The number of children diagnosed with autism will likely decline in the coming years, according to researchers who have reassessed population data and found a slight drop in prevalence based on new diagnostic criteria.
Definitions of autism changed last May in a key volume published by the American Psychiatric Association.
Often called the bible of psychiatry, the "Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition," is best known by its abbreviated title, the DSM-5. Before its appearance, fiery debates had arisen over the loss of certain subcategories of autism.
Now, researchers at the National Center on Birth Defects and Developmental Disabilities have taken a new mathematical look at populations of children previously diagnosed with autism and found a slight but notable percentage would not be so diagnosed under the revised criteria.
Researchers looked at 2006 through 2008 data involving 6,577 autistic children in 14 states diagnosed using the earlier criteria. They found that when applying the new guidelines, 81 percent of the children, or 5,339, would be diagnosed as autistic.
Put another way, said Dr. Matthew Maenner of the center, a division of the Centers for Disease Control and Prevention, 11.5 children per 1,000, ages 8 to 14, were diagnosed with an autism spectrum disorder under the old criteria, compared with 10 per 1,000 using new measures.
Maenner's mathematical reassessment is published in the current edition of the journal JAMA Psychiatry.
According to Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at Cohen Children's Medical Center in New Hyde Park, N.Y., most children who deserve an autism diagnosis will still receive one.
"I don't think the DSM-5 (committee) went into the revision with the idea of reducing the number of children with autism," said Adesman, who was not involved in the new diagnostic analysis.
"The DSM-5 is a step forward in that it eliminates some of the subcategories that were previously difficult to delineate and distinguish."
The committee of experts who wrote the DSM-5's guidelines eliminated such subcategories as Asperger's syndrome and the condition known as PDD-NOS - pervasive developmental disorder, not otherwise specified. The edition updated information from 1994's DSM-4.
During the 19 years between the two guidebooks, autism's incidence soared, based largely on broad diagnostic categories. Social, speech, educational and behavioral services for these children also expanded.
Before the DSM-5's publication, dozens of children's advocates had lambasted changing the criteria because it took decades to gain recognition of certain subcategories.
Asperger's, for instance, was first described in 1944 by Austrian physician Hans Asperger, who defined it as a condition with multiple symptoms, including awkward social skills.
Many people with Asperger's do not make friends easily and have eccentric or arcane interests, such as collecting and memorizing decades of sports statistics. They also have a poor sense of intuition and spontaneity, but the DSM-5 committee did not view the syndrome as part of the autism spectrum.
Deb Thivierge, founder of the Elija School in Levittown, N.Y., said she wonders whether children are being well-served under DSM-5 guidelines.
"I was just at a presentation by Catherine Lord," Thivierge said of the director of the Institute for Brain Development at NewYork-Presbyterian Hospital in Manhattan and member of the DSM-5 committee. "Her review of the new ... criteria seemed to make sense. Most of it had to do with the gray area between Asperger syndrome, autism and PDD, and that clinicians were not consistent in their diagnoses.
"From my perspective, as a professional and as a parent, it will definitely mean that those children and adults who are more mildly symptomatic might not get a diagnosis, which means they will not receive appropriate services," Thivierge said.