Chronic stress caused by growing up poor appears to impair a developing child’s working memory, the Washington Post reports, pointing to another link between childhood poverty and lessened long-term success. While environmental and experiential factors—such as having fewer toys and more exposure to lead—likely affect the achievement gap, an ongoing study of 195 children living above and below the poverty line shows that the everyday stresses of being poor adversely affect cognitive development.
Researchers measured stress hormones as well as body mass index and blood pressure when children were aged 9 and 13. The data showed the longer children lived with the stress of poverty, the lower they scored on working-memory tests at age 17—by as much as 20%, in some cases. “If you don't have good working memory, you can't do things like hold a phone number in your head or develop a vocabulary,” one researcher said.