The Effect of Different Dimensions of Socio-Economic Status on Cortical Surface Area and Associated Behavioural Phenotypes

Background: Lowered socio-economic status (SES) is associated with poorer brain development, behavioural and cognitive outcomes. While existing studies have characterised SES effects on brain development, the differential impacts of its distinct dimensions remain inadequately explored. This study investigates how income-to-needs, parental occupation and educational level affect cortical surface area (CSA), a key marker of brain development. Additionally, associations between significant CSA regions and behavioural phenotypes were examined. Methods: Data was taken from the Healthy Brain Network (HBN) dataset (N = 962; ages 5–21). Participants underwent T1w and T2w structural MRI and completed the Child Behaviour Checklist (CBCL). SES was operationalised using income-to-needs ratios and the Barratt Simplified Measure of Social Status. Structural images were pre-processed with FreeSurfer and analysed using VertexWiseR, covarying for age and sex. Meta-analytical image decoding of significant clusters was conducted, and significant clusters were correlated with behavioural measures. Results: Decreased SES predicted significantly reduced CSA across SES dimensions (Income-to-Needs, Barratt Combined Scale, Parental Education: p=0.001; Occupation: p=0.01). Meta-analytical image decoding suggest that these affected regions are involved in episodic memory and retrieval across SES dimensions, as well as motor functions in non-material dimensions. Significant CSA regions showed significant associations with rule-breaking and externalising behaviours. Conclusions: The results revealed CSA regions predicted by SES dimensions. These significant brain regions are modestly predictive of poorer behavioural outcomes, providing some evidence that behavioural outcomes associated with SES may have a neurobiological basis.