Previously mentioned weaknesses of TRAILS included the relatively low number of in-depth assessments, the lack of prospective data on determinants of pathology that occurred before the baseline assessment (except for Preventive Child Healthcare files) and insufficient power regarding rare disorders or small (gene-environment) interaction effects. In addition it should be noted that, despite extensive efforts to prevent attrition, adolescents dropped out of the study selectively. Attrition was associated with being male, low socioeconomic position, peer problems, substance use and externalizing problems.16
