Grant: Project Grant

Anxiety and depression affect millions of Canadians. These disorders often begin in adolescence and continue into adulthood. While effective treatments exist, many teenagers don't respond well to standard approaches. This is because clinicians currently lack tools to predict which teens will develop these disorders and which treatments will work best for each individual. As a result, treatment remains trial-and-error rather than personalized to each teen's unique historical and biological context. Many factors increase risk for anxiety and depression, including genes, family mental health history, parenting, poverty, bullying, discrimination, and neighborhood disadvantage. However, most research studies these factors in isolation. In reality, teens experience combinations of risk factors that interact in complex ways. Moreover, different combinations of risk factors shape adolescents' developing brains and bodies differently, creating distinct biological patterns that determine who develops symptoms and when. This study will follow 500 diverse Montreal adolescents (ages 12-16) over five years to understand how different combinations of risk factors lead to different biological profiles, and how these profiles predict whether teens develop anxiety or depression. We will measure neural and physiological responses to rewards and threats, stress hormones, and inflammation. By identifying distinct "biotypes" (groups of teens sharing similar biological patterns), we can begin to understand how complex contextual and biological systems predict onset and course of internalizing disorders. This research lays the foundation for programs that can identify vulnerable teens earlier and personalize care based on their specific risk histories and biological profiles. This precision prevention approach could allow mental health professionals to take a proactive, rather than reactive, approach, thereby reducing the staggering burden of these mental health conditions.