Stark and rising inequality plagues many countries, including the United States, and politicians, economists, and—fortunately—scientists, are debating its causes and solutions. But inequality’s effects may go beyond simple access to opportunity: a new study finds that family differences in income and education are directly correlated with brain size in developing children and adolescents. The findings could have important policy implications and provide new arguments for early antipoverty interventions, researchers say.
Researchers have long known that children from families with higher socioeconomic status do better on a number of cognitive measures, including IQ scores, reading and language batteries, and tests of so-called executive function—the ability to focus attention on a task. More recently, some studies have found that key brain areas in children of higher socioeconomic status—such as those involved in memory or language—tend to be either larger in volume, more developed, or both. However, these studies have suffered from some important limitations: For one thing, they don’t adequately distinguish socioeconomic status from racial background, which in the United States are difficult to tease apart because nonwhite groups tend to have higher poverty levels. And few studies treat family income and education levels as independent factors, even though they can act differently on the child’s developing brain. For example, income may be a better indicator of the material resources (such as healthy food and medical care) available to a child, whereas more highly educated parents may be better able to stimulate their child’s intellectual development.
But unknown genetic factors that influence brain size and also correlate with income could play a role in the results, says Ian Deary, a psychologist at the University of Edinburgh in the United Kingdom who is well known for his work on intelligence. He cites recent studies concluding that both genetic and environmental factors influence socioeconomic status.
Still, Martha Farah, a cognitive neuroscientist at the University of Pennsylvania, says that the study is “a real advance in characterizing how brain development differs” between children of lower and higher socioeconomic status, calling it a “crucial first step” in understanding how income and education levels “shape human development.” She agrees that the study provides compelling support for the idea of alleviating childhood poverty. “Even without neuroscience, the case for investment in society’s poor children is very strong,” she says. “But if brain imaging helps to focus people’s attention on the problem of childhood poverty, that’s great.”
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