A six-year study by researchers at the University of Wisconsin-Madison has added to the mounting evidence that growing up in severe poverty affects how children’s brains develop, potentially putting them at a lifelong disadvantage.

The study — which combined the expertise of neuroscientists and economists — found that the parts of the brain tied to academic performance were 8 per cent to 10 per cent smaller for children who grow up in very poor households.

It was based on a relatively large sample of predominantly white children whose mothers were much more educated than the general population. And the results show a biological link between growing up in extreme poverty and how well children do academically.

“The significance of the study is providing a hard physical link between the experience of growing up in poverty and how well children do on cognitive tests,” said Barbara (Bobbi) Wolfe, an economist at UW-Madison and one of the co-authors of the study.

The study, published in JAMA Pediatrics in July, builds on animal studies and other research suggesting that poverty affects the parts of the brain tied to self-control, attention, planning and other traits important for success in school and life.

The children often receive less nurturing from parents and live in environments characterized by increased stress from crowded housing, instability, poor nutrition, limited stimulation and more exposure to violence.

That children who grow up in poverty do less well in school is well documented. But studies increasingly show that at least part of that overall poor performance stems from how their brains grow and work.

The UW study estimated that as much as 20 per cent of the gap in test scores could be explained by slower development of two parts of the brain: the frontal lobe and the temporal lobe.

The frontal lobe is important for controlling attention, inhibition, emotions and complex learning. The temporal lobe is important for memory and language comprehension, such as identifying and attaching meaning to words.

Both areas of the brain develop through adolescence.

“It provides a brain-based explanation for why children living in poverty are not performing academically as well,” said Joan Luby, a professor of child psychiatry and director of the Early Emotional Development Program at Washington University School of Medicine. Luby was not involved in the study.

The UW-Madison study was led by Wolfe and Seth Pollak, a professor of psychology and director of the Child Emotion Lab.

The study drew on 823 magnetic resonance imaging, or MRI, scans of 389 children, ages 4 to 22, from a National Institutes of Health (NIH) study done to show normal brain development. The scans were done from November 2001 to August 2007, and the NIH study included complete information on the families’ social and economic status.

The design of that study provided additional support for how poverty affects brain development in children.

Here’s why:

The mothers of the children included in the study were much better educated than the general population — 84.9 per cent said they had at least some college education.

<bullet> Families were screened for several factors suspected to adversely affect brain development, such as children who were born prematurely or who had other risky neonatal histories, who had low IQs and whose families had a history of psychiatric conditions.

The sample, in other words, was not representative of children growing up in extreme poverty.

“And we still found this drastic difference in brain development,” Pollak said.

The study, though, also contained an encouraging nugget: It found no significant difference in the brain development of children who grew up in so-called near-poor households — those with incomes above 200 per cent of the federal poverty threshold, or $40,180 for a family of three — and those who grew up in middle-class or even upper-middle class households.

“What that says to me is that humans can actually deal with a quite a lot,” Pollak said. “We are not delicate orchids.”

Research shows that early interventions, such as home-visitation programs for families and preschool for children, are effective and have the potential to change lives.

That’s because the brain has more “plasticity” early in life — it responds more quickly to changes in environment.

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The studies on how poverty affects the development of children’s brains are relatively new. Few existed a decade ago. But now more studies exist, and they are getting more attention in policy circles.

They suggest the need to invest in children, Wolfe said.

If society doesn’t, she said, “they are worse off, and we are all worse off.”