Longitudinally Mapping Childhood Socioeconomic Status Associations with Cortical and Subcortical Morphology

Abstract

Childhood socioeconomic status (SES) impacts cognitive development and mental health, but its association with human structural brain development is not yet well characterized. Here, we analyzed 1243 longitudinally acquired structural MRI scans from 623 youth (299 female/324 male) to investigate the relation between SES and cortical and subcortical morphology between ages 5 and 25 years. We found positive associations between SES and total volumes of the brain, cortical sheet, and four separate subcortical structures. These associations were stable between ages 5 and 25. Surface-based shape analysis revealed that higher SES is associated with areal expansion of lateral prefrontal, anterior cingulate, lateral temporal, and superior parietal cortices and ventrolateral thalamic, and medial amygdalo-hippocampal subregions. Meta-analyses of functional imaging data indicate that cortical correlates of SES are centered on brain systems subserving sensorimotor functions, language, memory, and emotional processing. We further show that anatomical variation within a subset of these cortical regions partially mediates the positive association between SES and IQ. Finally, we identify neuroanatomical correlates of SES that exist above and beyond accompanying variation in IQ. Although SES is clearly a complex construct that likely relates to development through diverse, nondeterministic processes, our findings elucidate potential neuroanatomical mediators of the association between SES and cognitive outcomes.SIGNIFICANCE STATEMENT Childhood socioeconomic status (SES) has been associated with developmental disparities in mental health, cognitive ability, and academic achievement, but efforts to understand underlying SES-brain relationships are ongoing. Here, we leverage a unique developmental neuroimaging dataset to longitudinally map the associations between SES and regional brain anatomy at high spatiotemporal resolution. We find widespread associations between SES and global cortical and subcortical volumes and surface area and localize these correlations to a distributed set of cortical, thalamic, and amygdalo-hippocampal subregions. Anatomical variation within a subset of these regions partially mediates the positive relationship between SES and IQ. Our findings help to localize cortical and subcortical systems that represent candidate biological substrates for the known relationships between SES and cognition.

Trial registration: ClinicalTrials.gov NCT00001246.

Keywords: brain development; cortical surface area; longitudinal; socioeconomic status; structural MRI.

Copyright © 2019 the authors 0270-6474/19/391365-09$15.00/0.

Figures

Figure 1.

Main effects of SES on global and local anatomy after controlling for age and sex. A, Standardized effect size of SES on each global cortical and subcortical brain measure estimated using scaled variables: TBV, GMV, WMV, CV, SA, mean CT, hippocampus volume, amygdala volume, thalamus volume, striatum volume, and pallidum volume. B, Cortical surface regions that show a significant positive association of surface area with childhood SES. C, Subcortical surface regions that show a significant positive association of surface area with childhood SES.

Figure 2.

A, Correlation between childhood SES and full-scale IQ in a cross-sectional sample of 623 individuals, r(621) = 0.31, p < 0.001. B, Map of the main effects of SES and IQ on cortical surface area. Significant SES main effect is represented in red, IQ main effect in blue, and overlapping main effects in purple. Together, these main effects resemble the map of main SES effects on cortical SA without IQ as a covariate (Fig. 1B). C, Mediation analysis including surface area at each vertex as a separate mediator revealing regions of the left hemisphere that significantly mediate the relationship between SES and IQ.