Table 2 provides an overview of the measures included at the data collection waves conducted so far. This overview illustrates a number of key features of the study. First, its scope is highly multidisciplinary. The outcome measures encompass both mental and physical health conditions as well as various indicators of social functioning, and the determinants encompass a wide range of biological, psychological, and social markers. Second, the information is collected from multiple sources; in addition to self- and parent-reports the database contains teacher-reported data, peer nominations, partner-reports and registry-based data from preventive child healthcare and mental healthcare providers. Third, the TRAILS cohorts have been followed from pre-adolescence into adulthood. Adolescence is characterized by major psychobiological and social transitions, which requires continuous adaptation of measures and informants in order to keep them age-appropriate and relevant. Table 2.Overview of measures collected in TRAILSVariableInstrumentTypeaWave and informantb12345Sociodemographic variablesSociodemographic dataGender, age, ethnicity, living conditions, educational/work status.QPPTAAAMental healthInternalizing and externalizing problemsChild Behaviour Checklist (CBCL).42 Anxious/depressed, withdrawn/depressed, aggressive, and delinquent behaviour; somatic complaints; social, thought, and attention problems during the past 6 months, as well as DSM-IV
