Okay, I’m back. I really did fracture some ribs and I have a partially atelectatic lung. The prognosis is good as long as I keep breathing deeply, but it hurts like hell and I can’t sleep. I’ve been gone for about ten days and the world has gone berserk on the MMR vaccine & autism issue. Once more into the breech dear friends, once more, or close the wall up with our measles dead. As light background reading away from the fray, I recommend “Mercury, Vaccines, and Autism: One Controversy, Three Histories,” which was published in the American Journal of Public Health in the February 2008 issue. The author, Jeffrey P. Baker, MD, PhD, of Duke University, writes as a historian of the controversy in hopes that “…an understanding of this history provides important lessons for physicians and policymakers seeking to preserve the public’s trust in the nation’s vaccine system.” There seems to be a strong hint in Professor Baker’s paper that in early 2008 we were entering a cooling off period in which it might be possible to “take a first step toward transcending the powerful boundaries shaping today’s vaccines controversies.” No such luck.

I would like to dive right in and talk about the apparent rising frequency of autism, the so-called “epidemic.” I’m sure many of you know the arguments about how this autism epidemic might relate to the MMR vaccine. The simple argument goes like this: (1) There has been a drastic increase in the number of cases of autism over time; (2) this must be related to some new environmental exposure that didn’t exist before; (3) the only exposure that anyone’s come up with that seems to have coincided in time with the autism epidemic was (a) in the United Kingdom the MMR vaccine (b) in North America more specifically the preservative thimerosal in the MMR vaccine. There are a lot of problems with this line of reasoning. In this first post I’d like to show you that there probably has been little or no increase over time in autism.

There have been many epidemiological studies of time trends in autism rates among children born in the last three decades. All of the studies have reported increases. For each these studies, there seems to be one or more commentaries or reviews arguing that the apparent increase is an artifact due to changes in diagnostic practices, etc. In fact, I should make it clear that authors of the time trends studies themselves often concluded that the increases they found were due to such changes in diagnostic practices, etc. However, the most elegant paper I’ve come across on this topic was published in in the June 2007 issue of the Journal of the American Academy of Child and Adolescent Psychiatry. The three authors are Dr. Ashley Wazana of the Department of Psychiatry at Montreal Children’s Hospital, and Drs. Michaeline Bresnahan and Jennie Kline of Columbia University’s Department of Epidemiology. The authors looked at 12 studies that reported on time trends in the frequency of autistic disorder. Using a rather sophisticated modeling technique called prediction analysis, they concluded that observed increases in autistic disorder over time can be explained by three phenomenon:

  1. “Diagnostic criteria have changed over some part of the period during which increases have been observed.” The diagnostic criteria for autistic disorder were broadened over time.
  2. The average age of diagnosis for autistic disorder became younger (for example, in California, from about 7 years old for children born in 1987 to about 3 years old for children born in 1994 [Croen & Grether 2002]).
  3. Diagnostic substitution: “The efficiency of ascertainment (the probability that a true case is identified) has increased with greater awareness of the condition, introduction of new treatments and new resources, advocacy, broadening of diagnostic experience, and changes in diagnostic practices…”

Congratulations to Drs. Wazana, Bresnahan, and Kline for a most enlightening paper. The title is “The Autism Epidemic: Fact or Artifact*?”

Next post: Kudos to South African 24.com, for their story Rise in autism over-estimated? They seem to be the only media outlet to have reported on a paper in the May issue of Developmental Medicine and Child Neurology on Autism and diagnostic substitution.

*An artifact is (1) an error introduced by measurement methodology; or (2) a data error caused by the instrument of observation. In this case, measurements improved over time.

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28 Responses to “THERE IS NO AUTISM EPIDEMIC: It’s an artifact*”  

  1. 1 Kev

    This is a great post. Thanks for it. Have you by any chance been reading the epidemiological evidence presented as part of the Autism Omnibus?

  2. 2 EpiWonk

    @Kev: I’ve only read the evidence presented on your website (http://leftbrainrightbrain.co.uk/). I can’t disagree with the quantititative arguments put forth by Professor Sander Greenland, but he seems to be sabotaging the case from within.

  3. 3 Matt

    One point–

    the MMR doesn’t contain (nor has it ever contained) thimerosal. Those are two separate ideas. Neither appearst o be good.

  4. 4 Donna

    Even if there is no epidemic, isn’t it possible that there has still been an increase in autism cases. The large changes in diagnostic criteria could mask other changes. I’m very interested in the idea that since being autistic is associated with medical problems (like breech birth and using antibiotics) it is possible that there was a real increase in the number of autistic children surviving, especially in the earlier part of the twentieth century. This could help explain why autism came to the attention of people in authority, and could have led to a better understanding of autism and broadening of the autism definition. I know that the direction of causation is not proven, but it makes more sense to me that autism causes problems in childbirth and other medical problems, rather than such a wide range of medical problems causing autism.

