By now we're not suprised to learn autism is diagnosed in more children than in past decades (for no doubt a host of reasons - expanded criteria, earlier diagnoses, greater awareness, etc.). Lately we've been reading autism appears in 1 in 100 to150 kids. But a new study provides the highest prevelance rate yet:
1 in 91 children (aged 3 to 17) or 1.1%
That's considerably higher than what's been reported in the past few years. The new estimate comes from a fresh study published online at the journal Pediatrics from a team of researchers who examined data from the 2007 National Survey of Children’s Health.
Let's take a closer look. The 2007 NSCH study collected data from telephone interviews with parents/guardian in more than 78,000 households. So parents provided all the data here, including answering questions about whether children had autism.
A child was considered to have ASD (a disorder on the Autistic Spectrum) if a parent/guardian reported that a doctor or other health care provider had ever said that the child had ASD and that the child currently had the condition.So the investigators only had the parent's report and not the verified professional documentation of an ASD diagnosis. Just something to keep in mind. It's hard to imagine parents would overestimate (say kids had ASD when they didn't) in this case, but it's possible some might have misunderstood the language.
Parents were asked if they had ever been told by a doctor or other health care provider that their child had “autism, Asperger disorder, pervasive developmental disorder, or other autism spectrum disorder.”It may be that some might have misinterpreted "developmental delay" as a learning disability or some other non-autistic delay. But I'd imagine any of these errors would be balanced out by the people who didn't answer yes when there were ASD diagnoses. As Dr. Susan L. Hyman, a Rochester pediatrician, pointed out in the New York Times, it's a good study but “the next step scientifically is to see whether those diagnoses are being made accurately.”
Among the more interesting finding:
Of the 1,412 respondents who reported a health professional had called their child autistic (i.e. any of the autistic labels), 453 reported their child currently did NOT have autism!
So nearly 40% of the children previously identified as autistic no longer were according to parents. Pretty curious. Of course the researchers had to try to account for this odd finding. Their explanations? One involves difficulties in the relatively new early screening procedures, sometimes used for children as young as two years old. So there could be some quirk in the early identification methods. Some cases could be picked up in the early screening and really never autistic in the first place. Other conditions, like learning disabilities, mental retardation, other developmental delays also could look like autism early on and get misdiagnosed. Their final reason - parents might say "no" because they don't think their child has autism any longer because he or she isn't getting any more treatment or special services any longer.
All good and reasonable explanations. I can think of one more possibility - and that hinges on the early diagnoses - we sometimes place kids on the spectrum who show behaviors, delays, deficits, and the like that we can treat and correct if they're caught early on. They may never land kids on the spectrum. So once treated, these now more mild traits don't fall under the ASD so kids no longer get classified.
Which brings up the issue of curing autism. Regardless of what Jenny McCarthy says, many experts don't believe autism is "curable". I'd agree, the more moderate and severe forms are not. But we have this more greyish area of mild autism, especially the Pervasive Developmental Disorder, that applied to younger kids, may be applied for kids who seem to "get better".
And personally, I find this murky areas one of the more compelling facets of autism (and really, the mental health field, in general).
You can read the abstract for free at Pediatrics.
Kogan, Blumberg, Schieve, Boyle, Perrin, Ghandour, Singh, Strickland, Trevathan, van Dyck. (2009). Prevalence of Parent-Reported Diagnosis of Autism Spectrum Disorder Among Children in the US, 2007. Pediatrics, online October 5, 2009.