Although socioeconomic disparities in academic achievement are well documented, the question of how early exposure to poverty “gets under the skin” and is translated into deficits in cognitive and achievement outcomes remains largely unanswered.  Brain structure and development, affected by environmental circumstances (e.g. stress, nutritional intake, adequate sleep), represents one potential mechanism. 

Our study examines the influence of early exposure to poverty on brain development using a sample of children and adolescents form the Pediatric MRI Data Repository.  The size and scope of this database offers unprecedented potential to address questions surrounding the neurobiological consequences of low socioeconomic status.  The dataset includes neuroimaging measures (i.e., anatomic MRI scans) and cognitive/behavioral assessments, along with sociodemographic characteristics. 

In our analysis, we first establish a reference for normative brain development by estimating sex-specific developmental curves.  We then examine the influence of low parental SES on regions of the brain critical for cognitive ability. Finally, we explore the role of systematic differences in these portions of the brain as a potential route through which poverty is translated into lower levels of achievement.

Our brain regions of interest are selected based on two criteria: (1) they have a protracted period of development and, therefore, are likely to be vulnerable to environmental experience and (2) they represent portions of the brain thought to be critical to cognitive ability and academic achievement.  Throughout our analysis, we focus on gray matter – total gray matter and the gray matter volumes of the frontal lobe, temporal lobe, and hippocampus - which previous work suggests may be uniquely affected by early environment and is less heritable than white matter.

We find that children and adolescents exposed to poverty exhibit atypical development in portions of the brain thought to be critical for cognitive ability.  Specifically, our results suggest that children and adolescents from poor and near poor households display a maturational lag – their regional volumes are found, on average, to be 3 to 5 percentage points below developmental norms.  Estimated maturational lags are even more pronounced when focus is restricted to those children from the poorest households.  The regional volumes of children from families with household income below $25,000 are found to be 7 to 8 percentage points below developmental norms.  Moreover, we find that this atypical development has consequences for achievement (measured by Woodcock Johnson-III scores). 

Cognitive and noncognitive skills are important determinants of a range of adult outcomes including educational attainment, earnings, and criminal activity. Without interventions to mitigate the influence of poverty on development, it would appear that children’s potential is being limited at young ages by this tie.  The sensitivity of development in our critical brain regions to changes in the environment and nurturance – both negative and positive – lends credence to the idea that interventions to remediate early environments may have some success in altering this link.