By Vien Nguyen, CEI Intern, and Dana Asby, CEI Director of Innovation & Research Support
Today the nurture vs. nature debate has largely been resolved – experts agree that both are interrelated in a complex dance that shapes our behavior (Hackman & Farah, 2009). In the past few years, researchers have been especially interested in the interplay between one specific aspect of nurture, poverty, and one of nature, the brain. They have known for decades that both family and neighborhood level poverty are associated with cognitive and social-emotional deficits (Smith, Brooks-Gun, & Klebanov, 1997). Now, neuroscientists and child development researchers, like Dr. Kimberly Noble’s Neurocognition, Early Experiences, and Development (NEED) Lab at Teachers College, Columbia University, are refining their understanding of which deficits are especially affected and how early.
Poverty’s Effects Evident in Children’s Brain Structure & Function Early
By the age of 18 months, many children already experience the deleterious effects of poverty on their cognitive functioning. These effects may be predicted by early gaps in language (Fernald, Marchman, & Weisleder, 2013). For example, children who have smaller vocabularies learn new words slower than their peers. Over time, this gap compounds and contributes to large disparities in academic achievement. The language gap holds regardless of whether we use poverty or related constructs like social-economic status (SES) or parental education. All are highly correlated with each other. Poor kids are falling behind on literacy before the educational race even starts.
Subcortical Brain Regions Affected
Two key subcortical brain regions are altered by chronic stress – the hippocampus and amygdala. First, the hippocampus gets smaller in volume. This shrinkage inhibits the brain’s ability to reconsolidate short-term memories into long-term storage. Therefore, a chronically-stressed student may struggle to memorize their multiplication facts. Meanwhile the amygdala increases in size with prolonged childhood stress. This excessive growth leads to a dysregulated stress response (Lupien, McEwen, Gunnar, & Heim, 2009).
It may be possible to reverse the shrinkage of a child’s hippocampus. How? By enriching the child’s environment with positive care and attention. Such care can come from teachers, babysitters, therapists, counselors, or social workers. This may be effective even if the child has neglectful primary caregivers. Recent studies of mindfulness interventions have revealed similar reversal effects on amygdala size, albeit for adults (Taren, Creswell, & Gianaros, 2013). Congruent studies have yet to be conducted on children.
Changes in the Brain Result in Behavioral, Emotional, and Cognitive Changes
In a comprehensive report, The National Scientific Council on the Developing Child (2014) explains how toxic stress during critical periods of development can lead to a poorly functioning stress response system. This “hair-trigger” system may cause the child to overreact to situations where they perceive a threat that may not be present. For example, such a child may react to a friend’s playful nudge with anger, misinterpreting it as a threat of upcoming physical violence. The child may become violent themselves. Such children are also more likely to develop unhealthy internalizing strategies in an attempt to cope with their emotions. Students who excessively use internalizing strategies tend to have higher rates of depression and anxiety (Capistrano, Bianco, & Kim 2016). Such children may struggle to form strong social connections.
Poverty also impairs children’s ability to pay attention in a variety of ways. Children who come from families with lower SES are less able to suppress distracting stimuli (Stevens et al., 2009). And in the adolescent years, psychosocial stress impairs students’ ability to shift their attention (Liston, Mcewen, & Casey, 2009). The adolescent may then struggle to write papers or lab reports.
Overall, poverty puts children at risk for lower academic achievement and cognitive functioning. Indeed, childhood SES is strongly associated with achievement test scores, grade retention, literacy, IQ, and high school graduation. According to research conducted by Feinstein (2003) in a British Cohort Study, the SES gap in cognitive performance emerges early and widens throughout the elementary years.
Future Directions: Proving Poverty Affects Children from Birth
While brain research has long proven that poverty is correlated with poorer mental and physical health outcomes, we don’t have any evidence that definitively points to poverty being the cause of these detriments. A consortium of researchers* being led by Dr. Kimberly Noble and the NEED Lab are attempting to prove that poverty itself changes brain structure and function from birth with a randomized control trial giving monthly installments of unconditional cash to low-income mothers in New York City, New Orleans, the Twin Cities, and the greater Omaha area (Meyer, 2019).
Baby’s First Years, funded by the National Institutes of Health, will follow 1,000 mothers and their children from birth to 40 months of age, monitoring aspects of family life and measures of development. Researchers will investigate whether larger cash installments resulted in improved cognitive functioning and brain development for babies. Lauren Meyer, Baby’s First Years National Project Director, explained the decision to give unconditional rather than conditional cash payments: “Mothers are well positioned to know what they and their families need” (Meyer, 2019).
