Adversity in Infancy and Childhood Cognitive Development: Evidence from four developing countries

Abstract

Abstract Background The effects of early life experiences on adult outcomes manifest through the childhood years. Since adult outcomes take many years to appear, and less amenable for policy, investigating the relationship between early life experiences on childhood outcomes is more relevant for policy. This study, by examining the association between adverse experiences in early infancy (AEI) on childhood cognitive development, provides early actionable evidence on how early environment of children can be manipulated to make a tangible difference in their cognitive development during childhood to achieve better outcomes later in life. Methods A total of 8,000 children followed over three rounds from age 1 to 8 years (2002 to 2009), as part of the Young Lives study in Ethiopia, India, Peru and Vietnam were included. Childhood cognition was measured with the Peabody Picture Vocabulary Test (PPVT) administered in round 2 and round 3, at average ages of 5 (PPVT-5) and 8 (PPVT-8), respectively. The primary independent variable was adverse experience in infancy (AEI) score, constructed using measures on child's weight, exposure to adverse household, economic, and environmental shocks as reported by a parent or a care giver in round 1 (age 1). The AEI scores were classified as 0, 1, 2, 3, 4, or > =5, with smaller numbers representing less severe adversities. Ordinary least squares (OLS) regression model was used to estimate the association between the AEI at age 1, PPVT-5, and PPVT-8, controlling for key demographic and socioeconomic factors. Results Both PPVT-5 and PPVT-8 were significantly lower for children who were exposed to adverse experiences at age 1. As the AEI score (range: 0-5) rose from 0 to 1, 2, 3, 4 and > =5, the PPVT-5 score decreased by 0.6, 1.3, 1.2, 1.4, and 1.5 points, and PPVT-8 decreased by 0.9, 0.8, 5.4, 5.6, and 9.3 points. Conclusions Early life adversities negatively impact cognitive development as soon as in early and mid-childhood. Key messages Adversities in early infancy may determine childhood development. Since adulthood outcomes are directly related to childhood development, addressing early adversities before they get worse may help to successfully manage a society’s future.