Systematic review of Indigenous involvement and content in mental health interventions and their effectiveness for Indigenous populations.

To assess the effects of psychological, psychosocial, educational and alternative interventions on mental health outcomes of Indigenous adult populations in Australia, Canada, New Zealand and the United States and the Indigenous involvement and content in each study. We systematically searched databases, key journals and gray literature, for records until June 2020. Eligible studies were in English or French and examined the impact of interventions on mental health outcomes including anxiety disorders, posttraumatic stress disorder, depression, psychological distress or stress for Indigenous adults (⩾16 years). Data were extracted using a modified Cochrane Data Extraction Form and the Template for Intervention Description and Replication. Quality was evaluated using the Effective Public Health Practice Project quality assessment form. In total, 21 studies were eligible, comprising 8 randomized controlled trials, 10 single-group pre-post studies and 3 pre-post studies with comparison groups. Twenty studies had Indigenous individuals or organizations involved in some decision-making capacity, though extent of involvement varied widely. In total, 9 studies were rated moderate and 12 weak in the Effective Public Health Practice Project quality assessment. Eight studies measuring depression, three measuring posttraumatic stress disorder, three measuring psychological distress and two measuring stress showed statistically significant improvements following the intervention. A wide range of interventions demonstrated mental health improvements. However, it is difficult to draw generalizable conclusions on intervention effectiveness, given heterogeneity among studies. Studies should employ a thorough assessment of the Indigenous involvement and content of their interventions for reporting and for critical consideration of the implications of their research and whether they address Indigenous determinants of mental health.