Socioeconomic disparities are associated with differences in cognitive development. The extent to which this translates to disparities in brain structure is unclear. We investigated relationships between socioeconomic factors and brain morphometry, independently of genetic ancestry, among a cohort of 1,099 typically developing individuals between 3 and 20 years of age. Income was logarithmically associated with brain surface area. Among children from lower income families, small differences in income were associated with relatively large differences in surface area, whereas, among children from higher income families, similar income increments were associated with smaller differences in surface area. These relationships were most prominent in regions supporting language, reading, executive functions and spatial skills; surface area mediated socioeconomic differences in certain neurocognitive abilities. These data imply that income relates most strongly to brain structure among the most disadvantaged children.
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- Supplementary Figure 1: Family Income is Related to Cortical Surface Area at Stringent FDR Thresholds (N=1099). (113 KB)
When adjusting for age, age2, scanner, sex, and genetic ancestry, ln(family income) was significantly associated with surface area in widespread regions of children’s bilateral frontal, temporal, and parietal cortices as well as right occipital cortex. Relationships were strongest in bilateral inferior temporal, insula and inferior frontal gyrus, and in the right occipital and medial prefrontal cortex Results are shown thresholded at A. the traditional p < 0.05 threshold (FDR-corrected); B. at p <.01 (FDR-corrected); and C. at the stringent threshold of p < 0.001 (FDR-corrected), where results remained significant bilaterally in the insula, temporal pole, and anterior and posterior cingulate, and in the right dorsal frontal region extending onto the medial surface.
- Supplementary Figure 2: Surface Area Partially Mediates the Association between Family Income and Cognitive Control (N=1074). (30 KB)
Multiple regression analyses revealed that, when adjusting for age, age2, scanner, sex, and GAF, the direct effect of income on flanker scores (β=0.050, t(1074)= 2.68, p =.007) was reduced when controlling for surface area (β=0.043, t(1074) = 2.27, p =.023). A Sobel test indicated that this reduction was significant, suggesting partial mediation (Sobel z = 2.4, p =. 02).
- Supplementary Figure 3: Surface Area Partially Mediates the Association between Family Income and Working Memory (N=1084). (30 KB)
Multiple regression analyses revealed that, when adjusting for age, age2, scanner, sex, and GAF, the direct effect of income on working memory scores (β= 0.069, t(1084) =3.77, p = 0.0002) was reduced when controlling for surface area (β= 0.061, t(1084) = 3.31, p = 0.001). The Sobel test was significant, suggesting partial mediation (Sobel z = 2.6, p =. 009).