Poverty May Slow Early Brain Growth

Megan Brooks

December 19, 2013

Poverty has a negative impact on the rate of brain growth in children, new research suggests.

A longitudinal imaging study conducted by investigators at the University of Wisconsin-Madison and the University of North Carolina-Chapel Hill found that by age 4 years, children living in households with income below 200% of the federal poverty line (FPL) had less gray matter ― critical for processing information and executive function ― than their peers from more affluent homes.

"This is an important link between poverty and biology. We're watching how poverty gets under the skin," study investigator Barbara Wolfe, PhD, said in a statement.

The researchers also found that smaller gray matter volume correlated with greater behavioral problems in the preschool years.

"One of the things that is important here is that the infants' brains look very similar at birth. You start seeing the separation in brain growth between the children living in poverty and the more affluent children increase over time, which really implicates the postnatal environment," study coauthor Seth Pollak, PhD, added.

The study was published online December 11 in PLoS One.

Major Public Health Problem

Childhood poverty is a "major public health problem," with nearly 15 million children in the United States currently living in households with incomes below the FPL. Living in poverty puts children at high risk for problems at school as well as behavioral and health problems, the authors note.

The researchers assessed the impact of poverty on early brain development in 77 typically developing children from economically diverse backgrounds participating in the US National Institute of Health Magnetic Resonance Imaging (MRI) Study of Normal Brain Development.

They analyzed a total of 203 MRI scans. Most of the children were followed longitudinally, with the average age at first MRI of 13 months and subsequent scans occurring approximately every 6 months until the children were 4 years old.

When compared with children from affluent families (income > 400% FPL), children from poor and near-poor families (income < 200% FPL) had significantly lower average total gray matter volumes (P = .021). These differences were found for both the frontal and parietal lobes. No differences were detected in white matter, temporal lobe volumes, or occipital lobe volumes.

Differences in brain volumes between children from low- and high-income households were not accounted for by infants' birth weights, infants' early health, or differences in head size at birth.

The researchers did not detect any meaningful difference in gray matter when comparing children from moderate-income households with those from high-income households.

Stress, Poor Nutrition

The study also showed differences in the rate of brain growth by family income, with children from lower-income households having slower trajectories of growth during infancy and early childhood.

"As infants aged ― and presumably had increased exposure to the effects of their environments ― the differences in brain volume between poor children and those with greater resources widened," the investigators write.

Dr. Pollak told Medscape Medical News that more research is needed to understand exactly what is driving volumetric brain changes with poverty. There are some "likely candidates that researchers in general are examining and which there is good laboratory evidence to suggest might be the case," he said.

These include interpersonal and environmental stress associated with poverty, "which could trigger stress-related hormones that could impede brain development," he added.

Poor nutrition is another possible factor.

"A lot has been written about how poor neighborhoods tend not to have grocery stores, and parents are often shopping in convenience stores and buying unhealthy foods. It's possible these children just aren't getting the protein, nutrients, and iron that they need," said Dr. Pollak.

Commenting on the findings for Medscape Medical News, Hallam Hurt, MD, a neonatologist at Children's Hospital of Philadelphia, Pennsylvania, who has studied poverty and its effect on early brain development, said the study contributes to the literature and raises concerns about environmental effects of poverty on child brain development, "at a time when children, we hope, are given every opportunity to learn [and that] the effects of poverty occur very early and seem to grow over time."

As reported by Medscape Medical News, a study published earlier this year in JAMA Pediatrics also found that exposure to poverty in early childhood negatively affects brain development, but that good-quality caregiving may help offset this effect.

The study was funded by the National Institutes of Health. The authors and Dr. Hurt have disclosed no relevant financial relationships.

PLoS One. Published online December 11, 2013. Full article

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