Socioeconomic Differences in Global Brain Asymmetry: An Integrative Approach Using Image Similarity Measures and Structural Equation Modeling

The typical human brain exhibits a bilateral asymmetry that can be observed in the distribution of grayscale levels in brain magnetic resonance imaging (MRI). This asymmetry plays a crucial role in the development of higher-level cognition and can be influenced by both socioeconomic and biological factors. In this regard, the objective of this article is to investigate the relationship between brain asymmetry and socioeconomic status (SES) as the primary focus, alongside age and sex. To achieve this, we develop a global index of brain asymmetry using a novel methodology that combines two statistical tools in an innovative manner: the Gradient Magnitude Similarity Deviation image similarity measure, which assesses asymmetries in 2D slices of MRI, and Multiple Indicators Multiple Causes Structural Equation Modeling (MIMIC), which integrates the asymmetry of the 2D slices into a single global index. Our study, conducted on a dataset of 132 healthy individuals, reveals a significant association between SES and brain asymmetry, with individuals of higher SES displaying more pronounced asymmetry compared to those of lower SES. Additionally, asymmetry tends to increase with age, and males exhibit higher asymmetry than females. These findings provide new insights into the association between socioeconomic factors and brain asymmetry, highlighting the relevance of SES in relation to structural brain characteristics.