Biological Evidence That Low Functioning Autism Is A Different Disorder Than High Functioning Autism and Aspergers
Posted Sep 11 2008 8:04pm
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 hada prominent shape abnormalitycentered on the pars opercularis of the inferior frontal gyrusthat was associated with a sulcal depth difference in the anteriorinsula and frontal operculum. The high-functioning autism grouphad bilateral shape abnormalities similar to the low-functioninggroup, but smaller in size and centered more posteriorly, inand near the parietal operculum and ventral postcentral gyrus.Individuals with Asperger's syndrome had bilateral abnormalitiesin the intraparietal sulcus that correlated with age, intelligencequotient, 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.