Saturday, September 09, 2006

Dan Olmstead's New Pet Theory

It's no secret that many proponents of now discredited hypotheses are quietly pursuing new causation theories without explicitly admitting so. But more than pursing new causation theories in an effort to improve our understanding of autism, they seem intent in continuing to look exclusively for "something wicked."

Dan Olmstead, a journalist of "no autism among the Amish" fame, is a case in point, with his three new Age of Autism articles titled Something Wicked -- 1, Something Wicked -- 2 and About Those "Old Dads". In them he puts forth the hypothesis that autism may be caused by chemicals parents are exposed to. The mechanism or its plausibility are not clear, but let's leave that aside for the time being.

Olmstead cites work by Thomas Felicetti, who had found a higher prevalence of chemists among the parents of autistic children compared to controls. This confirmed prior work by Mary Coleman. He further goes into the case histories of Kanner's 11 autistic patients born in the 1930s. Let me quote from his "Old Dads" article:

We've also pointed out a possible connection in the very first cases described in the medical literature -- 11 children born in the 1930s -- with new chemical compounds, plausibly including mercury-based fungicides. One of those 11 kids was the son of a plant pathologist, another the son of a forestry professor at a southern university, and a third grew up in an area being heavily planted with seedlings to create a national forest in Mississippi (there's that southern forestry connection again -- in fact, his home town is named Forest).

A fourth was the son of a mining engineer. And the very first case to come to medical attention, at Johns Hopkins University in 1935, was the son of a 30-year-old chemist-attorney at the U.S. Patent Office. A chemist.

Anyone with more than a passing interest in autism research will recognize the obvious confound in this hypothesis. I would also point out that these studies are from a different generation, and we might find things have changed. For example, I would wager computing might be a relatively common occupation among parents of autistic children nowadays. (Readers are encouraged to provide anecdotal data in the comments section).

A series of articles (e.g. Baron-Cohen et al. (1998)) have shown that mathematicians, computer scientists, physicists and engineers are over-represented among the parents of autistic children. Jarrold & Routh (1998) analyzed the data and found that the parents of autistic children were also over-represented in accountancy and science, suggesting that perhaps there's a general professional over-representation. Wheelwright & Baron-Cohen (2001) argued that even taking into account a possible over-representation of professionals, engineers were still over-represented.

Further evidence of this confound comes from an AQ test assessment by Baron-Cohen et al. (2004). The researchers found that "scientists (including mathematicians) scored significantly higher than both humanities and social sciences students" and that "within the sciences, mathematicians scored highest." Further, the group of Mathematics Olympiad winners scored significantly higher than the male Cambridge Humanities students.

Dan Olmstead does try to address the confound by pointing out that there is no correlation between social class and autism, which is correct. But social class is clearly not what the confound is about.


  1. Ok, I'll go first. Anecdotal evidence:

    My father worked with computers starting in the mid 60's until his retirement.

    My husband is a systems architect at the moment, though he's had many different IT jobs at various times. He's kind of a jack-of-all trades with computers. I think he likes R&D best.

  2. My dad (a PhD sociologist) wasn't a programmer beyond the fact that anyone who used computers in the old days was doing so in COBOL, FORTRAN or BASIC. I grew up around punch cards and green-striped tractor feed paper. My first programming class used punch cards and green-striped tractor feed paper (ugh!) Maternal uncle is an engineer, and I suspect aspie. Aspie kid is into computer gaming. His dad is an IT guy, but "profoundly neurotypical". As for me, I've cracked open a case to install an AD converter board for some lab equipment, so I guess that makes me a level up from "savvy user" level. I'm second-generation geek, and will be 101101 on my next birthday.

  3. BTW, my formal training is in computer science, and I have several immediate relatives who are engineers.

  4. Joseph,

    Just this week there was a study released which showed that

    "In the main analyses, one marker of higher social class (higher median family income) was significantly associated with autism overall. Both markers of higher social class (higher maternal education and higher median family income) were significantly associated with autism/no MR, but not associated with autism/MR."

    J Autism Dev Disord. 2006 Sep 2; [Epub ahead of print]

    So, autism/no MR IS associated with a higher social class.