Meyer explained that sometimes money is used in the investment pathway to pay for books or quality childcare, and other times, it is used in the stress pathway perhaps to take a taxi in the rain rather than waiting outside with the baby for the bus. This frees up cognitive and emotional space for mothers to be more engaged and present with their babies and decreases the risk of toxic stress, which is correlated with both poverty and attachment disorders.
The Baby’s First Years project is the largest longitudinal study of its kind being implemented by a group of well-published neuroscientists, economists, social policy experts, and psychologists who are all committed to understanding the impact of poverty on children and family life. They’ve designed this research to be relevant to policy makers, because they want to show the general public that this is a realistic and simple intervention for the deleterious effects of poverty on brain development.
Stay tuned for more information about the webinar Dr. Noble will present for CEI’s Childhood-Trauma Learning Collaborative in October about interventions to counteract poverty’s effect on brain development.
*Baby’s First Year Core PIs:
- Dr. Kimberly Noble, neuroscientist and board-certified pediatrician, and director of the Neurocognition, Early Experience and Development (NEED) lab at Teachers College, Columbia University
- Dr. Greg Duncan, University of California, Irvine professor and economist whose focus is economic mobility in low-income families
- Dr. Katherine Magnuson, Professor and Doctoral Program Chair at the University of Wisconsin–Madison School of Social Work
- Dr. Lisa Gennetian, an applied economist whose work focuses on poverty, early childhood interventions, and racial and ethnic disparities
- Dr. Hirokazu Yoshikawa, NYU professor in the Psychology of Social Intervention and Human Development and Social Intervention programs who co-directs the Global TIES for Children Center and the Sesame Workshop for Syrian refugee families project
- Dr. Nathan Fox, University of Maryland, College Park Distinguished Professor in the Department of Human Development and Quantitative Methodology whose work in Romanian orphanages presented some of the most compelling neuroscience evidence of the effects of neglect we have to date
Capistrano, C.G., Bianco, H. & Kim, P. (2016). Poverty and internalizing symptoms: The indirect effect of middle childhood poverty on internalizing symptoms via an emotional response inhibition pathway. Frontiers in Psychology 7:1242.
Evans, G. W., & Schamberg, M. A. (2009). Childhood poverty, chronic stress, and adult working memory. Proceedings of the National Academy of Sciences of the United States of America, 106(16), 6545–6549.
Feinstein, L. (2003). Inequality in the early cognitive development of British children in the 1970 cohort. Economica,70(277), 73-97.
Fernald, A., Marchman, V. A., & Weisleder, A. (2013). SES differences in language processing skill and vocabulary are evident at 18 months. Developmental science, 16(2), 234–248.
Fernald, L. C., Weber, A., Galasso, E., & Ratsifandrihamanana, L. (2011). Socioeconomic gradients and child development in a very low income population: Evidence from Madagascar. Developmental Science,14(4), 832-847.
Hackman, D. A., & Farah, M. J. (2009). Socioeconomic status and the developing brain. Trends in cognitive sciences, 13(2), 65–73.
Leventhal T, Brooks-Gunn J. The neighborhoods they live in: The effects of neighborhood residence on child and adolescent outcomes. Psychological Bulletin. 2000;126:309–337.
Liston, C., Mcewen, B. & Casey, B. (2009). Psychosocial stress reversibly disrupts prefrontal processing and attentional control. Proceedings of the National Academy of Sciences of the United States of America. 106. 912-7.
Lupien, S. J., Mcewen, B. S., Gunnar, M. R., & Heim, C. (2009). Effects of stress throughout the lifespan on the brain, behaviour and cognition. Nature Reviews Neuroscience,10(6), 434-445.
Meyer, L. (2019, August 5). Personal Interview.
National Scientific Council on the Developing Child. (2005/2014). Excessive stress disrupts the architecture of the developing brain: Working paper 3. Updated Edition.
Smith, J. R., Brooks-Gun, J., & Klebanov, P. (1997). The consequences of living in poverty for young children’s cognitive and verbal ability and early school achievement. In G. J. Duncan & J. Brooks-Gunn (Eds.), Consequences of growing up poor (pp. 132-189). New York, N.Y.: Russell Sage.
Stevens, C., Lauinger, B., & Neville, H. (2009). Differences in the neural mechanisms of selective attention in children from different socioeconomic backgrounds: an event-related brain potential study. Developmental science, 12(4), 634–646.
Taren, A,A., Creswell J.D., Gianaros P.J., (2013). Dispositional mindfulness co-varies with smaller amygdala and caudate volumes in community adults. PLOS ONE 8(5): e64574.