Socioeconomic disparities are associated with differences in cognitive development. The extent to which this translates to disparities in brain structure is unclear. Here, we investigated relationships between socioeconomic factors and brain morphometry, independently of genetic ancestry, among a cohort of 1099 typically developing individuals between 3 and 20 years. Income was logarithmically associated with brain surface area. Specifically, 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 indicate that income relates most strongly to brain structure among the most disadvantaged children. Potential implications are discussed.

Recent advances in neuroimaging methods have made accessible new ways of disentangling the complex interplay between genetic and environmental factors that influence structural brain development. In recent years, research investigating associations between socioeconomic status (SES) and brain development have found significant links between SES and changes in brain structure, especially in areas related to memory, executive control, and emotion. This review focuses on studies examining links between structural brain development and SES disparities of the magnitude typically found in developing countries. We highlight how highly correlated measures of SES are differentially related to structural changes within the brain.

Very few studies have examined the cognitive advantages of bilingualism during the first two years of development, and a majority of the studies examining bilingualism throughout the lifespan have focused on the relationship between multiple languages and cognitive control. Early experience with multiple language systems may influence domain-general processes, such as memory, that may increase a bilingual child's capacity for learning. In the current study, we found that bilingual, but not monolingual, infants were able to generalize across cues at 18 months. This is the first study to show a clear bilingual advantage in memory generalization, with more equal or balanced exposure to each language significantly predicting ability to generalize.

Socioeconomic status (SES) is strongly associated with cognition and achievement. Socioeconomic disparities in language and memory skills have been reported from elementary school through adolescence. Less is known about the extent to which such disparities emerge in infancy. Here, 179 infants from socioeconomically diverse families were recruited. Using a cohort-sequential design, 90 infants were followed at 9 and 15 months, and 89 were followed at 15 and 21 months. SES disparities in developmental trajectories of language and memory were present such that, at 21 months of age, children of highly educated parents scored approximately .8 standard deviations higher in both language and memory than children of less educated parents. The home language and literacy environment and parental warmth partially accounted for disparities in language, but not memory development.