Barriers and facilitators for the implementation of preventative mental health interventions among secondary schools in high-income countries: a systematic review.

Recent societal crises have negatively impacted the mental health of adolescents, emphasizing the need for effective preventative mental health interventions. Schools as key environments for young people offer opportunities to deliver those interventions at low threshold. However, many interventions are not sustained beyond initial funding periods due to persistent implementation barriers, contributing to a significant gap between intervention development and long-term practice. This systematic review synthesizes qualitative research on barriers and facilitators affecting the implementation of school-based interventions in secondary schools in high-income countries. Seven databases were searched for qualitative and mixed-methods studies on the implementation of preventative school-based mental health interventions in regular secondary schools. Implementation determinants were synthesized using the updated version of the Consolidated Framework for Implementation Research. Study quality was assessed using modified checklists of the Critical Appraisal Skills Programme. Twenty-six studies, involving 5 to 8,630 pupils, met the inclusion criteria. A total of 336 implementation factors were identified, with barriers (N = 207; 61.6%) outweighing facilitators (N = 129; 38.4%). Barriers included scheduling conflicts, low prioritization of mental health, and logistical challenges. Key facilitators were leadership support, age-appropriate intervention design, and staff engagement. Sustained success of preventative mental health interventions requires integrating programs into school structures, aligning with academic priorities, and addressing resource limitations. Future research should focus on adapting interventions to fit school contexts and strengthening leadership and community support. Understanding multidimensional, interacting implementation factors is essential for creating sustainable interventions that positively impact adolescent mental health.