Finally, Hard Evidence Against The “Autism Epidemic”?

By Neuroskeptic | December 30, 2012 12:56 pm

The idea of an ‘autism epidemic’ has a lot of people very worried.

No-one disputes that diagnosed rates of autism have increased enormously over the past 15 years or so, around the world. However, other people write it off as essentially a cultural phenomenon: we’re getting better at detecting the disorder and more willing to label kids as having it.

I subscribe to the latter view, but there’s very little hard evidence for it. To prove that diagnostic changes have occurred, rather than a true increase in autism, you’d have to know what would have happened to today’s kids, say, 20 years ago. Would they have been diagnosed? We have no way of knowing. At least not until someone invents a time machine.

However, a new study just out offers a valuable new perspective on the debate: Spatial clusters of autism births and diagnoses point to contextual drivers of increased prevalence.

According to authors Soumya Mazumdar and colleagues, there’s a zone of high autism prevalence in California, areas where kids aged 0-4 years old are more likely to be diagnosed with the condition. The epicentre is L.A.; there’s actually three overlapping hotspots centred on Santa Monica, Alhambra and North Hollywood.

In these clusters, autism rates are between 2 and 6 times higher than the rest of the state.

Now an interesting thing about these areas was that they’re rich in paediatricians, autism advocacy organizations, and money. In other words, there’s better access to health services and probably more awareness of autism. This is suggestive evidence that the reason lots of kids get diagnosed here is about diagnosis, not autism per se.

But the blockbuster result is that children born outside the cluster, who later moved home into one, had a higher chance of getting a diagnosis than those who stayed out. The effect was smaller than for kids born inside the hot zone, but it was significant.

That’s also consistent with the idea that the clusters are clusters of diagnosis, not autism.

It’s not proof. You could argue that there’s some toxic chemical, say, present in the rich parts of L.A. that causes autism, even if you move into the toxic area only at age 3 or 4, and that’s been getting worse recently, leading to rising rates.

But it seems a stretch. What’s the chemical? And why hypothesize one, when the diagnostic services hypothesis nicely accounts for these findings? As the authors say:

The findings reported in this article do not fully reject the possibility that environmental toxicants drive some of the risk of autism … since there are a plethora of possible toxicants, it is impossible to falsify all hypotheses that researchers have started to explore.

ResearchBlogging.orgMazumdar S, Winter A, Liu KY, and Bearman P (2012). Spatial clusters of autism births and diagnoses point to contextual drivers of increased prevalence. Social Science And Medicine PMID: 23267775

CATEGORIZED UNDER: autism, mental health, papers
  • M.J.

    “But the blockbuster result is that children born outside the cluster, who later moved home into one, had a higher chance of getting a diagnosis than those who stayed out.”

    Couldn't this just as easily be caused by families who have concerns about autism moving into areas that have better diagnostic and therapy services available?

    So the reason that more children that moved into the area had a later diagnosis of autism could be that their parents had concerns about their development and had the ability to move into an area with better services.

    I personally know quite a few autism families who did exactly that – they moved into the area specifically because of the available services (diagnostic or otherwise). And if we didn't live in an area that had good services we would certainly move to an area that had better services.

  • ioianthe

    Let's not forget that there *is* a way to know if someone would have been diagnosed 20 years ago-diagnostic criteria has changed DSM III->DSM IV -> DSM IV TR all saw significant increase to prevalence rates. The new DSM 5 has a projected prevalence decrease of 43%, leaving many currently eligible for services under represented. I'm not saying the clusters aren't an interesting trend, just that the idea that we can't know if a kid would have been diagnosed 20 years ago is fallacious. Diagnostic change and diagnostic prevalence directly correlates!

  • Neuroskeptic

    ioianthe: That's part of it, but I suspect only a small part. Services won't even assess for autism with the criteria unless they know about the disorder & consider it a plausible diagnosis (20 years ago many doctors had never heard of it.) And parents won't request an assessment if they've not heard of it. So the criteria don't come into play without cultural factors.

  • Neurobonkers

    I think its worth pointing out Baron-Cohen's hypothesis here as an alternate explanation:

    “Baron-Cohen proposes that systemizing ability can be inherited — and that in information-technology (IT) enclaves such as Silicon Valley, where hypersystemizers are more likely to meet, pair off and have children, the result is a higher incidence of autism.”


