Fiona Stanley study finds important differences between intellectual disability and autism

Helen Leonard, Emma Glasson, Natasha Nassar, Andrew Whitehouse, Ami Bebbington, Jenny Bourke, Peter Jacoby, Glenys Dixon, Eva Malacova, Carol Bower, Fiona Stanley
Autism and Intellectual Disability Are Differentially Related to Sociodemographic Background at Birth.
PLoS ONE.
Received: January 8, 2011; Accepted: February 11, 2011; Published: March 30, 2011.
http://www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0017875

"This is the first population-based study of ASD to examine comprehensively the association of a range of sociodemographic effects according to the presence or absence of ID and provide comparisons with children diagnosed either solely with ID or without ASD or ID. Most previous research has investigated ASD as a single entity and, despite inconsistent findings, has rarely evaluated whether the presence of ID might modify any association. This is important given recent concerns that there may be some diagnostic accretion to ASD from ID and a potential change in the characteristics of ASD children over time."

"The profiles for the four categories examined, mild-moderate ID, severe ID, ASD without ID and ASD with ID varied considerably ..."

My interpretation of this study is that it shows that autism without intellectual disability is a different type of condition than intellectual disability (ID) or autism combined with intellectual disability. Pure autism was found to be associated with economic advantage, while mild-moderate ID was associated with increasing social disadvantage. Autism can be found with ID, but it is not a type of ID. It looks to me as though mild ID (which I presume is likely to be less genetic and more preventable than severe ID) is an underdevelopment that is the result of a poor environment, while pure autism looks like it is a type of enhanced or different development that could be the result of genes that are more likely to be found in the advantaged end of the social heap, that can give rise to autism or an autism diagnosis in males but not so much in females, or alternately pure autism could be the result of enhanced development that is the result of an advantaged environment. Is autism associated with intellectual giftedness? This important question is completely beyond the range of things investigated by this study, but an answer to this question would do a lot to explain the findings of this study.

"This was demonstrated clearly with increased odds of ASD without ID amongst older mothers aged 35 years and over (odds ratio (OR) = 1.69 [CI: 1.18, 2.43]), first born infants (OR = 2.78; [CI: 1.67, 4.54]), male infants (OR = 6.57 [CI: 4.87, 8.87]) and increasing socioeconomic advantage. In contrast, mild-moderate ID was associated with younger mothers aged less than 20 years (OR = 1.88 [CI: 1.57, 2.25]), paternal age greater than 40 years (OR = 1.59 [CI: 1.36, 1.86]), Australian-born and Aboriginal mothers (OR = 1.60 [CI: 1.41, 1.82]), increasing birth order and increasing social disadvantage (OR = 2.56 [CI: 2.27, 2.97])."

"The different risk profiles observed between groups may be related to aetiological differences or ascertainment factors or both."

What does "aetiological mean? It means to do with the cause of a condition.

"We suggest that the different risk profiles we have observed for maternal and paternal age for ASD with ID and ASD without ID represent aetiological differences for the two groups. Alternatively, as demonstrated best by sex ratio and birth order, the group with ASD with ID may represent a dilution of the pure ASD phenotype (i.e. ASD without ID). In either of these scenarios, we should caution about the repercussions for analysis and interpretation of combining such groups in epidemiological and genetic investigations."

So ASD with ID and ASD without ID are different things and it is possible that these different conditions are caused by different factors. Intelligent autistic people have every right to feel angry and offended if treated in the way that one might treat an intellectually disabled person. Knowing that a person is autistic tells you nothing about the level of intelligence of that person, in fact, I know of another study that has found that autistic people are less likely than non-autistic people to have an average IQ. So this means that knowing that a person is autistic should be a warning against making any type of assumptions about IQ based on an autism label.

"...parents are playing a greater role in seeking and securing an ASD diagnosis for their children, especially when, as in Western Australia, there are financial incentives to do so."

Something to bear in mind before believing nonsense about an "autism epidemic". Autism stats can be influenced by social factors.

"We nevertheless acknowledge limitations such as the difficulty in adequately assessing cognitive function in children with ASD. We therefore conservatively restricted our group of children with ASD without ID to those who, based on assessment information, we were confident did not have an IQ deficit. Any misclassification of this group would have meant that we may have underestimated some of the differences we identified."

Knowing that autistic intelligence can be significantly underestimated, it would seem to be reasonable to assume that the group of children with ASD without ID could well have been underestimated.

So, I think there are many messages that can be taken away from this study, and the most important one is the message that autism is not one thing. Autism with and without ID are different types of things that could well have entirely different causes. Any so-called autism expert (such as an academic researcher or a clinician or an autistic person who has taken on the role of a first-hand autism expert) who speaks of "autism" and not "autisms" or types of autism is no expert. Any so-called autism expert who offers a grand theory to explain autism, as though it is one thing with one cause, is no expert at all. Any so-called autism expert who fails to caution about the heterogeneity of autism and the likelihood that there are different types of autism with entirely different causes, is no expert. Any so-called autism expert who speaks of the factors that give rise to "autism" exclusively in terms of deprivations and disadvantages is an idiot who isn't even worth listening to. And any autism researcher who ignores differences in intelligence is an incompetent. Don't say I didn't warn you!

I think this study is also a warning against sweeping statements from any political or personal perspective about whether we should or should not seek to cure or prevent autism. I believe that parents have the right to seek to protect their child against anything that might significantly impair the intelligence of their child, although not all would choose to exercise that right. I also believe it would be a crime to seek to purge from the human gene pool variants of autism that increase or diversify human intellectual capacities, as I believe many variants do. The picture is a complex one, so simplistic and uninformed responses to the many questions surrounding autism should no longer be tolerated.