For this new report, the CDC collected data at 11 regional monitoring sites that are part of the Autism and Developmental Disabilities Monitoring Network in the following states: Arizona, Arkansas, Colorado, Georgia, Maryland, Minnesota, Missouri, New Jersey, North Carolina, Tennessee, and Wisconsin. However, the data can't tell us exactly why the autism prevalence increased. "As in past years, there are still more white children being identified with autism by our surveillance network compared with black or Hispanic children, but the prevalence of autism in black and Hispanic children is approaching that of white children", Dr. Christensen says. "Those substantial changes in prevalence between white, black, and Hispanic children could account for the different numbers", Christensen says.
Similarly, in the 2012 data, white children were 50 percent more likely to be identified by the surveillance network than Hispanic children. She says services for children and their parents are not increasing at the same rate as diagnoses.
Christensen says, "Over the '80s and '90s, the diagnostic criteria expanded to include more children, so I think that's definitely a possibility for the increase that we've seen".
Even if ASD prevalence is up, the study authors caution that the results of the survey shouldn't be taken to represent the United States as a whole.
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Tressa Dykstra is a nurse practitioner at Sanford Children's Hospital.
According to the data, the difference in ASD prevalence between white children and black children is now only 7 percent. "There can be a lot of variation from state to state. But that's not the case in every state". Despite advances, many children are probably receiving diagnoses later than they should. Early diagnosis and intervention are key to improving learning and skills. The CDC recommends that parents track their child's development and act quickly to get their child screened if they have a concern, and has made available online a free checklist and information resource for parents, physicians, and child care providers.
Some trends in the latest CDC report remain similar, such as the greater likelihood of boys being diagnosed with ASD, the age of earliest comprehensive evaluation, and presence of a previous ASD diagnosis or classification. "The sooner we make the diagnosis, the sooner we start treatment, and the better the outcome".
"We're getting better at identifying under-unidentified populations, so it's not as if the numbers are rising".