Anxiety and depression symptoms and disorders are among the leading causes of associated disability and burden of disease worldwide among young people (Whiteford et al., 2013; World Health Organization [WHO, 2021]). The worldwide prevalence of mental disorders in children and adolescents has been reported at 13.4%, anxiety disorder at 6.5%, and depressive disorder at 2.6% (Polanczyk et al., 2015). In Spanish adolescents, the estimated prevalence for all anxiety disorders is 11.8% (Canals et al., 2019), while for all depressive disorders it is 3.4% (rate of depressive symptoms 11.6%) (Canals-Sans et al., 2018). Anxiety and depression are comorbid conditions both at a clinical and subclinical level. Adolescents who report anxiety problems also have a higher risk of presenting mood problems and vice versa (Balázs et al., 2013; Canals et al., 2019). In addition, the first mental disorder occurs before the age of 14 in a third of cases and before the age of 18 in almost half (48.4%) (Solmi et al., 2021). The peak/median age of onset across all mental disorders is 14.5 years old (Solmi et al., 2022). Moreover, experiencing mental health problems before 14 years of age has been associated with an elevated risk for adult mental disorders (Mulraney et al., 2021).

The consequences of poor psychological adjustment have repercussions in other spheres of young people’s lives (i.e., personal, family, school, social, economic, health care) in the short, medium, and long term (Erskine et al., 2015; Marrero et al., 2020). In education, good health is linked to reduced drop-out rates and better educational attainment and performance (WHO, 2021). Economically, the annual human capital loss from mental health conditions in children aged 0-19 is $387.2 billion, of which $340.2 billion are related to anxiety and depressive disorders (UNICEF, 2021). For instance, a recent meta-analysis showed that depression was associated with higher direct costs in adolescents (König et al., 2020). In addition, global prevalence and the burden of depressive and anxiety disorders increased in 2020 due to the COVID-19 pandemic (Amorós-Reche et al., 2022; Santomauro et al., 2021). Given all of that, and the sustainable development goals (SDGs) for mental health (Patel et al., 2018), this emerging social challenge needs to be addressed through prevention strategies in significant developmental stages, such as adolescence.

Schools are at the forefront of promoting mental health, as well as prevention and early interventions during childhood and adolescence. They are the “natural” place for actions to promote mental well-being and, specifically, to prevent mental health problems. Most adolescents spend long periods of time in classrooms, with schools being one of the main agents involved in socialization, as well as in training and promoting optimal development. In this regard, the WHO Guidelines on School Health Services (WHO, 2021) highlight that schools are essential environments for acquisition of socio-emotional skills (e.g., self-regulation and resilience). In the last decade, a range of psychological interventions have been tested for promoting mental health and preventing mental health problems in schools with varying degrees of success (Feiss et al., 2019; González-Roz et al., 2023; Werner-Seidler et al., 2017). Previous research suggests that universal prevention programs for depression had smaller effect sizes post-test than targeted programs, but effect sizes for anxiety were similar for universal and targeted programs (Werner-Seidler et al., 2017). Overall, school-based mental health services demonstrated a small-to-medium effect (Hedges g = 0.39) in reducing mental health problems, with the largest effects found for targeted intervention (Hedges g = 0.76), followed by selective prevention (Hedges g = 0.67), compared with universal prevention (Hedges g = 0.29) (Sánchez et al., 2018). However, there is still a need for a stronger, broader evidence base in the field of mental health promotion and prevention in school settings (O’Connor et al., 2018; O’Reilly et al., 2018).

In recent decades, increasing efforts have been made to prevent mental health problems in adolescent populations, with the development of a plethora of interventions (Fonseca-Pedrero et al., 2021; Weisz & Kazdin, 2017). Research in the field has recently shown interest in understanding it from a transdiagnostic perspective, exploring variables that can account for the onset, progression, and maintenance of different emotional disorders and other co-occurring conditions. Various transdiagnostic psychological interventions have been designed and tested for treatment and prevention, and there have been encouraging findings regarding efficacy, efficiency, and effectiveness (Dalgleish et al., 2020; Fusar-Poli et al., 2019). Within this transdiagnostic approach, Barlow and colleagues developed the Unified Protocol for Transdiagnostic Treatment of Emotional Disorders (UP) for adults (Barlow et al., 2011; Barlow et al., 2017), adolescents (UP-A), and children (UP-C) (Ehrenreich-May et al., 2018). The UP was designed to be a flexible, evidence-based intervention that could treat a wide range of emotional disorders and other mental health conditions with strong emotional components. Previous systematic reviews also indicate that these adaptations usually achieved their intended outcomes; however, further research is needed (Cassiello-Robbins et al., 2020).

The UP-A is an emotion-focused, transdiagnostic cognitive behavioral therapy (CBT) for adolescents (aged 12-17) with a principal diagnosis of any anxiety disorder, any depressive disorder, or any combination of the two (Ehrenreich-May et al., 2018). The UP-A is a downward extension of the UP for adults. It is divided into five main treatment modules (Emotion education, Emotional awareness; Generalized emotion exposures, Nonjudgmental awareness; Cognitive reappraisal, Problem solving; Interoceptive and in vivo exposures, Behavioral activation; Skill consolidation and Relapse prevention) and three optional modules. It is designed to be delivered within 8-21 weekly sessions. Recent studies have shown it to be effective for reducing symptoms of anxiety and depression and functional impairment in adolescents with emotional disorders (Ehrenreich-May et al., 2017). In addition, a significant treatment effect in favor of UP-A was observed for all outcome measures at posttreatment (Bilek & Ehrenreich-May, 2012; Ehrenreich-May et al., 2017; Grossman & Ehrenreich-May, 2019; Kennedy et al., 2019; Weintraub et al., 2020). The UP-A has been adapted to Spanish as a School-Based Anxiety and Depression Prevention Program delivered in a school setting (García-Escalera et al., 2017; García-Escalera et al., 2020). Preliminary results showed that overall differences between conditions did not reach statistical significance. However, subgroup analyses showed a greater decrease of symptoms in the UP-A. Along these lines, and according to García-Escalera et al. (2019), the UP-A is an interesting protocol for application in prevention, since it has a manual, it can be flexibly administered, and it is relatively easy to apply. It also addresses the main risk and maintenance factors of emotional problems. The UP-A shows promise adapted to other formats (e.g., online) and goals (e.g., indicated prevention).

