Autistic children as young as 12 months can benefit from an early intervention program, new research suggests. 

Researchers at the University of Washington in Seattle studied 48 autistic children over a period of five years. The children, ages 18 months to 30 months, were divided into two groups.

One group received 20 hours a week of intensive therapy provided by University of Washington scientists and five hours a week of therapy from their parents, who were trained in the specific therapy being used in the study, called the Early Start Denver Model (ESDM).

ESDM integrates applied behavior analysis with specific developmental approaches that involve playing with the children and building a relationship with them. It is carried out in the child's home and led by researchers trained in early intervention, occupational therapists and speech pathologists. The idea is to work on developing the child's communication and other skills through interaction.

Autistic children often have problems with verbal communication and interacting with others.

The second group of children involved in the study received therapy solely from community-based programs. This group received an average of 9.1 hours of individual therapy and an average of 9.3 hours per week of group interventions.

The participants were assessed by researchers before the intervention began, one year after it started and either at 2 years after the study began or at 48 months of age — whichever represented a longer period of time.

The children in the ESDM group had the most dramatic improvement, with an 18-point increase in IQ during the study period versus four points for those in the community-based groups. Children in the ESDM group also had an almost 18-point improvement in listening and understanding skills versus those in the comparison group, who had a 10-point improvement.

Seven children in the ESDM group saw their diagnosis of autistic upgraded to "pervasive developmental disorder not otherwise specified."

The researchers believe the combination of play and a structured approach was responsible for the progress.

"We believe that the ESDM group made much more progress because it involved carefully structured teaching and a relationship-based approach to learning with many, many learning opportunities embedded in the play," Rogers said.

Intensive parental involvement also was credited with the success of the intervention.

The authors of the study believe that early intervention is critical in modifying autistic behaviour, even in children as young as 12 months.

"Infant brains are quite malleable so with this therapy we're trying to capitalize on the potential of learning that an infant brain has in order to limit autism's deleterious effects, to help children lead better lives," said Sally Rogers, a professor of psychiatry and behavioral sciences, a study co-author and a researcher at the UC Davis MIND Institute in Sacramento, Calif., in a news release.

The study is published Monday in the journal Pediatrics.