    When i was a child autism (except the severe form) wasn't on the radar, and aspergers even less so. didn't get diagnosed till in my 30's. To me it's a combo of finally proper diagnoses getting more frequent AND money/cult driven diagnoses not unlike ADHD with overall real autism staying %ge equal or slightly on the increase due to increased procreation chances for HFA/Aspergers persons. That a toxic element causes autism is absurd, saying that is not understanding autism.

    Which very few do, taking mostly the observable symptoms as being the entire issue. Which they are not, in fact the inverse.

    The symptoms are a tip of the iceberg, the totally different way of perception and worldview are lost on most.

    Many arguments can be made that it's a slow improvement away from limbic dominance towards a more rational way of being.

    Not something most people even want to consider, because emotions are still seen as the holy grail.

  • Neuroskeptic

    Neurobonkers: I find that plausible… but it can't explain the dramatic spike we've seen.

  • Anonymous

    'The surest way to corrupt a youth is to instruct him to hold in higher esteem those who think alike than those who think differently'.

    Of course anyone who is 'different' is classified as 'diseased' and 'treated' with 'medication'. It is the hivemind society that is really 'sick'. Please just sod off all you 'normals' with your middle class aspirations and just leave me alone. I do not need your 'cure'. Thanks.

  • Peter Hildebrand

    A small positive effect in an extremely multi-factorial condition? I predict this study will have an extremely hard time standing up to replication.

  • Anonymous

    Neurobonkers said…

    I think its worth pointing out Baron-Cohen's hypothesis here as an alternate explanation:

    “Baron-Cohen proposes that systemizing ability can be inherited — and that in information-technology (IT) enclaves such as Silicon Valley, where hypersystemizers are more likely to meet, pair off and have children, the result is a higher incidence of autism.”

    This would seem an easy hypothesis to refute. I would suggest it is the middle class parents who want their kids to follow in their own footsteps and become lawyers and bankers etc. Parents in the UK tend to move house to get their children into 'good' schools (i.e not working class) and claim the extra resources available when their children do not meet aspirations, interests or ambitions required. Child or adolescent rebellion can now be cured by psychiatric drugging.

  • Neurobonkers

    No absolutely – personally I don't doubt that increased rate of diagnosis is the major player here.

  • Anonymous

    A boy's natural behaviour has been demonised because education has been feminised. Unruly, aggressive competitive and 'disobedient' boys are compared unfavourably to the more co-operative female 'coyness' by female teachers. Male teachers have disappeared from infant and primary schooling. And are becoming rarer in secondary schools. So boys now 'suffer' from the 'brain diseases' of ADHD, autism and aspergers etc etc. This is so obviously a social problem and not a medical one. Bah.

  • Lindsay

    These results sound a lot like those from an earlier study by some of the same authors. That time, they looked at data from all over California, and found that kids who lived near another kid who'd just been diagnosed with autism were more likely to be diagnosed with autism themselves in the following year.

    That study also made it harder for environmental factors, like pollution or pesticides, to explain it because they looked at communities all over the state, including rural, urban and suburban ones, which would all have very different kinds of contaminants.

    I haven't read this one yet, so I don't yet know if they used the same data set or collected new data.

  • Lindsay

    @Anonymous – kindly tell me when it was that very young children were primarily cared for by men.

  • Anonymous

    I find that hypothesis implausible, because autism is so heritable, yet associated with such low fertility. That really smells like de novo mutations, ie not two nerd parents. The much simpler explanation (that does not require the idea of assortative mating leading to debilitating disease) is: in that area it's okay even cool to diagnose autism spectrum, because they think they're nerd savants.

  • seymourblogger

    There are 2 basic arguments here:
    1. the standard experimental hypothesis replication argument
    2. a more intuitive, connecting the dots arguement that does not necessarily conflict with some of the proposed evidence.

    I do not want to get in this ping pong game but I do want to suggest different ways of looking at it.

    Foucault's power/knowledge/normality Grid elucidated to extreme detail in his Lectures on Abnormal at the College de France 1974-75.

    Lacan's intellectual partner and his analyst Francoise Dolto in her case study book Dominique: Analysis of An Adolescent Boy goes into excruciating detail in a he said/she said account of their sessions over 2 years. A problem all his life there is no doubt when you read this that you will come to a diagnosis of autism. Her sessions with him are astonishing. After the first one you see the improvement in his language ability, whereas before he made no sense at all to ordinary ears.

