In a five-year study of more than 13,500 children, researchers at Australia's La Trobe University in Melbourne tested an early screening tool they had developed for autism.
They found that 83% of children aged between 12 and 24 months, who were "flagged by the tool," were later diagnosed with autism.
That is about four years earlier than current standard tests, the researchers said. And the earlier the diagnosis, they said, the better the life outcomes can be for people with autism.
"Children diagnosed early demonstrated better verbal and overall cognition at school age, were more likely to attend mainstream school and required less ongoing support than children diagnosed later," wrote lead researcher Josephine Barbaro in an email to DW.
Autism is not considered an illness or medical condition that can or needs to be cured — it's part of a person and stays with them their whole life. But people with autism can find it hard to communicate and interact with people or respond to sensory triggers like bright lights or loud noises without becoming overwhelmed.
Diagnosis tool translated into eight languages
Current tests, such as M-CHAT (the Modified Checklist for Autism in Toddlers), tend to diagnose autism between the ages of 4 and 6 years.
The new tool, known as SACS (Social Attention and Communication Surveillance), has two elements: SACS-Revised and SACS-Preschool.
When M-CHAT was used with the new tool on preschool-aged kids, 96% of children on the autism spectrum were identified by their 3.5 year health check.
Barbaro wrote that a meta-analysis of 13 studies found that M-CHAT had "a pooled positive predictive value (or accuracy) of 6%" when used in so-called 'low risk' community settings — lower than SACS-R's 83% accuracy.
The SACS tool has been translated into eight languages and used in 11 countries: Bangladesh, China, Italy, Japan, Nepal, New Zealand, Poland, Singapore, South Korea, Spain and the United Kingdom.
Diagnosis is difficult
Barbaro, who is based La Trobe's Olga Tennison Autism Research Center, wants to see the tool used even more widely.
"Putting this extremely effective tool in the hands of a trained primary health professional, so that during their routine health checks they are also screening for autism, makes a huge difference to early diagnosis," said Barbaro.
Another Australian study has shown that therapy to support social development with babies displaying early signs of autism can help significantly.
Later in life, diagnosing autism can be "difficult," writes the US Centers for Disease Control and Prevention, "because there is no medical test, like a blood test." Doctors look at a child's developmental history and their behavior to make a diagnosis.
The new study is published by the JAMA Open Network.