Tuesday, January 05, 2010

Do Study Results Involving High Functioning Autism Subjects Automatically Apply to Persons with Autistic Disorder and Intellectual Disabilities?

Can the results of studies involving subjects with High Functioning Autism automatically be applied to persons with Low Functioning Autism, to the 75-80%  of persons with Autistic Disorder who are cognitively impaired?

In Brain Serotonin and Dopamine Transporter Bindings in Adults With High-Functioning Autism the authors are careful in the title to make it clear that their study subjects were persons with High Functioning Autism.   The  authors also specify that the subjects all have IQ's equal to or greater than 99 and are not representative of a typical sample of adults in the community. Yet the conclusion stated in the abstract is described as pertaining to all persons with "autism":

"Conclusions  The brains of autistic individuals have abnormalities in both serotonin transporter and dopamine transporter binding. The present findings indicate that the gross abnormalities in these neurotransmitter systems may underpin the neurophysiologic mechanism of autism."

If it is important to identify the subjects of a study as having High Functioning Autism, as having average or greater IQ's,  is it valid to generalize those results to other persons with Autism Disorder and intellectual disabilities?

Does it not seem reasonable that there might be different abnormalities involved in the neurological systems that result in some having High Functioning Autism as opposed to those with Autisic Disorder and cognitive impairment?

And why are more studies not done involving subjects with Low Functioning Autism?

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farmwifetwo said...

(written in a completely sarcastic tone of voice)

The reason they aren't going to do testing on Low Function autistics is b/c they have to deal with behaviour, they have to do with non-verbal issues, and why should they bother... they're just going to end up in an institution anyways.

Besides... isn't it better to do "feel good" testing and maybe find the next "Rainman".

To truthfully answer your question. They have finally come to the conclusion that health/meds testing on men does not give the same results as it does on women. I think that would more than be the same when it comes to different autisms since there is still no genetic link between any of them. Toss in the male/female thing...

What scientists today forget (and the ND crowd) is that science is hypothesis... not engraved in stone... Tomorrow they may find something else, new testing methods, new equipment, better follow-up.... Which is why I find it ironic that we have a 100yr history of poor vaccines, yet the current crop are not followed up on. YET every day on the news there is another drug, and another side effect... why not vaccines??

jonathan said...

I don't know as much about the study you are citing in this post, but in a well-done study, the authors in a discussion section will cite the limitations of the study, stating that the autistics were higher functioning than usual had average or close to average IQ's and admit they are not necessarily applicable to lower functioning autistics. Lindsay Oberman did this in her studies on Mu wave suppression in some high functioning autistics.

Laurent Mottron and those who work with him and then give disingenuous spin to the media, fail to acknowledge the limitations in their studies.

As I have told you before, the reasons that higher functioning autistics are used as research subjects in most studies, is that they involve compliance issues, such as the ability to sit still in an MRI scanner so as not to confound the results, or cooperate and learn a neurofeedback task such as mu supression, etc. Low functioning autistics are not able to do these things, so they make for more difficult research subjects. It is true, this does limit the findings in multitudes of autism studies and the findings may not be generalizable to those at the lower end.

You only quoted part of the study. Did they or didn't they acknowledge limitations of their study in the discussion section?

Unknown said...

Jonathan you are asking a question I already answered. In my comment I expressly stated that they had 3 times made it clear that they were working only with HFA including in the title and that they had specified the actual IQ's as 99 or above which I quoted.

I understand the difficulties of working with a severely autistic child. My son is severely autistic. We have to learn ways to do necessary things with him in life like dental work, haircuts fractured arm repair etc.

The point of my comment was to ask whether it is valid to generalize the results of studies with HFA subjects to those with AD & ID.

Difficult or not I think it is important for ways to be found to work with lower functioning autistic subjects. Maybe researchers on such projects could even consult with .... parents ... for ways to have their children participate.

Kent Adams said...


I don't think they translate because I think more areas of the brain are affected in lower functioning autism. For instance language. Language, or the pragmatic use of language, is not affected in higher functioning autism. Therefore, it stands to reason that there is a different area of the brain that is affected in autistics that have limited speech. Self stimulatory behavior is far more pronounced in LFA than it is in HFA so it also stands to reason that vision could also be affected differently in LFA.

I do think that some parts of visual memory could be translated from HFA to LFA. I think some studies dealing with anxiety could also be translated from HFA to LFA.

I don't think there is much parents can do to help doctors with studies dealing with a child that needs to sit still. What they need to do is change the requirements of the computer software that analyze the data to take into account a person that is asleep (anesthesia). This is unlikely to happen anytime soon because there is limited marketability to alter the software.

My son could never sit still for an MRI, it wouldn't matter how much I bribed him to do it.

Lisa Jo Rudy said...

I suspect that when we finally do parse out "autisms" we will find that functional level and verbal ability are not the only ways to break down groups.

It may be, for example, that one of several autisms will turn out to be "people with GI issues, self-stimulatory behavior and sensory issues, with any level of IQ or verbal ability."

Just my two cents on this issue.


AutisticWisdom said...


I think I understand your point. A lot of media attention and research is directed at HFA, and as a result, lower functioning autistics seem to be "ignored". Unfortunately, this gives people a lot of false impressions about typical autistic disorder. A lot of people would rather look at a LFA as "retarded" rather than being autistic with a co-morbid intellectual disability (with both conditions being treated separately).

Again - unfortunately - I think many people doing research want positive results and since most people tend to think the HFA population has a better chance at a "normal life" they focus their energies there. It's ignoring the vast majority of autistics. It's the same argument for people who think "autism" is another kind of "normal". Any parent of a lower functioning autistic knows it's not another form of normal.