    Perhaps we can come to a clinical diagnosis of psychosis but where autism begins and psychosis ends is blurry at best for the ordinary layperson, particularly at the time of this case study. If you read it carefully you begin to hear the words of the person with a different hear. Theodor Reik's Listening With the Third Ear. Hope this helps someone.

  • Dan Mirman

    A few months ago Dorothy Bishop posted a very nice summary on her blog showing that the “autism epidemic” is due to diagnostic substitution, at least in the UK:

  • grumpy-xl

    i am puzzled by this blog. is it the accuracy of the diagnosis that is in doubt here? I have never read such study about influenza or obesitas. Or is it about the integrity or objectivity of those who do the diagnostic?
    Would be interesting if there are similar corrrelations for other diseases/disorders like ADHD.

  • Anonymous

    No it doesn't help anyone. Don't give people false hope with that psychoanalysis pseudoscience.

  • RAJ

    The debate over autism diagnosis as an old story between the 'lumpers' and the 'splitters' There has never been a consensus over a strict cutoff that distinguishes disabilty from normal human trait variation. Autism is a multifactorial disorder and what has to be asked is what exactly is inherited in autism, the so-called 'missing heritabilty' problem. Baron-Cohen has authored a study that found that the concordance and heritabilty of 'autistic-like' traits in thousands of general population twins recruited from the Twins Early Development Study (TEDS) registry was exactly the same as that reported in twin studies in autism diagosed twin population.

    See table 2 in the following PDF:

    The probandwise concordance rates in MZ and DZ twins were consistent with what was reported in Hallmeyer et al twin study:

    The greatest obstacle in autism research is failure to reach a consensus in what defines the difference between a disability and normal human trait variation and the defined cutoff between strict autism definition and broad autism definition and the broader autism phenotype.

    Rutter's definition is that what may be inherited in autism is the broader autism phenotype and that autism is always reliant on other genetic mutations, de novo or inherited, environmental risk factors and epigenetic events that disrupt early brain development.

    No easy answers and autism researchers continue to struggle with autism definition.

  • grumpy-xl

    See this lecture from Ted Carr

  • Anonymous

    'See this lecture from Ted Carr'

    Excellent. Especially when he trashes psychiatry. He must be a scientologist. 😉

  • Anonymous

    Lindsay said '@Anonymous – kindly tell me when it was that very young children were primarily cared for by men.'

    I never said that. I said that education today was controlled by women. Hence the rise in autism and ADHD which attempts to define natural male behaviour as a 'disease' because it is compared against 'perfect' female coy traits. I was taught in school by men who understood male behaviour and acted appropriately. My three sons were taught by females who even tried to ban competitive sport in schools!! It took the male parents to intervene and introduce rugby etc.

  • Anonymous

    Well of course, my son's inability to talk, to understand others, his self-damaging repetitive behaviours, his inability to perform even the most basic social interactions, his obsessive requirement that no one in the house touch anything in the room he was in and his refusal to go leave the house without having a violent meltdown, were all just because we've demonised male traits. And all that also completely explains why his perfectly male brother – who has none of these issues and is about as boyish as a boy ever gets – doesn't have autism.

    I can't find the sarcasm font.

    The idea of autism being an extreme male brain, has been falling out of favour for a long time now, and the increased recognition of autism in women is relevant here. Autism presents somewhat differently in girls than in boys.

    I get the impression you haven't had much interaction with autistic children, particularly those at the more severe end of the spectrum. Your speculations are inaccurate, unhelpful, and frankly offensive.

  • Anonymous

    'The idea of autism being an extreme male brain, has been falling out of favour for a long time now, and the increased recognition of autism in women is relevant here. Autism presents somewhat differently in girls than in boys.'

    A sarcasm font is very easy to find when you really need one. Autism = shit mothers. Watch the video.

  • Anonymous

    87.7 % of those with a mental illness have a female mother, I know correlation is not a cause but these statistics makes one thionk. yes?

  • Anonymous

    Yes my mummy was such a bitch too. I am so glad that I am older than her now and she lives in a nice home.

  • Anonymous

    “Anonymous said…

    87.7 % of those with a mental illness have a female mother, “

    As opposed to a male mother?

  • Anonymous

    Yes. Irony is wasted on you lot. Do I have to explain every fuckin joke?

  • Anonymous

    Anonymous said 'Yes my mummy was such a bitch too. I am so glad that I am older than her now and she lives in a nice home.'