Studies have provided preliminary evidence of the effectiveness of the UP-A in the treatment of anxiety and depression symptoms in adolescents. However, to date there have been few randomized controlled trials (RCT). In addition, the UP-A has not yet been applied in Spain to a large sample of adolescents with emotional problems (indicated prevention) in school settings, nor have medium- or long-term follow-ups (e.g., 12 and 18 months) been carried out to verify the efficacy of the UP-A. In this context, the main goal of the present study is to evaluate the effectiveness of the UP-A in adolescents with moderate emotional symptoms in educational settings. The main goals of the PSICE project are: a) to reduce symptoms of anxiety and depression, b) to prevent clinically elevated levels of anxiety and depression, and c) to improve adolescents’ socioemotional adjustment, learning processes, and academic achievement.

The study has been approved by the CEImLAR (Clinical Research Ethics Committee of La Rioja, number PI 552). Following gold standards in research on intervention effectiveness (CONSORT), the study design including the proximal and distal outcomes has been preregistered in ClinicalTrials.gov (ref: NCT05322642).

Emotional symptoms and disorders in young people stand out as an educational and public health problem because of both their prevalence and associated co-morbidity, as well as the risk of personal, family, social, and health consequences extending into adulthood. More specifically, these problems can have a negative effect on academic performance and learning processes in the short, medium, and long term. Mental health is an integral component of health and well-being and influences academic, social, and economic outcomes across the lifespan. Adolescence is an essential stage of human development during which the roots of later adulthood are put down. Young people hold the key to creating a better future. Ignoring this issue could be considered almost unconstitutional, as it affects the basic human rights and quality of life of a significant section of the country’s population. In addition, schools are one of the best settings for promoting and protecting mental health and psychosocial well-being during adolescence. This emerging educational, health, and social challenge needs to be addressed through evidence-based research and informed decisions.

In order to respond to these issues, we believe that using the UP-A, which has a treatment manual and is widely applicable to emotional disorders in adolescents, and assessing its effectiveness, will contribute to the evaluation and dissemination of school-based psychological interventions in Spain. The PSICE project aims to provide initial support for the effectiveness of manual-guided, transdiagnostic CBT preventive interventions for anxiety and depression in adolescents in regular school settings delivered by school psychologists. The central purpose is to reduce symptoms of anxiety and depression in adolescents as an indicated prevention, and at the same time, to improve adolescents’ social-emotional adjustment, learning processes, and school achievement.

Emotional disorders and symptoms can be prevented with timely, evidence-based, and often low-cost interventions. For instance, two transdiagnostic CBT protocols have been developed and evaluated for young children: a) EMOTION: “Coping Kids” Managing Anxiety and Depression (Kendall et al., 2013) and b) Super Skills for Life (Essau & Ollendick, 2013). The efficacy of these transdiagnostic programs has been demonstrated at international (Essau et al., 2019; Loevaas et al., 2020) and at national levels (de la Torre-Luque et al., 2020; Fernández-Martínez et al., 2019, 2020). The UP-A is an emotion-focused, standardized, transdiagnostic CBT for adolescents (ages 12-17) with anxiety or depressive disorders (Ehrenreich-May et al., 2018). However, new studies are required in order to extend the evidence. For instance, in Spain the UP-A has not yet been applied as an indicated prevention program, with an active control group, medium-term follow-up testing, incorporating the module for families, or using large and representative samples of the population.

This evaluation design is subject to at least two limitations. First, given that the measures are self-reported, some potential bias in substance use estimations is expected. Nonetheless, self-reporting is deemed suitable and has been used in previous evaluations of prevention programs in schools. Second, the participating schools will not be randomized; instead, they will be selected from those currently delivering the intervention, limiting the generalizability of the results, but ensuring ecological validity.

The implementation of preventive, standardized, empirically supported psychological interventions such as the UP-A will allow proper management of school, social, economic and/or care resources and make them accessible to a large proportion of the population. In addition, the PSICE project will, among other things, help us to: a) better understand the etiological mechanisms and target modifiable vulnerability factors—from a dimensional, transdiagnostic, dynamic perspective—that underlye emotional problems during adolescence; b) demonstrate that prevention strategies are effective in a real-world school setting, at low cost in the educational context, with benefits on personal, family, school, social, and health levels; c) determine the importance and relevance of psychologists in schools; d) ensure that empirically supported psychological interventions, carried out by school psychologists, are accessible to the whole population; and e) provide a novel line of action within the framework of promoting emotional well-being and prevention of child and adolescent mental health problems to improve, optimize or enhance, mental health policies and learning processes in educational contexts.

To conclude, it should be noted that it is a constitutional duty to promote, protect, and look after the entire population’s mental health, particularly, in children and adolescents. People deserve high-quality, accessible, inclusive, public psychological care that improves the quality of life for present and future generations. We all share responsibility and can play an important role in listening to and supporting our children and adolescents, helping them to build a good sense of belonging and a life worth living. It is time to act, generating hope through action.