) of each treatment. To compare this knowledge with the quantitative results of the study might be helpful for a better understanding of the entire process.

Inclusion Criteria:

• All participants will meet diagnostic criteria for mild or moderate depressive episode according to ICD-10 (current version in the Catalan health system), diagnosed using MINI, and a score above 13 and below 29 on the BDI-II questionnaire.

Exclusion Criteria:

• Patients presenting bipolar or other affective disorders (ICD-10), psychotic symptoms, substance abuse, organic brain dysfunction, acute suicidal ideation or mental retardation will be excluded from the study. The presence of other comorbid conditions (anxiety, eating or personality disorders, etc.) will not be cause for exclusion but they will be assessed and recorded and explored statistically. Finally, those who do not have enough level of competence to communicate in Spanish or Catalan, or patients with substantial visual, hearing and cognitive deficits cannot be included

Individual participant data for all primary and secondary outcomes, after deidentification

Data will be available after six months of study completion

Researchers who provide a methodologically sound proposal whose proposed use of the data has been approved by an independent review committee