Brain volumetric and white matter structural connectivity alterations in autistic children: case–control study

Abstract

Background: Autism spectrum disorder (ASD) is a neurodevelopmental disorder that includes a large heterogeneous constellation of disorders with overlapping symptoms and clinical features. The diagnosis is based mainly on clinical symptoms meeting DSM-5 criteria with no radiologic or laboratory diagnostic investigations available yet. The specific neuropathologic aberrations occurring in ASD are still under investigation. This study aimed at providing a preliminary database for better understanding of the neuropathologic aspects of ASD, regarding both macrostructure and microstructure of the brain using magnetic resonance imaging. This case–control study included total of 40 children, 20 cases (diagnosed with ASD) and 20 control (Typically Developing Children, TDC) aged 2–18 years. 3D-T1 and Diffusion Tensor Images (DTI) were acquired. 3D-T1 images were uploaded to Volbrain and brain segmentation was done using Volbrain 2.0 pipeline. DTI data were analyzed using FSL where Tract-Based Spatial Statistics analysis was carried out and mean fractional anisotropy values obtained. Independent samples t test was used to compare means of both groups. Results: ASD group displayed statistically significant larger intracranial cavity, brain, white matter, grey matter and cerebrospinal fluid volumes (p < 0.001 for all except CSF volume p = 0.01) with the white matter occupying higher percentage of intracranial volume in ASD compared to TDC group (p < 0.001). The cortical thickness showed statistically significant larger volume in entorhinal cortex in ASD group compared to TDC group at both sides (p < 0.001 at right side, p = 0.003 at left side). Widespread statistically significant (p < 0.001) higher mean FA value was observed at multiple white matter tracts. Conclusion: These findings suggest that the main pathology of ASD is within the white matter. It also supports the hypothesis that autistic brain undergoes period of precocious growth in early years of life. Further studies with age and clinical severity stratification are needed to investigate temporal changes and severity related macrostructure and microstructure changes in autistic brains.