The Early Start Denver Model: Moderators of Response to An Early Intervention for Toddlers with Autism Spectrum Disorder

Background: Studies of the efficacy of early behavioral intervention for improving outcomes for preschool-aged children with autism spectrum disorder (ASD) have yielded positive results. Less is known about the outcomes of children receiving early intervention below age 2 ½ years. 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.

Objectives: A randomized clinical trial of an early intervention designed for toddlers with ASD was recently published (Dawson et al., 2010, Pediatrics).  This study evaluated the efficacy of the Early Start Denver Model (ESDM), a comprehensive developmental behavioral intervention.  Compared with children who received community-based intervention, children who received ESDM showed significant improvements in IQ, adaptive behavior, and autism diagnosis. Similar to previous studies of early intervention for autism, there was significant inter-subject variability in response to the intervention.  This presentation will describe the results of new analyses examining several potential moderators of response to intervention, including IQ and severity of autism symptoms, among others. 

Methods: Forty-eight children diagnosed with ASD at 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.

Results: Compared with children who received community-based intervention, children who received ESDM showed significant improvements in IQ, adaptive behavior, and autism diagnosis. Two years after entering intervention, the ESDM group showed significantly improved cognitive abilities, as measured by the Mullen Scale for Early Learning. On average, the ESDM group’s early-learning composite score improved 17.6 standard score points (1 SD: 15 points) compared with 7.0 points in the comparison group relative to baseline scores. The ESDM group maintained its rate of growth in adaptive behavior compared with a normative sample of typically developing children. In contrast, over the 2-year span, the comparison group showed greater delays in adaptive behavior. Children who received ESDM also were more likely to experience a change in diagnosis from autism to pervasive developmental disorder, not otherwise specified, than the comparison group. 

Conclusions: This randomized, controlled trial demonstrated the efficacy of a developmental behavioral intervention for toddlers with ASD for improving cognitive and adaptive behavior and severity of diagnosis.  Results of this study underscore the importance of early detection of and intervention in autism.  Results of analyses examining several factors that contribute to intervention response will be presented.