Longitudinal Receptive-Expressive Language Profiles in Young Autistic Children

Abstract Background & Aims: Language development in autism is heterogeneous and strongly predicts later functioning. The balance between receptive and expressive abilities and their developmental trajectories, however, remains poorly understood. While some autistic children exhibit a relative expressive advantage (ExpAdv), others show receptive advantage (RecAdv) or a balanced profile. Prior studies report inconsistent findings and are often limited by cross-sectional designs and small samples. The present study aimed to (1) describe longitudinal trajectories of receptive and expressive language in autistic and typically developing (TD) children; (2) classify children into ExpAdv, Balanced, and RecAdv profiles across early childhood; and (3) examine the stability and transitions of these profiles over time, including associated clinical features. Methods: We analyzed 1,174 longitudinal time points from 318 autistic children and 294 time points from 108 TD children (1.2-5.8 years) from the Geneva Autism Cohort. Receptive and expressive language were assessed with the Mullen Scales of Early Learning. Receptive-expressive balance was quantified as the ratio of receptive to expressive age equivalent scores, classifying children into ExpAdv, Balanced, and RecAdv profiles using adapted cut-offs. Mixed-effects models examined developmental trajectories, and Sankey diagrams visualized profile transitions. Autism features and adaptive behavior were compared across profiles. Results: Autistic children displayed lower expressive and receptive language than TD peers, with receptive abilities exceeding expressive skills in both groups. Overall, 30-35% of autistic children were classified as ExpAdv at 18-36 months, declining to ~12% by 48-54 months, while Balanced and RecAdv profiles became more prevalent with age. ExpAdv was associated with slower verbal and non-verbal developmental gains. Stability was highest for Balanced and RecAdv profiles (50-60%), whereas ExpAdv often transitioned to Balanced. Autistic children with stable ExpAdv profiles were more often female, less likely to receive early intervention, and showed weaker adaptive communication. Conclusions: Receptive-expressive language profiles in autistic children are dynamic. ExpAdv profile is more frequent in younger autistic children, less stable, and linked to slower verbal and non-verbal development and higher autism severity. Implications: ExpAdv may represent an early marker of autism associated with slower expressive and receptive language growth. Longitudinal monitoring of receptive and expressive skills is essential, as transitions toward Balanced or RecAdv profiles are associated with improved developmental outcomes. Early intervention before age three may facilitate transitions toward Balanced or RecAdv profiles, supporting more favorable language development and long-term outcomes. Keywords: autism; early childhood; longitudinal design; expressive language; receptive language; language profile; early intervention; language gap; discrepant profiles