Child Poverty: Negative Impact on Brain Development

Nancy A. Melville

July 28, 2015

Children raised in poverty show significant differences in brain structures linked to learning and education that correspond with impaired academic performance and standardized test achievement, new research shows.

"We knew that poverty affects brain development and that there is an educational achievement gap between poor children and middle-class children," coauthor Seth D. Pollak, PhD, Letters and Sciences Distinguished Professor of Psychology at the University of Wisconsin, in Madison, told Medscape Medical News.

"This research closes the gap to show that the delayed brain growth associated with poverty explains the educational achievement disparities."

The study was published online July 20 in JAMA Pediatrics.

Long-term Impact

For the study, the investigators evaluated 823 MRI scans obtained between 2001 and 2007 from six data collection sites in the United States through the National Institutes of Health Magnetic Resonance Imaging Study of Normal Brain Development.

The scans were from 389 normally developing children and adolescents aged 4 to 22 years for whom complete sociodemographic and neuroimaging data were available. Assessments at baseline and 24- month intervals for three periods were available for 301 of the participants.

The participants were from economically diverse backgrounds, with approximately a quarter from families with incomes lower than 200% of the federal poverty level.

The MRI analysis showed that children from the poorest households had the greatest deficits: those from families with incomes lower than the federal poverty level had regional gray matter volumes that were as much as eight to 10 percentage points less than those of children with normal development (P < .05).

Children from families with income lower than 150% the federal poverty threshold had gray matter volumes that were 3 to 4 percentage points less than children with normal development (P < .05).

Compared with children from "near-poor" families, with incomes 150% to 200% higher than the federal poverty level, the poorest children showed significant maturational lags in brain regions, including the frontal lobe, the temporal lobe, and the hippocampus ― all areas involved in critical thinking skills, such as reading comprehension, language usage, and associative learning, the authors say.

"Dysfunction in these processes may significantly affect scholastic and later occupational success."

In contrast, there were no statistically significant differences in the brain regions between children of near-poor families and those from higher socioeconomic status groups.

"It surprised us that there were no differences between middle-class and affluent children's brains or achievement," Dr Pollak said. "The big differences were between those children living in poverty and those that, although not affluent, were not poor."

In terms of standardized test scores, children from low-income households with incomes lower than 150% of the federal poverty threshold had scores that were 4 to 8 points less than average (P < .05).

Using mediation analyses, the authors found that the neurobiological differences in the low-income children did correlate with academic achievement.

"We found that developmental differences in the frontal and temporal lobes may have explained as much as 15% to 20% of low-income children's achievement deficits," they explain.

Previous animal studies have shown that physical and psychosocial factors associated poverty, including environmental stimulation, parental nurturance, and early-life stress, can each affect brain structure and functioning.

"When compared with their more-advantaged peers, children living in poverty experience less parental nurturance while confronting elevated levels of life stress, increased family instability, and greater exposure to violence," the authors write.

"Their homes are more crowded and often provide less-cognitive stimulation."

The neurobiological deficits associated with such experiences have been further shown to have potentially significant long-term effects, extending beyond childhood and into adulthood.

Underestimated Risk?

Although the new study adjusted for various risk factors, the problem of the effects of poverty could in fact be even greater than suggested, writes Joan L. Luby, MD, of Washington University School of Medicine in St. Louis, in an accompanying editorial.

"Given the nature of the study sample investigated...it is likely that the effects reported represent an underestimate of the magnitude of risk in the general population," she writes.

That being said, other research has shown that, just as environmental factors are linked to deficits, various interventions have been shown to prevent or even reverse the effects, she told Medscape Medical News.

"We have shown the effects of poverty on brain development are mediated through parental or caregiver support, so interventions that target parental support and help caregivers to be more nurturing, attentive, and attuned to their children could be a critical specific intervention to prevent some of these outcomes."

"Programs such as the Perry Preschool Project and the Nurse-Family Partnership have been shown to be powerfully effective interventions, particularly in early childhood," Dr Luby said.

Other studies looking at the plasticity of neural outcomes have also shown promise, Dr Luby added.

"There have been a number of studies showing when you look at children who are experiencing deprivation and place them in settings with better nurturing, the negative brain outcomes go in the other direction, so there is every reason to believe that intervention early in life does reverse negative neural changes."

The study received support from the National Institute of Child Health and Human Development, the National Institute on Drug Abuse, the National Institute of Mental Health, and the National Institute of Neurological Disorders and Stroke. Dr Luby's research has received support from the National Institute of Mental Health of the National Institutes of Health. Dr Pollak and has disclosed no relevant financial relationships.

JAMA Pediatr. Published online July 20, 2015. Full text, Editorial

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