For approximately half of the individuals suffering from a mental disorder, the onset of illness occurs during adolescence, and in more than a third, the disorder emerges by the age of 14 (Solmi et al., 2022). The estimated worldwide prevalence of mental disorders was reported to be 13.4 % (CI 95% 11.3 – 15.9) for this population (Polanczyk et al., 2015). In addition, mental disorders among adolescents have increased in recent years, with the increase being most notable with respect to developmental and mood disorders (Steffen et al., 2018). Increasingly, digital technologies, such as mobile apps or web-delivered programs, are being used to try to counteract the declining mental health of adolescents. The range and variety of these tools is growing rapidly, and more and more studies report on their potential and value (Lucas-Thompson et al., 2019). An updated overview of tools and programs is essential and the proposed paper presentation aims to provide this overview. Findings from a systematic review and meta-analysis (Wright et al., in press) will be presented that outline the current state of digital, evidence-based programs promoting mental health in young people, and provide insight into the characteristics and effectiveness of such programs. The domain of interest is the promotion of mental health with a focus on mental health literacy, well-being, (mental health) help-seeking behavior, stress management, relaxation, mindfulness, resilience and positive psychology.

The ongoing advances in technology mean that more and more mental health promotion programs may be provided successfully, either partly or fully, through digital media (Kaess et al., 2021). As barriers to mental health services increased during the pandemic (due to lockdowns and restrictions), the advantages of choosing a digital mode of delivery have become manifold, e.g., cost-effectiveness, anonymity, accessibility, adaptability, etc. These all serve to lower the threshold when seeking mental health support (Bauer et al., 2005). Accessible, adaptable digital programs lower usage barriers in schools and other institutions, as they require relatively little expertise or effort compared to face-to-face (F2F) interventions. In addition to the high accessibility and availability of digital tools, their potential for successfully promoting young people’s mental health has repeatedly been reported in recent meta-analysis and/or systematic reviews. Harrer et al. (2019) found such tools to have positive effects on depression, anxiety, stress, eating disorder symptoms and role functioning. The findings of Clarke et al. (2015) and Sevilla-Llewellyn-Jones et al. (2018) support the effectivity of online interventions with respect to the treatment of anxiety and depressive symptoms. Noh and Kim (2022) reported beneficial results when preventing an increase in depressive symptoms, but not for anxiety or stress. Furthermore, well-tailored digital interventions are likely to increase engagement with a support tool and to aid the transfer of specific skills into the daily lives of young people (Lucas-Thompson et al., 2019). Indeed, web-based interventions have been reported to improve individuals’ quality of life and functioning (Sevil-la-Llewellyn-Jones et al., 2018).

Within this paper presentation, findings from a systematic review and meta-analysis (Wright et al., in press) on digital tools for mental health promotion among 11–18 year olds will be presented. The review focused on three areas. First, it was of interest to determine, what digital-based interventions promoting mental health are available for children and adolescents aged 11 to 18. Second, the effectiveness of these interventions was analyzed. Third, the factors underlying their effectiveness were assessed. In this paper presentation, special attention is given to the third area, and deeper insights are provided into the impact of moderating factors that potentially influenced the effectiveness of the interventions. In addition, import implications for the design of future interventions are suggested.

This study made use of the recommendations of the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement. Search Strategy. Two literature reviews were conducted (May & October 2021) using the electronic databases PubMed, The Cochrane Library and PsycInfo. Eligibility Criteria. Studies with participants aged between 11 to 18 years were of interest. These studies needed to be controlled studies with a mixed-methods or quantitative design reporting on mental health interventions. Furthermore, only peer-reviewed, English publications published between 2000 and 2021 were eligible for inclusion. Clinical trials, studies lacking a control group or quantitative measures were excluded. Study Selection Process. The searches yielded 3.809 results and 27 studies were found eligible for inclusion. Both searches followed the same procedure and four reviewers were involved in the application of eligibility criteria. Study identification followed a three-step process: (1) removal of duplicates, (2) screening for inclusion criteria, (3) resolution of discrepancies between reviewers. Data Extraction. Relevant extractions involved, but were not limited to: theoretical background, medium(s) and mode of intervention, intervention and sample characteristics, study design, method, outcome data/results, effect size, and potential moderators of intervention efficacy (setting, duration of intervention, adherence, attrition, and levels of interaction, support, guidance and digitization). Quality Assessment. In order to assess the risk of bias, the Cochrane Risk of Bias Tool - RoB and the Risk Of Bias In Non-Randomized Studies – ROBINS-I were applied. Analysis. In the process of narrative synthesis, the key features of the studies and their interventions were summarized (summary table), and potential intervention barriers and facilitators were put forward. Additionally, a detailed description was provided for variables identified as potential moderators of intervention efficacy. Eight conceptually-related clusters were identified based on the main outcomes of the primary studies (anxiety, depressive symptoms, well-being, stress, internalizing symptoms, externalizing symptoms, protective factors). A meta-analysis was performed separately on each cluster for post-intervention measurements. For each analysis, forest plots were generated, observing effect size (Hedges’ g) and heterogeneity between studies (τ2). A sensitivity analysis was carried out when the heterogeneity for a cluster was higher than moderate (> 50%). To study possible sources of heterogeneity, subgroup analysis was then performed including the previously identified moderators. Finally, to address potential publication bias, funnel plots were inspected and Egger's tests were performed. Where evidence of publication bias was found, the bias was adjusted using the Duval and Tweedie Trim and Fill procedure.

In total 27 studies were identified to meet the inclusion criteria. Half of these studies reported significant effects in improving mental health. A meta-analysis was performed based on post-intervention measurements for each of the seven clusters with a total sample of 13,216 participants to identify the effectiveness of the interventions and to examine the impact of eight predefined, underlying factors. Even though the high heterogeneity of the results calls for careful interpretation, the findings support previous research in that digital interventions have the potential to promote adolescent mental health. Small effects regarding a decrease of anxiety and an increase of well-being were identified. After outlier-removal, small effects were also detected relating to the promotion of protective individual factors, including self-esteem, self-compassion, or help-seeking behavior. No significant effects were found for depressive symptoms, stress, externalizing symptoms (e.g., hyperactivity), and internalizing symptoms (e.g. loneliness). When examining the impact of underlying predefined factors, the analysis showed that interventions with a school-based setting, consistent adherence, low levels of attrition and some level of professional support and guidance, were found to be most effective. The length of the intervention, the level of digitization, and the level of interaction had no significant impact in the reviewed studies. With regard to narrative synthesis, in addition to the moderating factors mentioned above, three other important factors need to be considered in the future design of mental health interventions. First, it is suggested that study designs incorporate elements of participatory design research so that interventions are more closely tailored to the preferences and needs of youth. Second, it is recommended that the design and content of the intervention be diversity-sensitive. Third, it is suggested that further research focus as much on maintaining and promoting the availability of an intervention as it does on developing the intervention.

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