Meta-analysis of aberrant white matter microstructure and gray matter volume in autism spectrum disorder

Our aim was to conduct a comprehensive meta-analysis of structural neuroimaging studies investigating white matter (WM) microarchitecture and gray matter volume (GMV) abnormalities in patients with autism spectrum disorder (ASD).

Totally 24 diffusion tensor imaging studies using tract-based spatial statistics (TBSS) or voxel-based analysis (VBA) approach were included in this meta-analysis. The discrepancies in WM fractional anisotropy, mean diffusivity, axial diffusivity and radial diffusivity between ASD patients and typically developing (TD) individuals and the results of two common methods were compared. Besides, we detect GMV alternations by analyzing 44 voxel-based morphometry studies in ASD and comparing the difference in different developing stages.

Compared with TD, ASD exhibited significantly WM microstructure alterations in corpus callosum, cortico-spinal projections, anterior thalamic projections, superior longitudinal fasciculus and middle cerebellar peduncles. There is some heterogeneity in aberrant WM microstructure between the TBSS and VBA subgroup. ASD had increased GMV in gyrus rectus, superior and inferior temporal gyrus, and precentral gyrus, and decreased GMV in cerebellum, anterior cingulate/paracingulate gyri, cingulum, and inferior parietal gyri. ASD displayed an age-related trajectory of brain morphometry.

Our main findings reveal the variable WM microarchitecture and GMV in ASD and offer a neuroanatomical framework that may guide multimodal and longitudinal research.