Co-design methodologies to develop mental health interventions with young people: a systematic review.

Co-design methodologies are increasingly being used to develop mental health interventions with young people (aged 10-24 years), but the adoption of this participatory approach has been accompanied by concerns around quality, reporting, and participation. We aimed to identify and critically assess the characteristics, quality, outcomes, barriers, and facilitators of co-design methodologies used to develop mental health interventions with young people. We searched MEDLINE, PubMed, PsycINFO, SCOPUS, and Web of Science for articles published from database inception to Feb 6, 2024. We included articles describing empirical studies that used co-design in the development of a mental health intervention with young people, and identified 41 unique co-design studies. Our systematic review revealed that the use of co-design methodologies to develop mental health interventions has expanded substantially over the past 5 years. We also found that the application of co-design terms, frameworks, and methods varied across the studies, and most co-designed interventions had not been evaluated. A third of the studies evaluating the co-design process were assessed as being low quality, and two-thirds had a low degree of participation of young people in the co-design process. In the future, this area should be guided by clearer terms and frameworks, higher quality and degree of participation, and greater evaluation of co-designed programmes.