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Unformatted text preview: Childhood poverty, chronic stress, and adult working memory Gary W. Evans 1 and Michelle A. Schamberg Departments of Design and Environmental Analysis and Human Development, Cornell University, Ithaca, NY 14853-4401 Edited by Bruce S. McEwen, The Rockefeller University, New York, NY, and approved February 24, 2009 (received for review November 22, 2008) The incomeachievement gap is a formidable societal problem, but little is known about either neurocognitive or biological mecha- nisms that might account for income-related deficits in academic achievement. We show that childhood poverty is inversely related to working memory in young adults. Furthermore, this prospective relationship is mediated by elevated chronic stress during child- hood. Chronic stress is measured by allostatic load, a biological marker of cumulative wear and tear on the body that is caused by the mobilization of multiple physiological systems in response to chronic environmental demands. A large, robust literature demonstrates a pervasive income achievement gap. Family income is a strong and consistent predictor of multiple indices of achievement, including standard- ized test scores, grades in school, and educational attainment. Family income matters to childrens cognitive development (13), with more enduring economic hardship particularly harm- ful (4, 5). The incomeachievement gap is already present by kindergarten and accelerates over time (6, 7). The longer the duration of childhood exposure to poverty, the worse achieve- ment levels become. Achievement test scores and school per- formance, however, do not inform us about what neurocognitive processes are influenced by childhood poverty. Furthermore, the voluminous incomeachievement gap literature is silent on underlying biological explanations. Here, we test 2 hypotheses. One is that childhood poverty will interfere with working memory in young adults. Working mem- ory is the temporary storage mechanism that enables us to hold a small amount of information active over a short interval and to manipulate it. Working memory is essential to language comprehension, reading, and problem solving, and it is a critical prerequisite for long-term storage of information. The second hypothesis we test is that the prospective relationship between childhood poverty and adult working memory will be mediated by chronic stress exposure, (i.e., poverty 3 chronic stress 3 working memory). Farah and colleagues (8) found significant deficits in working memory between low- and middle- socioeconomic status (SES) kindergarten children and, in a second sample, between low- and middle-SES 11-year-olds (9). In a third study of first-graders, SES was a significant predictor of working memory (10). An important, missing component of this groundbreaking work is the underlying biological mecha- nisms to account for the SESneurocognitive link....
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