Structural language profiles in children with autism spectrum disorder and developmental language disorder: a systematic review.

Background: Autism Spectrum Disorder (ASD) and Developmental Language Disorder (DLD) are both associated with language difficulties, yet the extent to which they share common structural language profiles remains unclear. Previous research has reported both overlap and divergence across phonological, morphosyntactic, semantic, and narrative domains, creating challenges for differential diagnosis and intervention planning. Objective: This systematic review aimed to synthesize empirical evidence comparing structural language abilities in children with ASD and DLD and to identify areas of convergence and divergence across language domains. Methods: A systematic literature search was conducted in PubMed, ERIC, PsycINFO, Google Scholar, and Semantic Scholar following PRISMA guidelines. Studies published in English between 2013 and 2025 were eligible if they included children aged approximately 3-18 years with ASD and DLD and examined structural language domains, including phonology, morphology, syntax, semantics, or narrative measures. 44 studies met the inclusion criteria and were synthesized using a narrative approach due to methodological heterogeneity. Results: The included studies suggested overlapping performance between children with ASD accompanied by language impairment (ASD-LI) and children with DLD across receptive and expressive language, morphosyntax, sentence repetition, nonword repetition, and complex syntactic processing. Overlapping performance was particularly evident in grammatical morphology, tense and aspect marking, clitic production, and comprehension of syntactically demanding structures. However, important differences emerged. Children with DLD generally exhibited more consistent and pervasive structural language deficits, whereas language performance in ASD was characterized by greater heterogeneity. Difficulties in ASD were more frequently influenced by pragmatic, attentional, cognitive, and processing-related factors, and atypical error patterns were observed in several linguistic domains. Conclusion: The available evidence suggests a partially overlapping structural language phenotype between children with ASD and co-occurring language impairment (ASD-LI) and those with DLD, while also highlighting important disorder-specific characteristics. Across several structural language domains, the included studies frequently reported similar performance on standardized language measures. The findings further suggest that similar behavioral performance may reflect distinct underlying linguistic and cognitive mechanisms, resulting in different patterns of language impairment. Overall, the evidence suggests that ASD-LI and DLD share several structural language characteristics but do not represent a single, unified language disorder. These findings have important implications for differential diagnosis, language assessment, and the development of targeted intervention approaches for children with ASD and DLD.