It's a sad fact that children born in poverty start out at a disadvantage and continue to fall further behind kids who are more privileged as they grow up. In developing countries, chiefly in Africa and Asia, some 200 million children under age 5 won't reach the same milestones—for physical growth, school performance, and earnings later on—as children who are less deprived. But a new analysis of a long-term study in Jamaica shows that surprisingly simple ways of stimulating children’s mental development can have dramatic benefits later in life.
The children were participants in the Jamaican Study, a project geared toward improving cognitive development begun in the mid-1980s by child health specialists Sally Grantham-McGregor of University College London and Susan Walker of the University of the West Indies, Mona, in Jamaica. They focused on children between the ages of 9 and 24 months whose growth was stunted, placing them in the bottom 5% of height for their age and sex (an easy-to-quantify gauge of extreme poverty). Children of normal height in the same neighborhoods were also studied for comparison.
For 2 years, community health workers visited the families weekly. One group was given nutritional assistance only (a formula containing 66% of daily recommended calories, along with vitamins and minerals). One group received a mental and social stimulation program only, and one group got stimulation and nutritional assistance. A final group had no intervention and served as a control. The mental stimulation program involved giving parents simple picture books and handmade toys, and encouraging them to read and sing to their children and point out names of objects, shapes, and colors. They were also taught better ways to converse and respond to their toddlers. These everyday interactions aren't always part of the culture in low-income countries, explains Paul Gertler, an economist at the University of California, Berkeley. "Parents might have five or six kids and few toys. They might be working really hard and have a lot of competing demands. They might not have been taught how to talk to their children, or how important and effective it is," he says. Past research attests to the importance of everyday conversation for children’s mental development: A recent study suggests that children of affluent parents do better in life in large part because their parents talk to them more.
Follow-up studies over the next 20 years revealed that the Jamaican children who received the mental stimulation had better grades and higher IQs, showed fewer signs of depression, and got in fewer fights. The new study, reported online today in Science, focused on the children's economic achievement as young adults. Gertler, Grantham-McGregor, Walker, and colleagues tracked down 105 out of the original 129 growth-stunted children. Those who had received the stimulation intervention had earned 25% more than the children in the control group. Even more exciting, Gertler notes, is that they had closed the gap—in physical and economic stature—between themselves and children in their neighborhoods with normal height and weight. Adding nutritional assistance to the mental stimulation didn’t improve outcomes any further, and nutritional assistance on its own had no effect—likely because this kind of intervention must be used before a child’s growth has been stunted, Gertler says.
"Mental and social stimulation at around 1 year of age really matter," Gertler says. "It was enough to reduce and possibly eliminate inequality in the long term." Gertler emphasizes that the interventions were inexpensive, consisting of toys, books, and conversation—not pricey, high-tech gadgets like iPads, for example.
Jere Behrman, an economist at the University of Pennsylvania who was not involved in the research, says the study is the first to demonstrate a long-term economic benefit to early intervention stimulation programs in developing countries. But he is more cautious about saying that the program greatly reduces inequality. "A 25% increase in earnings will improve the welfare of people who are very poor, and that's something to be glad about. But it may not reduce overall inequality by very much." He points out that although the mentally stimulated children caught up to other poor children who weren't malnourished, their later earnings didn’t begin to compare to those of more affluent kids.
Still, Behrman agrees that the simplicity of the interventions in the Jamaican Study is a point in its favor. "Flying in world-class psychologists to work with the kids for hours would give impressive results, but that wouldn't be easy to duplicate.” The Jamaican Study’s methods now are being used in Bangladesh, India, and Colombia. The study provides proof that “homemade toys and weekly visits from someone from within the community can also have a dramatic impact,” Behrman says.
Joan Lombardi, who was deputy assistant secretary for early childhood development in the U.S. Department of Health and Human Services from 2009 to 2011 and is now a senior adviser to the Bernard van Leer Foundation in The Hague, the Netherlands, says the study adds to the growing body of research from around the world confirming that what happens in the early years has an impact on long-term health, learning, and well-being. "Investing in the early years pay off," she says. "It's time to translate this growing science into improved policies and new investments in young children and their families around the world."
*Clarification, 2 June, 11:29 a.m.: This article has been updated to clarify that according to Jere Behrman, the study is the first to demonstrate an economic benefit for early intervention programs that focus on mental and social stimulation in developing countries. Behrman’s research in Guatemala has shown that programs aimed at improving nutrition for infants and toddlers can improve earnings in adulthood.