Thursday, October 25, 2007

Biological Evidence That Low Functioning Autism Is A Different Disorder Than High Functioning Autism and Aspergers

One of the current autism debates on the internet is over the distinction between low functioning and high functioning autism. Mere mention of the differences between lower functioning and higher functioning autism are enough to attract condemnation from some quarters. The indisputable fact that some autistic persons have little or no communication ability, or ability to understand abstract concepts, is denied vigorously by some. Neurodiversity icons like Laurent Mottron and Michelle Dawson, who actively lobby against government provision of ABA services for autistic children in Canada, the Quirks and Quarks duo, also devise studies to "prove" that even low functioning autistic persons actually have hidden, unappreciated, intelligence. Apart from the communication deficits and lack of real world skills of low functioning autistic persons there is now also biological evidence of the very real differences between these autism disorders.

Researchers Christine Wu Nordahl, Donna Dierker, Iman Mostafavi, Cynthia M. Schumann, Susan M. Rivera, David G. Amaral, and David C. Van Essen tested for cortical shape abnormalities using surface-based morphometry across a range of autism spectrum disorders. The results reported in Cortical Folding Abnormalities in Autism Revealed by Surface-Based Morphometry, The Journal of Neuroscience, October 24, 2007, 27(43):11725-11735; ; doi: oi:10.1523/JNEUROSCI.0777-07.2007 are summarized in the online abstract.

Using structural MRI imaging maps were created which showed that a low functioning autism group had a prominent shape abnormality centered on the pars opercularis of the inferior frontal gyrus that was associated with a sulcal depth difference in the anterior insula and frontal operculum. The high-functioning autism group had bilateral shape abnormalities similar to the low-functioning group, but smaller in size and centered more posteriorly, in and near the parietal operculum and ventral postcentral gyrus. Individuals with Asperger's syndrome had bilateral abnormalities in the intraparietal sulcus that correlated with age, intelligence quotient, and Autism Diagnostic.

Evidence of biological differences between low functioning and high functioning autism could have many implications and raise many questions. One important question such differences, and the drastic differences in communication and intellectual levels raise is whether very high functioning autistic persons, persons capable of making submissions to legal and political bodies, attending conferences and chatting with CNN interviewers have any legitimate basis on which to speak on behalf of lower functioning autistic persons who can not speak for themselves.

These high functioning autistic persons do not share the same life realities and ... they do not share the same disorder as low functioning autistic persons. Unless they are a parent, a caregiver or legal representative of autistic persons it is not clear that they have any inherent right to speak on behalf of lower functioning autistic persons. And certainly not to lobby against provision of services for those less fortunate individuals.


Raphael Alexander said...

And interesting comment. I was diagnosed with Aspergers as an adult, and while I do not perceive any functional difficulties on the internet, I am more socially inept in person. I wouldn't feel qualified to speak to the thoughts of low-functioning autistic people, as my difficulties faced are dwarfed by their experiences. I may have had various problems with work and education and friendships, but my social problems can hardly be compared when my cognitive abilities have allowed me to enjoy a good life. Perhaps Aspergers syndrome is erroneously diagnosed to people with low-functioning social skills, but having studied quite a bit about Aspergers I won't write it off as an illegitimate form of autism.

I've known parents who have autistic children who seem more concerned with the social cohesion of their children than their cognitive functioning, and this differentiates greatly from the problems faced by low-functioning autistic children who "live in their own world". I feel grateful that, whatever my problems, I live in this world and have a fully functioning concept of what it is and what it means to me. That I have socially inept problems is a disability I am willing to live with.

Unknown said...

Thank you for your comment. I don't call Asperger's an illegitimate form of autism though. Just that Asperger's and High Functioning Autism are different disorders in terms of deficits and .. now there is evidence of biological differences.

Anonymous said...

Who are these autistic adults you refer to who have claimed to speak for all autistics? I'd like to see some supporting quotes.

BTW, it's not at all surprising that underlying biological differences are found to exist across two different constructs.

Anonymous said...

BTW, Harold, since you accept the results of this study, doesn't this contradict your view that Jenny McCarthy's ideas on biomed may yet be proven correct. How would an antifungal go about altering these brain differences?