Grant: Doctoral Award - Frederick Banting and Charles Best Canada Graduate Scholarships

Mid to late adolescence is the peak onset period for internalizing disorders, including anxiety and depression. To date, we do not know whether childhood dysregulated diurnal cortisol can predict clinical diagnoses of internalizing disorders across the transition to adolescence. The proposed study will examine the questions: 1) Does dysregulated diurnal cortisol in pre-adolescence (ages 10-12), predict development of depressive and anxiety disorders in early and mid adolescence (ages 13-15 and 16-18, respectively)? 2) Will patterns of dysregulation at pre-adolescence be differentially linked to types of internalizing disorder (i.e. anxiety disorder or depression), or to age of onset? 3) Are there differential predictors of internalizing disorders for girls and boys, in terms of dysregulated diurnal cortisol patterns and other predictors at pre-adolescence? Participants will be ~120 children recruited from the Concordia Longitudinal Risk Research Project, a large intergenerational study of families from disadvantaged backgrounds. Children have been followed across 5 time points every 3 years since early childhood. Salivary cortisol samples will be taken at 2-hour intervals over two consecutive days during between ages 10-12, and again at ages 13-15, to assess diurnal cortisol. Children's depression and anxiety will be assessed using clinical diagnostic interviews K-SADS and ADIS, respectively. Hypotheses to be tested using growth mixture modeling (M+) include: 1) Atypical diurnal cortisol patterns at pre-adolescence will predict new internalizing disorders at early-adolescence and mid-adolescence, controlling for baseline internalizing disorders and on-going behavioural problems; and 2) The relations between dysregulated diurnal cortisol patterns and other predictors will differ for girls and boys. Dysregulated diurnal cortisol at pre-adolescence might serve as a bio-marker indicating elevated risk for internalizing disorders during adolescence.