Children who grow up in poor environments were found to have slower brain development than their middle-income and high-income peers, a study published this week found by comparing images of children's brains as they aged.

Child development researchers looked at neuroimaging scans of nearly 400 children across socio-economic backgrounds and found the ones who were raised in poverty had less gray matter in their prefrontal lobe, temporal lobe, and hippocampus, areas that control executive function, language ability, and memory, according to the results of the study published in JAMA Monday.

"We've known for a long time that poor children tend to have worse outcomes in school, but the question remains as to why, so what we wanted to understand was what might explain the achievement gap," Nicole Hair, a Robert Wood Johnson Foundation scholar in health policy research at the University of Michigan and lead author of the study, told VICE News. "There are a number of factors that might influence achievement, but we were interested in whether there might be a biological pathway, and whether the brain development might explain the behavior differences."

The study found that "poverty is tied to structural differences in several areas of the brain associated with school readiness skills, with the largest influence observed among children from the poorest households," the authors wrote, noting that there were larger gaps in achievement the wider the income gap was.

The authors built on a foundation of research that has long found links between school performance and poverty, but the technique of using brain scans to find actual biological, concrete signs of the link were new and noteworthy, Hair and coauthor Barbara Wolfe, professor of economics, public affairs, and population health sciences at the University of Wisconsin and another author of the study, told VICE News.

"We know that children's brains continue to develop through childhood and are responsive to stimulus; we have seen in work with animals that these regions are sensitive to stress and nutrients and caregiving and cognitive stimulation," Hair said. Children living in poverty have long been known to have lower scores on standardized tests, poorer grades in school, and lower attainment, and as they reach adulthood earn less than their peers, the study said.

"The part that's unique about this is by measuring something physical and concrete, you can much more easily see the influence of poverty. It really does open up the potential that you could have an intervention and rather than waiting to see the effect of intervention three or five or 10 years later, you can measure the brain quickly, and may be able to better design policies. That's really exciting to me. I'm very interested in poverty policy," Wolfe said.

The study focused particularly on whether environmental factors, including parental nurturance and the stress of poverty, affected the growth and functioning of the brain. Gray matter, the researchers explained, was the part of the brain that does "the firing," as opposed to the white matter, which makes up the other parts of the brain and acts as the wiring or conduit. They focused on gray matter in parts of the brain that are known to be vulnerable to the environment, not just inherited traits.

Children had images of their brain created once every 24 months for three periods, and children whose brains may have been affected by other factors, such as adoption, risky pregnancy, or birth histories, family mental health histories, and low IQ were screened out of the study.

"What we have measured is that growing up in poverty seems to have diminished areas like the prefrontal lobe and hippocampus, which are important both for academic performance and decision making. There is this effect on children who are growing up in poverty," Wolfe said.

Wolfe said there are many hypotheses about what may cause the differences in brain development, from more stress in low-income families, to less stimulation, or that the families may move more frequently, or have poorer nutrition, or are more frequently exposed to toxins in the air.

"All of these would be possibilities," she said.

"What we hope to do in our next phase would be to test whether children who, maybe their family has housing instability, if they moved to a better area whether we could capture and see whether that has any effect on the child. Or if you have subsidy or regulations for childcare, does that improve possibilities for the child? Almost any policy you can think of, if you can take an image of the child you may be able to gauge whether it has positive influence on the development of the child," Wolfe said.

"Our work suggests we should prioritize efforts aimed at improving children's environments," Hair said. "The brain is plastic and continues to develop into young adulthood, so with intervention it might be possible to alter this link."