Children and teens from families with lower incomes have differences in their brain structure compared with wealthier children, a new analysis of MRI scans reveals.
Scientists report today (March 30) in the journal Nature Neuroscience a correlation between growing up in a lower-income family and having a smaller surface area in brain regions associated with skills that are important for academic success.
The association is independent of the children's race or ethnicity, the researchers found. Encouragingly, however, they also found that even small increases in income among the poorest seem to be associated with relatively large increases in brain surface area, and thus learning potential.
"We do not know exactly what [it is] about having more money [that] leads to these brain size differences, but we suspect it involves all the resources that more affluent people can afford, such as good nutrition, health care, better schools, etc.," said Elizabeth Sowell, senior author on the report and a professor of pediatrics at Children's Hospital Los Angeles and the University of Southern California Keck School of Medicine.
The researchers examined nearly 1,100 individuals between ages 3 and 20, the largest study of its kind. The children's family income levels were assessed through questionnaires, and measurements of the surface area of the brain were assessed with high-resolution brain MRIs. [ 10 Things You Didn't Know About the Brain ]
The researchers found that as family income increases so, too, does the brain surface area of the child, on average, in regions supporting language, reading, spatial skills and executive functions, which are the mental processes that enable focusing, remembering and multitasking.
The study also showed that parental education was linked with a child's total brain surface area, implying that the more education the parent had, the greater the brain surface area for the child throughout his or her development.
However, the link between higher income levels and greater brain surface area showed a "logarithmic" increase among poor families. This means that small increases in income among the poor — for example, from $20,000 a year to $30,000 a year — translated to proportionally larger gains in surface area, far greater than the same $10,000 increase for those in the middle- or high-income brackets.
When the researchers compared children whose families make $25,000 or less per year to families with $150,000 or more, they found about a 6 percent difference in brain surface area; whereas when they compared children of parents with a high school education or lower to a college degree or higher, they found a 3 percent difference, Sowell calculated.
The findings do not imply that income is causing the brain differences (for example, there could be some other underlying factor that affects both brain size and family income level). Nor do they imply that a child's socioeconomic circumstances would necessarily dictate a child's cognitive or brain development in all cases, the researchers stressed.
"The important thing to realize is that, even though we are able to measure differences in brain structure in childhood and adolescence as a function of SES [socioeconomic status], it does not mean that disadvantaged children were or are 'doomed,'" said lead author Dr. Kimberly Noble, assistant professor of pediatrics at Columbia University Medical Center and an associate professor of neuroscience and education at Teachers College, Columbia University, in New York.
"We strongly believe that these differences reflect differences in experience --- learning experiences inside and out of the home, family stress, nutrition, environmental toxicants, quality child care --- that themselves shape brain development," Noble said. "By intervening at the level of those experiences, especially early in childhood, we could prevent or redirect children's detrimental outcomes."
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