Proportion and Profile of Autistic Children Not Acquiring Spoken Language Despite Receiving Evidence-Based Early Interventions

OBJECTIVE: To determine the proportion and profile of preschoolers on the autism spectrum who do not acquire spoken language despite receiving evidence-supported interventions that target spoken language. METHODS: We examined an aggregate dataset comprising 707 preschoolers on the autism spectrum who had received evidence-supported interventions to determine the proportion and profile of those who experienced limited progress in spoken language. Interventions were delivered through programs affiliated with university research settings and ranged in duration from 6 to 24 months. Spoken language outcomes were determined from parent-report measures, which were validated against direct assessments and natural language samples. RESULTS: Approximately two-thirds of children who were non-speaking at baseline were using single words or more complex spoken language by intervention exit. Those who remained non-speaking had lower baseline motor imitation scores, derived mainly from parent reports. Approximately half of the children who were minimally speaking (i.e. had single words or no words) at baseline were combining words by intervention exit. Those who did not acquire word combinations had lower baseline scores in cognitive, social, adaptive and motor imitation measures, and shorter intervention duration. Age at intervention start influenced spoken language advancement differently depending on the initial spoken language level. The odds of acquiring spoken language did not differ based on the intervention received. CONCLUSIONS: Approximately one-third of children who had limited or no spoken language at baseline did not advance to spoken language stages following intervention. Development of spoken language was associated with modifiable factors at the child and intervention level.