Given the escalating mental health crisis (Wong et al., 2021), there is a substantial need for effective ways to improve depression and anxiety among school-age children. There exists a prolific amount of school-based mental health interventions, yet the quality of such interventions varies greatly. Previous meta-analyses provided many insights on effective interventions; however, they failed to use stringent inclusion criteria. There is a need to review high-quality randomized controlled trials to generate new and evidence-based insights. This study aims to synthesize research on existing mental health interventions targeting depression and anxiety of school-aged children and adolescents to provide updated guidance on effective interventions.
Prevalence of Depression and Anxiety in School-aged Children and Adolescents
In recent years, depression and anxiety have increased rapidly among 6-17 years old American children (Centers for Disease Control and Prevention (2022)). Approximately 9.4% 3–17-year-old children were diagnosed with anxiety problems (Centers for Disease Control and Prevention (2022)) and 31.5% 13-18-year-old children have experienced depression (Feiss et al., 2019). These statistics are concerning not only because of what they tell, but also because of what they do not tell. In the mental health area, numbers often underestimate the actual prevalence of mental health problems due to diagnostic challenges (Mathews et al., 2011), stigmatization (Moses, 2010), and subsequent reluctance to seek help (Reavley et al., 2010). On top of that, there is a gap between those who are diagnosed and those who receive treatment: around half of diagnosed American adolescents receive mental health treatments in the form of medication or counseling (Zablotsky, 2020). More needs to be done to provide accessible mental health support for school-aged children and adolescents (i.e., aged 10–19; World Health Organization (2022)).
Apart from the increasing prevalence and inadequate treatment in depression and anxiety, the associated consequences highlight the need to intervene early and effectively. Past literature found that depression and anxiety among children are associated with poor academic outcomes (Owens et al., 2012), deteriorating physical health (Naicker et al., 2013), substance abuse or dependence (Conway et al., 2006), negative coping strategies (Cairns et al., 2014), self-injury (Giletta et al., 2012), and suicidal attempts (Nock et al., 2013). In addition, anxiety and depression among adolescents are likely to be recurrent (Gillham et al., 2006), chronic (Costello et al., 2003), and persistent through adulthood (Lee et al., 2018). Treating depression and anxiety effectively can create great social, educational, and economic benefits. A meta-analysis of randomized controlled trials can produce guidance for policymakers by providing insights into the effectiveness of all related interventions. This meta-analysis intends to provide evidence to help school districts understand what types of mental health interventions work in the school environment.
School-based Mental Health Interventions
The importance of addressing mental health in children and adolescents cannot be understated. The long-term adverse outcomes outlined above exist not only for those who meet diagnostic criteria, but also for those with subclinical levels of depression (Copeland et al., 2021). Schools provide an ideal setting within which to both implement preventative interventions as well as identify and serve those with or at-risk of depression or anxiety. School settings can provide access to all school-age children, while overcoming barriers such as location, time, and stigma (Stephan et al., 2007). Compared to primary-care settings, school-based mental health programs can reach larger populations, provide more convenient access, and enhance social relationships between classmates and teachers (van Loon et al., 2020). An additional advantage of school-based interventions is that they can serve to identify students at high risk for depression and anxiety and provide them with clinical support. This is especially important because one major reason for untreated depression is the failure to identify or diagnose depressive symptoms (Hirschfeld et al., 1997). This challenge can be mitigated by school-based mental health programs. With these advantages, school-based mental health interventions are increasingly gaining popularity (Werner-Seidler et al., 2017).
Past Meta-analyses
Past meta-analyses have conflicting views on the effectiveness of school-based interventions targeting depression and anxiety. One review identified 118 randomized controlled trials with 45,924 participants and found that these interventions had a small effect on depression and anxiety (Werner-Seidler et al., 2021). Similarly, another recent review analyzed 18 included studies and found that school-based programs had a small positive effect on self-reported anxiety symptoms (Hugh-Jones et al., 2021). These conclusions were challenged by another meta-analysis, where authors identified 137 studies with 56,620 participants and found little evidence that school-based interventions which focused solely on the prevention of depression or anxiety are effective (Caldwell et al., 2019). These three meta-analyses focused on children within the age group of 4–19 years old. When meta-analysts narrowed their focus to adolescents (11–18 years old) in the USA, they found significant effects of school-based programs on both depression and anxiety, but not on stress reduction (Feiss et al., 2019). One possible reason behind these conflicting conclusions is the distribution of age groups; perhaps school-based interventions are generally more effective for adolescents compared to younger children. Another possible source of conflict may be the subjective inclusion criteria created by researchers, which can bias the results (Cheung and Slavin, 2013). When applying more stringent inclusion criteria, the magnitude and statistical significance of effect sizes tends to diminish (Neitzel et al., 2022). The association between inclusion criteria and outcomes was demonstrated in another school-based meta-analysis, where the authors found that removing low-quality studies led to changes in average effect sizes (Tejada-Gallardo et al., 2020).
Outcome domain
Depression is a clinical symptom that involves persistent sadness and loss of interest in previously enjoyable activities (National Institute of Mental Health, 2018). Anxiety disorder refers to persistent anxiety that interferes with daily life (National Institute of Mental Health, 2022). In past meta-analyses, there are conflicting views on the effectiveness of depression- or anxiety-focused school-based interventions, ranging from no evidence of effectiveness in either depression or anxiety (Caldwell et al., 2019), to effectiveness dependent on program features (Feiss et al., 2019), to a small positive average effect size in both outcome domains (Werner-Seidler et al., 2021), to sustainable positive effect sizes even after 12 months (Hugh-Jones et al., 2021).