    This is not surprising to me. There are many shadow-autistic traits in the scientists I work with.

  5. In looking at Kanner's research notes for cases #1 and #2 there appears to be significant history with the fathers in regards to their behaviors. This is conveniently NOT mentioned because it really would make the supposed "point" about the professions of the fathers invalid.

    Also this theory would bring into question the "no autism among the Amish" supposition since not all Amish are organic farmers. Some do not have issue with using pesticides or chemicals so than there should be autism among them if this is related to chemicals.

  6. Got a computer programmer here.

  7. Jennifer,

    There are a number of studies that dispute the link to social class - going back many years. The link to mother's level of education is very plausible, though.

  8. Joseph wrote:

    these studies are from a different generation, and we might find things have changed.

    Indeed. Many people were involved in forestry during the 1930s. Those were the Depression and Dust Bowl years, when forestry projects put many people back to work. Just about any randomly chosen group during this time period would have had some connection to forestry.

  9. On the social-class connection, I wonder how much unconscious bias in differential diagnosis contributes to the differences. Although it's gotten better, there at least used to be a pattern where diagnosticians would tend to give lower-class/minority kids more "dismal" diagnoses than otherwise comparable middle-class white kids; a poor kid would be considered MR where a middle-class kid would be considered dyslexic; a black male would be considered schizophrenic whereas a white male would be considered depressed. The pattern looked suspiciously as if members of "outgroups" were getting diagnoses that 1) implied that it would be a waste of resources to provide them with significant services because there was little hope of improvement and 2) were often treated with highly sedating medication ("keeping them under control").

    As for the "chemical exposure" allegations, the people making them seem to forget that it's production workers, not engineers or scientists, who are exposed to the highest levels of potentially toxic chemicals. Kanner's chemist in the patent office was probably doing exclusively pencil-and-paper chemistry.

  10. Awareness and use of specialists also probably plays a role in the social class connection, similar to the correlation with degree of urbanization. The study Jennifer cites draws a distinction between autism with MR and without MR, but it's not really surprising that there would be a social class difference there as there is with MR alone. It might be significant that there's a social class correlation when comparing to non-autistics matched by IQ. As far as higher education, that is not so interesting unless we know what type of higher education. Are moms with advanced education in Humanities equally over-represented as are moms with advanced education in scientific fields? I bet they are not. The abstract doesn't elaborate. (If anyone has the full text, please send it over).

  11. If a career in forestry = exposure to chemicals = autistic child, then what is it about a career in IT that would = autistic child?

    Exposure to pizza?

    There was a study that showed low cholesterol in some autistics, does that mean exposure to Lean Cuisine pizza = autistic child?

    Or could it be that IT workers are famous for their love of pizza due to attempting to self medicate?

    It has also been shown recently that older fathers have a greater chance of having autistic children. Could this be due to consuming a healthier diet as we age? Maybe all those IT workers get sick of pizza as they get older and switch to salad.


    Gee, I could chase my own tail on this one for hours...

    Sorry, back to the regularly scheduled program.

  12. Exposure to pizza?

    Well... don't be surprised if Dan Olmstead comes up with the notion that sitting in front of CRTs causes autism. After all, the Amish don't have computers and the autism epidemic coincides with the internet boom of the 1990s. Kind of tough to explain mathematicians and physicists still, but hey, most everyone is exposed to computers these days.

    If the mining engineer is significant in Kanner's original sample, I wonder why miners in general aren't overrepresented, which is what is Ebohlman is saying.

  13. NT's who take up science or engineering have to train their minds to thinking more like an autistic brain. I have a systemizing brain, to use Baron-Cohen's term, even though I'm female. I never did get into the teenage girl social scene-gossip is only interesting to me when the person is long dead, which is what history is. : ) I am totally clueless when it comes to workplace politics though.

  14. I'm a journalist at the autism one conference right now. I will be presenting with Dan in the morning. I have never met him. I have heard of his hypothesis. I am so glad to hear you guys talking about your professions. This topic came up today. A mom just told me almost every man in her family is an engineer and she has two boys on the spectrum.