8/20/2010

Autism, Intellectual Disability and Research Criteria: Ecker et al., A Defense

**Apr 24, 2011: For any who come from Harold Doherty's blog where he would have you believe I am against mention of severe autism and accompanying intellectual disability, just reading this blog should make it clear he misconstrued my position completely. As the mother of a son with autism and ID, I find this inaccuracy offensive, especially since Doherty is fully aware of other articles I've written on autism and ID that acknowledge the sizable minority (around 40%) of autistic who also have an ID. He should be ashamed. He won't be, but he should.


Do some researchers exclude autistics with intellectual disability because they are trying to distort the research information or because they are controlling confounders? Some folks would have you think that researchers deliberately exclude those with intellectual challenges in order to distort information.

Some folks give the example of the latest research concerning brain scans, which excluded those with ID. In order to get a picture of whether there are differences in the architecture of the brain that would allow diagnosis of autism, comparisons need to be made, and this is done incrementally. Notice this study also didn't have females or children included, or left-handed individuals and that comorbid conditions like epilepsy were excluded.

Based on the nature of the study, a baseline needed to be found. Add those other variables in and you have no idea if the differences in the scans are because the person was a female, left-handed child with an intellectual disability or because of the autism. There are plenty of reasons to discuss this study. There's even room to criticize the media coverage and blogging coverage. What there shouldn't be room for is ignorance of the scientific method, the specific science behind a particular study, and the constraints in preliminary (or basic) research.

So, how much research is out there that involves these twin questions of intellectual disability and autism? The EBSCO database at my local university, using the following databases, Academic Search Complete, Psychological and Behavioral Sciences Collection, Health Source: Nursing/Academic Edition, PsycINFO, and PsycARTICLES, found 2,458 full-text peer reviewed journal articles with both intellectual disability and autism as search terms. In nearly 2500 full-text articles, both ID and autism were examined! That's not a dearth of research involving both autism and ID.  Remove the full-text limit and 3,210 results are available. Remove the peer review limiter, and 3,504 articles written between 1977 and 2010 come up in the search results.  When you replace intellectual disability with intelligence, the full-text, peer reviewed articles available for the same time span rises to 10,327 articles. Remove the limiters except for time, and it rises to 14,330 articles.

Expand out from the narrow parameters of autism and ID and focus in only on intellectual disability, and there are 18, 475 full-text peer reviewed articles available in my university's database. Add therapy into the mix, and you find that there are over a thousand articles that have looked at therapy for ID.

It should be noted that this was a limited database search (there are many more possible databases to look at, and I only looked for what I could immediately pull and read). There is a phenomenal amount of scientific literature out there, both on the combined disabilities of autism and intellectual disability and intellectual disability alone.

It seems to me that the charge that researchers are ignoring intellectual disability when researching autism is at best an absurd allegation based on a woefully inadequate understanding of the available science as well as ignorance on how studies are designed and carried out.

I understand that people want their particular issue looked at and an answer found, that there is a peculiar need to rage against anyone who doesn't see the world in the exact same way, but charges, specifically in regards to the recent study by Ecker et al. and their decision to exclude ID, is nonsensical when their research is viewed in its appropriate context.

8 comments:

Socrates said...
This comment has been removed by the author.
Socrates said...

There are some hints that ID and AD aren't really linked at all.

There are also further hints that such worries about the perceived biases in the research surrounding ID an AD may in some quarters, have in its aetiology, a deeply suppressed desire for an horse-riding holiday in Wyoming.

KWombles said...

Hah, Socrates, thank you for that!

Roger Kulp said...

You know what would make an interesting project? Finding out how many people with an ASD diagnosis only have the DSM symptoms for autism,and noting else.No intellectual disability,no learning disabilities,no developmental delay,no seizures, no metabolic disease,no chromosomal mutations/ deletions/etc,just plain old vanilla triad of impairments autism.

Autism Mom Rising said...

