Early trajectories and moderators of autistic language profiles: A longitudinal study in preschoolers

Abstract

Both expressive and receptive language difficulties in autism emerge early and significantly have an impact on social functioning and quality of life. Despite their wide heterogeneity, autistic language abilities can be stratified into three distinct profiles. Language unimpaired exhibit near-typical verbal performance, language impaired show significant alterations in language structure, and minimally verbal display limited verbal abilities. However, little is known about the early trajectories and moderators specific to each profile. Here, we used a longitudinal sample of 286 preschoolers with autism and 85 typically developing (aged 1.5–5.7 years old), yielding 1164 visits. Our cluster analysis replicated the three well-established autistic language profiles (language unimpaired, n = 86; language impaired, n = 85; minimally verbal, n = 44) and revealed their specific early trajectories in expressive vocabulary, syntax, and pragmatics. At age 2.4, non-verbal cognition moderated the participants’ attribution to each language profile. Moreover, early stereotyped language specifically moderated the later verbal performance of language unimpaired participants, while the language outcome of language impaired participants was moderated by early intensive behavioral intervention. In conclusion, we provided a fine-grained description of language acquisition trajectories and moderators of autistic language profiles in a longitudinal sample exposed to French language, paving the way toward personalized medicine to autistic language difficulties. Lay Abstract Language development can greatly vary among autistic children. Children who struggle with language acquisition often face many challenges and experience lower quality of life. However, little is known about the early language trajectories of autistic preschoolers and their moderators. Autistic language can be stratified into three profiles. Language unimpaired experience little to no language difficulties; language impaired show significant difficulties in language; minimally verbal never develop functional language. In this study, we used a longitudinal sample of preschoolers with autism and with typical development (aged 1.5–5.7 years). We replicated the three language profiles through a data-driven approach. We also found that different factors modulated the language outcome within each group. For instance, non-verbal cognition at age 2.4 moderated the participants’ attribution to each language profile. Moreover, early intervention moderated verbal outcome in the language impaired profile. In conclusion, we provided a detailed description of how autistic preschoolers acquire language, and what factors might influence their trajectories. Our findings could inspire more personalized intervention for early autistic language difficulties.