Like starting a ball rolling down a hill, treating autism early, when children are around two years old, leads to improvements that continue when a child is six. According to a recent study, early intervention appears to continue helping children with autism spectrum disorders (ASD) even after the program has ended.

The study is the first in more than 20 years to look at long-term outcomes after early intensive autism intervention.

The children who had received the one-on-one care of ESDM saw their autism symptoms continue to diminish further — even without treatment.

Its focus was on a treatment called the Early Start Denver Model (ESDM). In ESDM parents and therapists work with the children for more than 15 hours each week, one-on-one in the home. Many parents are drawn to ESDM because it is a naturalistic approach that does not significantly interrupt their day-to-day lives.

An earlier study had shown many beneficial effects for ESDM on children with autism spectrum disorders.

The current study, published in the Journal of the American Academy of Child and Adolescent Psychiatry, is a follow-up and looked at 39 of the children from the original study at age six, two years after ESDM had ended.

After two years, children in the ESDM group showed a significantly greater increase in IQ, adaptive functioning, communication and other measures than did a comparison group that had received two years of community intervention — a mix of programs available in the community such as speech therapy and developmental preschool.

Both groups of children had begun treatment when they were between 18 and 30 months old.

The children who had received the one-on-one care of ESDM saw their autism symptoms continue to diminish further — even without treatment, while children who had received community intervention did not.

The results make the case for autism-specific, one-on-one intervention to begin as soon as autism symptoms emerge, which for many children is before 30 months of age, said lead researcher Annette Estes.

“This is really important,” Estes said in a statement. “This is the kind of evidence that is needed to support effective intervention policies for children with autism, whether it's insurance coverage or state support for early autism intervention.”

“Although a number of studies have shown the positive effects of early intervention on children’s abilities during the preschool period, there have been few studies to date that have followed these children,” added senior researcher Geri Dawson. “The results suggest that early intervention results in long-term benefits for children across a wide range of skills.”

Annette Estes, PhD, is a research associate professor in the Department of Speech and Hearing Sciences and an adjunct research assistant professor in the Department of Psychology at the University of Washington. She is also director of the University of Washington Autism Center.

Geraldine Dawson, PhD, is a professor of psychiatry and behavioral sciences and director of the Duke Center for Autism and Brain Development at Duke University Medical Center. She is also co-developer of the Early Start Denver Model.