Researchers are giving new hope to parents of children with autism by showing for the first time that a form of behaviour therapy can benefit kids as young as 18 months.

Pediatricians have long been told to screen children for autism as early as possible. But what to do for a young child after a diagnosis has not been clear.

This new research, published in the journal Pediatrics, finds that a form of behaviour treatment called the Early Start Denver Model, can vastly improve symptoms in autistic toddlers.

The study found the treatment improves IQ, language ability, and social interaction, often resulting in a milder form of the condition.

Dr. Wendy Roberts, the director of autism research at Sick Kids Hospital in Toronto who was not involved in this research, says that while the study was small, it was rigorous.

"It is a groundbreaking study in that it's the first time we have had a really good randomized controlled trial," she told Canada AM Monday.

For the study, 48 children aged 18 months to 30 months were randomly assigned to receive either the Early Start Denver Model of behaviour therapy or community-based autism programs, which typically offer less comprehensive therapy.

Children in the Early Start group had four hours of therapist-led treatment at their homes five days a week, plus at least five hours weekly from parents.

After two years, IQ increased an average of almost 18 points in the specialized group, versus seven points in the others. Language skills also improved more in the specialized group.

Most remarkably, almost 30 per cent in the specialized group were re-diagnosed with a less severe form of autism called "pervasive developmental disorder not otherwise specified," or PDD-NOS, compared to just 5 per cent - i.e.: one patient -- among the others.

Roberts explained that the Early Start Denver Model resembles other types of autism behaviour treatment but focuses more on social interaction and communication, which are both areas of difficulty for most autistic children.

For example, therapists repeatedly hold a toy near a child's face to encourage the child to make eye contact. Or they reward children when they use words to ask for toys.

"It's a really intensive method of intervention and I think that really is the key. It involves a huge amount of parent training," Roberts noted.

Geraldine Dawson, chief science officer of the advocacy group Autism Speaks and one of the study's lead authors, says it offers good evidence that autistic children between 18 and 24 months can benefit from the therapy.

"By starting as soon as the toddler is diagnosed, we hope to maximize the positive impact of the intervention," she said in a statement from Autism Speaks.

Sally Rogers, who developed the intervention with Dawson and who is a professor of psychiatry and behavioral sciences at the UC Davis MIND Institute in Sacramento, Calif., says the therapy can even be used for 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," she said.

Dr. Roberts says the study is more evidence that therapy for autism needs to be started as early as possible. She says most provinces don't screening programs for autism. Ontario is rolling out a new surveillance program for kids at age 18 months, and other provinces are getting on board as well but more needs to be done.

Parents of autistic children usually start to notice the signs in their children at around 12 months, when the children stop responding to their name, don't mimic and show less interest in play.

Even when parents see the signs, their doctors sometimes delay referring the children to a specialist who can offer a diagnosis.

"So you can lose sometimes up to a year in that process," says Roberts, who notes that many kids aren't diagnosed until they are three or four years old.

Even after diagnosis, there is often a long wait for therapy, she says.

"So really, I think early intervention needs to start prior to diagnosis, when the earliest warning signs are detected," Roberts believes.