Less gray matter in key areas of the brain could account for as much as 20 percent of the achievement gap between children living in poverty and those who are not, according to a new study.
The results of brain scans of 389 typically developing children, ages 4 to 22, showed that children whose family income was below the federal poverty line were the most adversely affected. They had less gray matter, which processes information in the brain. Brains of “near-poor” children in families whose income was 1.5 times the poverty threshold also showed significant structural differences from the brains of children in higher-income families, though those differences were not as extreme. In 2015, a family of four with an income below $24,250 is considered living in poverty.
The study did not determine why living in poverty impedes the natural maturation of the brain, said lead author Nicole L. Hair, a Robert Wood Johnson scholar in Health Policy Research at the University of Michigan, Ann Arbor. Although some research has pointed to caregiver interactions and stress in low-income families as reasons for the achievement gap, Hair said more research needs to be done about which poverty-related factors have the biggest impact on brain development.
“The brain continues to develop and continues to change structurally into our 20’s,” said researcher Nicole L. Hair. “With intervention, it may be possible to alter this link between poverty and academic achievement.”
The results “don’t imply that low-income children’s ability is predetermined or a permanent disadvantage,” Hair said. “The brain continues to develop and continues to change structurally into our 20’s. With intervention, it may be possible to alter this link between poverty and academic achievement.”
Hair noted that there were no significant adverse effects on children in families whose income was between 1.5 times and two times the poverty threshold. And, in an earlier study by Hair, she found that children’s brains look similar when they are born. “Clear differences begin to emerge once they are 3 or 4,” she said.
Her research reinforces the efforts of California to improve the quality of daycare centers and provide more funding for childcare providers. Some school districts, as part of their efforts to close the achievement gap, have also decided to invest in children starting at birth
The children and adolescents in the study were screened for a variety of factors that could affect brain development, such as low birth weight, exposure to lead, a risky pregnancy or a family history of psychiatric problems. Children in those categories were not included in the study. In addition, the educational attainment of the families in the study was similar, regardless of their economic situation. The study, Association of Child Poverty, Brain Development, and Academic Achievement, was published on July 20 in JAMA Pediatrics, a publication of the American Medical Association.
The researchers found that poverty affected the structure in three parts of the brain that have an impact on academic achievement:
- The frontal lobe, which controls attention, inhibition and emotions, and affects complex learning;
- The temporal lobe, which is important in memory and language comprehension, such as learning the alphabet, identifying words and attaching meaning to words; and
- The hippocampus, which processes spatial and contextual information and has been tied to long-term memory functioning.
The volumes of gray matter overall were 3 to 4 percentage points below the developmental norm for children whose family’s income was at the poverty line or 1.5 times above. A larger gap of 7 to 10 percentage points was observed for children below the poverty line.
On average, children from low-income households scored 4 to 8 points lower on two standardized tests. The Wechsler Abbreviated Scale of Intelligence (WASI) scores include a verbal IQ that measures word knowledge, verbal reasoning, concept formation, visual information process, abstract reasoning and visual motor coordination. The second test, the Woodcock-Johnson III Tests of Achievement (WJ-111), included math computation, letter-word identification and the ability to understand written text. For both tests, a composite score between 90 and 110 is considered average.
Using a statistical technique called mediation analysis, the researchers estimate that 15 to 20 percent of the gap in test scores could be explained by the structural differences in
the three parts of the brain they examined. Researchers employ mediation analysis to understand what underlies a known relationship — in this case, that children living in poverty have lower test scores.
The researchers — including Jamie L. Hanson from Duke University and Barbara L. Wolfe and Seth D. Pollak from the University of Wisconsin-Madison — conducted the study from November 2001 through August 2007, scanning the children’s brains in most cases three times at about two-year intervals. About 5 percent of the children and adolescents lived in families below the poverty level, and 10 percent were “near-poor.” The participants were recruited from six different parts of the country.
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