Autism And Wealth

By Neuroskeptic | July 14, 2010 2:45 pm

We live in societies where some people are richer than others – though the extent of wealth inequality varies greatly around the world.

In general, it’s sad but true that poor people suffer more diseases. Within a given country almost all physical and mental illnesses are more common amongst the poor, although this isn’t always true between countries.

So if a certain disease is more common in rich people within a country, that’s big news because it suggests that something unusual is going on. Autism spectrum disorders (ASDs) have long been known to show this pattern, at least in some countries, but this has often been thought to be a product of diagnostic ascertainment bias. Maybe richer and better-educated parents are more likely to have access to services that can diagnose autism. This is a serious issue because autism often goes undiagnosed and diagnosis is rarely clear-cut.

An important new PLoS paper from Wisconsin’s Durkin et al suggests that, while ascertainment bias does happen, it doesn’t explain the whole effect in the USA: richer American families really do have more autism than poorer ones. The authors made use of the ADDM Network which covers about 550,000 8 year old children from several sites across the USA. (This paper also blogged about here at C6-H12-O6 blog.)

ADDM attempts to count the number of children with autism based on

abstracted data from records of multiple educational and medical sources to determine the number of children who appear to meet the ASD case definition, regardless of pre-existing diagnosis. Clinicians determine whether the ASD case definition is met by reviewing a compiled record of all relevant abstracted data.

Basically, this allowed them to detect autism even in kids who haven’t got a formal diagnosis, based on reports of behavioural problems at school etc indicative of autism. Clearly, this is going to underestimate autism somewhat, because some autistic kids do well at school and don’t cause any alarm bells, but it has the advantage of reducing ascertainment bias.

What happened? The overall prevalence of autism was 0.6%. This is a lot lower than recent estimates in 5-9 year olds in the UK (1.5%), but the UK estimates used an even more detailed screening technique which was less likely to leave kids undetected.

The headline result: autism was more common in kids of richer parents. This held true within all ethnic groups: richer African-American or Hispanic parents were more likely to have autistic children compared to poorer people of the same ethnicity. So it wasn’t a product of ethnic disparities.

Crucially, the pattern held true in children who had never been diagnosed with autism, although the effects of wealth were quite a bit smaller:

The difference in the slope of the two lines suggests that there is some ascertainment bias, with richer parents being more likely to get a diagnosis for their children, but this can’t explain the whole story. There really is a correlation with wealth.

So what does this mean? This is a correlation – the causality remains to be determined. There are two obvious possibilities: to put it bluntly, either being rich makes your kids autistic, or having autistic kids makes you rich.

How could being rich make your children autistic? There could be many reasons, but a big one is paternal age: it’s known that the risk of autism rises with the age of the father, maybe because the sperm of older men accumulates more genetic damage, and this damage can cause autism. In general richer people wait longer to have kids (I think, although I can’t actually find the data on this) so maybe that’s the cause.

How could having autistic kids make you richer? Well, unfortunately I don’t think it does directly, but maybe being the kind of person who is likely to have an autistic child could. Autism is highly heritable, so the parents of autistic children are likely to carry some “autism genes”. These could give them autistic traits, or indeed autism, and autistic traits, like being intensely interested in complex intellectual matters, can be a positive advantage in many relatively well paid professions like scientific research, or computing. Marginal Revolution‘s Tyler Cowen recently wrote a book all about that. I hope I will not offend too many when I say that in my experience it’s rare to meet a scientist, IT person or, say, neuroscience blogger, who doesn’t have a few…

ResearchBlogging.orgDurkin, M., Maenner, M., Meaney, F., Levy, S., DiGuiseppi, C., Nicholas, J., Kirby, R., Pinto-Martin, J., & Schieve, L. (2010). Socioeconomic Inequality in the Prevalence of Autism Spectrum Disorder: Evidence from a U.S. Cross-Sectional Study PLoS ONE, 5 (7) DOI: 10.1371/journal.pone.0011551

CATEGORIZED UNDER: autism, genes, mental health, papers, surveys
  • http://ecophysio.wordpress.com/ ecophysio

    I'm actually most interested in the studies involving reduced oxytocin levels in autistic individuals from the last 15 years or so. I have to wonder if there's some sort of correlation between oxytocin and intelligence or socioeconomic status, and if so, what the causes are.

