Sexually Dimorphic Developmental Trajectories of Cortical and Subcortical Subfields in Early Childhood.

Chronic socio-economic adversity is associated with altered neurodevelopment. However, its relation to sex-specific brain structure during early childhood remains incompletely understood. We examined structural magnetic resonance imaging (MRI) data from 79 children aged 6-7 years. These participants reside in conditions of socio-economic deprivation in Bangladesh. Using voxel-based morphometry, whole-brain parcellation and subfield segmentation, we quantified cortical, subcortical and cerebellar volumes. These measures characterize sex-dependent neuroanatomical variation within this cohort. Boys exhibited larger total intracranial volumes. Voxel-based analysis showed greater volumes across several subcortical regions in boys. These included the hippocampus, amygdala, putamen, caudate and hypothalamus. In contrast, girls demonstrated relatively greater brainstem volumes, including pons and medulla. These findings indicate sex-dependent variation in stress-sensitive limbic-thalamic and brainstem regions. This variation occurs during a critical developmental window in a socio-economically vulnerable cohort. Although the present design does not permit direct comparison across economic contexts, the results provide a detailed characterization of structural sexual dimorphism. This study provides valuable evidence from children exposed to chronic adversity. Furthermore, it contributes neuroimaging data from an under-represented population to models of early brain development.