Socioeconomic Status Inequalities Partially Mediate Racial and Ethnic Differences in Children's Amygdala Volume

Abstract

Background: While race/ethnicity and socioeconomic status (SES) impact brain structures such as the amygdala, less is known on whether or not family SES partially explains why amygdala volume is smaller for racial and ethnic minority groups.

Purpose: This study tested the mediating effects of family SES on racial and ethnic differences in right and left amygdala volume.

Methods: We borrowed the structural Magnetic Resonance Imaging (sMRI) data of the Children Brain Cognitive Development (ABCD) study, a brain imaging investigation of childhood brain development in the US. The total sample was 8977, 9-10-year-old children. The independent variables were race and ethnicity. The primary outcomes were right and left amygdala volume. Age, sex, household size, and marital status were the covariates. Multiple SES indicators such as family income, subjective family SES, parental employment, parental education, and neighborhood income were the mediators. To analyze the data, we used regression models without and with our mediators. Sobel test was used to test if these mediational paths are statistically significant.

Results: Black and Latino children had smaller amygdala sizes than non-Latino White children. The effects of race and ethnicity on amygdala volume were partially mediated by SES indicators, suggesting that one of the many reasons Black and Latino children have smaller volumes of right and left amygdala is their lower SES.

Conclusions: For American children, lower family and neighborhood SES indicators partially, but not fully, explain smaller amygdala sizes of Black and Latino children compared to non- Latino White children.

Keywords: amygdala; brain development; limbic system; socioeconomic position; socioeconomic status.