Intervention effects on spoken‐language outcomes for children with autism: a systematic review and meta‐analysis

Background Although spoken‐language deficits are not core to an autism spectrum disorder (ASD) diagnosis, many children with ASD do present with delays in this area. Previous meta‐analyses have assessed the effects of intervention on reducing autism symptomatology, but have not determined if intervention improves spoken language. This analysis examines the effects of early interventions on spoken‐language in children with ASD. Method A systematic review of 1756 studies of children with ASD who participated in early intervention resulted in the inclusion of 26 studies in the current review. These studies included 1738 participants with ASD who were, on average, 3.3 years old ( SD  = 0.91). Results This random‐effects meta‐analysis of spoken‐language outcomes for children with ASD who received early intervention as compared with usual treatments yielded a significant overall mean effect size of g  = 0.26 (CI = 0.11 to 0.42). On average, children with ASD significantly increased their use of spoken‐language following experimental early interventions. Treatments delivered simultaneously by a clinician and a parent resulted in greater gains in spoken‐language than treatments delivered by a clinician or parent only. No other participant or study characteristics predicted individual‐study effect sizes. Conclusions Early intervention improves spoken‐language outcomes for children with ASD, and the largest effects are found when both parent and clinician implement the intervention. Recommendations for practice include adding systematic parent training to interventions for spoken language to potentially improve outcomes. Future research should report standard language measures as well as child (cognitive ability and socio‐economic status) and intervention characteristics to improve evidence related to the effects of interventions on spoken communication in children with ASD.