We know that lots of things shape children’s brains – reading to them, letting them play outdoors, teaching them to play music. Now a new study, the largest of its kind to date, has found a relationship between family income and children’s brain structure.
Looking at the brains of more than 1,000 typically developing kids ages 3 to 20, researchers found that the brains of those growing up in households with an income of $25,000 a year or less were six percent smaller than the brains of kids in households earning $150,000 a year or more.
Neuroscientist Elizabeth Sowell, Ph.D., who participated in the study, explains that connections within the brain are reinforced through “insulation” that makes them quicker and more efficient, and that this insulation takes up space, causing the brain to expand.
It is likely the enriched surroundings of higher-income children that accounts for the boost in brain growth. “The brain decides what to wire up based on experiences in the environment,” says Sowell, who is director of the Developmental Cognitive Neuroimaging Laboratory at Children’s Hospital Los Angeles, which participated in the study along with Columbia University Medical Center. Expanded brain area also seemed to translate into skills, especially in the areas of language and problem-solving.
But perhaps the most important point in the study, published in the online edition of the journal Nature Neuroscience in March, was that this money-brain relationship didn’t always hold true. “We have some of our poorest children in our sample whose brains look much like the wealthiest,” says Sowell, and the reverse is also true. And figuring out why could help experts bridge this income gap.
“We did not measure what sorts of experiences these kids are actually having,” Sowell says. Researchers in this study didn’t ask about nutrition or extracurricular activities or books in the home, but strongly suspect that those are the kinds of things that more-advantaged children have access to. Money can buy a home away from air pollution, with outdoor space for kids to play. It can get kids into better schools. “We are definitely going to delve deeper into the things that we think money can buy in the research going forward,” says Sowell.
One bright note in the study was that for the lowest-income families, small differences in income were linked with large differences in brain development. This means that small income improvements could lead to big environmental changes – and big boosts in kids’ brains.
Sowell also points out that a child’s brain development continues well past adolescence, so there’s time for experts to figure all of this out. “It’s not done at 3, it’s not done at 5, it’s not done at 12,” she says. “It keeps happening. It’s dramatic.”