Autism diagnosis and hyper-systemizing parents: Nottingham vs. Eindhoven

Family life in Eindhoven?

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With an insensitivity one might have expected from a Sun headline writer, the New Scientist summarised the findings from a recent study thus: Childhood autism spikes in geek heartlands.  The bottom line is that autism is diagnosed more than twice as often in Eindhoven, a city in the Netherlands where many are employed in the IT industry, than in two other cities of comparable size, Haarlem and Utrecht. The explanation favoured by the researchers is that autism is characterised by a ‘systemizing’ style of thinking, which is part of normal human variation, and which is common in those in technical and mathematical occupations. Cities with a strong IT presence will attract an unusually high number of high-systemizer residents, and these people will be more likely to have offspring with autism. This is, then, a genetic explanation, and it’s given some plausibility by a large body of research demonstrating that parents of children with autism are more likely than other parents to show indicators of mild autistic-like characteristics, the so-called ‘broad autism phenotype’. (Although, on an admittedly quick search, the evidence that parents of children with autism tend to be high systemizers seems rather weak: mild symptoms of social and communicative problems seem a more pronounced feature of the broad autism phenotype than hyper-systemizing behaviours (Bishop et al., 2004; Wheelwright et al., 2010; Windham et al., 2010)).

As the researchers themselves note, the hyper-systemizing account is not the only possible explanation for their result. Crucially, the study relied on counting diagnoses from school records, rather than screening the population in a standard fashion. Although it’s not hard to recognise a case of classic Kanner autism, there’s far more disagreement about diagnoses for children with milder symptoms. As I argued on a Guardian blog, unless we have clear objective criteria for diagnosis, it’s hard to compare one prevalence rate with another. The different numbers could just reflect local expertise, policy or practice in diagnosing autism.

One limitation of the published study is that the researchers are quoted as saying that their study was prompted by anecdotal reports that autism was abnormally common in Eindhoven. While it is worth checking out if the anecdote is accurate, this makes Eindhoven less than ideal for testing the hyper-systemizing hypothesis, as it potentially capitalises on a chance blip. What would be better would be a study with clear a priori predictions, based solely on levels of IT industries in different cities. In theory, it should be possible to do this using publicly-available data from the UK published by the Department of Children, Schools and Families. This dataset has the advantage of being comprehensive, unlike the school report data from the Eindhoven study, which relied on schools providing the data (- the response rate was 75% for Eindhoven but only 50% for Haarlem and 46% for Utrecht). A recent report by Lindsay (2011)  presented some data from this UK database on numbers of children with Special Educational Needs categorised as having Speech, Language and Communication Needs (SLCN) or Autistic Spectrum Disorder (ASD). The numbers of children with these labels varied massively from place to place, as shown in Table 1.

Table 1: Percentages of children with SEN diagnosed with SLCN or ASD; 

Data from local authorities with the highest or lowest % of either diagnosis

I have no idea whether the number of IT experts is higher in Nottingham than Leeds, but it’s noteworthy that places where you might expect high levels of hyper-systemizing, such as the university towns of Oxford and Cambridge, don’t feature among the places with very high rates of ASD diagnoses. Lindsay also points out that “the two neighbouring authorities of Nottingham and Nottinghamshire have almost identical prevalence rates for SLCN and ASD, despite one being a large city, and the other a shire county” (p. 143). Clearly, my intuitions are no substitute for real data, and it’s also important to note that the data in Table 1 are not population prevalence figures, but instead are proportions of children who have already been identified as having Special Educational Needs. One would need to use the frequencies of ASD in the population as a whole to test the hypothesis of a correlation between level of IT industry and rates of autism. The data are available, and this might seem like a nice project for someone to do, except for a major problem. As Lindsay emphasised, it is impossible to conclude from the UK data whether prevalence really do vary across the country, because the definitions of disorders are inconsistent from one area to another. It’s possible that criteria for autism are more standardised in the Netherlands than in the UK, but the UK data make me suspect that it’s just not possible to draw meaningful conclusions about prevalence from data based on educational records.

References

Bishop, D. V. M., Maybery, M., Maley, A., Wong, D., Hill, W., & Hallmayer, J. (2004). Using self-report to identify the broad phenotype in parents of children with autistic spectrum disorders: a study using the Autism-Spectrum Quotient. Journal of Child Psychology and Psychiatry, 45, 1431-1436.

Lindsay, G. (2011). The collection and analysis of data on children with speech, language and communication needs: The challenge to education and health services. Child Language Teaching & Therapy, 27(2), 135-150.

Roelfsema, M., Hoekstra, R., Allison, C., Wheelwright, S., Brayne, C., Matthews, F., & Baron-Cohen, S. (2011). Are Autism Spectrum Conditions More Prevalent in an Information-Technology Region? A School-Based Study of Three Regions in the Netherlands Journal of Autism and Developmental Disorders DOI: 10.1007/s10803-011-1302-1 

Wheelwright, S., Auyeung, B., Allison, C., & Baron-Cohen, S. (2010). Defining the broader, medium and narrow autism phenotype among parents using the Autism Spectrum Quotient (AQ). Molecular Autism, 1(1), 1-9. 

Windham, G. C., Fessel, K., & Grether, J. K. (2009). Autism spectrum disorders in relation to parental occupation in technical fields. Autism Research, 2(4), 183-191.