The Centers for Disease Control (CDC) has published the results of their latest study on the prevalence of autism. There is no question that in the last 20 years the number of autism spectrum disorder (ASD) diagnoses has increased. What is also clear is that during this time there has been increased surveillance and a broadening of the diagnosis of ASD. Whether or not this accounts for the entire increase in ASD numbers, or if there is a true increase in there as well, is unknown.
Into that context, the CDC adds their most recent numbers, concluding:
In 2006, on average, approximately 1% or one child in every 110 in the 11 ADDM sites was classified as having an ASD (approximate range: 1:80–1:240 children [males: 1:70; females: 1:315]). The average prevalence of ASDs identified among children aged 8 years increased 57% in 10 sites from the 2002 to the 2006 ADDM surveillance year. Although improved ascertainment accounts for some of the prevalence increases documented in the ADDM sites, a true increase in the risk for children to develop ASD symptoms cannot be ruled out. On average, although delays in identification persisted, ASDs were being diagnosed by community professionals at earlier ages in 2006 than in 2002.
That 1 in every 110 children on average now carry an ASD diagnosis is not new news. This CDC data was actually released ahead of publication in October. At the same time a phone survey published in Pediatrics found 110 in 10,000 children carried an ASD diagnosis – or a little more than 1%. This 1% figure seems to be highly replicated – a National Health Services survey released in September also found a prevalence of 1% for ASD in the UK.