Moderators of Language Outcomes in Randomized Controlled Esdm Intervention Trial for Toddlers with Autism

Background:   As more children are diagnosed with ASD during the infant-toddler period, the availability of efficacious interventions that can be delivered at a young age is a significant priority. In addition, establishing core treatment targets, delineating the developmental trajectories of those targets, and further elucidating certain child characteristics that moderate treatment response are essential to the clinical impact and dissemination of these interventions.

Objectives:   The purpose of the current study is to address two primary questions: “What are the effects of ESDM intervention on language outcomes in toddlers with ASD, using intent to treat analysis to account for study attrition?” and “How do individual child characteristics moderate the relationship between language and intervention?” The current study examined social orienting, response to joint attention, and object use as moderators of treatment response.

Methods:   Forty-eight children diagnosed with ASD between 18 and 30 months of age were randomly assigned to: (1) ESDM intervention, based on developmental and applied behavioral analysis principles and delivered by trained therapists and parents for 2 years; or (2) referral to community providers for intervention commonly available in the community. Linear regression was employed to determine whether Time 1 child social orienting, response to joint attention, or object use moderated the effect of ESDM intervention on child outcomes at Time 2 and Time 3 (i.e., one and two years after ESDM was initiated). When moderation was observed, regions of significance were derived to specify the upper and lower values of the moderator at which the ESDM and comparison groups were significantly different. 

Results:   Compared with children who received community-based intervention, children who received ESDM showed significantly greater improvements in receptive language outcomes at Time 2 and Time 3, as well as expressive language outcomes at Time 3. Moderation analysis revealed that ESDM was more effective than the community intervention at promoting language gains for children with higher Time 1 levels of social orienting, response to joint attention, and object use. Social orienting moderated expressive language gains at Time 2 and Time 3, while object use moderated only Time 2 expressive language gains, and response to joint attention moderated only Time 2 receptive language gains.

Conclusions:   This randomized, controlled trial provides a rich source of longitudinal information demonstrating the effectiveness of the ESDM for improving language gains for young children with ASD and further examines certain child characteristics that moderate treatment response. Future research investigating the relationship between such endophenotypes and treatment will contribute important information regarding the individualization of treatment and the impact of early intervention on brain function and organization. Within the ESDM, certain intervention targets for language may include activities incorporating early social communication skills, with those children with higher levels of these skills benefitting more from the ESDM curriculum. For example, improved social orienting may augment the capacity of children with ASD to appreciate stimulus-reward associations and, therefore, display enhanced speed and maintenance of learning within a behavioral intervention paradigm.