Neuroanatomical differences in early bilingual and monolingual children

Area of Science:

• Neuroscience
• Developmental Neuroscience
• Cognitive Neuroscience

Background:

• Prior studies on bilingualism and brain structure show inconsistent findings, often limited by small sample sizes and adult-focused research.
• Gray matter volume (GMV) and cortical thickness (CT) are key neuroanatomical metrics, but their convergence in bilingual research is unclear.
• Few studies have examined CT in early bilingual children, a metric offering greater anatomical specificity than GMV.

Purpose of the Study:

• To compare neuroanatomy between large groups of early Spanish-English bilingual and English monolingual children.
• To investigate whether different neuroanatomical metrics (GMV, CT) and analysis approaches yield consistent findings.
• To explore the influence of socioeconomic status (SES) on neuroanatomical differences in early bilingual children.

Main Methods:

• Utilized data from the Adolescent Brain Cognitive Development (ABCD) Study (N = 1,209) with matched groups of bilingual and monolingual children.
• Employed whole-brain voxel-based morphometry for GMV analysis and vertex-wise analyses for CT.
• Conducted parcel-wise CT analyses using two atlases (Destrieux and Desikan-Killiany) and tested for SES interactions.

Main Results:

• Bilingual children exhibited widespread differences in both GMV and CT compared to monolinguals.
• Vertex-wise CT analyses revealed both thicker and thinner cortical regions in bilinguals.
• Parcel-wise CT results corresponded with vertex-wise findings when using a fine-grained atlas (Destrieux), but not a coarser one (Desikan-Killiany).
• Socioeconomic status modulated CT differences between bilingual and monolingual children in several brain regions.

Conclusions:

• Early bilingualism is associated with extensive neuroanatomical differences in children.
• Neuroanatomical findings in bilingual children can vary based on the metric, analysis approach, atlas granularity, and SES.
• These results highlight the complex interplay between bilingualism, brain development, and environmental factors like SES.