  • http://www.blogger.com/profile/00147156174467903264 Mike Keesey

    It would be interesting to know if this trend is true just for the present or if it extends further back in time. If it doesn't, mightn't it also have something to do with how rich children are raised nowadays?

  • Howard

    I have to admit I'm a bit confused.

    Was there something in this study that disproves the possibility that doctors and teachers in wealthy neighborhoods document the children differently than doctors and teachers in poorer neighborhoods?

  • http://www.blogger.com/profile/06647064768789308157 Neuroskeptic

    Well yes and no. They say that:

    “An important limitation of this study was that [it] relies on information for children
    who have access to diagnostic services for developmental
    disabilities. We could not rule out the possibility that the quality and quantity of evaluations and information available for case
    ascertainment might have varied by SES. We looked for evidence
    of this by examining the number of evaluations per child with ASD
    recorded in the ADDM Network surveillance system, reasoning
    that if the higher prevalence of ASD among children of higher
    SES was due to increased access to diagnostic services, high SES
    might be associated with a higher number of diagnostic
    evaluations per child. However, we found no association between
    the number of evaluations per child and SES.
    We also examined
    the mean ages at diagnosis by SES and found that children of high
    SES received an ASD diagnosis at an average age of 58.0 months,
    1.1 month earlier than those of middle SES (p = 0.2838) and 2.7
    months earlier than those of low SES (p,0.0272)
    . This modest
    difference in age at identification may indicate that diagnostic bias
    contributes to the SES gradient in ASD prevalence in some
    studies, though not necessarily in the present study which relied on
    surveillance at the age of eight years and included cases with and
    without a pre-existing ASD diagnosis.”

    That's enough to convince me that there aren't massive effects at work, but ultimately, no we don't know.

    On the other hand there is one reason to be skeptical: the SES disparity in autism wasn't seen for autism with mental retardation (IQ < 70); arguably this is "harder to miss" meaning that ascertainment bias would be less.

    BUT equally you could argue that rich people do better on IQ tests (which they do), so their children are likely to better, meaning that the rich autistic kids were less likely to be classed as “mentally retarded”, even though there are more rich autistic kids, so it cancels out and you get no curve for autism with MR.

  • B Riley

    Seth Roberts has mentioned the possibility that prenatal care, specifically ultrasounds, may contribute to autism: http://www.blog.sethroberts.net/2010/01/23/does-prenatal-ultrasound-cause-autism/

    The wealthy presumably use prenatal ultrasounds more intensively. Some states decreased Medicaid coverage for prenatal care, followed by a decrease in autism rates among low-income populations.

  • http://www.blogger.com/profile/02219505720807067694 NeuroKüz

    There are also theories that autism is exacerbated or even caused by certain dietary components. There few a studies (such as this one) in which the injection of prioprionic into rats generated a proposed animal model of autism.

    Proprionic acid is a preservative found in refined wheat/white bread… maybe rich people consume more of this?

    More likely, I think, many factors associated with being rich act together to increase the incidence of autism.

  • MikeS

    I'm not saying I necessarily support this argument, but I think it's worth bringing up the vaccine issue here, since wealthier people tend to have better access to vaccinations. I thought this theory was largely debunked, but I did see this new book that just came out (haven't read it yet):

    http://www.amazon.com/Callous-Disregard-Autism-Vaccines-Tragedy/dp/1616081694/ref=cm_cr_pr_product_top

  • EK

    MikeS – that theory has been debunked. As for that that book, I would suggest you read this: http://www.sciencebasedmedicine.org/?p=5343

  • http://www.blogger.com/profile/06647064768789308157 Neuroskeptic

    I just thought of another possibility: assortative mating.

    Imagine that two people with autistic traits, who presumably carry a few autism genes, have kids together. Those kids are going to inherit two sets of autism genes (to put it crudely) and assuming the genetic effects are additive, they'll be highly likely to have autism or autistic traits.

    Now imagine that the chance of a person with autistic traits meeting another likeminded (like-brained?) person and having kids is
    correlated with their wealth… not too hard to see how that would work, it is probably easier to meet such people though, say, studying at MIT, than working in a low paid job.