I don't have a problem if this study is saying "this is what we learned about those with HFA" but I don't think that is what they are saying - they are using it for generalization purposes. Problems is that we don't know yet that the etiology is exactly the same between HFA & LFA or even from males to females, so such generalizations could be a huge dis-service.

I wonder if sometimes if in the very act of removing possible confounders, confounders are unwittingly being created. Here is an example. It is one of the old Autism & Thimerosal studies ( note: I do not bring this up to debate the vaccine/Autism deal. I have no interest in that. I bring this study up merely to back up the posing of the above question).
Early Thimerosal Exposure and Neuropsychological Outcomes
at 7 to 10 Years
http://www.nejm.org/doi/pdf/10.1056/NEJMoa071434. This study excludes children with low birth weight, twins, and those with congenital health problems. I understand why they did this: to remove possible confounders. However, in the intervening years we have learned that these very groups are more likely to have Autism Spectrum. And, we don't yet know if being those things inherently puts them more at risk OR if being those things makes them more vulnerable to environmental injury of any kind or if it is a little from column A and a little from column B. Yet, unless we know there is a possibility, possible a strong one, that a confounder has been created. My son certainly would have been excluded from this study (heart murmur) and he has Autism.

Problem is several subsequent studies have used the data sets from this study as their foundation, including the recent Univ of Louisville study comparing delayed schedule to the regular one.

Kim this is really a good article. I wish you were a science writer (well you are, really, but you know what I mean). A lot of the science writers in newspapers don't seem to understand the subject this well.

Autism Mom Rising said...

I don't have a problem if this study is saying "this is what we learned about those with HFA" but I don't think that is what they are saying - they are using it for generalization purposes. Problems is that we don't know yet that the etiology is exactly the same between HFA & LFA or even from males to females, so such generalizations could be a huge dis-service.

I wonder if sometimes if in the very act of removing possible confounders, confounders are unwittingly being created. Here is an example. It is one of the old Autism & Thimerosal studies ( note: I do not bring this up to debate the vaccine/Autism deal. I have no interest in that. I bring this study up merely to back up the posing of the above question).
Early Thimerosal Exposure and Neuropsychological Outcomes
at 7 to 10 Years
http://www.nejm.org/doi/pdf/10.1056/NEJMoa071434. This study excludes children with low birth weight, twins, and those with congenital health problems. I understand why they did this: to remove possible confounders. However, in the intervening years we have learned that these very groups are more likely to have Autism Spectrum. And, we don't yet know if being those things inherently puts them more at risk OR if being those things makes them more vulnerable to environmental injury of any kind or if it is a little from column A and a little from column B. Yet, unless we know there is a possibility, possible a strong one, that a confounder has been created. My son certainly would have been excluded from this study (heart murmur) and he has Autism.

Problem is several subsequent studies have used the data sets from this study as their foundation, including the recent Univ of Louisville study comparing delayed schedule to the regular one.

Kim this is really a good article. I wish you were a science writer (well you are, really, but you know what I mean). A lot of the science writers in newspapers don't seem to understand the subject this well.

Roger Kulp said...

Autism Mom Rising's post sort of mentions something I know I have read,but given the way Google is set up,I can't find.I'm looking for pages that spell out the differences between HFA,and Asperger's.I sort of got the idea,where you have developmental delay,learning disabilities,plus all the other problems people associate with severe autism,and you are verbal,and don't have ID,you have HFA,and that true HFA is much rarer than Asperger's.

If you have links to such articles,book chapters,or papers, I would appreciate it.

Socrates said...

HFA/AS dif. dx: "in contrast to Autistic Disorder, there are no clinically significant delays in early language (e.g., single words are used by age 2, communicative phrases are used by age 3)"

from http://conversationalhysteria.blogspot.com/p/autism-defined-dsm-iv.html

As far as I can tell this is the single, supposed marker defining the boundary between hfa/as.