White and gray matter correlates of theory of mind in autism: a voxel-based morphometry study

Autism spectrum disorder (ASD) is characterized by difficulties in theory of mind (ToM) and social communication. Studying structural and functional correlates of ToM in the brain and how autistic and nonautistic groups differ in terms of these correlates can help with diagnosis and understanding the biological mechanisms of ASD. In this study, we investigated white matter volume (WMV) and gray matter volume (GMV) differences between matching autistic and nonautistic samples, and how these structural features relate to age and ToM skills, indexed by the Reading the Mind in the Eyes (RMIE) measure. The results showed widespread GMV and WMV differences between the two groups in regions crucial for social processes. The autistic group did not express the typically observed negative GMV and positive WMV correlations with age at the same level as the nonautistic group, pointing to abnormalities in developmental structural changes. In addition, we found differences between the two groups in how GMV relates to ToM, particularly in the left frontal regions, and how WMV relates to ToM, mostly in the cingulate and corpus callosum. Finally, GMV in the left insula, a region that is part of the salience network, was found to be crucial in distinguishing ToM performance between the two groups.

Automated summary

This study investigated white matter volume and gray matter volume differences between autistic and nonautistic samples, and their relationships with age and theory of mind (ToM) skills. The results showed widespread differences in both gray and white matter volumes between the two groups in regions crucial for social processes. The autistic group exhibited different correlations between age and structural changes compared to the nonautistic group, suggesting abnormalities in developmental structural changes. Additionally, differences were found in how gray and white matter volumes relate to ToM skills, particularly in the left frontal regions and cingulate/corpus callosum, respectively. The left insula was identified as a crucial region distinguishing ToM performance between the two groups.