Jordan Weissmann has an interesting article over at Slate about recent research which shows that poor children have smaller brains than rich children. Weissmann noted that social scientists have found that “by the time children enter kindergarten, there is already a large academic achievement gap between students from wealthy and poor families.” He added, “We still don’t know exactly why that’s the case.” Some have sensed that the educational gap may have something to do “with the fact that affluent mothers and fathers have more intensive parenting sytles—they’re more likely to read to their kids…and have enough money to make sure their toddlers grow up well-nourished, generally cared for, and intellectually stimulated. At the same time, poor children often grow up in chaotic, food-insecure, stressful homes that aren’t conducive to a developing mind.”
Weissman said the new study, which was published in the journal Nature Neuroscience, has added “an interesting biological twist to this issue.” The researchers used “MRI scans of more than 1,000 subjects between the ages of 3 and 20.” They found that children from poor families tended “to have somewhat smaller brains, on some dimensions” than children who grew up in affluent families.
Specifically, low-income participants had less surface area on their cerebral cortexes—the gray matter responsible for skills such as language, problem solving, and other higher-order functions we generally just think of as human intelligence. Poorer indviduals in the study also fared worse on a battery of cognitive tests, and a statistical analysis suggested the disparities were related to brain dimensions.
In a Nature article titled Poverty shrinks brain from birth, (March 2015), Sara Reardon wrote the following:
The stress of growing up poor can hurt a child’s brain development starting before birth, research suggests — and even very small differences in income can have major effects on the brain.
Researchers have long suspected that children’s behaviour and cognitive abilities are linked to their socioeconomic status, particularly for those who are very poor. The reasons have never been clear, although stressful home environments, poor nutrition, exposure to industrial chemicals such as lead and lack of access to good education are often cited as possible factors.
In the largest study of its kind, published on 30 March in Nature Neuroscience1, a team led by neuroscientists Kimberly Noble from Columbia University in New York City and Elizabeth Sowell from Children’s Hospital Los Angeles, California, looked into the biological underpinnings of these effects. They imaged the brains of 1,099 children, adolescents and young adults in several US cities. Because people with lower incomes in the United States are more likely to be from minority ethnic groups, the team mapped each child’s genetic ancestry and then adjusted the calculations so that the effects of poverty would not be skewed by the small differences in brain structure between ethnic groups.
The brains of children from the lowest income bracket — less than US$25,000 — had up to 6% less surface area than did those of children from families making more than US$150,000, the researchers found. In children from the poorest families, income disparities of a few thousand dollars were associated with major differences in brain structure, particularly in areas associated with language and decision-making skills. Children’s scores on tests measuring cognitive skills, such as reading and memory ability, also declined with parental income.
Reardon said that the study findings were in line with unpublished research “that scanned the brains of 44 African American girls, each approximately a month old, from various socioeconomic groups in Philadelphia.” She added that even “at this early age, the researchers found, infants in the lower socioeconomic brackets had smaller brains than their wealthier counterparts.”
Abstract of the Research Study published by Nature Neuroscience:
Socioeconomic disparities are associated with differences in cognitive development. The extent to which this translates to disparities in brain structure is unclear. We investigated relationships between socioeconomic factors and brain morphometry, independently of genetic ancestry, among a cohort of 1,099 typically developing individuals between 3 and 20 years of age. Income was logarithmically associated with brain surface area. Among children from lower income families, small differences in income were associated with relatively large differences in surface area, whereas, among children from higher income families, similar income increments were associated with smaller differences in surface area. These relationships were most prominent in regions supporting language, reading, executive functions and spatial skills; surface area mediated socioeconomic differences in certain neurocognitive abilities. These data imply that income relates most strongly to brain structure among the most disadvantaged children.
This research should give people like Arne Duncan and the school reformers who believe that a focus on high-stakes testing in schools is somehow going to make our children smarter pause for thought. We need to address the problem that millions of children grow up in poor families in this country! Maybe we should look for new and better better ways to help the the children in the United States who live in poverty.