A group of infants and toddlers in Jamaica who received developmental stimulation—via home visits and nutritional support—continue to show benefits from this intervention as adults three decades later, according to a new study published in the Journal of Child Psychology and Psychiatry.

At an average age of 31, those who received stimulation (with or without nutritional support) exhibit significantly greater IQ and cognitive flexibility, better mental health, and fewer risk behaviors compared with a group that did not receive these interventions as children. 

Findings were reported by authors Susan P. Walker, Susan M. Chang, and Amika S. Wright of the Caribbean Institute for Health Research at The University of the West Indies; Sally M. Grantham-McGregor of the Institute of Child Health, University College London; Rodrigo Pinto of the University of California at Los Angeles Department of Economics; and James J. Heckman of the Center for the Economics of Human Development at the University of Chicago.

The long-term benefits of early childhood programs have been documented in the United States, but there has been little evidence on the effects of such interventions in adults in low- and middle-income countries, where the impact on the lives of children could be the greatest. This is the longest follow up of a randomized controlled trial of an early childhood stimulation in a low-income nation. It shows that home visiting programs that support mothers and families have lasting benefits.

The original 1987 study identified 127 children ages 9 to 24 months with stunted growth in Kingston, Jamaica, and enrolled them in a two-year trial. Children were randomly assigned to receive milk-based formula; sessions in which a child health worker guided mothers to provide stimulating play and interaction; both nutrition and stimulation; or no intervention. Researchers reassessed participants at ages 7, 11, 17 and 22 years.

In the latest follow-up at age 31, researchers traced 95 (75%) of the study participants, including those who had migrated to the US, UK and Canada. They measured participants’ IQ, executive function, mental health, psychosocial skills, personality traits and risk behaviors. Participants in the stimulation-only or stimulation and nutrition groups had significantly greater IQ and cognitive flexibility compared with those who received no treatment or nutritional supplements only. The treatment group also showed fewer symptoms of depression and increased conscientiousness and grit (persistence in working toward a goal over time). They had less history of substance abuse and less risk-taking related to health and work

To assess the effects of migration, researchers compiled results for the non-migrants only and found that the pattern of treatment effects for non-migrants was similar to the total sample.

An important finding is that a comparison group of children from the same Kingston neighborhoods who were in the normal growth range had higher IQ than those in both the treatment and non-treatment groups, who had stunted growth.  This highlights the importance of early childhood interventions that prevent such delays.  

Globally, an estimated 250 million children under age 5 in low- and middle-income countries fall short of their developmental potential due to poverty, poor nutrition, stunted growth and limited stimulation. This study provides support for the long-term benefits of early childhood interventions designed to empower parents in their role as a child’s first teacher and to promote development that increases opportunity for disadvantaged children into their adult lives.

 “The wide-ranging benefits at 31 years from the stimulation intervention supports investment in larger scale programs to promote early childhood development in disadvantaged children,” the authors write.