  5. 5 EpiWonk

    @Donna: Your idea is interesting and certainly possible. The concept is similar to what most perinatal epidemiologists now hypothesize about spastic diplegia (the most common form of cerebral palsy) — that spastic diplegia occurs during the prenatal period, but is then causes problems during labor and delivery.

  6. 6 Donna

    Epiwonk - How interesting! I started reading some about spastic diplegia, and I see what you mean. I hadn’t known that. I really would love to have people discuss and debate this idea as it relates to autism, but so far I haven’t seen it, or I generally get silence when I try to introduce it into a conversation. I’m guessing that it doesn’t fit well in the current autism conversation which seems to have only two sides 1) bad environment causing epidemic or 2) no epidemic, no increase. Also, even though I think we should do everything we can to improve and extend people’s lives, I’m afraid that someone might see my argument as a call to stop saving people. I don’t mean that! Anyway, thanks.

  7. 7 jdc

    Fascinating post Epi Wonk. Thanks.

    Re diagnostic criteria changing - I remember reading something very interesting about the changing diagnostic criteria for AIDS meaning that the median survival time for AIDS had increased. (If I have it right, more people were diagnosed with AIDS due to the changing criteria and the population of diagnosed AIDS victims became, on average, healthier due to the inclusion of healthier people who previously would not have ‘ticked enough diagnostic boxes’).

    Of course, some people will never accept changing diagnostic criteria or diagnostic substitution as reasons for increases in autism. I read on a forum recently that autism was only identified in the 1940s some 5 years or so after the introduction of mass vax schedules - it didn’t seem to occur to them that pre-1940s autism might have been diagnosed as something else.

    Anyway - a great post and I look forward to reading more.

    Cheers,
    jdc.

  8. 8 Uncle Dave

    “The prognosis is good as long as I keep breathing deeply,
    but it hurts like hell and I can’t sleep.”

    Even though it is May 23rd I bet you still have trouble sleeping?

    Fractured ribs make for lousy sleep for a least few weeks as I recall.

    Best of luck to renewed REM sleep nights.

  9. 9 Uncle Dave

    This is a great post.

    1. “Diagnostic criteria have changed over some part of the period during which increases have been observed.” The diagnostic criteria for autistic disorder were broadened over time.
    2. The average age of diagnosis for autistic disorder became younger (for example, in California, from about 7 years old for children born in 1987 to about 3 years old for children born in 1994 [Croen & Grether 2002]).
    3. Diagnostic substitution: “The efficiency of ascertainment (the probability that a true case is identified) has increased with greater awareness of the condition, introduction of new treatments and new resources, advocacy, broadening of diagnostic experience, and changes in diagnostic practices…”

    Absolutely!!!

  10. 10 Dr. T

    “In this case, measurements improved over time.”

    Is that true? With autism diagnoses being made at very young ages and at much greater frequency, isn’t it likely that many diagnoses are wrong? Can physicians truly diagnose mild to moderate autism at age two? And do physicians ever reevaluate the supposedly autistic children and change their diagnoses? I doubt it.

    I believe that we have two false childhood epidemics that arise from incompetent physicians jumping on popular bandwagons: autism and attention deficit disorder/attention deficit hyperactivity disorder. How low has the diagnostic bar for autism dropped? Is diagnosis better than before or is misdiagnosis more prevalent? The diagnoses of ADD/ADHD increased approximately 20-fold over two generations, which seems quite impossible to me. Apparently, a 5-year-old boy who fidgets while the kindergarten speaks now qualifies as ADHD.

    I often wonder how much of this is physician greed. Applying a diagnostic label of autism or ADD/ADHD means a steady stream of office visits to assess the condition, to check for drug side effects, and to change drugs or adjust dosages. It means more visits from drug reps who provide gifts and perhaps big perks such as all-expenses-paid invitations to “speak” at CME meetings in Hawaii or Jackson Hole. (Yes, I’ve grown to distrust many physicians. As a pathologist, I’ve seen much incompetence and greed-related physician behaviors.)

  11. 11 RAJ

    There is no autism epidemic, it is a myth generated by new concepts of what autism actually is. The conditon was first recognized by Leo Kanner in 1943. Kanner’s brilliance and insight was that he was able recognize the core defining feature, what he called the ’sui generis’ of infantile autism, an ‘in difference to the existence of other people’. The children he described would not realize a parent had been gone for an afternoon or a month and upon returning home it was as if the child had no concept of what a human being was, even the existence of the childs own parents. Parents were treated as ’sticks of furniture’.

