Factors Associated with Receptive and Expressive Language in Autistic Children and Siblings: A systematic review

Abstract Background Language abilities of autistic children and children at elevated likelihood for autism (EL-siblings) are highly heterogeneous, and many of them develop language deficits. It is as of yet unclear why language abilities of autistic children and EL-siblings vary, although a multifactorial risk model for language deficits seems more plausible than a single exploratory factor. In this review, we discuss research articles that identify factors implicated in the receptive or expressive language abilities of autistic children and EL-siblings since the introduction of the DSM-5. Method The search strategy of this review followed the PRISMA guidelines. The following databased were consulted: Embase, MEDLINE, Web of Science Core Collection and Scopus. Risk of bias (ROB) assessment was completed on using the Newcastle-Ottawa Scales. Results Out of 25624 records screened, 54 articles were included. We identified 56 factors implicated in receptive or expressive language abilities of autistic children and EL-siblings and divided them into ten categories: autism traits; biological factors; brain-based factors; child characteristics and early child development; environmental factors; gestures; motor skills; parental input; social factors and other factors. Although many of the identified variables were only examined in one article, some well-researched factors stood out, in particular joint attention, nonverbal cognitive abilities and frontal EEG power. Conclusions Our results confirm that a multifactorial risk model is most likely for language deficits in autism. Important aspects that should be considered in such a model are, amongst others, social factors such as joint attention, child characteristics such as nonverbal cognition, and neurocognitive factors.