"It could be tougher to qualify, because before you could have a greater range of kinds of symptoms that you were displaying, now you have to show a more consistent symptom profile to qualify," said Dr. James McPartland, from the Yale University Child Study Center.
Dr. McPartland spoke to Eyewitness News via Skype.
He is the co-author of a new study, which was just presented.
It says the new definition of autism would dramatically reduce the number of children who are diagnosed.
Proposed changes to the definition would eliminate the diagnosis of Asperger's Syndrome and what's known as Pervasive Developmental Disorder, not otherwise specified.
They would be combined with autism into one diagnosis, Autism Spectrum Disorder.
"When we looked at individuals with cognitive abilities in the average range, it looks like half of them will continue to meet and half wouldn't meet criteria," Dr. McPartland said.
But not all experts agree the impact would be that big.
It's a crucial issue for parents of children with autism because you need an official diagnosis to receive state-funded services and behavioral therapy.
Child behavioral expert Dr. Andrew Adesman, who was not involved in the study or in developing the new criteria, says the new guidelines would simplify the definition, but that the true impact remains to be seen.
"I think it's premature for parents to worry about the impact in terms of services," Dr. Adesman said. "Those children will likely still qualify if they have some other form of communication disorder."
This is not a done deal yet.
The new definition of Autism Spectrum Disorder is reportedly still under review by the American Psychiatric Association.
The final definition will not be out until 2013.
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