Tuesday, March 27, 2012

Autism Research Bias and the DSM-5 Autism Do-Over Exclusion of Those with Intellectual Disabilities

Why has the APA decided that the DSM-5 Autism Spectrum Disorder should eliminate or substantially reduce the numbers of persons with ASD who are intellectually disabled?   The removal from an ASD diagnosis of persons with ID will be accomplished by the express wording of Mandatory Criterion A of the DSM-5's New Autism Spectrum Disorder which requires "A. Persistent deficits in social communication and social interaction across contexts, not accounted for by general developmental delays.."  Where the numbers of persons with intellectual disability constitute the vast majority of persons with Autistic Disorder under the DSM-IV they will now be removed from the autism spectrum under the DSM-5 Autism Do-Over which will now define autism largely in terms of the current Asperger's definition of social communication and repetitive behavior deficits.  The DSM-5 Autism Spectrum Diosrder would be more accurately titled Aspergers Spectrum Disorder.  But why the substitution of Asperger's for Autism in the DSM-5 Autism Do-Over?

The answer may be found in the convenience of autism researchers, clinicians and pharmaceutical manufacturers.  It is easier to treat, and even research, high functioning autism and Aspergers than to deal with patients and subjects with classic, severe autism and intellectual disability.  Interviewed for an article in the Financial Times about the DSM-5's new autism spectrum diagnostic criteria Dr Craig Erickson, chief, Christian Sarkine Autism Treatment Center, Indiana University School of Medicine noted the presence of  a high functioning autism bias in autism research:

"The DSM-5 modifications will be great for drug development, as there will be greater standardization in clinical trials, said Dr Craig Erickson, chief, Christian Sarkine Autism Treatment Center, Indiana University School of Medicine. With hardened criteria, there will be better, clearer studies that are easier to interpret, he said. DSM-5 changes will be a positive for research as the improved diagnostic clarity would ensure proper enrollment criteria, Ring agreed.

Erickson noted that there is often a bias in clinical trials, where high-functioning patients are typically enrolled as they are more readily able to tolerate routine procedures such as blood tests part of clinical trials. Further, it is easier to make improvements in less-impaired children, Elliott said, noting the Phase II Kuvan in autism trial included children with IQs in the 50-60 range as well as Asberger patients.

To avoid a bias in developing treatments only for higher-functioning patients, it would be especially advantageous to target specific symptoms rather than a broad lump of ASD so that specific interventions can target symptoms for a particular severity, for example stereotypic motor movements, Elliott said."

I have commented several times about what I perceived as high functioning bias in autism research.  Dr. Erickson confirms my perception as Dr. Catherine Lord has done previously in  Social Policy Report, Autism Spectrum Disorders Diagnosis, Prevalence, and Services for Children and Families:

""However, research in ASD has tended to use overwhelmingly White, middle to upper middle class samples, and has often excluded children with multiple disabilities and/or severe to profound intellectual disabilities". [underlining added - HLD]

The APA has stated in its form letter reply to those who submitted concerns to them about the new Autism Spectrum Disorder criteria that the new definition is based on existing research:

[DSM-5 Autism Spectrum Disorder] proposal is based on years of accumulated clinical, epidemiological, and neuroscience research which was thoroughly examined by the members of the DSM-5 work group on Neurodevelopmental Disorders."

A problem with that explanation  is that the research on which the DSM-5 autism spectrum disorder is based is biased in favor of high functioning autistic and Asperger's subject participation.  The existing research as admitted by Dr. Lord and Dr. Erickson tends to exclude the severely challenged, intellectually disabled population.  The new DSM-5 reflects that research bias by expressly excluding the intellectually disabled from a DSM-5 era Autism Spectrum Disorder diagnosis.

The DSM-5 Autism Do-Over will exclude the intellectually disabled to make life easier for autism researchers, clinicians and pharmaceutical manufacturers.  There is no compelling reason to expressly exclude the intellectually disabled from the ASD except for the convenience of these groups.

There is no legitimate research basis for removing the intellectually disabled from an autism spectrum disorder diagnosis.  There is only bias ... bias against the intellectually disabled. 


Nick Taggart said...

Do you know if people with intellectual disabilities who were previously diagnosed with Autism will lose their autism diagnosis (and associated funding, therapy etc) after the new DSM comes out?
Nick Taggart

Unknown said...

Nick I have read that existing diagnoses will NOT be lost BUT I have no idea how reliable that information is.