The longitudinal BELLA study: design, methods and first results on the course of mental health problems.

The high prevalence of mental health problems (MHP) in childhood and adolescence is a global health challenge of the 21st century. Information about age of onset, persistence and development of MHP in young people is necessary to implement effective prevention and intervention strategies. We describe the design and methods of the longitudinal BELLA study, which investigates developmental trajectories of MHP from childhood into adulthood, their determinants, and the utilisation of mental health services. First results on the developmental course of MHP in children and adolescents are reported over a 6-year period. The BELLA study is the mental health module of the German National Health Interview and Examination Survey for children and adolescents (KiGGS). BELLA examines the mental health and well-being of children and adolescents aged 7-17 years (a representative subsample of KiGGS, n = 2,863 at baseline). Standardised screening measures served to identify MHP at baseline and at follow-ups (1, 2, and 6 years later). Among children and adolescents participating at all measurement points (n = 1,255), 10 % showed clinically significant MHP at baseline (n = 130). Over the 6-year period, 74.3 % showed no signs of MHP (n = 933), 15.5 % had remitted (n = 194), 2.9 % showed persistent (n = 36) and 7.3 % acute or recurrent MHP (n = 92). Overall, MHP were more likely to occur between the age of 7 and 12 and after the age of 19 years. Regarding mental health service use, 33 % of the participants with acute or recurrent MHP (n = 30) and 63.9 % with persistent MHP used mental health services (n = 23). Mental health problems in children and adolescents have a high risk to persist into adulthood. In children and adolescents a low rate of mental health service use was observed, even among those with mental health problems.