The new study suggests a link between childhood poverty and academic deficits.
The results published in the journal JAMA Pediatrics suggest the differences for low-income children could explain "as much as an estimated 20% of the achievement gap."
Seth Pollak, PhD, of the University of Wisconsin-Madison, and colleagues analyzed magnetic resonance imaging (MRI) scans of 389 children and adolescents aged between 4 and 22 years who were developing typically. Complete sociodemographic and neuroimaging data were available for them.
The children's scores on cognitive and academic achievement tests were also taken with the scans of brain tissue, which included gray matter of the total brain, frontal lobe, temporal lobe and hippocampus.
The researchers found regional gray matter volumes were 8-10% below the developmental norm in the brains of children below the federal poverty level.
Children below 150% of the federal poverty level had regional gray matter brain volumes 3-4% below the developmental norm.
The researchers say socioeconomic disparities in school readiness and academic performance are well documented. On standardized tests in the study, children from low-income households scored 4-7 percentage points lower.
Little has been known about the mechanisms underlying the influence of poverty on children's academic achievement, however.
The study concludes:
"Development in these brain regions appears sensitive to the child's environment and nurturance. These observations suggest that interventions aimed at improving children's environments may also alter the link between childhood poverty and deficits in cognition and academic achievement."
'Unassailable body of evidence'
An editorial about the study has been published in the same issue of the journal, written by Dr. Joan Luby of the Washington University School of Medicine in St. Louis, MO. She says:
"Building on a well-established body of behavioral data and a smaller but expanding body of neuroimaging data, [the authors] provide even more powerful evidence of the tangible detrimental effects of growing up in poverty on brain development and related academic outcomes in childhood.
"In developmental science and medicine, it is not often that aspects of a public health problem's etiology and solution become clearly elucidated. It is even less common that feasible and cost-effective solutions to such problems are discovered and within reach.
"Based on this, scientific literature on the damaging effects of poverty on child brain development and the efficacy of early parenting interventions to support more optimal adaptive outcomes represent a rare roadmap to preserving and supporting our society's most important legacy, the developing brain.
"This unassailable body of evidence taken as a whole is now actionable for public policy."