Contrary to widespread belief, mental disorders are common during childhood and adolescence with 10–20% of all children experiencing one or more of these problems, incurring severe social burden; consequently, mental health promotion is an urgent issue, and early detection and intervention are essential [1]. Moreover, a recent meta-analysis estimated that the worldwide prevalence of mental disorders was 13.4% (95% confidence interval 11.3–15.9) among a sample of 87,742 children [2]. This suggests that approximately 241 million youths are affected by at least one mental disorder globally.
Although fear and anxiety are considered normal emotions that every child experiences during typical development, some children have profoundly high anxiety levels compared to typically developing children, which can cause severe impairment in their daily lives. Anxiety disorders are the most common psychological problem among children and adolescents [2, 3]. Moreover, anxiety disorders in children and adolescents predict mental health difficulties broadly in their later life including anxiety disorders, mood disorders, and substance abuse [4].
Children and adolescents are also currently experiencing depression at an unprecedented rate [5]. Recently, prevalence studies in Japan have shown that 8.8% of adolescents aged 12–14 years met one or more depressive disorders based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision [6]. Depression in children and adolescents often co-occurs with anxiety disorders [7]. Furthermore, anxiety and depression are also frequently occurring in children and adolescents with neurodevelopmental disorders such as attention-deficit/hyperactivity disorders (ADHD) or autism spectrum disorder.
Finally, anger and irritability are relatively common behaviors in children and adolescents aged 9 to 16 years (51.4% showed phasic irritability in a community sample) [8] and are the most frequent reasons for mental health referrals [9]. Although anger/irritability is a core symptom of oppositional defiant disorder or disruptive mood dysregulation disorder, irritability is also seen in children with anxiety disorders, depressive disorders, or ADHD [10]. Children and adolescents frequently experience a wide variety of emotional and behavioral difficulties throughout their development. Regardless of whether the severity of these issues meet the clinical criteria for a diagnosis, preventive interventions can support behavioral and emotional regulation related to a wide variety of concerns, ultimately promoting positive youth development and even mitigating the onset or severity of later disorders.
Preventative actions in schools
Since students learn and develop their social and emotional competence in school, schools play a key role in fostering healthy social and emotional development among youths [1]. Specifically, teachers, as models, are in a very powerful position and their opinions concerning what constitutes mental health impacts the concepts of mental health adopted by their students [11]. School-based approaches, especially those implemented by schoolteachers, are a crucial avenue for the prevention of mental health problems [12].
Diverse school-based prevention programs have been developed and examined in several countries. There are three types of school prevention programs: universal, selective, and indicated [13]. Universal prevention includes all members regardless of their risk status. Selective prevention focuses on individuals who have a risk for mental disorders, such as parental psychopathology or adverse circumstances. Indicated prevention means an intervention for individuals who already have mild to moderate symptoms.
Among the three types of prevention programs, universal prevention in school has several inherent advantages. First, a universal prevention program can access most students who are enrolled in each school district, while rarely experiencing attrition. Second, a universal approach can minimize the risk of “labeling” for students who are removed from a classroom for selective or indicated interventions. Third, a universal approach can strengthen the protective role of the school environment, which might have proximal influences on children, according to the ecological model of child mental health [14]. Fourth, because all students can participate regardless of risk or diagnostic status, implementation of a universal prevention program can support future selective and/or indicated interventions as a framework for layered or stepped preventive approaches. Universal prevention based on a cognitive-behavioral approach is designed to enhance individuals’ specific coping strategies for current/future adversity, and encourages application of those skills to support other students. A previous trial for adult outpatients with anxiety and depressive symptoms suggested that group cognitive-behavioral therapy (CBT) can ameliorate their emotional symptoms as well as improve their self-stigma [15]. A group-based CBT in the classroom showed increased knowledge about mental health and decreased stigma to individuals with mental disorders. Moreover, students in the 5th and 6th grades who participated in the intervention showed significant improvement in self-efficacy, indicating that they can support friends and people around them with mental health problems [16]. Therefore, students, as well as school personnel, can acquire mental health literacy and reduce stigma for mental disorders through teaching cognitive-behavioral skills.
Evidence of prevention programs in schools
Most school prevention programs for mental health were based on cognitive-behavioral interventions [17]. Some were created as universal programs, whereas others were originally designed for selective or indicated programs. For example, open trials for universal depression prevention interventions have shown a significant improvement in social skills and a reduction in depressive symptoms among elementary school children aged 8 to 12 years [16, 18], and the positive effect was maintained three years later [19].
Several systematic reviews of school-based prevention programs for depression covering ages ranging from 5 to 22 years old have been published [20,21,22]. These studies showed that targeted (i.e., selective and indicated) programs could be marginally superior to universal prevention programs, while the efficiency of universal prevention programs was somewhat inconsistent. The Cochrane Review in 2011 affirmed some evidence that universal, as well as targeted depression, prevention programs may prevent the onset of depressive disorders compared with no intervention in children and adolescents aged 5 to 19 years [23]. However, the latest review of depression prevention programs concluded that prevention programs delivered universally to child and adolescent populations aged 5 to 19 years showed “a sobering lack of effect when compared with an attention placebo control” ([24] p. 49).
