Background: Mental health problems are a major health issue for children and adolescents around the world. The school environment allows adolescents to be reached comprehensively and on a low threshold, making it a potential environment for mental health interventions. The aim of this review was to describe interventions delivered by health-care workers in school environment for individual adolescents aged 12–18 with mental health problems and to assess the effectiveness of these interventions.Methods: This systematic review was conducted in adherence with the PRISMA guidelines. Altogether 349 studies were screened and 24 of them were included in full text assessment. Eight studies were included in the qualitative synthesis. Only in three studies the intervention was compared to another intervention or the study setting included a control group. Five of the interventions were based on cognitive-behavioral therapy and three on other approaches. In seven studies, one of the main response variables was based on assessment of depressive symptoms and/or a depressive disorder. The quality of the studies was limited with notable risk for bias for some studies.Results: Based on reported symptom reductions, for most of the interventions, the results were good. Symptom reductions were also typically achieved in a rather low number of sessions (12 or less) supporting the feasibility of these type of interventions in school environment. However, the lack of use of control groups and actual comparisons between the interventions, limit the possibility to draw firm conclusions regarding their effectiveness and thus, the results should be interpreted with caution. Confirming the effectiveness of the studied interventions requires more robust evidence and thus, improving the quality of studies in the school environment is encouraged.

A theory-based exergame was developed for tweens to promote their self-efficacy towards physical activity and increase their physical activity levels. We used protocols from both health science and gamification research in piloting the exergame. First, we assessed the usability and feasibility of the exergame and conducted a preliminary exploration of its effectiveness. After technical improvements were made based on our findings, we reiterated the pilot study and analysed the gamification elements of the exergame by using Octalysis analysis. The overall findings suggest that a theory-based exergame can positively influence the self-efficacy of tweens towards physical activity. The exergame showcased theoretical strength, achieved using diverse gamification elements but its overall game design and usability can be further improved. The study concludes that health-related components of the purpose of intervention must be incorporated in parallel with the engaging design of the game, taking into utmost consideration the theories, evidence as well as the needs and perceptions of its target users. This study provides valuable insights on future development and evaluation of gamified health interventions.