The shifting sands of the ‘autism epidemic’

The Economist has a short but telling article on whether the so-called ‘autism epidemic’, occasionally touted in the media, may simply be a change in how developmental problems are diagnosed.

It covers a new study that did something really simple – it tracked down 38 people who, years ago, had been diagnosed with a delay in language and re-assessed them using the latest diagnostic interviews.

They used the ADOS (an activity and observation schedule) and the ADI (an interview for parents). This combination is often considered the ‘gold standard’ for a reliable and comprehensive diagnosis.

All the people were originally diagnosed with a problem in the development of language, so it was clear they weren’t without difficulties. Language delay is part of the autism diagnosis, so the researchers wondered whether we’d just classify them differently now.

Despite the fact that none were diagnosed with autism spectrum disorders when they were first assessed, when re-assessed using modern methods, a third were classified as on the spectrum.

It’s only a small study, but matches with the findings of previous research that found that while the narrow diagnosis of autism is at less than 0.4% in the UK, the newer, wider definition of the less severe ‘autism spectrum’ diagnoses, unsurprisingly, is much more prevalent (just over 1%).

In other words, the looser the diagnosis becomes the more people get the diagnosis and more good evidence that the increase in cases of autism is due to wider classification rather than new ‘narrow definition’ cases.

Link to Economist article ‘Not more, just different’.
Link to Ben Goldacre on last autism epidemic media scare.


  1. Posted April 14, 2008 at 11:34 pm | Permalink

    I have heard of similar theories. I think it’s certainly interesting to note the fall in other diagnoses such as ‘mental retardation.’ I think it’s a question of ‘define your terms.’
    Best wishes

  2. Posted April 14, 2008 at 11:49 pm | Permalink

    Child psychologists I know are certainly aware of this miraculous ‘cure’ for mental retardation.

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