    How can you be older than your mother? You are wrong here.

  • Anonymous

    Anonymous said 'anonymous' said “anonymous” said… Oh yeh I made a logical mistake… thanks for pointing it out. I must be stupid.

  • Anonymous

    Jesus wept. I don't blame him.

  • Neuroskeptic

    Great stuff guys! – Bogbrush

    (That's a British meme, it means: lol, these comments.)

  • usethebrains godgiveyou

    A visual for your point. This was put out by Sfari, who I believe outshine Autism Speaks for funds raked in. Click on the map to see what causes autism…green dots.

    Please take a peek. It's so obvious. My son finally got a label of dyslexia, which I fought for. As an autist, he was treated “behaviorally”. His learning differences in Math/writing (dyscalculia/dysgraphia…related and considered stealth dyslexia by some) were TOTALLY ignored. After homeschooling in order to pass his GED at the 93%tile with cold turkey preperation, he is receiving accommodations at the Tech College he attends. As earlier those who were previously diagnosed as MR became “autistic” because there was more money in it, learning disabled kids are getting the shaft, being the new autism epidemic.

    Thanks for your wisdom. We do our kids no favors…

  • Anonymous

    'Great stuff guys! – Bogbrush'

    Guys? It was just me talking to myself. Give me some credit. I have enough trouble proving I am not a bleeding robot.

  • Anonymous

    A spokesman fron the DSM 5 review board said 'well that was a waste of ten years hard work'

    A renowned neurology blogger said 'wibble wobble woobie..

  • Neuroskeptic

    wibble wobble woobie… or in other words, my response to that paper is I don't believe the claims but that's just a gut feeling because I don't have time to read the extremely long methods properly.

  • Aggie

    Autism does not equal shit mothers. If you really think what you say, then I hope you will never have children.
    And if you do not mean what you say – then why do you say anything at all…?

  • Anonymous

    Someone suggests that parents are moving into areas with high numbers of diagnoses to get access to better services, thus explaining the higher number of diagnoses in newcomers. I suppose this could happen, but how far apart are the high-diagnosis areas from the low-diagnosis ones? North Hollywood and Alhambra are districts of Los Angeles, not distant cities; its not like people with TB moving to Colorado for the climate back in the 1900s.

  • M.J.

    I don't think the actual distance between the areas is that relevant. What (typically) matters is whether the services in question are only provided within a certain geographic area and whether you live inside that area.

    If you aren't inside the boundary then you aren't inside and might not qualify whether you miss the boundary by ten feet, one mile, ten miles, or a hundred miles.

    I know families that have moved one mile to gain access to services and I know families that have literally moved from half way across the world for the same services.

  • Anonymous

    Re: maleness and autism. I suspect Anonymous was referring to Asperger's, which Hans himself never linked to autism proper and which, based on the current evidence, has no business being called an “autism spectrum disorder” for sharing a couple of traits in common. Real autism is a big deal (ask Anonymous 2 with the autistic son), Asperger's is made up and its myth embraced and perpetrated in no small part by 4channers who wanna be special snowflakes.

  • Anonymous

    'Re: maleness and autism. I suspect Anonymous was referring to Asperger's'

    When the diagnostic criteria is so open to abuse.. who knows what we are actually talking about?

  • Anonymous

    I read most of the comments, no one mentions the idea that it could be a few overzealous doctors (it would only take a small medical practice)that are causing this hotzone.

  • Neuroskeptic

    That's a good point. Although that wouldn't change my interpretation of the data much. Whether 5 or 50 doctors who are diagnosing lots of autism, it's still the same basic process.

  • Paula

    I think it could also be said that people are no longer warehoused in institutions as they once were and that it's more difficult to kill children with impunity, as in “They fell down the stairs,” and other improbable explanations. Thank goodness for that.

  • Black Book doc


    It is very easy for an incredibly bright aspie having had a successful career and a wife like yourself to do NT bashing and consider that aspies are the future of the species.

    Let's write about the autisms to start with.

    Please petrossa, do not refuse to take into account those who cannot talk or even cannot get a job and a wife beacause they are very slow eaters with a slurred speach etc..

    Anyway with the DSM5 people like you will not qualify to speak for the autistic people…(NB: This is a joke petrossa !)

  • Black Book doc

    My educated view on that topic is that in some places parents and associations of parents put pressure on doctors to diagnose autism in order to get extra support at school for children being left behind for any reason.