    You'd then get more assortative mating and more autism in richer groups.

  • dearieme

    Rich people feed their children fashionable foods i.e. too much broccoli and not enough pizzas. Though, on the other hand, rich people's nannies feed their charges too much pizza and not enough broccoli. Tricky business, medical science.

  • http://www.blogger.com/profile/18427182088608626183 Jennifer

    I must say my husband and I have relatively high IQs and would be considered by most to be “successful” people. I believe our genetics are the perfect storm that created out daughter… she has terrible sensory processing disorder, which is one piece of the autism puzzle. Having said that, which came first, the chicken or the egg? Which variable is the spurious one? Regardless, there are children out there who need help. Our daughter is doing great now. Here are some websites that helped us help her…
    http://www.brainbalancecenters.com
    http://www.sensoryplanet.com

  • dearieme

    How old were you (both) when you had her, Jennifer?

  • http://passionlessdrone.wordpress.com passionlessDrone

    Hi Neuroskeptic –

    Thanks for posting this. In addition to the assortive mating, and older parents being wealthier, we might also consider that it appears that some endocrine disruptors and other pollutants are not distributed normally within populations that vary by age, cultural practice, and indeed, wealth.

    http://www.ncbi.nlm.nih.gov/pubmed/20129604

    Six PBDE congeners were detected among greater than 70% of samples, with BDE-47 having the highest concentration (median 42.2, range 4.9–855 ng/g lipid). Girls in California had adjusted geometric mean (GM) PBDE levels significantly higher than girls in Ohio. Furthermore, Blacks had significantly higher adjusted GMs of all six PBDE congeners than Whites, and Hispanics had intermediate values. GMs tended to be lower among more obese girls, while other variables were not strongly associated. In contrast, GMs of the six PCB congeners most frequently detected were significantly lower among Blacks and Hispanics than Whites. PCBs and the three pesticides most frequently detected were also consistently lower among girls with high BMI, who were not breast-fed, whose mothers were younger, or whose care-givers (usually parents) were less educated. Girls in California had higher GMs than in Ohio for the pesticides and most PCB congeners, but the opposite for CB-99 and -118.

    There is a lot of speculation that some types of environmental pollutants could contribute to autism through disruption of developmental practices. I can see pretty easily a different chemical exposure based on income, among other things.

    - pD

  • Nena

    One issue with this study I haven't seen anyone bring up yet is that they are using geographic district-level data as a proxy for SES and related metrics. This is understandable since getting accurate data of this sort at the individual/family level is a whole different can of worms.

    But this is also a slight confounder since one can imagine that areas which fare better in most SES metrics tend to have better infrastructure and more schools with strong special ed programs.
    Hence it's possible that some of the children from lower income areas who require extra help (e.g. autistic, multiple developmental disorders, etc.) end up going to schools with better programs at some of these wealthier areas.

    Also, I'm not sure how I feel about the idea of counting children as ASD based on behavioural records even if they do not have a diagnosis — I think that's just a really easy way to potentially overestimate population prevalence, as there are many other disorders that can lead to sometimes similar behavioural problems.

  • http://www.blogger.com/profile/06647064768789308157 Neuroskeptic

    Nena: That's a good point about kids with special needs maybe being sent to other schools – however, I'm not sure that would explain the difference in people without a diagnosis (although maybe they have a diagnosis of something other than autism).

    Re: diagnosing autism based on school records, it might overestimate prevalence, but 0.6% is actually pretty low by modern standards, in the UK the latest big study found 1.5% and the one before that (less rigorous) 0.8%. And relying on diagnoses would introduce its own problems.

    Overall I think this was a very good study given the data available. But ultimately we need more detailed data i.e. going out and surveying every individual kid in a certain area…

  • Anonymous

    Neuroskeptic,

    I think that another part of the puzzlemay be the isolation of wealthier kids. THey are less likely to have nearby neighbors or siblings (as the wealthier have bigger houses, less kids). This is also a drastic change from all of human history and poorer countries now.

    The amygdala's emotional and social processing could simply be understimulated during development and never develop the robust connections it should. (This would also explain stuff like the low oxytocin.) It also makes me less likely to believe environmental explanations, since the rich would typically be better off in that respect.

