Sex Differences in the Association of Household Income with Amygdala Volume

Background: Household income and other socioeconomic position (SEP) indicators are among the most salient social determinants of children’s emotions and behaviors. Some research has shown that income and other SEP indicators may have certain sex-specific effects on the structures and functions of particular brain regions. Objectives: To investigate sex differences in the association of household income with amygdala volumes in US children. Materials Methods: This is a cross-sectional study using data from the Adolescent Brain Cognitive Development (ABCD) study. The study data was collected between 2016 and 2018 across 21 sites distributed across US states. Wave 1 ABCD included 10262 American children aged between 9 and 10 years old. The independent variable was household income. The primary outcome was the left amygdala volume, which was measured by T1-weighted structural brain Magnetic Resonance Imaging (MRI). We used a data exploration and analysis portal for our data analysis. Results: Overall, the household income was positively associated with left amygdala size in children. Sex showed a statistically significant interaction with household income on children’s left amygdala volume, net of all confounders, indicating a stronger effect of high household income on male children compared to female children. Conclusion: Household income is a more salient determinant of left amygdala volume for male children compared to female American children. Low-income male children remain at the highest risk of a small amygdala.