Research has shown that a person's position in the economic pecking order can have a lasting effect on cognitive development. But can it also affect the size and shape of the brain?
A new study suggests that a family's socioeconomic status correlates with the surface area of children's brains, regardless of genetic ancestry, race and other factors.
Not only does mom and dad's salary appear to account for variability in surface area of children's brains, but a small raise for those on the low- or middle-income scale seems to have a disproportionately bigger effect on children's brain size and scores on cognitive tests, according to the study, published online in the journal Nature Neuroscience.
"We've known for a long time that cognitive development, school performance and productivity in adult life can be impacted by socioeconomic status, but now we're actually seeing it in the brain," said Elizabeth Sowell, a developmental neuroscientist at the Saban Research Institute at Children's Hospital Los Angeles, and lead investigator of the study.
Still, exactly how parental income might determine brain development is uncertain - many factors come along with income, and each may turn out to have a role.
"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."
Those experiences physically reshape the brain over time. Researchers were particularly interested in changes in surface area, which have been associated with the way the brain improves connectivity through a process somewhat analogous to adding insulation to wiring.
They used a pediatric database that includes brain images, genotypes, cognitive tests and developmental history for more than 1,000 young people, ages 3 to 20. That database, known as the Pediatric Imaging, Neurocognition and Genetics project, also includes information on parental income and education.
Both income and education correlated with brain surface area, particularly in areas associated with language, reading and executive function. But further analysis showed that only income uniquely accounted for the variance in surface area, the study found.
Both Income and surface area also correlated with four tests of cognition, the study found.
Perhaps as important, genetic ancestry and race did not prove to be decisive factors, according to the study. Those factors often wind up intertwined with socioeconomic status, the authors said.
So are we damned by our parents' income? Not quite, the researchers say. Not only are there notable exceptions - lots of poor achieve high education goals - but small investments at critical periods can have big effects, the data suggest.
"We think that if we could make changes to enrich environments that we could alter development," Sowell said.