Program type
The universal approach delivers the treatment to the whole population (e.g., class, school, cohort) regardless of their conditions while the targeted approach delivers the treatment to a selective group of students who show elevated symptoms of depression or anxiety. In targeted interventions, students were first screened using self-reported surveys to detect at-risk students. Universal programs are preventive in nature while targeted programs are curative. Each approach has its advantages and disadvantages. Targeted interventions may be difficult to apply at a large scale due to the tremendous amount of screening efforts required (Merry et al., 2004). Moreover, compared to the universal approach, the targeted approach involves taking students from classes, which may cause unintended effects of labeling and stigmatizing students (Huggins et al., 2008). Past research has shown that students selected for targeted mental health treatments feel embarrassed and may have negative attitudes towards receiving medication (Biddle et al., 2006). Universal programs avoid potential dangers of social stigmatization and can reach more children, but they may be more costly due to the larger group of participating populations (Ahlen et al., 2012). Furthermore, targeted programs were more effective compared to universal programs (Werner-Seidler et al., 2021). Since both approaches have pros and cons, investigating the effectiveness of one compared to another can generate useful scientific and implementation implications.
Program content
Cognitive behavioral therapy (CBT) is a traditional type of program targeting depression and anxiety (Feiss et al., 2019). In clinical settings, CBT treatment usually involves changing thinking and behavioral patterns, helping individuals to understand the problem, and developing a treatment strategy together with the psychologist (American Psychological Association, 2017). In K-12 school settings, CBT techniques and components can be adjusted and applied to the behavioral social-emotional needs of students even without clinical diagnosis (Joyce-Beaulieu & Sulkowski, 2019). Through CBT interventions, students gain skills to understand and cope with their own feelings, such as using relaxation techniques and interacting with peers more effectively (Joyce-Beaulieu and Sulkowski, 2019). School-based interventions with CBT components are found effective to reduce depressive symptoms (Rooney et al., 2013) and anxiety (Lewis et al., 2013), and to improve coping strategies (Collins et al., 2014). Apart from CBT, evidence suggests promising effects of other innovative program features, such as physical education (Olive et al., 2019), student-family-school triads (Singh et al., 2019), and Hatha yoga sessions (Quach et al., 2016). One past meta-analysis suggested that there are no significant differences between CBT programs and other approaches in treating either depression or anxiety (Werner-Seidler et al., 2021). Yet, another meta-analysis reported weak evidence of CBT’s effectiveness in reducing anxiety in both elementary and secondary school populations (Caldwell et al., 2019). Comparing traditional program types to other new program types can help us understand components that make interventions effective.
Delivery personnel
To meet the rapidly growing demand for school-based mental health services, the teacher’s role shifts from being a supportive figure to being a service provider (Park et al., 2020). The appeal of hiring teachers to deliver interventions is increasing, yet there is lack of research that compares teacher-delivered interventions to clinician-delivered interventions. In school-based mental health interventions, interventions are normally delivered by either trained teachers or certified clinicians. Although trained psychologists or clinicians have more professional and practical knowledge than teachers, hiring specialists is more expensive compared to training schoolteachers through a short workshop. Moreover, students spend most of their time during schools with teachers and have developed rapport and trust with each other. In contrast to teachers, clinicians are less familiar with students’ backgrounds and personalities. Very few meta-analyses were able to include the provider as a moderator in their meta-regression because very few interventions were delivered by teachers. Findings on providers are mixed, ranging from no significant moderation effect on delivery personnel (Ahlen et al., 2015), to external providers being more effective than school staff (Werner-Seidler et al., 2021), to teachers being more effective (Neil and Christensen, 2009), and to teachers being more effective under some treatment conditions (Franklin et al., 2017). This article contributes to the literature by comparing teacher-delivered interventions to clinician-delivered interventions.
Program duration
Past research has established that interventions delivered within a short span of time tend to produce much larger effect sizes than long-duration interventions (Cheung & Slavin, 2013). Factors contributing to this effect include novelty factors, a more experimentally-stable environment, and the feasibility of conditions only sustainable for short-duration interventions (Cheung & Slavin, 2013). Those findings suggest using 12 weeks as a benchmark to separate short-duration and long-duration studies.
Sample size
Study sample size has also been found to strongly impact effect sizes, with small sample sizes tending to inflate effect sizes (Slavin & Smith, 2009). One reason behind this observation is the “superrealization” effect (Cronbach et al., 1980), which means that the high implementation fidelity maintained within a small sample can hardly be scaled to a larger sample. Another reason may be that small-scale studies are more likely to use researcher-developed measures compared to standardized tests (de Boer et al., 2014). Lastly, publication bias may have contributed to this phenomenon since small-scale studies have limited statistical power, which often requires higher effect sizes than large-scale studies to reach statistical significance. To the best of the authors’ knowledge, no prior meta-analysis has included sample size as a moderator.
Student age
As summarized in the previous section (i.e., past meta-analyses), results of the meta-analysis may be different across age groups. For example, one investigation of academic achievement found that students in the elementary grades gain much more academic progress than secondary school students in one academic year (Bloom et al., 2008). A separate meta-analysis of academic interventions found the same disparity between age groups, but the significance of these results disappeared when they restricted inclusion criteria to only randomized and quasi-experimental designs, which further demonstrated the importance of applying rigorous inclusion criteria (Cheung & Slavin, 2013).
