Content area
The anterior cingulate cortex (ACC), a region involved in executive functions such as inhibition, attention shifting, and emotional regulation, has been shown to differ in structure and connectivity in individuals with autism spectrum disorder (ASD). However, most studies of ACC microstructure rely on postmortem adult brains, limiting understanding of early developmental patterns and possible links to cognitive abilities. This study examined gray matter microstructure in the ACC and its relationship to executive functioning in young children with and without ASD using diffusion-weighted magnetic resonance imaging (MRI).
Participants included 38 children aged 18–64 months (24 with ASD, 14 typically developing [TD]). Diagnoses of ASD were confirmed using the Autism Diagnostic Observation Schedule, Second Edition (ADOS-2), and the Autism Diagnostic Interview, Revised (ADI-R). Groups were matched on age, intracranial volume, and image quality.
Executive functioning was measured with the Behavior Rating Inventory of Executive Functioning, Preschool Edition (BRIEF-P), focusing on inhibition, shifting, and emotional control. Developmental functioning was measured using the Mullen Scales of Early Learning (MSEL). MRI data were acquired during natural sleep. Gray matter diffusion metrics were extracted from bilateral rostral and caudal ACC regions using diffusion tensor imaging (DTI) to measure fractional anisotropy (FA) and mean diffusivity (MD); and Neurite Orientation Dispersion and Density Imaging (NODDI) to measure neurite density index (NDI) and orientation dispersion index (ODI). Group differences were tested using analysis of covariance; within-group structure–function correlations were tested using Spearman’s rho.
No significant group differences were observed for MD or NDI after controlling for age, and exploratory brain–behavior correlations in the ASD group did not remain significant after correction. However, across groups, FA significantly decreased and MD increased with age in the right ACC, and both NDI and ODI significantly increased with age in right rostral and bilateral caudal ACC regions, indicating age-related microstructural changes.
Findings highlight measurable developmental changes in ACC gray matter across early childhood. While diagnostic and behavioral associations were not statistically robust, the study demonstrates the value of advanced diffusion imaging models in young children and provides direction for future longitudinal research in early ASD.