Date of Award

8-10-2009

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

First Advisor

Linda Mayes

Second Advisor

James Leckman

Abstract

THE RELATIONSHIP BETWEEN ECONOMIC DEPRIVATION AND EMERGING INHIBITORY CONTROL IN YOUNG CHILDREN. Rachel S. Weston, David J. Bridgett, Linda C. Mayes. Yale Child Study Center, Yale University School of Medicine, New Haven, CT. An extensive body of research has documented detrimental effects of growing up in poverty on children's global cognitive development, particularly when economic deprivation occurs in early childhood. However, little is known about the impact of poverty on children's component neurocognitive capacities. The prefrontal cortex is one brain region, responsible for the executive control functions, that has a prolonged period of postnatal development and therefore may be especially susceptible to environmental influences like poverty. Inhibitory control is an important executive function to investigate because it appears to be a significant predictor of language and math skills in preschool and later school years. In the current study, we hypothesized that children living in more economically disadvantaged families would have delayed development of their inhibitory control abilities and would have altered developmental trajectories with increasing developmental lag compared to children living in more economically advantaged families. The current study employed latent growth curve modeling to model the developmental trajectories of inhibitory control for a cohort of 125 children followed longitudinally between ages 5 and 8. Commission errors from a picture AX Continuous Performance Task were used to measure inhibitory control. Consistent with developmental expectations, we found that as children get older, they make progressively fewer inhibitory control errors (age 5 mean = 19.86 vs. age 8 mean = 4.76). Significant interindividual differences were also present in both slope and intercept factors. Adding child gender and income-to-need ratio at age 5 to the model as predictors, we found that both factors accounted for significant interindividual differences, together explaining 12 percent of the variance in the intercept (i.e., 5-year-old inhibitory control ability). This predictor model provided an excellent fit for the data. At age 5, male children made more inhibitory control errors than female children. Also, children from more economically disadvantaged families made more inhibitory control errors than their peers from more advantaged families. An unexpected finding was that child gender and income-to-need at age 5 did not account for significant interindividual differences in trajectory slope (i.e., no developmental lag was observed). These results suggest that the impact of economic deprivation on prefrontal cortex development and subsequent development of inhibitory control occurs early (before age 5), putting children on a particular trajectory based on this early exposure to poverty. Tailoring interventions (e.g., early education programs) to reinforce executive functions like inhibitory control below the age of 5 years could potentially maximally improve cognitive outcomes among low-income children.

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