By Janice Wood
Reviewed by John M. Grohol, Psy.D.
December 15, 2013
A new study shows that poverty may have a direct impact on the early development of the brain, with children from poor families lagging behind in two key regions of the brain.
The study from researchers at the University of Wisconsin-Madison found that, by age 4, children in families living with incomes under 200 percent of the federal poverty line have less gray matter than kids growing up in families with higher incomes.
Gray matter is brain tissue critical for processing information and execution of actions.
“This is an important link between poverty and biology. We’re watching how poverty gets under the skin,” said Dr. Barbara Wolfe, a professor of economics, population health sciences and public affairs and one of the authors of the study, published in the journal PLOS ONE.
The researchers found the differences after analyzing hundreds of brain scans from children beginning soon after birth and repeated every few months until the age of 4.
They found that the poor children lagged behind in the development of the parietal and frontal regions of the brain — deficits that help explain the behavioral, learning and attention problems more common among disadvantaged children, the researchers noted.
The parietal lobe works as the network hub of the brain, connecting disparate parts to make use of stored or incoming information. The frontal lobe is one of the last parts of the brain to develop.
“It’s the executive. It’s the part of the brain we use to control our attention and regulate our behavior,” said psychology professor Dr. Seth Pollak. “Those are difficulties children have when transitioning to kindergarten, when educational disparities begin: Are you able to pay attention? Can you avoid a tantrum and stay in your seat? Can you make yourself work on a project?”
The researcher noted that the children’s brains looked very similar at birth.
“You start seeing the separation in brain growth between the children living in poverty and the more affluent children increase over time, which really implicates the postnatal environment,” he said.
The study used brain scans provided by the National Institute of Health’s MRI Study of Normal Brain Development. This data excludes children whose brain development may have been altered by a number of factors, such as mothers who smoke or drank during pregnancy, birth complications, head injuries, family psychiatric history and other issues.
As a result, the findings may underestimate the actual deficit in brain development among children from poor families, the researchers noted.
For poor families — who ranged from extremely poor with almost no cash income to a few tens of thousands of dollars per year — the list of potential negative environmental factors is lengthy, according to Wolfe. She points to poor nutrition, a lack of sleep, lack of books and educational toys, parental stress, an unsafe environment and limited enriching conversations as just a few of the potential contributors.
“All of these may play a role,” she said. “We don’t really know their individual contribution or the combined effect. But we do know we observed no apparent structural differences very early in life. This might be viewed as very good news, as it suggests that public policy can reduce the gap.”
Pollak said he believes the absence of enriching activities and interactions are of particular importance.
“We know from nonhuman animal studies that being left in cages without toys and exercise, without stimulation and opportunities to explore, can cause a decrease in the generation of neurons and synapses in the brain,” he said.
If lack of enrichment is a major cause of delayed human brain growth, there is good news, the researchers report. Less gray matter at age 4 is not necessarily a permanent problem.
“These people are not doomed, and can hopefully fully recoup if they are appropriately stimulated,” Wolfe said. “It means that we as a society need to find ways to help provide an enriched, stimulating and safe environment for these young children.”
As many as 16 million children are living below the poverty line in the United States, making interventions a daunting task, she noted. But this suggests a great opportunity for these children and for society, and one that is not necessarily expensive.
“When we say enrichment, we’re not talking about flashcards or special software,” said graduate student Jamie Hanson, the study’s lead author. “We’re talking about providing normal interactions: Talking to and comforting your child, giving children time to play and explore with you out in a park without stress.
“Still, those are hard things to provide for a poor family working multiple jobs, often working the hours when their children are home, taking long commutes, often looking for safe and affordable places to live,” Wolfe added.