    The entire autism epidemic can be traced to the introduction of the various editions of the APA’s DSM beginning in 1987 with the introduction of DSM-III-R. In that edition the criteria for social deficits relegated Kanner’s definition to one of five isolated symptoms with no requirement that Kanners definition must be present. DSM-IV was introduced in 1994 and Kanner’s definition was completly removed and replaced with the vague, ambigous and subjective ‘impairment in social reciprocity’, and the trajectory of the epidemic exploded.

    In 1965 Kanner wrote an article on the medical community’s response to his 1943 article defining the syndrome:

    http://neurodiversity.com/library_kanner_1965.html

    A few comments by Kanner which are entirely relevant to the current epidemic and discusses what might be called the first autism epidemic that took place a decade after Kanners article was published in 1943.
    ——————————
    This sage advice was not heeded by many authors. While the majority of the Europeans were satisfied with a sharp delineation of infantile autism as an illness sui generis, there was a tendency in this country to view it as a developmental anomaly ascribed exclusively to maternal emotional determinants. Moreover, it became a habit to dilute the original concept of infantile autism by diagnosing it in many disparate conditions which show one or another isolated symptom found as a part feature of the overall syndrome. Almost overnight, the country seemed to be populated by a multitude of autistic children, and somehow this trend became noticeable overseas as well. Mentally defective children who displayed bizarre behavior were promptly labeled autistic and, in accordance with preconceived notions, both parents were urged to undergo protracted psychotherapy in addition to treatment directed toward the defective child’s own supposedly underlying emotional problem.

    By 1953, van Krevelen rightly became impatient with the confused and confusing use of the term infantile autism as a slogan indiscriminately applied with cavalier abandonment of the criteria outlined rather succinctly and unmistakably from the beginning. He warned against the prevailing “abuse of the diagnosis of autism,” declaring that it “threatens to become a fashion.” A little slower to anger, I waited until 1957 before I made a similar plea for the acknowledgment of the specificity of the illness and for adherence to the established criteria.

    The 1960’s have witnessed a considerable sobering up. The fashion deplored by van Krevelen has gradually subsided. This is perhaps caused in part by the fact that those who go in for the summary adoption of diagnostic cliches have now found another handy label for a variety of abnormalities. Instead of the many would-be autistic children who are not autistic, we have the ever-ready rubber stamp of “the brain-injured child.” While this certainly is regrettable, it has at least driven the acrobatic jumpers onto another bandwagon and has left the serious study of autism to those pledged to diagnostic accuracy. Hence, it is easier to single out properly designated cases, not lost in the shuffle of a peculiarly miscellaneous deck, for an investigation of their pathognomonic characteristics. And indeed, in the past few years, the diagnoses made have been more uniformly reliable and the discussion has been considerably less obfuscated by the smuggling in of irrelevant materials.
    —————–

    The bandwagon jumpers now have a new diagnostic liche to embrace… The Autism Spectrum Disorders (ASD’s). It is entirely reasonable to quote Kanner’s 1965 article and argue that none of the isolated symptoms contained in the various ASD diagnostic gold standard checklists are actually specific to autism since they are all based on the same DSM-IV criteria and the removal of Kanners core defining feature.

    When such diverse and unrelated conditions as mentally retarded Fragile X boys, children with specific developmental language impairments and even Romanion orphans who were institutionalized as infants all qualfy for an ASD diagnosis, it has nearly rendered the concept of ‘autism’ meaningless.

  12. 12 Uncle Dave

    Much diagnosis likely comes from
    public schools in the form of recommendations
    that a child needs a special needs classroom
    or some degree of assistance that the regular
    education classroom cannot offer.
    From this point it is the obligation of the school
    or school district to asses or test the child
    (standard IQ, Woodcock Johnson assessement etc etc.).

    Parents likely send thier child to a pyhsician at this point,
    however it would be my opinion that many physicians are
    not the best source of developmental diagnosis. Some maybe,
    but I am not sure how well they can evaluate a child based on
    the minimal exposure most physicians have with each patient.

    There is great varitability within school districts and
    individual schools as to thier ability to correctly
    diagnose the actual handicapping condition as well based on teacher
    and staff experince ever decreasing funds and support.

    As EpiWonk advised me as to the source of Autism data used in
    the Gier study;
    “In the Vaccine Safety Datalink the outcome files are based on “passively” collected
    data from hospitalizations, emergency department visits, and outpatient visits within
    the HMOs, and the diagnoses are then coded as ICD-9 codes. There is no active effort
    to seek out, screen, or diagnose autism or autism spectrum disorders.”

