This chapter explores the critical importance of child and adolescent mental health in understanding and mitigating mental illness across the life course. Because the majority of mental disorders emerge during childhood or adolescence, early mental health interventions are key to prevent long-term health burden. We emphasise the need for a developmental perspective in mental health research, highlighting the challenges and opportunities in studying both typical and atypical development, addressing diagnostic comorbidity, and evaluating environmental influences on mental health outcomes. We discuss four examples to illustrate the breadth of research in child and adolescent mental health: (1) conceptualising psychopathology across the lifespan, (2) establishing valid measures of childhood maltreatment to assess its impact on mental health, (3) testing the mechanisms that might explain why maltreatment contributes to the risk of psychopathology, and (4) optimising psychiatric crisis care for adolescents in the UK. By examining these critical issues, the chapter outlines how advances in child and adolescent mental health research can lead to innovative strategies for preventing and managing mental health problems, with the potential to improve wellbeing throughout the life course.

Chapter 4 takes a developmental perspective. It begins by looking at how embodied metaphors develop in infants and at how the ways in which they are experienced by infants and children differ from the ways in which they are experienced by adults. It then explores the ways in which they are experienced by older adults. It discusses work that has looked at how young children (aged 5–8) make use of embodied metaphor to reason about mathematics and music, and how their embodied metaphorical reasoning behaviour differs from that of adults.