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Of No Import: Autism Bran Scan Study Excluded Subjects With Intellectual Disability

Posted Aug 12 2010 4:08am
My Lords, view these letters full of bad mischance.
France is revolted from the English quite, 
Except some petty towns of no import

- The Second Messenger, The Fifth Part of King Henry VI, Act I, Scene I, William Shakespeare

The new MRI Bran Scan study   promises to be a major event with important consequences for diagnosis of autism disorders and  establishment of autism biomarkers. The results could affect our understanding of the nature of autism disorders, what causes them and ... who is, or is not, autistic.  Unfortunately the study, like so many other autism studies and discussions of autism disorders,  excluded those with intellectual disabilities.

It is common in public discussions of autism as reflected in Hollywood movies and major media institutions like CNN, CBC and the New Yorker, government institutions like the IACC, and autism advocacy groups like Autism Speaks and ASAN to talk about "autism" from the perspective of very high functioning persons with autism or Aspergers like Temple Grandin, Alex Plank, Ari Ne'eman, Jon Elder Robison, Amanda Baggs and Michelle Dawson.  Virtually no effort is made to discuss the realities of those very substantial number of persons with autism who are intellectually disabled,  those who constitute the "vast majority", as much as 75-80% of persons with Autistic Disorder.

Even in the  DSM-IV era with its broadly expanded definition of autism which includes all those with Aspergers who, by diagnostic definition, are not intellectually disabled, the total numbers of persons with intellectual disabilities  constitutes between 41-44% of all persons with Autism Spectrum Disorders of any type ... according to two recent CDC surveys. Yet many research projects purporting to study "autism" exclude from their subject pool persons with autism disorders and intellectual disabilities. The autism brain scan study by Ecker et al published in the August 11, 2010 edition of  the Journal of Neuroscience is no exception to this trend. It expressly excludes those persons with autistic disorder who are intellectually disabled
"Participants. Twenty control adults were recruited locally by advertisement and 20 adults with ASD were recruited through a clinical research program at the Maudsley Hospital/Institute of Psychiatry (London). All volunteers (see Table 1) gave informed consent (as approved by the Institute of Psychiatry and Bethlem and Maudsley Hospital Trust research ethics committee), and had a full-scale intelligence quotient (FSIQ)>75 [WASI (Wechsler, 1999)]."
There may have been ethical and practical limitations which precluded the participation of  autistic subjects with intellectual disabilities. But it does not seem reasonable to this humble father of a 14 year old son with Autistic Disorder and intellectual disabilities to expressly exclude from a study of the brains of persons with "autism" such a large group of autistic persons distinguished in such an important way from those who are the subject participants in the study.  Notwithstanding the express exclusion of autistic participants with intellectual disabilities the study authors draw conclusions about persons with "Autism Spectrum Disorder":

"Discussion

Autism affects multiple aspects of the cerebral anatomy, which makes its neuroanatomical
correlates inherently difficult to describe. Here, we used a multiparameter classification approach to characterize the complex and subtle gray matter differences in adults with ASD.  SVM achieved good
separation between groups, and revealed spatially distributed and largely nonoverlapping patterns of regions with highest classification weights for each of five morphological features. Our results confirm that the neuroanatomy of ASD is truly multidimensional affecting multiple neural systems. The discriminating patterns detected using SVM may help further exploration of the genetic and neuropathological underpinnings of ASD."

It appears that Ecker et al, when drawing conclusions about the brains of persons with "Autism Spectrum Disorder" do not feel that the participation of subjects with "ASD" who are intellectually disabled is necessary, despite the large percentage of the Autism Spectrum that they comprise. It seems that when it comes to persons with autism disorders who are intellectually disabled Ecker et al are of the view that the fact of being autistic and intellectually disabled is of no import, that it is sufficient to categorize the various subtypes of autism spectrum disorder without actually looking at such a large and severely affected component of that spectrum.

Is the Ecker study a precursor of the New Autism Spectrum Disorder in the DSM5? Will those with Autism Spectrum Disorder and intellectual disabilities simply be excluded from autism diagnosis? It is obviously too early to draw such a conclusion but this study with its cavalier exclusion of intellectually disabled autistic subjects from an attempt to establish biomarkers for "autism" raises that possibility. Intellectually disabled autistic adults are largely hidden from society physically in institutions and from public awareness. as reflected in Hollywood and mainstream media portrayals of autism. They are now excluded from some important autism research. In the DSM5 exclusion from the "autism spectrum" itself may be the final result.
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