As always – there is no autism epidemic.
For the 2011-2013 survey, parents answered a series of three questions. The first asked if their child had intellectual disability. The second asked if their child had any developmental delay. And the third question listed several conditions, from Down syndrome to sickle cell anemia to autism spectrum disorder (ASD), and parents were asked if their child had been diagnosed with any of them.
But 2014 brought some tweaks, and those tweaks made a difference. The intellectual disability question came first again. But the second question directly asked parents if their child had an ASD diagnosis. The third question then asked about any other developmental delay. More than 10,000 parents are interviewed in each year of this survey.
The simple change to emphasize the autism question resulted in the near doubling of prevalence from 2011–2013 to 2014. Underscoring that this increase reflects a shift in how parents responded to the questions, the prevalence of ‘other developmental disorders’ dropped in that same time period from 4.84% in 2011-2013 to 3.57% in 2014. Intellectual disability prevalence remained pretty much the same in the two periods, and the collective prevalence for all three conditions (intellectual disability, ASD, and other developmental disorders) also remained stable.
What a difference a question can make. But that might not have been the sole influence on the results.
1) Autism and neurodiversity are natural parts of the human condition.
2) The high rate has to do with changing diagnostic questions.
3) Always read Emily Willingham.