In the largest-ever interdisciplinary study of its kind, researchers have established links between low socioeconomic status and brain structure.
A consortium of researchers from Columbia, Children’s Hospital Los Angeles and Yale, among other institutions, investigated the relationship between brain structure and socioeconomic factors, independent of genetic ancestry. Based on a sample size of 1,099 individuals between the ages of three and 20 years, the study found that among children from the lowest-income families, small differences in income were positively related to relatively large differences in cortical surface area. Cortical surface area is connected to skills needed for academic success, such as language, reading and attention span. The study was published in the journal Nature Neuroscience on March 30.
“This study is the first of its kind looking at real life population,” said senior author of the study Walter Kaufmann, professor of neurology at Harvard Medical School and director of the Rett Syndrome Program at the Boston Children’s Hospital. “We tried to represent the ethnic and social composition of the U.S. and we collected imaging, genetic and socioeconomic data.”
Kaufmann noted that small increases in income within the lowest socioeconomic rungs had the largest impact on increases in cortical surface area.
There were three distinctive features of the study, said Natalie Brito, a postdoctoral student at Columbia who studies developmental psychology and works with Columbia University professor of pediatrics Kimberly Noble, first author of the study. First, the researchers investigated the effects of parental education and family income separately, two variables often “lumped together” in studies but which may separately influence the result. Second, while past studies only focused on cortical volume, this study separated its two components, namely cortical surface area and cortical thickness. Third, the study controlled for genetic ancestry.
David Glahn, professor of psychiatry at the Yale School of Medicine, who was not involved in the study, said he was struck by the interdisciplinary nature of the project.
“My first thought when I read this paper was neuroscience meets social justice,” he said.
While he said he was “not surprised” by the results, Glahn acknowledged that the scientists successfully demonstrated the effect of socioeconomic factors on brain development.
Although past scientific research has shown that environment influences development trajectory, the paper made two innovations, Glahn said. First, the study’s focus on actual brain structure and sample size made it “by far the largest and most authoritative study in this field.”
In addition, he noted that extracting minority status from poverty is very difficult, but the study does so by taking into account genetic ancestral variables.
“If we didn’t believe it before, this study tells us there are specific biological consequences of having a poor environment as a child, namely things like not enough food or not enough consistency, “ Glahn said.
Noble said it is important to note that the study indicates correlation and not causation. She added that she and her colleagues are in the process of planning a large research study to establish causal impact.
Kaufmann said the results of the study have important consequences for both the sciences and the social sciences. He added that it would be interesting to conduct research studies following individuals over time and explore what other factors in brain structure could explain the results of the study.
Similarly, Glahn said the study raises several questions for future explanation.
“Part of what is exciting is that the biggest changes are happening in the lowest socioeconomic level,” he said. “I would like to see more studies possibly showing similar results, particularly in the lowest socioeconomic groups, which is where you would possibly have the most important statement from a policy perspective.”
He added that he would also like to see studies that probe the method used by the authors to dissociate genetic effect and environment, and investigate whether it would be a viable method to study other topics like aging.
According to the National Center for Children in Poverty, more than 16 million U.S. children are growing up in families whose incomes fall below the federal poverty line.