min D deficiency truly contributes to mental health in childhood deserves further study. Furthermore, limited exposure to light is related, in some individuals, to the occurrence of seasonal affective disorder. More brightly lit classrooms are associated with fewer classroom problems for children with ADHD (Kemper and Shannon, 2007).

This and the preceding chapter have documented substantial progress since the 1994 IOM report in approaches to prevention in multiple developmental stages. The strength of evidence related to prevention of symptoms and incidence of externalizing disorders and problem behaviors has significantly increased, particularly through school-based interventions. There is emerging evidence that preventive interventions not only can reduce symptomatology, but also can reduce the number of new cases of depression. And there is promising evidence of the potential to intervene in the lives of young people in the early stage of schizophrenia, prior to full-blown disorder.

Many programs that have been tested in multiple randomized controlled trials demonstrate efficacy, and an increasing number have demonstrated effectiveness in real-world environments. Increasing numbers of programs are culturally adapted and, while still relatively limited, some have been tested with multiple racial, ethnic, or cultural groups. It is no longer accurate to argue that emotional and behavioral problems cannot be prevented or that there is no evidence for the prevention of MEB disorders experienced during childhood, adolescence, and early adulthood.

Interventions variously target strengthening families by modifying discipline practices or parenting style; strengthening individuals by increasing resilience and modifying cognitive processes and behaviors of young people themselves; or strengthening institutions, such as schools, that work with young people by modifying their structure or management processes. Parenting and family-based interventions have demonstrated positive effects on reducing risk for specific externalizing disorders, for multiple problem outcomes in adolescence, for reducing prevalence of diagnosed MEB disorders, and for reducing parenting and family risk factors.