For the first time, researchers say they have evidence that parent-led intervention for young kids with autism continues to yield gains several years later.

Children who participated in an intervention between the ages of 2 and 4 displayed less severe symptoms six years later, exhibiting fewer repetitive behaviors and better social communication, according to findings published this week in the journal The Lancet.

“Our findings are encouraging, as they represent an improvement in the core symptoms of autism previously thought very resistant to change,” said Jonathan Green of the University of Manchester and Royal Manchester Children’s Hospital in England who led the study.

The findings come from a follow-up to what’s known as the Preschool Autism Communication Trial, or PACT, which was published in 2010.

For the trial, children with autism were randomly assigned to either participate in a 12-month early intervention program or simply receive standard care. All of the kids initially displayed similar levels of autism severity.

Parents of those in the intervention group participated in 18 sessions over the course of the year where they watched videos of themselves interacting with their child and got feedback from therapists so that they could understand how to better communicate. These moms and dads also agreed to spend 20 to 30 minutes each day engaged in planned communication and play with their child.

Six years after completing the initial study, researchers conducted new assessments of 59 children who received the parent-focused intervention and 62 kids who did not. They found that 17 percent fewer children in the intervention group had severe symptoms as compared to kids whose parents did not get the specialized training.

What’s more, researchers found that children in the treatment group communicated better with their parents even though assessments showed no difference in language scores between them and the other kids studied. However, both groups of youngsters continued to display comparable levels of anxiety, challenging behaviors and depression.

“This is not a ‘cure,’ in the sense that the children who demonstrated improvements will still show remaining symptoms to a variable extent, but it does suggest that working with parents to interact with their children in this way can lead to improvements in symptoms over the long-term,” Green said.