Reciprocal Associations between Language Ability and Social Functioning Development over a Two-Year Period in Young Pre-Verbal Children with Autism Spectrum Disorder

Impairments in language and social functioning are core symptoms of autism spectrum disorder (ASD). Longitudinal research on language abilities and social functioning in young children whose development is proceeding as expected and those with development delays suggests that skill development in one domain affects skill development in the other. However, much extant research with young children with ASD has examined developmental trajectories of these abilities separately, with little focus on the relations of these domains across the early childhood years. Pre-verbal young children with ASD, who have significantly impaired expressive language in toddlerhood, are a group of particular clinical relevance, given that greater language abilities at school entry have been shown to predict positive long-term adjustment in many areas, including social functioning. Further, given that attention to and engagement with social contexts is necessary for language to develop, and that growing language skills can facilitate further social engagement, there is reason to hypothesize that early social functioning may exert effects on language development over time. This has yet to be tested empirically within samples of very young children with ASD. Thus, the present study examined reciprocal associations between language and social functioning in a sample of very young pre-verbal children with ASD over a two-year period. In addition, moderating effects of previously-identified predictors of language and social functioning outcomes (nonverbal cognitive functioning, initiation of and response to joint attention, and autism symptom severity) on these associations were explored. Cross-lagged panel analyses revealed significant within-timepoint synchronous correlations and within-domain autoregressive paths over time. All cross-lagged paths were significant while controlling for construct stability paths and synchronous correlations. Nonverbal cognitive functioning moderated autoregressive language ability paths, while autism symptom severity moderated T2 to T3 language ability and social functioning paths. For very young pre-verbal children with ASD, language ability and social functioning appear to exert concurrent and cascading developmental influences on one another, with skills in one domain influencing the other both cross-sectionally and longitudinally. These findings support simultaneous targeting of these skill domains during intervention for very young pre-verbal children with ASD