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Autism Intervention for Toddlers Improves Developmental Outcomes

Science Update

Adult swinging child, playing outside

Children with autism who receive a high intensity developmental behavioral intervention starting by age 18-30 months show major improvements in IQ, language, adaptive behavior, and severity of their diagnosis, according to an NIMH-funded study.


Current guidelines by the American Academy of Pediatrics recommend screening children for autism spectrum disorder (ASD) by age 18 months. However, no randomized clinical trials of intensive interventions for this age group had been conducted.

To address this gap, Geraldine Dawson, Ph.D., who was at the University of Washington at the time of the study, and colleagues randomly assigned 48 children, ages 18-30 months, to one of two intervention groups:

  • Early Start Denver Model (ESDM), a comprehensive, developmental behavioral intervention designed for toddlers with ASD as young as 12 months old. ESDM combines aspects of applied behavioral analysis (ABA) with developmental and relationship-based approaches.
  • Assess and Monitor (A/M), the comparison group intervention in which parents received recommendations on ASD interventions for their children, as well as referrals to local community providers of the interventions. A/M represents typical community-based care.

Children in the ESDM group were provided 20 hours per week of therapy from study clinicians, while their parents received related training to use ESDM strategies for at least five additional hours per week during their daily activities. Parents of all study participants were also free to receive other community services they thought appropriate.

All children in the study had been diagnosed with autism or a milder form of ASD called pervasive developmental disorder not otherwise specified (PDD-NOS). They were assessed yearly for two years or until the child turned four years old, whichever was longer.

Results of the Study

By the first- year assessment, children in the ESDM group gained 15.4 IQ points on average, while children in the A/M group gained an average of 4.4 points.

Over the two-year study period, children in the ESDM group consistently improved on measures of communication skills. They also showed improvements in motor skills, daily living skills, and other adaptive behaviors.

While children in the ESDM group were significantly delayed in their adaptive behaviors compared to typically developing children, they showed similar rates of improvement. In contrast, children in the A/M group fell further and further behind over time.

By the end of the study, more children who had received ESDM received improved diagnoses than children in the A/M group—seven children initially diagnosed with autistic disorder had their diagnosis change to PDD-NOS after receiving ESDM (30 percent), compared to only one child in the A/M group (5 percent).


According to the researchers, this is the first randomized controlled trial to study a potentially useful intensive intervention for very young children with ASD.

The study's findings suggest that ESDM can help children with ASD achieve better outcomes in terms of IQ, language, and behavioral skills, and in severity of their ASD diagnosis, than if they receive community-based care. Compared to research on other, similar interventions, this study showed greater differences between groups, suggesting that ESDM, delivered at a very young age, may be more effective than other approaches. The researchers noted that parents' use of ESDM strategies at home may have been key to this intervention's effectiveness.

What's Next

The University of Washington research team has been funded through the NIH Autism Centers of Excellence (ACE) program to follow this study's participants to determine whether the effects of ESDM can be sustained over time. In addition, Dr. Sally Rogers, Ph.D., a co-author on the study and co-developer with Dr. Dawson of the ESDM model, is leading a multi-site, randomized clinical trial of ESDM, also funded through the NIH ACE program. With a larger sample size, the investigators hope to better understand factors that predict level of response to the ESDM intervention.


Dawson G, Rogers S, Munson J, Smith M, Winter J, Greenson J, Donaldson A, Varley J. Randomized, Controlled Trial of an Intervention for Toddlers With Autism: The Early Start Denver Model . Pediatrics. 2009 Nov 30. [Epub ahead of print] PubMed PMID: 19948568.