Autism Spectrum Disorder as Early Neurodevelopmental Disorder: Evidence from the Brain Imaging Abnormalities in 2–3 Years Old Toddlers

Zhou Xiao,Hui Fang,Bing Zou,Xiang Xiao,Jiuping Zhang,Ting Qiu,Yijun Liu,Fengjing Liang,Kangkang Chu,Ting Xiao,Haiqing Huang,Xiaoyan Ke

doi:10.1007/s10803-014-2033-x

Abstract

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition that occurs within the first 3 years of life, which is marked by social skills and communication deficits along with stereotyped repetitive behavior. Although great efforts have been made to clarify the underlying neuroanatomical abnormalities and brain-behavior relationships in adolescents and adults with ASD, literature is still limited in information about the neurobiology of ASD in the early age of life. Brain images of 50 toddlers with ASD and 28 age, gender, and developmental quotient matched toddlers with developmental delay (DD) (control group) between ages 2 and 3 years were captured using combined magnetic resonance-based structural imaging and diffusion tensor imaging (DTI). Structural magnetic resonance imaging was applied to assess overall gray matter (GM) and white matter (WM) volumes, and regional alterations were assessed by voxel-based morphometry. DTI was used to investigate the white matter tract integrity. Compared with DD, significant increases were observed in ASD, primarily in global GM and WM volumes and in right superior temporal gyrus regional GM and WM volumes. Higher fractional anisotropy value was also observed in the corpus callosum, posterior cingulate cortex, and limbic lobes of ASD. The converging findings of structural and white matter abnormalities in ASD suggest that alterations in neural-anatomy of different brain regions may be involved in behavioral and cognitive deficits associated with ASD, especially in an early age of 2–3 years old toddlers.

Highlights

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder characterized by impairments in social interaction and communication that begin at a young age, which commonly exhibits repetitive behaviors and restricted interests
Global gray matter (GM) and white matter (WM) volumes for ASD and control group were shown in Table 2, indicating larger global GM and WM volumes in ASD (p = 0.048 and p = 0.047, respectively)
The neurophysiological results provided three important findings: (1) These young ASD children possessed larger global GM and WM volumes than developmental delay (DD) group of the same ages, genders and developmental quotient (DQ) scores; (2) these ASD children exhibited elevated GM volumes most commonly observed in the right superior temporal gyrus of the temporal lobe and elevated WM volumes most commonly observed in the right superior temporal gyrus, left middle temporal gyrus, right insular cortex, and right Heschl’s gyrus; (3) ASD exhibited higher FA and lower mean diffusion (MD) in the CC, posterior cingulate cortex, and limbic lobe as well as lower MD in the insular cortex

Summary

Introduction

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder characterized by impairments in social interaction and communication that begin at a young age, which commonly exhibits repetitive behaviors and restricted interests. There is increasing evidence that the heterogeneity and complexity of core symptoms in ASD can be explained as a fundamental impairment in both grey and white matter structure (Minshew and Williams 2007). In this perspective, a recent noninvasive magnetic resonancebased method of combined structure imaging and diffusion tensor imaging (DTI) sensitive to the presence of brain structure and WM integrity alterations, has allowed for a better understanding of the neuroanatomical abnormalities in ASD. Brain overgrowth was probably the most replicated finding in this population (Brynska 2012; Courchesne et al 2003).

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