• Population cohort (N = 2230, started in 2000)
• TRAILS CC; Clinical cohort (N=543, started in 2004)
• Age at first wave is 10-12 years
• Take measurements from participants every two years until they are at least 24 years old
• Gather information from different sources; participants, parents, teachers, classmates, brothers and sisters
• Gather information about social, psychological and biological factors
 

One of the main features of TRAILS is the width of the study. In TRAILS we investigate what happens with young people as they grow into adults. For this we need to know how they are doing in life. We focus mainly on the adolescent and we measure both personality, health and substance use as well as biological characteristics such as genes and their biological response to stress.

To have a better understanding of the development of adolescents, we must not only know a lot of the adolescents themselves but also of their environment. For example, how they cope with their parents, how popular they are at school, if they have many friends…but also the genes of the parents, the personality of parents and their health and, last but not least, which important (life) events adolescents experience. Each measurement of TRAILS is a combination of questionnaires, interview and physical measurements. Sometimes we add a part, such as neuropsychological testing or questioning classmates about friendships and popularity in the classroom.