Testing an integrated model of population mental health: study protocol for the Mannheim incidence and inception cohort study (MAKO)

Background : Monitoring of population mental health is now considered to play a vital role in health, risk factor and demographic surveillance systems across the globe. Adopting a public mental health perspective on monitoring and surveillance requires us to consider the entire spectrum of mental health, which broadly ranges from positive mental health and well-being to severe mental disorders via at-risk populations. This population mental health approach has become the mainstay of public mental health provision in many European countries, but there is a dearth of research on this issue in Germany in the past 20 years, and fundamental conceptual and methodological issues remain to be addressed at both the national and international level. Methods : The Mannheim incidence and inception cohort study (MAKO) is a recently established two-arm population-based incidence (arm 1) and inception cohort (arm 2) study in the catchment area of Mannheim, Germany. In the incidence-arm, case ascertainment of incident cases is carried out for the years of 2024 and 2025 based on clinical assessment via structured clinical interviews and retrospective case record evaluation. In the inception cohort arm, we recruit and follow an epidemiologically characterized, population-based cohort of individuals a) without symptoms (i.e., stage 0), b) with criteria for non-specific psychological distress (i.e., stage 1a), or c) a clinical high at-risk mental state for severe mental disorder (i.e., stage 1b) at baseline and up to four follow-up assessments every six months. Assessments include clinical interviews, self-report measures, and ecological momentary assessment. Results : Enrolment started in January 2024. Data collection is expected to be completed in 2027. Conclusion : A combined, two-arm incidence and inception cohort study reflects the optimal design in terms of both efficiency and capacity for delineating the basic epidemiology of population mental health for the first time in over 20 years in Germany. Given the heterogeneity in neighbourhood characteristics and migrant and ethnic minority populations in the city of Mannheim, our methodology will offer a unique population laboratory to study variation in incidence and clinical stage transitions in terms of place and ethnicity with high external validity.