Why are rates of autism rising?

A survey carried out in the U.S. has reported an increase in rates of children with autism spectrum disorder (ASD) from 1 in 80 births in 2011-2013 (1.25%) to 1 in 45 (2.24%) in 2014.  While many of the headlines referred to ‘autism doubling’ most of the reporting quickly pointed out that the increase does not reflect an epidemic but a change in the way autism symptoms are assessed.

What did the survey involve?

The survey was carried out by the U.S. Centers for Disease Control and Prevention’s (CDC) National Center for Health Statistics. The increase relates to the fact that autism spectrum disorder is now regarded as reflecting a broader set of symptoms than earlier diagnoses, as well as changes in the format and content of the survey itself.

How did the media handle reporting of this survey?  

Apart from a few sensationalist headlines, the media on the whole handled coverage of the findings of this survey extremely well. Most sought the opinion of an independent expert and indeed in some cases specifically pointed out that the expert was indpendent of the CDC survey. The most concerning aspect of the media coverage was the headlines which frequently referred to the rates doubling – hopefully readers went beyond the headlines to realise this meant a change of 1%, or one extra person per 100 people.  One headline was highly accurate though running with ‘higher autism rate is due to changes in reporting, not kids’. The opening sentence of the full article also shows accurate non-sensationalist reporting: ‘Looking at the numbers, you’d think the number of children with autism might have doubled — but the things that changed were a US government survey and a diagnostic manual’. This media reporting by the Verve was very informative. It went on to tell readers that ‘psychiatry’s bible’, the Diagnostic and Statistical Manual (DSM), was recently updated to move a diagnosis of ‘Asperger’s syndrome’ and ‘pervasive developmental disorder not otherwise specified’ into the diagnosis of autism spectrum disorder.

Careful media handling of this topic is extremely important because of the historical link made between rising autism rates and vaccinations. This link recently reared its head in the media. Donald Trump referred to an ‘autism epidemic’ in a Presidential debate based on personal ‘evidence’ of 1 child with autism he knew that started showing the symptoms around the same time as having an adverse reaction to a vaccination. Fortunately the reporting of the recent CDC survey addresses the reason for the increase, rather than leaving readers open to develop spurious links between the increase and other potential causal factors.

Bottomline

Changes in the reporting rates of autism do not reflect an epidemic, but instead a change in the way autism is assessed. The ‘doubling’ of autism rates reflects a very small increase of 1% or 1 person per 100.