Quantitative autistic traits ascertained in a national survey of 22 529 Japanese schoolchildren
Article first published online: 22 NOV 2012
© 2012 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd
Acta Psychiatrica Scandinavica
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Quantitative autistic traits ascertained in a national survey of 22 529 Japanese schoolchildren., , , , , , , , , , .
- Article first published online: 22 NOV 2012
- Manuscript Accepted: 1 OCT 2012
- the Ministry of Health, Labour and Welfare of Japan. Grant Number: H19-KOKORO-006 and H20-KOKORO-004
- National Institute of Child Health and Human Development. Grant Number: HD42541
Recent epidemiologic studies worldwide have documented a rise in prevalence rates for autism spectrum disorders (ASD). Broadening of diagnostic criteria for ASD may be a major contributor to the rise in prevalence, particularly if superimposed on an underlying continuous distribution of autistic traits. This study sought to determine the nature of the population distribution of autistic traits using a quantitative trait measure in a large national population sample of children.
The Japanese version of the Social Responsiveness Scale (SRS) was completed by parents on a nationally representative sample of 22 529 children, age 6–15.
Social Responsiveness Scale scores exhibited a skewed normal distribution in the Japanese population with a single-factor structure and no significant relation to IQ within the normal intellectual range. There was no evidence of a natural ‘cutoff’ that would differentiate populations of categorically affected children from unaffected children.
This study provides evidence of the continuous nature of autistic symptoms measured by the SRS, a validated quantitative trait measure. The findings reveal how paradigms for diagnosis that rest on arbitrarily imposed categorical cutoffs can result in substantial variation in prevalence estimation, especially when measurements used for case assignment are not standardized for a given population.