Diminished Association between Parental Education and Parahippocampal Cortical Thickness in Pre-Adolescents in the US

Introduction: Socioeconomic status (SES) indicators, such as parental education and household income, are associated with the thickness of various cortical areas. However, less is known about the parahippocampal region. Additionally, more research is required regarding how the correlation between SES indicators and cortical thickness differs among diverse racial groups. Purpose: This study uses a national sample of pre-adolescents ages 9 to 10 years old in the US and was performed with two aims in mind. First, to investigate the correlations between two SES indicators, namely parental education and household income, and parahippocampal cortical thickness. Second, to explore racial differences in these associations. Methods: In this cross-sectional study, we used data from the Adolescent Brain Cognitive Development (ABCD) study to analyze the Structural Magnetic Resonance Imaging (sMRI) data of 9,849 US pre-adolescents between the ages of 9 and 10 years old. The main outcomes were parahippocampal cortical thickness separately calculated for the right and the left hemispheres using sMRI. The independent variables were parental education and household income, which were both treated as nominal variables. Age, sex, ethnicity, and family structure were the covariates, and race was the moderator. Mixed-effects regression models were used for data analysis with and without interaction terms. Results: High income positively associated with right and left parahippocampal cortical thickness in the fully adjusted models. Race showed a statistically significant interaction with parental education on children’s parahippocampal cortical thickness, suggesting that the correlations between parental education with the right and left parahippocampal cortical thickness were significantly larger for White than Black and other/mixed race pre-adolescents. No interaction was found for household income and race. Conclusions: The association between parental education and pre-adolescents parahippocampal cortical thickness may be weaker in Black than in White American children. Consistent with the findings of Marginalization-related Diminished Returns (MDRs), parental education shows weaker links for some brain indicators, such as parahippocampal cortical thickness, in Black and other racial and minority children when compared to White children.