  • http://www.blogger.com/profile/06082411537913891826 The Reporter

    What about the influence of explaining a disease and increasing its diagnosis? For instance, teenage girls in Hong Kong are starting to develop Western anorexia more often now that it has been characterized as such.

    Considering the role of chemical exposure, too, it's possible poorer kids are having much more severe conditions than wealthy children whose parents are able to avoid toxic areas, pesticides, etc.

  • http://www.blogger.com/profile/06837467954881003505 Ian Smith

    “This is a serious issue because autism often goes undiagnosed and diagnosis is rarely clear-cut.”

    In 99/100 “cases” of autism there is nothing wrong. The diagnoses of autism and ADHD are how parents avoid hating their disappointing children.

    “OMG”. This is so f—ing retarded. I guess the smartest medical students avoid psychiatry.

  • EK

    …Wow.

    Disregarding the previous comment, one of my thoughts is that children of different socioeconomic status, even if they display the same behavior, may still be subject to very different social standards and expectations. This in turn may have a significant effect on which behavior is more likely to attract notice, and how this behavior may be interpreted and subsequently described in school records.

  • http://www.neurodiversity.com/ Anon Autie

    Fact: Wealthy people (in the US) are taller, thinner, healthier, better looking and smarter. Now we find they're also more likely to be autistic. Autism is genetic; kids get it from their parents. The relationship is not a casual one.

    Has it not occurred to anyone that autism could be indicative of a more highly evolved brain? The average autistic is more like Bill Gates than the kid banging his head against a wall in TV PSAs designed to elicit sympathy.

    Bury me up to my waist and stone me, but autism is a sign of a more evolved brain, not an inferior one. Most people will know that 30 years from now.

  • http://www.blogger.com/profile/01695896117685218995 J

    “autistic traits, like being intensely interested in complex intellectual matters, can be a positive advantage in many relatively well paid professions like scientific research, or computing”

    That would probably explain most of any difference. People tend to be attracted to similar people, so it stands to reason genetic traits will concentrate in a given demographic.

    That assumes the analysis is valid. I suspect there's a lot more truth to Ian and EK's posts (which, notwithstanding EK's “disagreement” say essentially the same thng) than many here want to admit.

    For those who, like, me found themselves extremely skeptical of depiction of wealth inequality in the CIA chart, note that is it mislabled; it indicates income inequality, not wealth inequality.

  • http://www.blogger.com/profile/06647064768789308157 Neuroskeptic

    J: Good point about the map, I'll fix that.

    Sure, it could be that wealthier parents have different expectations about their kids behaviour, leading to “autistic” behaviours getting noticed and remarked on, and that's driving the effect.

    But based on what I know about autism and based on people I've known over the years I don't think this is any more likely than the idea that the correlation is real and driven by assortative mating or the idea that autistic traits can boost your income.

    I think they're both plausible. I don't see one of these as the null hypothesis which we should believe until proven otherwise.

  • Human

    Girls are underdiagnosed relative to boys because they manifest autism and autistic-spectrum syndromes differently. It is entirely probable the same thing is happening across SES levels.

  • http://www.blogger.com/profile/01695896117685218995 J

    “I don't think this is any more likely”

    I don't think one is any more likely than the other either. I guess my point was there probably isn't any one explanation. The idea that people with potentially autistic characteristics tend to intermarry doesn't strike me as at all unlikely. I also know people (including a couple of neighbors) who claim their children are mildly autistic, whose kids are smart and basically OK but suffer from atrocious social skills, not autism. Granted, parts of the medical community seem bent on defining that condition as autism; I'm not convinced.

  • EK

    I'm not sure that I made my point clearly. What I suspect is that autistic children of different SES, while manifesting the same behavior, are likely to be observed and described differently in school records. For example, some suspect that ASD's are underdiagnosed in girls. While autistic girls are unlikely to fly under the mental health radar, one argument is that certain behaviors (such as excessive “shyness”) may not be paid much attention, while they may be far likely to attract notice in boys.

