We've long known that children from affluent families get a head start that can translate into a long-lasting advantage, especially when it comes to academic achievement. Now, scientists have found what may be part of the explanation: Children who grow up in higher-income families appear to have larger brains.
Researchers from nine universities across the country, led by neuroscientists at Children's Hospital Los Angeles and Columbia University Medical Center, conducted a major new study of the effects of family income and parental education on child and adolescent brain development.
"We've known for a long time that kids from lower-income or disadvantaged families don't do as well in school and have more difficulties on standardized tests," Dr. Elizabeth Sowell, director of the Developmental Cognitive Neuroimaging Laboratory at Children's Hospital Los Angeles, told The Huffington Post. "We know that the brain is driving cognition and behavior, so there must be some difference in the brain. This is the largest study to look at things like family income and the size of the brain."
The researchers studied nearly 1,100 individuals between the ages of 3 and 20, collecting data on their socioeconomic situation and conducting MRI brain scans and cognitive tests measuring executive functions like self-control and anticipation of consequences.
The results revealed a strong positive association between family income and brain surface area, largely in those brain areas that are linked to skills instrumental in learning and academic success.
The brain of "the kid whose family makes less than $25,000 is about 6 percent smaller in surface area than the kid whose family made $150,000," Sowell said.
Higher family income was also associated with better performance on tests of executive function. The researchers hypothesize that the better performance is linked to the greater brain surface area.
They found that the relationship between family income and brain surface area was most dramatic at the lower end of the socioeconomic spectrum.
Why the differences in brain size? Since the researchers controlled for genetic factors, it's likely the advantage observed in children from higher-income families arose from other influences -- such as their exposure to better nutrition, health care, schools, play areas, air quality and other environmental factors known to play a role in brain development.
The good news is that improving a disadvantaged child's environment -- through after-school programs, healthier school lunches and other initiatives -- may have a long-lasting positive effect on the child's brain development and cognition.
"We know that experiences in the environment impact the way the brain wires itself through childhood and adolescence," Sowell said. "If we could somehow enrich the environments of particularly the poorer children, we might be able to change that trajectory to equalize it, to some extent."
The study's findings were published March 30 in the journal Nature Neuroscience.