Defining language impairments in a subgroup of children with autism spectrum disorder.

Helen Tager-Flusberg

doi:10.1007/s11427-012-4297-8

Abstract

Autism spectrum disorder (ASD) is diagnosed on the basis of core impairments in pragmatic language skills, which are found across all ages and subtypes. In contrast, there is significant heterogeneity in language phenotypes, ranging from nonverbal to superior linguistic abilities, as defined on standardized tests of vocabulary and grammatical knowledge. The majority of children are verbal but impaired in language, relative to age-matched peers. One hypothesis is that this subgroup has ASD and co-morbid specific language impairment (SLI). An experiment was conducted comparing children with ASD to children with SLI and typically developing controls on aspects of language processing that have been shown to be impaired in children with SLI: repetition of nonsense words. Patterns of performance among the children with ASD and language impairment were similar to those with SLI, and contrasted with the children with ASD and no language impairment and typical controls, providing further evidence for the hypothesis that a subgroup of children with ASD has co-morbid SLI. The findings are discussed in the context of brain imaging studies that have explored the neural bases of language impairment in ASD and SLI, and overlap in the genes associated with elevated risk for these disorders.

Highlights

Autism spectrum disorder (ASD) is diagnosed on the basis of core impairments in pragmatic language skills, which are found across all ages and subtypes
The findings are discussed in the context of brain imaging studies that have explored the neural bases of language impairment in ASD and specific language impairment (SLI), and overlap in the genes associated with elevated risk for these disorders
Two important clinical markers for SLI have been identified for English-speaking children [22]: deficits in grammatical morphology, marking tense in obligatory contexts and impaired repetition of nonsense words

Summary

Introduction

Autism spectrum disorder (ASD) is diagnosed on the basis of core impairments in pragmatic language skills, which are found across all ages and subtypes. Autism and language impairment is viewed as a subgroup of ASD with co-morbid SLI This hypothesis of co-morbidity between these disorders has been challenged by some investigators (e.g., Williams et al [21]), there have been few studies that have gone beyond comparing these groups on standardized language measures, which provide little insight into the mechanisms that underlie linguistic performance. Nonword repetition is an important clinical marker of language impairment because it has been linked to the acquisition of more general language skills, including both vocabulary and grammar [30,31,32] and, unlike tense morphology, it has cross-linguistic validity It is not known, whether problems in nonword repetition involve the same underlying processing deficits in ASD and SLI as no studies have directly compared these groups. The goal of this study was to investigate this question by comparing well-matched groups of children in their performance and error patterns on carefully designed experimental tasks of nonword discrimination and repetition

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