    If diagnosis is made on the basis of behavior noted in school records – and if some characteristically autistic behavior is less likely to be observed and noted in autistic kids of lower SES (e.g. “severe tantrums” may well make it into school records, but “intense interest in obscure subjects” may not, and so forth) – I would suspect that a diagnosis of ASD may be less frequently made on the basis of those records. In short, I suspect that children of lower SES may be underdiagnosed, rather than children of higher SES overdiagnosed (although the latter is a possibility as well).

    J – how is my point similar to Ian's? I'm genuinely stumped.

  • http://www.blogger.com/profile/11546678711462612777 Harold Rongey, Ph.D.

    I have been researching autism for more than three years and have a profile that identifies many parents of autistic children.
    Yes, I believe many of the wealthy, well educated, affluent parents have a higher incidence of autism in their children. This I believe is due largely to their wanting to follow the latest news on health that has taken them from the healthy foods to those that cannot possibly provide the nutrients required for the proper development and function of the brain. At least sixty nutrients are reported to be deficient in autistic children and my recent study of more than 500 autistic children has confirmed these deficiencies. It was also found, with fewer numbers, That the symptoms are reversible when the deficiencies are eliminated.

  • http://www.blogger.com/profile/06647064768789308157 Neuroskeptic

    EK: Isn't it also possible, though, that the opposite could be true – that high SES parents consider some autistic behaviours to be normal?

    Suppose your kid turns out to be obsessed with mathematics, and very good at it, and doesn't really socialize with other kids. If you're a mathematician or engineer or whatever yourself, you might think that's great.

  • EK

    Neuroskeptic – I agree; I think that different forms of observer bias may create a mechanism for how a disparity like this can appear, but I'm far less sure how it would actually play out (or in whose 'favor').

    That's an interesting point – as an anecdote, my mother was a mathematician, and my father a physicist. I would also venture that both are somewhere on the spectrum. Their conviction that I was normal, however, in no way allowed me (or my younger ASD poster child half-sibling) to get through school without incident. When I was much later diagnosed, both of my parents were interviewed. I still got diagnosed several times on the basis of those interviews, including for research purposes, and my sibling's teachers are still becoming increasingly (and vocally) concerned by his behavior. It is, however, also the case that both of us at times have gotten free passes on our behavior in a school setting, on the basis of either academic performance or perceived intelligence..

  • http://www.blogger.com/profile/13896185855308028393 Ruth

    Sorry for the typo-filled previous post.

    There may be something to this, but ASD is complex, obviously. With maternal age, the risk of having an autistic child also goes up. One theory is that fetal testosterone levels go up with maternal age and that this contributes to “masculinizing” of the brain. So wealth is probably an indirect factor; maternal and paternal age is higher, as is the chance that you are in a systemizing profession.

    I have 2 kids with ASD (HFA/high-normal IQs); first-born came when I was 38 and second when I was 40. Husband is EE/CS from MIT. I am an analytic philosopher. My father is EE and my uncle was an accountant; his son has severe Asperger's and has an accounting degree (apparently unusable because of social impairment and anxiety). We also are all high SES. Given all these risk factors, it would be surprising if my kids didn't have it. Clearly, paternal age (42 with the first one) could be a factor, but it is confounded by so many others.

    It would be good to know if there is a difference in prevalence of ASD w/mental retardation in different income groups, as I would bet that ASD with MR probably has a different etiology. Do wealthy people's kids with ASD show the same rate of co-occurring MR? Simon Baron Cohen talks about the S-type brain, but if you read his popular book on this, he really only talks about ASD people without MR.

    Also, where does Ian (?) get the statistic that 99/100 people diagnosed with ASD have “nothing wrong with them.” Do we just get make things up here? It probably is true that some people are misdiagnosed, but that's a far cry from “nothing is wrong with them.”

    © 1999-2010 Google

  • http://www.blogger.com/profile/12135843616500795566 froggyprager

    I agree with passionlessDrone that further exploration of the environmental factors that could explain part of this result. Either the parents, in-utero or something babies are exposed to. Given the low incidents of ASD, it would not have to be something all rich people are exposed to but something a higher share would be exposed to. In addition to endocrine disruptors, what about medicines that more wealthy pregnant women would take or wealthy people would more often give to a baby. What about mercury in fish that are more typically eaten by wealth (sushi?)? We are fairly rich and when my wife was PG, she got many medicines which are commonly given to pregnant women who get “good” maternal health care that maybe lower income people would not get as often? This finding may lead to a discovery that has little to do with money.

