Autism Spectrum Disorders in the Stockholm Youth Cohort: Design, Prevalence and Validity

28 Aug

A recent study from Sweden presents another autism prevalence estimate. Autism Spectrum Disorders in the Stockholm Youth Cohort: Design, Prevalence and Validity is available online free. My analysis is on the Autism Science Foundation blog as Autism Spectrum Disorders in the Stockholm Youth Cohort: Design, Prevalence and Validity

I will point out that the methodology differs from the American prevalence estimates from the CDC. In particular, where the CDC looks at children of a given age (8 years old) in a given year, the Stockholm Youth Cohort study considers a cross section of autistics, ages 4 to 23. The prevalence, especially for autistic disorder, is relatively flat for autistics born in the 1990s, a time when there was supposedly an increase of 100’s of percent in autism prevalence. In other words, the study doesn’t support the idea of an epidemic.


By Matt Carey

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One Response to “Autism Spectrum Disorders in the Stockholm Youth Cohort: Design, Prevalence and Validity”

  1. futuredave5 August 28, 2012 at 02:41 #

    This seems like a good approach, and a question that is worth asking. I have often wondered how much of the increase in diagnosis was due to changing awareness and changing definitions.

    The largest part of the increase seems to be from about 25 years ago to about 15 years ago, rising from about 10 per 1000 to about 15 per 1000. Although this is a big increase, it is hardly the explosion that we hear about.

    Considering the study date was 2007, and the median age at diagnosis was 8, I am not sure the data can shed much light on any trends in the last eight years. I suppose if there were a significant increase in diagnosis, it would appear on the chart, but it seems to me that to know for sure, we would have to know what the chart looked like ten (or so) years previously. It may have looked the exact same, or the “bump” may have been shifted.

    It could just be that their health care system (and media expectations) are very different, but I had always heard that the median age at diagnosis in the U.S. was about 6. The lower median in the U.S. could be that the parents are paying closer attention, or it could be that signs are showing up earlier.

    Even that seems fairly late to me. Do people seriously not realize that anything is wrong until the first day of school? If so, then maybe the DSM-V is right.

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