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.

Multi-Racial Normative Data for Lobar and Subcortical Brain Volumes in Old Age: Korean and Caucasian Norms May Be Incompatible With Each Other†

“…Previous studies have shown that the temporal gyrus among cortical structures could be affected by some ethnic or genetic factors resulted in morphological differences such as brain shape or size (Zilles et al, 2001 ; Chee et al, 2011 ; Tang et al, 2018 ), possibly because the Asian brain is relatively wider than the Caucasian brain (Liang et al, 2015 ) and the temporal cortex is located on both sides of the brain. Our findings align with previous research reporting the significant effects of race or ethnicity on the hippocampus and amygdala volumes even in black and white children (Assari, 2020a , b ). In contrast, ventricles and left pallidus did not significantly differ from the ethnicity in our result.…”

Ecological stress, amygdala reactivity, and internalizing symptoms in preadolescence: Is parenting a buffer?

“…While these analyses are the first to examine the mediating role of amygdala function in the association between baseline cumulative stress and 1-year follow-up internalizing symptoms in the ABCD data, several cross-sectional analyses have considered associations between socioeconomic variables and brain structure and cognitive function. In a cross-sectional analysis of the baseline ABCD study data, Assari (2020) reported that parental socioeconomic status (SES), as measured by neighborhood income (ADI) and family income, mediated the relationship between ethnoracial differences and amygdala volume. Meanwhile, in their crosssectional analysis, Taylor and colleagues (2020) probed the relationship between neighborhood poverty, as measured by 9 of 17 ADI variables, hippocampal and prefrontal cortex (PFC) volumes, and cognitive assessments across seven cognitive domains from the NIH toolbox.…”

“…Although all of these analyses considered cross-sectional associations, it will be important to consider how SES and brain associations change across time --a strength of the ABCD design. Furthermore, although the brain was identified as mediator in cross-sectional analyses of the ABCD sample (Assari, 2020;Assari et al, 2020;Vargas et al, 2020), it will be important to reexamine the mechanistic role of specific brain regions using the longitudinal ABCD data to distinguish between cross-sectional and longitudinal effects. Finally, to describe how SES manifests in the brain (Farah, 2017) and relates to cognitive and behavioral outcomes, future work should examine differences in the analytic pipeline that contribute to convergence and differences in findings.…”

Parental Education, Household Income, Race, and Children’s Working Memory: Complexity of the Effects

“…Similarly, an increase in discrimination was associated with stronger functional connectivity between the amygdala and several neural regions such as the anterior insula, putamen, caudate, anterior cingulate, medial frontal gyrus. The most robust effect of discrimination was seen for the connectivity between the amygdala and thalamus [156]. As high SES, particularly high subjective SES, is a proxy of high not low discrimination [50][51][52][53][55][56][57][58]137], high SES Black American children still report lower than expected brain and behavior outcomes because of the effect of discrimination.…”