The relationship between language and executive function in DLD and FXS over time

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PROJECT SUMMARY/ABSTRACT Language impairments have a persistent, lifelong impact on social communication, academic performance, and adaptive behaviors. Clinical groups impacted by language impairments include developmental language disorder (DLD), fragile X syndrome (FXS), and Down syndrome (DS). DLD affects 7-13% of school-age children, and is characterized by pervasive impairments in the grammatical system in the absence of an intellectual disability. Individuals with FXS and DS have significant language impairments, but unlike DLD, language impairment is part of a constellation of broader developmental issues, including intellectual disability. Notably, there is a significant overlap in the language phenotype between DLD, FXS and DS, in terms of grammatical production. This is striking given the difference in general cognitive abilities between the groups. Importantly, nothing is known regarding areas of overlap and distinction in grammatical comprehension between these disorders. Additionally, although FXS and DS have very different cognitive profiles from DLD in terms of IQ, there are overlaps in other aspects of cognition, namely executive functions. This is particularly interesting, given evidence of a relationship between executive functions and language skills during typical development as well as in children with DLD, however, this work is nonexistent in FXS and DS. Comparative studies between disorders with known (FXS and DS) and unknown (DLD) etiology have the potential to inform both theory and clinical practice. Thus, through this supplement we will test two specific aims designed to systematically investigate areas of overlap and distinction in terms of language with a focus on grammatical production and comprehension and the association with executive functions in children with DLD and FXS (parent R01) and DS (supplement) in a developmental framework. Through careful investigations we will be able to determine the relationship between grammatical comprehension and production in addition to executive function skills in DLD, FXS, DS and a language matched group of children with typical development. For this supplement, we propose to recruit children with DS (n = 20). For the parent project, we are recruiting children with DLD (n = 40), children with FXS (n = 40), and children with typical development (n = 60). All groups will be matched on clause length to ensure similar language abilities. This supplement will include a combination of standardized assessments, language samples, experimental tasks, and parent report measures. The proposed study will yield key information regarding children’s comprehension of grammar, best assessment methods, and critical information on the relationships between executive functions and grammatical development. The data collected in this study will be used to inform treatment studies designed to maximize both the effectiveness and efficacy of language learning in DLD, FXS and DS in targeted intervention studies.