Poverty Can Harm Early Brain Development, Researchers Say

A host of recent studies show that growing up in poverty can shape the wiring and even the physical dimensions of a young child’s brain, with negative effects on language, learning, and attention. Those findings raise important policy questions in areas ranging from education and health to juvenile justice and social welfare, researchers said at a Capitol Hill briefing organized by AAAS.

Deep insight. Functional magnetic resonance imaging allows neuroscientists to assess the structure and function of children’s brains.

[Credit: Thierry Berrod, Mona Lisa Production/ Science Photo Library]

Scientists have long known that brain development can be harmed by factors such as poor nutrition and exposure to lead. But researchers at the briefing cited studies that are probing how a lack of “cognitive nurturing”—talking and reading to a child, for example—and sustained exposure to “toxic stress” set off a cascade of hormonal and neural responses far different than those in a child who is raised in a more secure, stimulating environment.

“Where a child grows up in impoverished conditions... with limited cognitive stimulation, high levels of stress, and so forth, that person is more likely to grow up with compromised physical and mental health and lowered academic achievement,” said Martha Farah, director of the Center for Neuroscience and Society at the University of Pennsylvania. Once grown up, those children may be more likely to raise their own children in poverty, “and there you have a vicious cycle.

“The promise of neuroscience,” Farah added, “is to understand how this works so that you can intervene” to disrupt that cycle.

Recent technological advances, such as functional magnetic resonance imaging (fMRI), are giving neuroscientists a window onto some of the brain’s deepest structures and innermost workings. But in a culture that tends to venerate free will and view poverty as evidence of weak character and moral breakdown, the emerging insights face an uncertain road to acceptance.

The briefing, held 26 June, drew an audience of over 100 people, including congressional staff, federal scientists, and journalists. It was held with the support of U.S. Representatives Chaka Fattah (D-Pennsylvania) and Brian Bilbray (R-California), and was the first in a series of three Capitol Hill briefings on neuroscience organized by the AAAS Office of Government Relations with support from The Dana Foundation.

In the opening presentation, James Griffin, director of the Early Learning and School Readiness Program at the National Institutes of Health, described the early growth of the brain. By the time a child is 3, the brain is 80% the size of an adult’s, with 1000 trillion neuron connections that will be critical to continuing development. Areas such as the prefrontal cortex that govern more complex functions—language, problem-solving, self-regulation, and social bonding—develop most rapidly from ages 1½ to 4.

“This really is a crucial period in brain development,” Griffin explained. “We know we need to... take full advantage of what we can do for children (at that age) so they reach their full potential.”

That’s the importance of cognitive nurturing, the researchers said. When parents or caregivers spend time reading with a child, the intellectual activity helps build neural connections. Without that engagement, important connections will not be activated—and those not activated often are pruned away as the brain develops.

Stressful lives can cause parents to engage less with children, and stress also acts directly on young brains, leaving a physical signature. Farah said her lab and others are finding that higher income levels are associated with greater volume in the prefrontal cortex and in the hippocampus, a center for memory and learning.

Related studies suggest disparities in brain function between low-income and higher-income children. Farah cited “highly robust, sizeable differences” in the functions of these areas, affecting language, self-regulation, and working memory.

Both Griffin and Farah emphasized that the brain can recover from effects of childhood poverty. But, they said, preventing harm is more efficient than repairing it.

Developing strategies to address these issues would require broad shifts in public policy. Even without that, the researchers said parents and caregivers can have a constructive impact just by talking and reading to their children and doing what they can to build a sense of security.

For children, the future “depends on us understanding really, fully, what is the science... and how do we put it into practice,” said Annapurni Jayam-Trouth, chair of the Department of Neurology at Howard University. “The science must be transmitted via many channels of education to the general public, especially to poor communities, so intervention can begin early at home.”