Association Between Cortical Thickness and Childhood Body Mass Index: Role of Race and Income

Background: There is mixed literature on the association between cerebral cortex morphometry and body mass index (BMI), with only some but not all studies documenting an inverse association between cortical thickness (CT) and BMI. As the association between CT and BMI is inconsistent in the literature, we propose that racial and socioeconomic status (SES) differences may exist in this regard. Objectives: We borrowed the adolescent brain cognitive development (ABCD) data to investigate racial and SES differences in CT and childhood BMI associations. Methods: This cross-sectional study included 10,185 children between ages 9 and 10. Mixed-effects regression was used to analyze the data. The independent variable was CT measured using structural MRI. The dependent variable was BMI treated as a continuous variable. Covariates included ethnicity, sex, age, family structure, parental education, and intracranial volume. Race (White, Black, Asian, and Other/mixed) and household income levels (< 50 k, 50 - 100 k, and 100 + k) were the effect modifiers. Results: High CT was predictive of lower BMI (b for main effect of CT on BMI = -3.134; P < 0.001). However, the inverse association between CT and BMI was stronger in Black than White (b for interaction between race and CT = -2.39; P = 0.01255), and low-income than high-income children (b for interaction between income 50 - 100 k = 1.86; P = 0.02906; for interaction between income 100 + k b = 3.77; P < 0.001). Conclusions: Our findings suggest that although high CT is associated with lower BMI in children, this association varies across racial and SES groups. More research is needed on obesogenic environments’ role in altering the salience of cerebral cortex morphometry as a risk factor for high BMI.