Poverty and the Developing Brain

People love “Rags to Riches” stories—those sanguine tales in which someone who grew up in poverty manages to become extremely wealthy and professionally successful. These stories breathe life into the American Dream, inspire hope, and illustrate how humble beginnings can’t stand in the way of wealth and success for those who work for it.

Politicians in particular love to invoke the trope that no matter who you are or where you come from, you can make something of yourself. Paul Ryan, the Republican Speaker of the U.S. House of Representatives, recently wrote on Twitter, “In our country, the condition of your birth does not determine the outcome of your life. This is what makes America so great.”

But how true is this?

A recent study, using federal tax records and revealing incomes of more than 40 million children and their parents between 1996 and 2012, showed that whether a child is able to reach a higher income rank than their parents depends a great deal simply on the geographical location in the U.S. in which the child grew up.

While location is important, there are more reasons to doubt the notion that everyone is strong enough to create their own success story as long as they are motivated and put in the effort. Plenty of social science research has shown that children growing up in poverty perform worse at school, have poorer cognitive functioning, and are at higher risk for emotional problems. This work inspired neuroscientists to ask a new question: Does poverty impact brain development?

This work inspired neuroscientists to ask a new question: Does poverty impact brain development?

Neuroscientists are trying to answer this question by comparing brain images of children from either poor families or families with low socioeconomic status with brain images of children from middle class or affluent families. Early studies have looked specifically at whether there were any structural differences in brain volume or cortical thickness.

The results were striking. While poverty did not impact brain development in its entirety, it did affect some brain regions more than others. Differences in brain structure were particularly present in areas involved in memory, language processing, and decision-making and self-control.

The most consistent finding was that the stressful or traumatic life events experienced by children growing up in poverty were associated with a smaller hippocampus. The hippocampus is a key structure involved in the consolidation from short-term memory to long-term memory, and contains a high density of stress hormone receptors. Interestingly, parents’ caregiving style and the amount of environmental stimulation in the child’s home mediate the relationship between poverty and brain structure. Having nurturing parents and increased exposure to things such as books, trips, and musical instruments at home appears to reduce the impact of poverty on a child’s brain structure.

What can this new data actually contribute toward a solution for poverty? Some argue that it can ultimately help policy makers by yielding detailed insights into the specific mechanisms underlying the predictive link between poverty and children’s cognitive and emotional functioning. Behavioral interventions may be developed more effectively when there is a better understanding of the factors that mediate the impact of poverty on the developing brain, and neuroscience can provide targeted hypotheses about what cognitive processes are affected most. Critics, however, argue that it will be difficult for neuroscientists to improve on the more practical insights garnered by evaluating intervention programs directly.

Although not everyone agrees whether neuroscience is needed to describe the problems of poverty or provide solutions, most scholars do agree that the field is young and the future will determine its value. For instance, only recently have studies started to link differences in brain structures to real-world outcomes, such as scores on academic achievement tests.

These links beg important questions from researchers in this new subfield of neuroscience: Is the impact of poverty on the brain reversible? At what age is the brain most sensitive to the detrimental influences that come with growing up poor? Furthermore, given that poverty and socioeconomic status are broad terms, how do different components of poverty and socioeconomic status impact brain development? For instance, poverty is not only associated with economic deprivation but also correlates with stress, limited cognitive stimulation, parental care, poor nutrition, and environmental toxin exposure. Answers to these questions, and a better understanding of the factors that mediate the impact of poverty on brain development, would be extremely valuable.

Neuroscientists are looking for clues to answer these questions in what is perhaps an unexpected place: animal research. For instance, the finding that stress and parent’s caregiving style mediate the impact of poverty on children’s hippocampal volume resonates with rodent studies showing that stress and parental care impact the physiology of the hippocampus in rat pups. Additionally, stimulating new environments—like new toys or paths to explore—promote neuron generation in rodents, which is associated with improved spatial and memory performance. Animal models like these may explain how cognitive stimulation in a child’s home environment mediates the effect of poverty on human neural development.

An alarming 21 percent of the children in the United States live in poverty. To lower this number, and transform the American Dream into an American Reality, we should seek to understand the complicated effects of poverty on the brain.

Of course, humans are not rodents. The extent to which parental care, or environmental stimulation, has the same effect on human children undergoing the chronic, cumulative physical and psychosocial stressors of poverty by is less certain. However, results from animal research can provide targeted hypotheses for studies exploring the specific mediators of poverty’s effect on children’s mental health and cognition. Examining these hypotheses in humans will illuminate the potential of neuroscience to expand our understanding of poverty. In the longer term, combining what is learned from these studies with behavioral research and field studies testing the effect of real-world interventions may bring new explanations to the detrimental effects of poverty on children.

That said, there is a risk to using neuroscience to understand poverty. Framing the effects of poverty as biological differences can give the impression that they are permanent.

This isn’t necessarily true. Brains are plastic—especially the brains of children. This means that the effects of poverty on the brain may be reversible and the brain may well be able to compensate for damage in the long term. Indeed, smaller hippocampal volumes were found for children who suffered physical abuse or grew up in families with low socioeconomic status, but not for children who suffered early neglect and were later adopted into enriched, and potentially less stressful, environments. Perhaps different forms of stress impact the brain differently, or perhaps the brain is more likely to compensate over time for some types of stress than others.

There are clearly a lot of open questions. Hopefully, researchers will continue to search for answers to each of them. At present, an alarming 21 percent of the children in the United States live in poverty. To lower this number, and transform the American Dream into an American Reality, we should seek to understand the complicated effects of poverty on the brain.

Further Reading & Resources

  • Luby, J., Belden, A., Botteron, K., Marrus, N., Harms, M. P., Babb, C., ... & Barch, D. (2013). The effects of poverty on childhood brain development: the mediating effect of caregiving and stressful life events. JAMA pediatrics167(12), 1135-1142. (Link)
  • Katsnelson, A. (2015). News Feature: The neuroscience of poverty. Proceedings of the National Academy of Sciences112(51), 15530-15532. (Link)
  • Hackman, D. A., Farah, M. J., & Meaney, M. J. (2010). Socioeconomic status and the brain: mechanistic insights from human and animal research. Nature reviews. Neuroscience11(9), 651. (Link)
  • Farah, M. J. (2017, September 6). Childhood Poverty and Brain Development: From Science to Policy with Martha J. Farah. Lecture presented at Penn Center for Neuroscience & Society in Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania. (Link)