The sky is rising! The sky is rising!
Wait, sorry. What now?
The autism rates are rising! The autism rates are rising!
Alright kids, let’s go over this again. Autism rates, really the autism spectrum disorder (ASD) rates, are on the increase. You’ve heard the new 1 in 100 number quoted, right? I’m not saying that’s inaccurate. It’s just that there is no real increase represented. How can that be? Clearly something (or someone) must be to blame for this terrible condition. Who can we hang? Quick, after them!
There were two recent studies concerning the prevalence of autism in the US that have attracted a lot of attention. One study conducted by the CDC (not yet published) reports that the new prevalence of autism spectrum disorder (ASD) is now estimated at 1% or 100 in 10,000 children. This is an increase over the last few years. In 2002 the prevalence was estimated to be 66 per 10,000 (0.66%).
The second study published in the journal Pediatrics was a telephone survey of parents where they asked if they had any children who had ever been diagnosed with an ASD. This non-clinician scored study estimated ASD point-prevalence at 110 per 10,000. These are slightly higher numbers than the CDC data but that is to be expected, since diagnoses from the phone survey were not confirmed by a doctor.
There is no argument that the number of ASD diagnoses has been steadily increasing for the last 20 years. The real question is whether or not the increase is a true increase in the disorder or an artifact of increased surveillance and an expanded diagnosis. Without a doubt, the evidence strongly supports the conclusion that the increasing autism prevalence is due to increased efforts to make the diagnosis and a broadening of the definition of autism. The evidence is not sufficient to conclude that there is not also a real increase in ASD incidence, but nor is there data to support this conclusion.
Recently, more data have come out of the National Health Service (UK) that looked at a very interesting statistic. They looked a the prevalence of ASD in adults. See, if there is a true rise in autism, the adult population should have a lower number of cases than the current children. Guess what? 1% across the board. Kids and grown-ups. Oops. Sorry conspiracy theorists, move it along…nothing to see here.
What can be concluded is that 1% is likely close to the true prevalence of ASD in the population. And, the strong evidence points to the lack of an increase ASD rates. Let’s continue to use good science to get to the bottom of ASD and not sheer panic and anti-vaccination finger pointing.
Dr. Brett L. Kinsler is a chiropractor in Rochester, NY who blogs at www.RochesterChiro.wordpress.com