Corpus callosum organization and its implication to core and co-occurring symptoms of Autism Spectrum Disorder.

Autism Spectrum Disorder (ASD) is characterized by social interaction and communication deficits, repetitive behavior and often by co-occurring conditions such as language and non-verbal IQ development delays. Previous studies reported that those behavioral abnormalities can be associated with corpus callosum organization. However, little is known about the specific differences in white matter structure of the corpus callosum parts in children with ASD and TD peers and their relationships to core and co-occurring symptoms of ASD. The aim of the study was to investigate the volumetric and microstructural characteristics of the corpus callosum parts crucially involved in social, language, and non-verbal IQ behavior in primary-school-aged children with ASD and to assess the relationships between these characteristics and behavioral measures. 38 children (19 with ASD and 19 typically developing (TD) controls) were scanned using diffusion-weighted MRI and assessed with behavioral tests. The tractography of the corpus callosum parts were performed using Quantitative Imaging Toolkit software; diffusivity and volumetric measurements were extracted for the analysis. In the ASD group, fractional anisotropy (FA) was decreased across the supplementary motor area and the ventromedial prefrontal cortex, and axial diffusivity (AD) was reduced across each of the corpus callosum parts in comparison to the TD group. Importantly, the AD decrease was related to worse language skills and more severe autistic traits in individuals with ASD. The microstructure of the corpus callosum parts differs between children with and without ASD. Abnormalities in white matter organization of the corpus callosum parts are associated with core and co-occurring symptoms of ASD.

Structural brain abnormalities and their association with language impairment in school-aged children with Autism Spectrum Disorder.

Language impairment is comorbid in most children with Autism Spectrum Disorder (ASD) but its neural basis is poorly understood. Using structural magnetic resonance imaging (MRI), the present study provides the whole-brain comparison of both volume- and surface-based characteristics between groups of children with and without ASD and investigates the relationships between these characteristics in language-related areas and the language abilities of children with ASD measured with standardized tools. A total of 36 school-aged children participated in the study: 18 children with ASD and 18 age- and sex-matched typically developing controls. The results revealed that multiple regions differed between groups of children in gray matter volume, gray matter thickness, gyrification, and cortical complexity (fractal dimension). White matter volume and sulcus depth did not differ between groups of children in any region. Importantly, gray matter thickness and gyrification of language-related areas were related to language functioning in children with ASD. Thus, the results of the present study shed some light on the structural brain abnormalities associated with language impairment in ASD.

Language Abilities of Russian Primary-School-Aged Children with Autism Spectrum Disorder: Evidence from Comprehensive Assessment.

The purpose of the present research was to comprehensively assess the language abilities of Russian primary-school-aged children with Autism Spectrum Disorder (ASD), varying in non-verbal IQ, at all linguistic levels (phonology, lexicon, morphosyntax, and discourse) in production and comprehension. Yet, the influence of such non-language factors as children's age, the severity of autistic traits, and non-verbal IQ on language functioning was studied. Our results indicate a high variability of language skills in children with ASD (from normal to impaired) which is in line with the previous studies. Interestingly, the number of children with normal language abilities was related to the linguistic levels: according to more complex morphosyntax and discourse tests, fewer children with ASD were within the normal range unlike the results in simpler phonological and lexical tests. Importantly, we found that language abilities were best predicted by non-verbal IQ but were independent from age and the severity of autistic traits. The findings support the claim that formal language assessment of children with ASD needs to include all linguistic levels, from phonology to discourse, for helping speech-language therapists to choose an appropriate therapy target.

Expressive and Receptive Language in Russian Primary-School-Aged Children with Autism Spectrum Disorder.

BACKGROUND: Abnormal language development in both expressive and receptive domains occurs in most children with Autism Spectrum Disorder (ASD), although the language deficit is not a core symptom of ASD. However, previous studies disagree on the difference in the degree of impairment between expressive and receptive language in ASD. Existing research has concentrated on vocabulary and 'global expressive and receptive language', often using parental reports for language assessment. Moreover, most of these studies have focused on toddlers and preschoolers with ASD, whereas data from school-aged children with ASD are very limited. At the same time, the age of children might account for the inconsistencies across publications on expressive-receptive language difference in children with ASD. AIMS: The goal of the study was to directly compare the expressive and receptive language abilities of Russian primary-school-aged children with ASD (7-11 years old) at the levels of vocabulary, morphosyntax, and discourse. METHODS: 82 children with ASD participated in language testing. We used tests from the Russian Child Language Assessment Battery in order to assess vocabulary, morphosyntax, and discourse in expressive and receptive domains. RESULTS: Our results revealed different expressive and receptive patterns, depending on the linguistic level and tests complexity. Importantly, we showed that children's non-verbal IQ partly accounted for the difference between production and comprehension abilities. CONCLUSIONS: The expressive-better-than-receptive pattern in language has been considered by some authors as the unique hallmark of ASD. However, several studies, including our own, show that this is not a universal characteristic of ASD. We also revealed that expressive and receptive language patterns differed depending on the linguistic level, children's non-verbal IQ, and assessment tools.