Comparing Morphosyntactic Profiles of Children With Developmental Language Disorder or Language Disorder Associated With Autism Spectrum Disorder

Purpose: Previous cross-population comparisons suggest a considerable overlap in the morphosyntactic profiles of children with developmental language disorder (DLD) and children who experience language disorder associated with autism spectrum disorder (LD-ASD). The goal of this study was to further examine and compare the morphosyntactic profiles of the two populations using both standardized, norm-referenced assessments and language sample analysis. Method: We used the Structured Photographic Expressive Language Test-Third Edition (Dawson et al., 2003) and the Index of Productive Syntax (in Applied Psycholinguistics, 11(1), 1990 by Scarborough) to compare the morphosyntactic profiles of 21 children with DLD (5;6-8;1 [years;months]) and 15 children with LD-ASD (4;4-9;8). Results: Overall, both groups' morphosyntactic profiles were not significantly different based on the 26 structures assessed by the Structured Photographic Expressive Language Test-Third Edition. Chi-square analyses identified two structures on which the DLD group outperformed the LD-ASD group (i.e., participle and the conjunction "and"). Likewise, the groups' morphosyntactic profiles were not significantly different based on the 56 items assessed by the Index of Productive Syntax. Analyses identified only one structure on which the DLD group outperformed the LD-ASD group (i.e., S8: Infinitive) and four structures on which the LD-ASD group outperformed the DLD group (i.e., Q9: Why/when/which, etc.; Q6: Wh-question with auxiliary, modal, or copula; Q4: Wh-question with verb; and Q2: Routine question). Conclusions: Study results suggest that the morphosyntactic profiles of children with DLD and children with LD-ASD are not significantly different. Results also suggest potential weaknesses on forms that have not been the focus of previous studies. It is important for clinicians to assess each of these forms using both standardized assessments and language sample analysis to gain a full understanding of the language profiles of children with DLD or LD-ASD.