Updated

A new study suggests that about half of all cases of autism spectrum disorders (ASD) may be diagnosable during the toddler years. The other half may be diagnosed later and may be a very different type of the behavioral and social disorder.

Researchers found that certain early signs of autism spectrum disorders (including autism) were evident in children at 14 months of age, and this early diagnosis was then confirmed by age 3.

"The fact that we can identify this at such a young age is extremely exciting because it gives us an opportunity to diagnose children with ASD very early on when intervention may have a great impact on development," says researcher Rebecca Landa, PhD, director of the Kennedy Krieger Institute Center for Autism and Related Disorders, in a news release.

Earlier Autism Diagnosis

Researchers say autism spectrum disorders are rarely diagnosed before age 3, and diagnosis at 14 months of age, as found in this study, is the earliest ever reported.

In the study, published in the Archives of General Psychiatry, researchers followed 107 children considered at high risk for autism spectrum disorders because they had a brother or sister with autism, and 18 children with no family history of the disorder.

The children's social interaction, communication, and play behaviors were evaluated at ages 14, 18, 24, 30, or 36 months of age. At each assessment, researchers noted any significant signs of delay or impairment that might be a sign of autism.

At the final 30- or 36-month visit, each of the children was given a final diagnosis. Thirty of the children who had siblings with autism were diagnosed with autism spectrum disorder. This group was then divided into two groups: those who had displayed early signs of autism at 14 months and those who developed impairment later.

Researchers found half of the children diagnosed with autism had been diagnosed with autism at the first 14-month visit and the other half were diagnosed later.

Early Signs of Autism

Landa says the results identified the following early signs of autism that parents and pediatricians should be on the lookout for:

— Abnormalities in initiating communication with others: Rather than asking for help with something, the child may struggle alone without looking around for assistance.

— Impaired ability to initiate and respond to opportunities to share experiences with others: Children with autism may not follow their parents gaze or initiate contact with others.

— Irregularities when playing with toys: Instead of using a toy as it is meant to be used, like picking up a toy fork and pretending to eat with it, the child may do something unusual with the toy.

— Significantly reduced variety of sounds, words, and gestures used to communicate: Compared with typically developing children, children with autism have a much smaller inventory of sounds, words, and gestures that they use to communicate with others.

"For a toddler with autism, only a limited set of circumstances — like when they see a favorite toy, or when they are tossed in the air — will lead to fleeting social engagement," says Landa.

There are no standardized criteria for diagnosing autism as early as age 1, but Landa says they hope to develop them soon.

Researchers say parents should discuss any of these developmental problems early on with their pediatrician because early treatment can significantly reduce the impairment caused by autism.

This article was reviewed by Lois Chang, MD