Cohort profile: the Quebec Longitudinal Study of Kindergarten Children (QLSKC).

The Quebec Longitudinal Study of Kindergarten Children (QLSKC) is an ongoing population-based prospective longitudinal study presently spanning ages 6-29 years, designed to study the prevalence, risk factors, development and consequences of behavioural and emotional problems during elementary school. Kindergarten boys and girls attending French-speaking public schools in the Canadian province of Quebec during the 1986-87 and 1987-88 school years were included in the cohort: 2000 children representative of the population and 1017 children exhibiting disruptive behaviour problems. To date, 12 waves of data have been collected, and three generations of participants have been involved in the study (i.e. the study child, his parents and the first child of the study child). Information on demographics, psycho-social and lifestyle factors, child and family member characteristics (physical and mental health), and outcomes such as psychiatric diagnoses, delinquency or school diploma were assessed during three important developmental stages (childhood, adolescence and early adulthood). Blood samples were also collected in early adulthood for genetic analyses. Information on publications, available data and access to data can be found on the following website (http://www.gripinfo.ca/Grip/Public/www/).