Impaired Structural Connectivity of Socio-Emotional Circuits in Autism Spectrum Disorders: A Diffusion Tensor Imaging Study

Stephanie H Ameis,A Ting Wang,Jin Fan,Eric Hollander,Nancy J Lobaugh,Evdokia Anagnostou,Conrad Rockel,Latha Soorya,Aristotle N Voineskos,Xi-Nian Zuo

doi:10.1371/journal.pone.0028044

Abstract

BackgroundAbnormal white matter development may disrupt integration within neural circuits, causing particular impairments in higher-order behaviours. In autism spectrum disorders (ASDs), white matter alterations may contribute to characteristic deficits in complex socio-emotional and communication domains. Here, we used diffusion tensor imaging (DTI) and tract based spatial statistics (TBSS) to evaluate white matter microstructure in ASD.Methods/Principal FindingsDTI scans were acquired for 19 children and adolescents with ASD (∼8–18 years; mean 12.4±3.1) and 16 age and IQ matched controls (∼8–18 years; mean 12.3±3.6) on a 3T MRI system. DTI values for fractional anisotropy, mean diffusivity, radial diffusivity and axial diffusivity, were measured. Age by group interactions for global and voxel-wise white matter indices were examined. Voxel-wise analyses comparing ASD with controls in: (i) the full cohort (ii), children only (≤12 yrs.), and (iii) adolescents only (>12 yrs.) were performed, followed by tract-specific comparisons. Significant age-by-group interactions on global DTI indices were found for all three diffusivity measures, but not for fractional anisotropy. Voxel-wise analyses revealed prominent diffusion measure differences in ASD children but not adolescents, when compared to healthy controls. Widespread increases in mean and radial diffusivity in ASD children were prominent in frontal white matter voxels. Follow-up tract-specific analyses highlighted disruption to pathways integrating frontal, temporal, and occipital structures involved in socio-emotional processing.Conclusions/SignificanceOur findings highlight disruption of neural circuitry in ASD, particularly in those white matter tracts that integrate the complex socio-emotional processing that is impaired in this disorder.

Highlights

Autism spectrum disorders (ASDs) are neurodevelopmental disorders, characterized by impaired social interaction, impaired communication, and repetitive, restrictive, and stereotyped interests, activities and behaviors [1]
We investigated white matter in autism spectrum disorders (ASDs) children and adolescents compared to controls using diffusion tensor imaging (DTI)
Linear regression scatterplots for whole-brain fractional anisotropy (FA), mean diffusivity (MD), axial and radial diffusivity values, each plotted against age indicated significant differences in diffusivity values between ASD and control groups (Figure 1)

Summary

Introduction

Autism spectrum disorders (ASDs) are neurodevelopmental disorders, characterized by impaired social interaction, impaired communication, and repetitive, restrictive, and stereotyped interests, activities and behaviors [1]. Magnetic resonance imaging (MRI) studies have found regional volumetric differences when comparing ASD subjects to healthy controls [3]. Among these brain regions, the frontal lobe is often reported as susceptible by virtue of differences in gray matter volume, white matter volume, or both [4]. DTI based approaches can be used to characterize microstructure in white matter tracts that serve to integrate complex neural circuitry, responsible for the higher-order brain functions that are otherwise impaired in ASD. We used diffusion tensor imaging (DTI) and tract based spatial statistics (TBSS) to evaluate white matter microstructure in ASD

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Discussion

Conclusion