Mental health interventions targeting children and young people: A mapping review of interventions, follow-up, and evidence gaps [version 1; peer review: 1 approved with reservations]

Background: Young people with mental illness should be offered evidence-based treatments. In 2018, we developed a national evidence portal in Norway providing mental health professionals and others with living evidence summaries. This immense work has been an important contribution to mental health care in Norway but is also a rich data source for exploring the characteristics and evidence gaps of the existing research internationally. At the time of this study, eight overviews of systematic reviews (OoOs) had been published. These addressed treatments for attention deficit / hyperactivity disorder (ADHD), anxiety, depression, bipolar disorder, psychosis, obsessive compulsive disorder (OCD), self-harm and trauma/ post-traumatic stress disorder. The objective of this study was to do a secondary analysis of this evidence to describe the state-of-the art in this field, and to map: treatments evaluated for each patient group and the longest time of follow-up treatment comparisons evaluated for more than one patient group Methods: We performed a mapping review of the eight OoOs. Data extraction was performed by one author and double-checked by another. All data was entered into Excel. Findings were visualized in descriptive tables and using Sunburst-diagrams. We used statistical thresholds to determine the size of effect and report the associated certainty. Results: We identified 200 treatment comparisons including a wide variety of interventions. Some mental illnesses are treated mostly with pharmacological or combination therapies and others solely with psychological or psychosocial treatments or with more diversity. The evidence supporting most treatments is of low to very low certainty. Ten percent of the comparisons included follow-up assessments beyond 12 months. Cognitive behavioural therapy, dialectic behavioural therapy, physical activity and mindfulness interventions were effective across populations. Conclusions: The evidence supporting treatment of mental illness in young people has important limitations. Future research efforts should address these evidence gaps.