Background. As part of a longitudinal study, prevalence findings of DSM-IV disorders are presented for a random sample of 3021 respondents aged 14 to 24, with response rate 71%.

Method. Assessment included various subtypes of disorders, subthreshold conditions and disorders that have only rarely been studied in other epidemiological surveys. The computer-assisted Munich-Composite International Diagnostic Interview (M-CIDI) was used to derive DSM-IV diagnoses.

Results. Substance disorders were the most frequent (lifetime 17·7%; 12-month 11·4%), with abuse being considerably more frequent than dependence. Other mental disorders had a lifetime prevalence of 27·5% (12-month, 17·5%) with depressive disorders (16·8%) being more frequent than anxiety disorders (14·4%). Eating disorders (3·0%) and threshold somatoform disorders (1·2%) were rare disorders. Subthreshold anxiety and somatoform disorders, however, were more frequent than threshold disorders. Prevalence of disorders was equally high for males and females, although specific disorder prevalence varied significantly by gender. The co-occurrence of disorders (co-morbidity) was substantial and was significantly related to greater reductions in work productivity and increased rates of professional helpseeking behaviour.

Conclusions. Findings underline that mental disorders in young adults are frequent and impairing, limiting work and education ability and social interaction. Given the fact that adolescents and young adults are in a key phase of socialization in terms of professional career and interpersonal relationships, our findings indicate a considerable risk potential for an accumulation of complicating factors and future chronicity. This paper is the first report of this ongoing longitudinal study about early developmental conditions of mental disorders.