# **_Impact of Interventions Affecting Early Childhood Development_**

Mounting evidence from economics, psychology, and neuroscience indicates that early investments in young children profoundly affect their long-term physical and mental health, earnings, and well-being. Early experience shapes brain architecture (Knudsen and others 2006), and early childhood development has a long reach that affects physical and mental health and well-being later in life (Drukker and Tassenaar 1997; Fogel 1994; Mustard 2006). Knudsen (2004) has shown that there are sensitive periods for neurological development early in life that affect long-term memory. Thus the critical period for intervention is in the preschool years. Recent work has produced considerable evidence on the issue.

Victora and others (2008) summarize the results and long-term implications of maternal undernutrition from five developing-country cohort studies and review the literature on the same topic. They find that undernutrition can cause structural damage to the brain and that maternal and child undernutrition result in shorter adults, less schooling, lower productivity, and lower birth weights among their offspring. There is also a link with adult cancer, lung disease, and mental illness, all of which compromise productivity and earnings.

Thomas and Frankenberg (2002) provide a useful review of microeconomic studies of the impact of nutrition on economic outcomes at the individual level. They summarize their findings as indicating that “while the establishment of this link [from health to income] is not straightforward, the weight of evidence points to nutrition, and possible other dimensions of health, as significant determinants of economic productivity.” Walker and others (2007), in a meta-study of risk factors for young children, note that stunted children consistently show cognitive and educational deficits, although the size of the deficit varies across settings. They argue for intervention to prevent stunting, inadequate cognitive stimulation, iodine deficiency, and iron deficiency anemia.

Heckman (2007) points out the importance of noncognitive skills in preparing children for school, adulthood, and the workplace, and his research suggests that both the cognitive and social-emotional abilities of individuals as children explain many features of their later economic and social performance. Gaps in cognitive ability are established early, and in the United States they explain much of the differential in individuals’ educational performance across income levels (Cunha and others 2006).

Grantham-McGregor and others (2007) summarize the scientific and behavioral evidence from developing countries and point to poverty, malnutrition, poor health, and unstimulating home environments as compromising the cognitive, motor, and social-emotional development of children. Their meta-study finds that both poverty and childhood stunting (due to persistent undernutrition) correlate with poor school performance, lower income in adulthood, higher fertility, and inadequate care of their own offspring.

Longitudinal studies show the relationship between early childhood development and language, intelligence, and criminality. Black and others (2008) show how low birth weights significantly affect longer-run outcomes such as adult height, intelligence quotient, earnings, and education. Verbal exposure by reading and talking has significant effects on children’s verbal skills and 17