Scientists, politicians, and economists continue to examine the possible causes of economic inequality to identify the solutions that might help make progress. Beyond simple access to opportunity, a new study shows that the differences in income and education in families correlate directly with brain size in developing children and adolescents. These findings could result in stronger arguments for early antipoverty interventions, according to researchers.
Michael Balter, writing for Science Magazine, reports that it has long been known that children from families with higher socioeconomic status test more highly on a number of cognitive measures, like IQ scores, reading, language, and executive function, or the ability to focus attention on a task. More recent studies have found that key brain areas, especially memory and language, in children raised in higher socioeconomic status tend to be larger in volume, more developed, or both.
The studies fall short in some areas, however, such as adequately differentiating socioeconomic status from racial background. In the US, this differences can be difficult to unravel, since nonwhite groups tend to have higher poverty levels. One example of this puzzle is that income may be a better indicator of material resources available to a child, but more highly educated parents might be better at stimulating their child's intellectual development.
The researchers, led by Kimberly Noble of Columbia University and Elizabeth Sowell of Children's Hospital Los Angeles in California, are cognitive neuroscientists who specialize in child development. The team recruited 1099 children and young adults with the assistance of researchers from nine US universities and hospitals through the use of Internet and community advertising and word of mouth. They also controlled the factors of race and genetic ancestry through DNA samples.
The results, published in Nature Neuroscience, showed that "cortical surface area was indeed correlated with different measures of socioeconomic status". There was not, however, any difference in test results based on race and ethnicity.
The reasons that living in poverty causes the inhibition of brain growth could have to do with family stress, greater exposure to environmental toxins, or insufficient nutrition. Higher status families may be able to offer more more "cognitive stimulation" to their children. According to Martha Farah, a cognitive neuroscientist at the University of Pennsylvania:
"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."
The study is based on magnetic resonance imaging of the brains of the participants. The surface area of the cortex increases, it was found, in relation to household incomes. Bradley J. Fikes of The San Diego Union-Tribune explains that the cortex is the center of higher cognitive abilities. The brain's deep nooks and crannies make the surface area larger than if the brain's surface were smooth.
The socioeconomic gap has been addressed by programs such as Head Start, begun in 1965, which provides early childhood education, nutrition and family help to lower-income families.
"We do know that interventions work, but we just don't know why. Now with the study, which provides objective information about what changes take inside the brain, research can be more precisely directed," said Lisa Freund, a developmental psychologist and cognitive neuroscientist at the National Institute of Child and Human Development.
Even a small raise in salary for a low income family can have a dramatic effect on a child's brain size and scores on cognitive tests, reports Geoffrey Mohan of the Los Angeles Times.
"Money can buy better education, homes in areas further away from freeways; It can buy guitar lessons. It can buy after-school programs; it can buy better healthcare, better nutrition," Sowell said. "It's all of those things that money can buy that lead to more enriched experiences for children in wealthier families."
Are we at the mercy of our parents' income? Researchers say that there are exceptions. Plenty of poor children go on to achieve high education goals. The data suggests that small investments at critical periods can have huge effects. Sowell says that development can be altered if changes to enrich the child's environment are made.
In an article by the Children's Hospital Los Angeles Saban Research Institute, published this week in (e)Science News, the authors wrote that income was more associated with the brain than was parental education.
"Specifically, among children from the lowest-income families, small differences in income were associated with relatively large differences in surface area in a number of regions of the brain associated with skills important for academic success, " said first author Kimberly G. Noble, MD, PhD, assistant professor of pediatrics and director of the Neurocognition, Early Experience and Development (NEED) Lab of Columbia University Medical Center.