Randomized, Controlled Trial of an Intervention for Toddlers with Autism: The Early Start Denver Model
Dawson, G., Rogers, S., Munson, J., Smith, M., Winter, J., Greenson, J., Donaldson, A., & Varley, J. (2009). Randomized, controlled trial of an intervention for toddlers with autism: The Early Start Denver Model. Pediatrics, 125 (1), 17-23.
Reviewed by Amy Hansford,
Why study this topic?
Prior research has shown that early behavioral intervention may improve overall functioning and produce significant gains in IQ for children with autism who enter treatment at age 2-3 years. With the recommended screening age for autism spectrum disorders recently being lowered to 18 months, there has been an increased need to identify intervention approaches that are effective for this younger age group.
What did the researchers do?
The researchers in this study evaluated the effectiveness of the Early Start Denver Model (ESDM) — a behavioral model designed for the treatment of young children with autism from infancy to preschool age. The ESDM combines developmental intervention techniques and an applied behavior analytic (ABA) approach called Pivotal Response Treatment (PRT). Developmental interventions aim to promote social communication by making highly motivating items available to the child, being responsive to what the child does (e.g., imitating or commenting on the child’s activities), and encouraging ongoing interaction around these activities. PRT aims to increase a child’s motivation to learn, monitoring of his/her own behavior, and initiations of communication with others.
Forty-eight children between the ages of 18 and 30 months, with a diagnosis of autistic disorder or pervasive developmental disorder, not otherwise specified (PDD-NOS), participated in this investigation. Participants were randomly assigned to one of two groups, and received their assigned intervention for two years. The first group was assigned to ESDM, which included twenty hours per week of intervention from clinicians and parent. The second group (assess-and-monitor group) was a "treatment as usual" model, including comprehensive assessments as well as treatment recommendations and referrals to providers in the community.
Children were assessed at three time points: before the start of the assigned intervention, after one year of intervention, and then after two years of intervention, or when the child turned forty-eight months (choosing the later point). At each time point, measures were taken to assess diagnosis, cognitive ability (IQ), adaptive skills, and repetitive behaviors.
What did the researchers find?
Although the ESDM group and the community treatment groups did not differ significantly on most measures at the one-year time point, the ESDM group outperformed the community group on measures of cognitive skill and adaptive behavior at the two-year time point. The ESDM group was also more likely than the community group to show improved diagnostic status (for example, going from a diagnosis of full autism to a diagnosis of PDD-NOS, indicating fewer symptoms of autism), though the groups did not differ from each other in overall diagnostic severity scores.
What were the strengths and limitations of the study? What do the results mean?
The researchers concluded that children receiving ESDM showed greater overall improvements than those in the assess-and-monitor group. Specifically, gains were seen in diagnostic category, IQ, and adaptive behavior. These results indicate that the ESDM model may be a beneficial treatment for toddlers with autism spectrum disorders. The results require replication by independent investigators but are significant in that they provide evidence that ESDM is effective for children with autism as young as 18 months old, and because they suggest that an intervention model combining developmental and ABA approaches may be successful.