Depression from childhood through adolescence: risk mechanisms across multiple systems and levels of analysis

• Summarizes recent developmental epidemiological research in depression from preschoolers, children, and adolescence.
• Reviews recent risk factor and mechanism research.
• Emphasizes that risks are instantiated across multiple systems and levels of analysis.
• Highlights dynamic interplay, developmental cascades, and transactions over time.

This paper selectively reviews recent research, especially in the last two years (2012–2014) in preschool, child, and adolescent depression. In particular, attention is paid to developmental epidemiology as well as risk factors and processes that contribute to depression trajectories over time. Emphasis is placed on a developmental psychopathology perspective in which risks are instantiated across multiple systems and levels of analysis, including genetics, stress contexts and processes, biological stress mechanisms, temperament, emotion, reward, cognitive factors and processes, and interpersonal influences. These risks dynamically transact over time, as they emerge and stabilize into relatively trait-like vulnerabilities that confer risk for the increasing rates of depression observed in adolescence. Overall, this summary illustrates that considerable progress has been made recently in understanding the complex developmental processes contributing to depression. Finally, a few gaps are highlighted as opportunities for future research.