  • Anonymous

    The vaccine theory has been debunked. Or has it?

    Poor families are far less likely to have their kids get all their shots on time.

    Where's the study that has tracked non-vaccinated kids? They're the control group.

    By the way, my son has been constipated since he's born. Solving his gut issue (still ongoing) has led to huge gains. Digestive enzymes baby!

  • http://www.blogger.com/profile/03336013668591821868 Orson

    The hypothesis that the parent's age is a factor could be tested. For example, if age is a factor, then the risk of Autism should presumably be higher for the 2nd or 3rd child than for the first child.

  • http://www.blogger.com/profile/11232752398252841794 Don Cox

    “The vaccine theory has been debunked. Or has it?”

    Yes, completely.

  • http://www.drberg.com/ Dr Eric Berg

    nice to read comments / reaction. i just don't learned from the article itself but from the comments also.

  • http://www.blogger.com/profile/13250178392806163363 Elan
  • Matthew

    How about birth induction and synthetic oxytocin?
    Given that there's a correlation between wealth and birth induction rates, and also one between autism and oxytocin levels. It's therefore logical to hypothesise that the administration of synthetic oxytocin during the birth process may be having a permanantly damaging effect on the brains of some infants.

  • http://www.blogger.com/profile/01087601235530226889 A Bitter Pill

    “autism spectrum” is quite the thing now, isn't it? I have to question how you diagnose from abstracted data. I also have to question why you believe that some children with autism would go through their childhood unnoticed as such. Is it because the boundaries of the diagnosis have expanded so radically that we now want to diagnose children with even the slightest aberration in communication skills, etc? I'm not going to speculate about etiology because there is no definitive evidence pinning it down as yet, but autism does seem to be a disease of affluence, as asthma is.

    Mostly, I want to point out that whether or not the findings of this study are accurate, in the poorer places of the globe, the child who makes a little less eye contact is not going to be recognized as having a disease. That mentality is itself a disorder of wealth. I mean, when you have children dying of malnutrition, dysentery, cholera, tuberculosis and rabies, your priorities are going to be a little different. Just ask anyone who has done health care in the Third World or the Fourth World.

    Just my thoughts, but thanks for posting this.

  • http://www.blogger.com/profile/06647064768789308157 Neuroskeptic

    A Bitter Pill:

    “I also have to question why you believe that some children with autism would go through their childhood unnoticed as such. Is it because the boundaries of the diagnosis have expanded so radically that we now want to diagnose children with even the slightest aberration in communication skills, etc?”

    This is certainly a big worry, because it's pretty clear that other child and adult psych disorders are being over-diagnosed and over-treated.

    I think this probably will happen with autism, because it almost always does, eventually.

    However that doesn't mean it's happened yet. At the moment a lot of autism goes undiagnosed. What tends to happen is that the child or adult clearly has “something going on” but it's not formally diagnosed as anything. When you look into it in detail, it quite often turns out to be autism.

    Whether a diagnosis of autism helps those people is an entirely separate question of course.

  • http://www.blogger.com/profile/00187465138890222167 LokaSamasta

    Hi, Sorry I'm late.

    Maybe it's a case of C, D, E, F… X, Y and Z correlating with B and B causing A.

    B being 'hyper-nutrition' and A being Autism.

    http://silencedbysilencedbyageofautism.blogspot.com/2011/10/hyper-nutrition-as-driver-for-asd.html

  • Anonymous

    Autism is a lot simpler than they think.

    Smart kids are forced to socialize with large groups of inferiors who subtly recognize their abilities and gang up on them.

    The cure for autism is more private schools for smart kids.

    Less smart kids get to go to private schools, because of the Great Depression which knocked a lot of rich people out of wealth. That's what's causing the epidemic.

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Neuroskeptic

No brain. No gain.

About Neuroskeptic

Neuroskeptic is a British neuroscientist who takes a skeptical look at his own field, and beyond. His blog offers a look at the latest developments in neuroscience, psychiatry and psychology through a critical lens.

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