The children placed in foster care showed rapid increases in height and weight. By 12 months, all were in the normal range for height and 90 percent were in the normal range for weight. The children left in institutions lagged in both measurements.
Diet does appear to play a role, Johnson said, probably because close attention was not being paid to their eating habits. "If someone is not paying attention, they probably are not getting enough to eat," he said.
But food intake is just one aspect of eating, Johnson added. "So much of our interactions occur while children are eating," he said.
The study also showed that children whose height caught up to normal levels also had improved thinking, learning and memory abilities. "Each incremental increase of one in standardized height scores between baseline and 42 months was associated with a mean increase of 12.6 points in verbal IQ," the report said.
There is a biological explanation for the relationship, said Nathan A. Fox, a human development professor at the University of Maryland and a member of the research team.
"Psychosocial stimulus interacts with the physiological system," Fox said. "It increases production of growth hormone and reduces stress. Providing adequate psychosocial stimulus is necessary for growth."
While it is not clear whether such maltreatment can affect the development of psychological disorders, "physical growth and development, brain growth and activity, all of those have shown the effects of intervention," Fox said.
"Kids require a good diet, but they also require good nurture," Johnson said. "Without both those factors, kids will not do well."
There's more on child development at the U.S. Centers for Disease Control and Prevention.
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