    I believe many of the universities (UCLA locally here) have programs that offer
    exemplary developmental diagnostic evaluations for children.
    Many parents faced with a problem will send thier child
    or be recommended to send thier child to a institute like UCLA
    for a “full workup” to determine with a bit more precision
    the childs handicapping or predominant handicapping condition.

    see UCLA’s website below;

    http://www.uclahealth.org/body.cfm?xyzpdqabc=0&id=502&action=detail&ref=47

    I am sure there are many similar university programs throughout the country,
    but UCLA is local and what I have heard and become familiar with.

  13. 13 Maddy

    [Newbie visiting from Liz] Slightly off topic, but how long do you think it will be until DSM IV is revamped?

    Also, is there any way of comparing the data [number of cases] each time the criteria changed? [Probably not very well phrased, but hopefully that makes sense]
    Cheers

  14. 14 EpiWonk

    @Maddy: My understanding is that DSM-V is currently in consultation, planning and preparation, due for publication in 2012. An early draft will be released for comment in 2009.

    Your question about comparing cases each time the criteria change is a good one. Special studies have to be done. I think there were 5 studies comparing DSM-III to DSM-IV on autistic disorder; all five found that DSM-IV broadened the diagnostic criteria. The study that is generally considered the best of the five was: FR Volkmar et al. Field trial for autistic disorder in DSM-IV. Am J Psychiatry 1994; 151: 1361-1367.

  15. 15 Allegra

    I don’t know whether to take the news of a DSM-V optimistically or pessimistically as regards autism. Will Kanner’s very specific and succinct diagnostic criteria and description be restored? If not, then there is no reason to be hopeful that the spectrum/epidemic chaos will end, or even be ramped down.

    My 33-year-old daughter was diagnosed in 1986, at age 11, according to Kanner’s criteria - just before the disastrous changes in the DSM-III-R. She had been previously misidentified and wrongly diagnosed as emotionally disturbed by school district special education personnel, since at that time only the lowest functioning autistic children were considered “really” autistic.

    Through the years since Kanner’s criteria were first diluted, then discarded, I have broken ranks with every professional, educational, and research organization involved in autism because of the rampant panic and lack of any critical appraisal of the increasingly ridiculous theories based on speculation, junk science, and most regrettably the APA’s snail’s-pace response to the resultant circus.

    I’m cautiously pleased to see speculation and debunking appearing more and more. My question to EpiWonk is this: Will Kanner’s criteria be restored and the notion of ASD be clearly rejected in DSM-V? Will there be any opportunity for lay review and input based on case histories such as those of my daughter and thousands of others correctly identified pre-1987?

    What is the future of what has become a wastebasket diagnosis?

    I would love to see an end to the chaos somewhere on the horizon.

    Many thanks for your scholarly work on this critical issue and the other commenters to this article.

  16. 16 Lobby

    what a real story..

  17. 17 Mali

    commenting usually isnt my thing, but ive spent an hour on the site, so thanks for the info

  18. 18 Blaine

    “Diagnostic criteria have changed over some part of the period during which increases have been observed.The diagnostic criteria for autistic disorder were broadened over time”

    This is a hypothesis that would have to be substantiated by data. No studies have been made that prove that a significant majority of the rise in autism consists of cases that would previously not have been diagnosed as autism. This is reasonable speculation, not proof.

    If autism has become a default diagnosis for other categories of cognitive/emotional imparement, we would expect a statistical decrease in the frequency of non-autistic cognitive/emotional imparements that would be coterminous with the increase in frequency of autism. There seems to have been no attempt to establish that this is the case.

  19. 19 Taylor Finco

    Thanks friend. Good article. Thank you.

  20. 20 noneya

    do any of you have autistic children? spent time with a child ‘diagnosed’ with it? my son is autistic and the mmr you’re carrying the torch for?, my son has a twin brother and he was a normal developing child. we took them regularly for vaccination. after pulling my son from that pediatrician i fought for over a year and had to get a lawyer for them to release his medical records to his MOTHER. guess what? that mmr? my autistic son received two of them. One was to go to his twin and because there were multiple shots involved, which shouldn’t have been given anyway due to their fragile state in prematurity,(medical handbook requirement not to do such) the doctor wasnt paying attention and administered the same two back to back on my now autistic child. His regression began the day of..after the incredible rash, fever, and vomiting, he wasn’t able to sit up on his own at age one, lost modes of transportation and we are working with him now with a natural approach and seeing progression very slowly.

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  1. 1 The Autism Epidemic | Autism Myths
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