Body Mass Index Mediates the Effects of Low Income on Preschool Children's Executive Control, with Implications for Behavior and Academics

Background: Children from low-income backgrounds are more likely to have cognitive impairments, academic problems, and obesity. Biological mechanisms for the relationship between adiposity and neurocognitive functioning have been suggested, but the direction of effects is unclear. Methods: The relations among income, BMI, and cognitive-behavioral functioning were modeled longitudinally. Children (n=306) were assessed at 36-39 months (Time 1; T1) and 63-67 months (Time 4; T4) through anthropometry, measures of executive control (EC), delay ability (DA), and questionnaires on academic readiness, social competence, and behavioral adjustment. Results: Income was positively related to T1 EC and DA and negatively related to T1 BMI. T1 BMI was negatively related to T4 EC, after controlling for T1 EC, but was unrelated to changes in DA. Neither T1 EC nor DA was related to changes in BMI. T4 EC predicted greater academic readiness and social competence and lower adjustment problems at T4. T4 BMI was related to higher T4 adjustment problems. There was an indirect effect of income on T4 EC through T1 BMI. There were indirect effects of T1 BMI on academic readiness, social competence, and adjustment through T4 EC. Children who were obese at T1 had a 19% lower rate of growth of EC, compared to nonobese children. Conclusions: BMI mediates the effect of income on children's EC and has negative implications for academic readiness, social competence, and behavioral adjustment. The dual impact of obesity and cognitive-behavioral problems underscores the importance of early identification of and intervention for overweight children which could have neurocognitive and social-emotional benefits. What's New: BMI mediates the effect of income on preschoolers' executive control (EC) and has negative implications for academic readiness and behavioral adjustment. EC and delay ability did not predict changes in BMI. Early identification of, and intervention for, overweight children may have neurocognitive and social-emotional benefits.