    As the first grade cousin of Pr Simon Baron-Cohen, Sasha B-C , made a character tell in one of his movies “Autism is hot” ..

    In other places you get less awareness which protects from false positives at the cost of false negatives -so to speak.

    In my own practice I am battling quietly since June 2012 to get a person to a sleep clinic in order to assess a putative diagnostic of mine of a very bad temper being explained by sleep obstructive multiple apneas since the client sleeps with a lot of pillows and a ventilator to his face since he awakes often in the night suffocating…

    A French association whose leader is -and as the French association often are – is antipsychiatrist has convinced the man of a very wrong diagnosis in my view…But that association has to sell many things to aspies and the more the better.

    Unfortunatly the neuropsychanalysis of many French psychiatrists seing the packing of autistic children in cold wet sheets as the ultimate cure open a boulevard to those charismatic leaders of autisitc associations…

  • Balck Book doc


    And by the way a drawback about seing the autism as the future of humanity is that so many aspies want their NT children to be diagnosed as aspies with the same energy and dedicatyion you put in denying the climate change-so to speak…

    This, in my educated view, might also explain an increase in autism diagnostics in places where aspies thrive professionaly and can afford “to buy Mercedes” and get a wife or husband and raise children.

    To believe it you have to hear for yourself a very bright and good aspie parent telling you that a little social animal of a girl of 5 who wants only pink toys and clothes is autistic based on that obession in pink of hers.I did once.

  • ilovetrash

    alhambra is not a rich area. neither is much of north hollywood. otoh, yr conclusion is correct. autism &, particularly, asperger's syndrome have lost their meanings & become together just one more disease of the week, another label that can be affixed to people who do not label easily. this isnt good & it isnt helpful but it is what is cooking. not just in los angeles, either, but, instead, like so many other things: a seed planted in the filthy fertile ground herein grows a shaky tree whose leaves scatter everywhere.

  • Black Book doc


    Thanks, but really I am just a clinician and mine is only an educated guess (or educated opinion in my pitiful English of yesterday.

    That autism diagnostic is trendy and opens in many areas school support for the parent and membership fees, meetings fees and sometimes (in France at least for one “aspie association” group therapies and costly procedures) are facts.

    Still, SSRIs and many other toxic Pharma and street drugs and food additives taken during pregnancies , for example, might also be one of many explanations for the subject of that post: Arch Gen Psychiatry. 2011 Nov;68(11):1104-12. doi: 10.1001/archgenpsychiatry.2011.73. Epub 2011 Jul 4.
    Antidepressant use during pregnancy and childhood autism spectrum disorders.

    ///The prevalence of autism spectrum disorders (ASDs) has increased over recent years. Use of antidepressant medications during pregnancy also shows a secular increase in recent decades, prompting concerns that prenatal exposure may contribute to increased risk of ASD.
    A total of 298 case children with ASD (and their mothers) and 1507 randomly selected control children (and their mothers) drawn from the membership of the Kaiser Permanente Medical Care Program in Northern California.

    (…) In adjusted logistic regression models, we found a 2-fold increased risk of ASD associated with treatment with selective serotonin reuptake inhibitors by the mother during the year before delivery (adjusted odds ratio, 2.2 [95% confidence interval, 1.2-4.3]), with the strongest effect associated with treatment during the first trimester (adjusted odds ratio, 3.8 [95% confidence interval, 1.8-7.8]). No increase in risk was found for mothers with a history of mental health treatment in the absence of prenatal exposure to selective serotonin reuptake inhibitors.

    Although the number of children exposed prenatally to selective serotonin reuptake inhibitors in this population was low, results suggest that exposure, especially during the first trimester, may modestly increase the risk of ASD. The potential risk associated with exposure must be balanced with the risk to the mother or fetus of untreated mental health disorders. Further studies are needed to replicate and extend these findings. ///

  • Lucilyn labajo

    The GED is a collection of five separate tests. These components cover high school level Reading, Writing, Social Studies, Math, and Science. The ACE Testing Service administers the test and provides support to examinees in the form of tips and practice GED exams. They also man an online Q&A portal where they provide responses to frequently asked questions.

    free printable ged practice tests

  • elhnad

    should we not at least consider asking teachers/daycare workers, etc with lots of experience what they’ve observed in kids 20-30 yrs ago vs now. Not the best data, obviously but individual reports could reveal something striking and worth researching more



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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