Regarding anxiety, Neil and Christensen [25] reviewed 27 randomized controlled trials of school-based programs for children (5–12 years) or adolescents (13–19 years). Over half the studies (59%) were universal prevention programs (30% were indicated programs and 11% were selective programs). Approximately eleven of the sixteen (69%) universal trials reported significant improvement post-intervention (ES = 0.31 to 1.37), while five trials failed to find significant improvement (ES = − 0.21 to 0.28). According to a meta-analysis of school-based prevention programs focused on both anxiety and depression for kindergarten through 12th grade, including 31 universal trials [26], there was no clear effect for anxiety; however, a significant improvement for depression was shown in a direct comparison between intervention and control participants (Zs = 0.99 and 2.77, respectively, p < 0.01). Whereas universal preventive actions for anger and anger-related problems have been addressed as being useful to improve children’s social and academic development in kindergarten and early childhood [27], there is no research using CBT-based universal prevention programs for anger-related problems in middle to late childhood (6–18 years) [28]. Therefore, despite its promising results and partial support for its effectiveness, there is room for improvement in universal prevention research, especially concerning the magnitude of its effects.
The current research tasks for universal prevention programs in schools
Previous studies suggested two issues that should be addressed in future studies of universal prevention programs in school: (1) to optimize inherent advantages of universal prevention in school overcoming limited effects, and (2) to explore the user-centered design of a universal prevention program for enhancing participants’ motivation that might facilitate more reliable gains.
Recently, a transdiagnostic approach is gathering much attention. This approach can address comorbidities frequently seen in clinical populations and redundancies of learning distinct treatment manuals for practitioners [29, 30]. There are three types of transdiagnostic approaches: the core dysfunction approach, common elements approach, and principle-guided approach [30]. First, the core dysfunctional approach addresses multiple psychological problems by targeting underlying common dysfunction. As a typical example, the Unified Protocol for the Transdiagnostic Treatment of Emotional Disorders (UP) [31] shows the frequently used approaches include treatment for problems that possess overlapping etiology, underlying shared pathological processes, or maintaining common processes [32]. Therefore, whereas it might be one of the first-line options for anxiety and depression, it needs further consideration to expand its utilization to more diverse disorders. Second, a common elements approach intends to select as many as common components that are derived from empirically supported treatments designed for distinct disorders. The approach may be workable when the elements can be compiled as separable, independent, and structured components [30]. Given that classroom teachers are used to teaching structured components in the classroom, the approach might be advantageous for universal prevention in schools. On the other hand, a flexible approach which allows therapists to use these components discreetly is not adequate for universal prevention programs. Third, the principle-guided approach possesses a high level of flexibility for intervention content and sequencing based on therapists’ clinical decisions. Therefore, the principle-guided approach might be efficacious for clinical settings due to its flexibility; however, it is also difficult to apply to the universal prevention protocols that are implemented by schoolteachers.
As mentioned, previous studies regarding school-based preventive CBT programs have focused on a single type of psychopathology. However, CBT programs among clinical populations can produce diverse therapeutic gains for a variety of psychological disorders that are often co-occurring in a child or adolescent [33]. Given that CBT was originally conceived as a broad paradigm for treating psychological disorders [34] and that the current components of empirically supported treatments for internalizing and externalizing disorders are largely shared [35], a universal prevention approach based on CBT might be effective for diverse mental health domains using a transdiagnostic approach. To the best of our knowledge, no research has examined CBT’s applicability in universal preventive approaches, although several trials of targeted programs are in progress [36, 37]. Even if a transdiagnostic approach is promising, it is essential to determine which design would be suitable for, and applicable to, universal prevention programs in schools. A universal prevention program might inherently reduce motivation for attendance due to the diffusion of its focus. Therefore, we should consider these aspects during the development phase, a priori, since research is often concerned with adaptation and implementation after completion of efficacy studies [38]. Specifically, (a) as previously stated, some efficacy trials of universal prevention programs targeting a single psychological problem failed to show clear evidence according to the rigorous criteria; (b) however, each program targeting a single psychological problem included evidence-based components derived from CBT, which is strongly empirically supported; and (c) we should explore if an entirely new transdiagnostic universal program that can be applied to diverse children and adolescents in actual school settings.
Study purpose
To tackle these issues, first, we developed a new school-based universal prevention program—the Universal Unified Prevention Program for Diverse Disorders (Up2-D2), which targets transdiagnostic mental health problems based on a cognitive-behavioral approach in schools. Our second purpose was to examine the acceptability and fidelity of the Up2-D2 in school settings after schoolteachers implemented the Up2-D2. Since the acceptability and fidelity of the program should be confirmed in real school settings, classroom teachers and their students evaluated the implementation of the Up2-D2 rather than researchers and clinicians.