Friday’s long-awaited release of the CDC’s autism prevalence report revealed a long-ignored, disturbing trend: our news and entertainment media still don’t get it.
”Autism affects about 1 in every 110 American children, a 57 percent increase over the last estimate in 2002,” said the Philadelphia Inquirer.
“The new data represent a 50% increase from two years ago, when the agency estimated the prevalence of the disorder at about 1 in 150 children,” says Thomas H. Maugh II at the LA Times blog.
”Autism rates have soared among Maricopa County children in the past five years, increasing 95 percent from 2002 to 2006, according to federal data released Friday,” says the Arizona Republic.
But there is nothing new and shocking about the fact that 1% of children have an autism spectrum disorder. In 1998, UK researchers Lorna Wing and David Potter wrote:
”Because we concentrated on the children with learning disabilities (IQ under 70) we saw very few with the pattern described by Asperger. We had to wait for the study by Christopher Gillberg in Gothenberg to find out how many children with IQ of 70 and above were also in the autistic spectrum. …combining the results of these two studies gave an overall prevalence rate for the whole autistic spectrum, including those with the most subtle manifestations, of 91 per 10,000 – nearly 1% of the general population.”
Got that? It’s been more than 10 years since two leading epidemiologists told the academic world that 1% children show symptoms of autism. So why is this news?
Part of the blame lies with the CDC’s press office, which told reporters in a Friday conference call that autism is an “urgent public health concern.” That’s like waving a doughnut in front of Homer Simpson. Anything that comes after is background noise to journalists angling for a narrative hook. Throw in the fact that most news outlets can’t afford real science writers, and you get reports like this:
”The rate of increase of autism disorders in children is 4 to 5 percent higher in boys than it is in girls.” *
That same Fox News report quoted a vaccine rejectionist at length, who shared his unique version of autism epidemiology:
(Mark) Blaxill said the CDC and National Institutes of Health need to develop a plan of action and work harder to find out why autism spectrum disorders are increasing at such a rapid rate.
”Autism was first identified in the 1940s,” said Blaxill, who has a 14-year-old daughter with autism. “Back then, 1 in 10,000 children were believed to have it and now 1 percent of our children have autism. And it’s not only improvements in the way we diagnose autism. … We’re outraged and we want more research.”
“We’re not anti-vaccination,” Blaxill said. “I support vaccines. … But we see what’s happened with the concern over Methicillin resistant Staphylococcus aureus and the overuse of antibiotics. One thing that’s changed dramatically over the years is the number of vaccinations we’re pumping into our kids. What we’re saying is, let’s investigate our vaccine program. Let’s evaluate safety.”
A real science writer would have caught Blaxill’s spin. First, there are no studies from the 1940s showing a 1:10,000 rate for autism. Second, comparing over-use of antibiotics to vaccines reveals a weak grasp of the science from a from the man who founded a group called SAFEMINDS, but we do appreciate the irony.
In fairness, counting and reporting cases of autism is tricky business, and the story does not easily lend itself to 300 words and a quotebar. There are three main difficulties with counting autism, according to researchers Wing and Potter, the prescient UK epidemiologists:
There is no medical test that can determine whether or not a person has autism. Diagnostic criteria are in terms of descriptions of behaviour. The earliest criteria, suggested by Leo Kanner, were very narrow. The current standard classification systems (ICD-10 and DSM-IV) are much wider, even for the sub-group of ‘childhood autism’ (or ‘autistic disorder’ in DSM-IV). Professionals differ in the way they apply the criteria, even if they are, theoretically, using one of the standard systems. Diagnoses may be recorded in different ways in case notes and centralised data collections.
Diagnostic terms tend to be used in different ways. Sometimes the term ‘autism’ is used to mean Kanner’s original group, sometimes it refers to the wider group called ‘childhood autism’ in ICD 10 and sometimes the whole autistic spectrum, including the individuals described by Asperger. In any case, there is a very great deal of overlap among all the sub-groups named in ICD-10 and DSM-IV and many individuals fit more than one diagnosis within the spectrum.
In epidemiological studies of prevalence, case finding methods vary. Those that involve seeing, assessing and diagnosing every individual in the sample to be examined will tend to find higher numbers than studies that rely on using case notes of individuals who have already been given the diagnosis in local clinics.
In short, any method that relies on medical and administrative records is bound to under-count, unless awareness is extremely good. As awareness improves, the under-reporting diminishes. The biennial CDC count relies on doctors and schools to identify children with autism. As awareness of the disorder grows, and more services become available, more children receive diagnoses, and the rate climbs.
Sullivan at LeftBrainRightBrain reports that a significant number of children categorized as autistic in the study hadn’t been given that diagnosis prior to the study.
”That’s worth repeating—about 23% of 8 year olds identified as autistic were mislabeled as non-autistic by their schools, parents and doctors,” says Sullivan. “That’s an interesting fact for those who claim that autism is easily identified.”
This is not a gloom and doom story, and without firm data that the autism rate is truly rising, there is little cause for alarm. Increased diagnoses means children who were previously ignored are being screened, diagnosed, and, one would hope, accommodated.
* Fox News speak. In reality, the rate of autism is 4.5 times higher in boys than in girls.