Jan 08 2009

Is the Rise In Autism Rates Real?

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Comments: 35

It is without controversy that the number of autism diagnoses being made is on the rise. In 1991 there were about 6 cases per 10,000 births, and in 2001 there were about 42. This number continues to rise at about the same rate.

The cause of this rise, however, is very controversial. There are basically two schools of thought: 1 – that true autism rates are on the rise, and 2 – that the measured rise is an artifact of increased surveillance and a broadening of the definition. A new study published today in the journal Epidemiology lends support to the school claiming that autism rates are truly rising – or at least that is how proponents are interpreting it. After a closer look, I am not so sure.

Prior studies generally support the contention that autism rates are rising due to changes in diagnosis and surveillance. (see my list of references below) For example, Taylor, after reviewing the evidence, wrote in 2006:

The recorded prevalence of autism has increased considerably in recent years. This reflects greater recognition, with changes in diagnostic practice associated with more trained diagnosticians; broadening of diagnostic criteria to include a spectrum of disorder; a greater willingness by parents and educationalists to accept the label (in part because of entitlement to services); and better recording systems, among other factors. (Taylor 2006)

This is a fascinating epidemiological question – and one with huge implications. If autism rates are truly static, that would  compatible with the majority opinion that autism is dominantly a genetic disorder. If there is a true dramatic rise in the incidence of autism, then that strongly suggests an environmental cause or trigger.

As an aside, we need to avoid the false dichotomy of genetic vs environmental. Even if autism is dominantly genetic, as the evidence suggests, the effects of gene products ultimately interact with the environment. Complex genetic disorders, such as a neurodevelopmental disorder, is going to have environmental influences.

A “trigger”, on the other hand,  means that that the genes just set the stage, but the disorder does not manifest unless the environment pulls the trigger. This could be an infection, toxin, coexisting disease, or (for neurodevelopmental disorders) the social and cultural environment.

For further background on this discussion I should also mention that at present the majority opinion is that the epidemiological evidence does not demonstrate a true rise in autism rates, but a small true rise could be hiding in the data and has not been ruled out.

I take pains to make these points because critics of the mainstream opinion often attack oversimplified straw men, while scientists working on this question tend to have and express appropriately nuanced opinions.

The UC Davis Study

This new epidemiological study, which must be put into the context of all the other studies on this question, looked at the California database of autistic children. They wanted to specifically test the “increased surveillance and diagnostic range” hypothesis, so they looked at autism rates by age. They found that younger age at diagnosis only accounts for a 12% increase in the diagnostic rates. Meanwhile, autism diagnosis rates have increased by 500-600% since 1991.

They then controlled for two further specific variables. First they eliminated all children who were not born in California. This was meant to eliminate children who were brought into California in order to receive services. They also looked at the severity of the symptoms and concluded that the “inclusion of milder cases” resulted in a 56% increase in diagnoses. So in total they could explain only about a 68% increase in autism diagnosis, which is about 10% of the total increase.

They conclude:

Autism incidence in California shows no sign yet of plateauing. Younger ages at diagnosis, differential migration, changes in diagnostic criteria, and inclusion of milder cases do not fully explain the observed increases. Other artifacts have yet to be quantified, and as a result, the extent to which the continued rise represents a true increase in the occurrence of autism remains unclear.

And yet in the press release for this study lead author Irva Hertz-Picciotto is quoted as saying:

“It’s time to start looking for the environmental culprits responsible for the remarkable increase in the rate of autism in California,”

The disconnect between the appropriately conservative conclusion in her paper and her statements to the media is interesting This probably reflects the fact that peer-reviewed papers have to pass tight scrutiny, and so she could not get away with over-interpreting her results. But to the media she let her true biases be known.

The key to putting this study into context is the phrase “other artifacts”. This study did not control for all possible artifacts resulting in higher diagnosis rates. Specifically, it did not address surveillance, which is likely the dominant factor. It also did not control for shifting diagnosis. In other words, 20 years ago a child may have been diagnosed with a non-specific speech disorder, and today they would be diagnosed with autism, so-called diagnostic substitution as was found by Bishop in 2008.

Another factor is that physicians, teachers, and parents have increased awareness not only of the symptoms but of the autistic label. How many parents who notice that their child is socially withdrawn are going to seek out services or medical attention?

This study did nothing to assess these potentially huge factors. So what this study really did was account for 10% of the increase in autism diagnosis. But it did not show anything about the other 90%, nor rule out the leading contenders for diagnostic artifact. I will add it to my list of references on this question, but it certainly does not overturn all the prior studies listed.

The Vaccine Connection

Of course, the anti-vaccine crowd can be counted on to grab hold of this study, cherry pick it from the other studies whose conclusions they don’t like, and overinterpret the results.  David Kirby has already done so over at the Huffington Post. He wrote a piece today titled: UC DAVIS STUDY: “Autism is Environmental” (Can We Move On Now?) He wants to declare premature victory and “move on,” even when, officially, the study authors had to admit that the question is “unclear.”

He writes:

Autism is predominantly an environmentally acquired disease, the study seems to conclude. Its meteoric rise, at least in California, cannot possibly be attributed to that shopworn mantra we still hear everyday, incredibly, from far too many public health officials: It’s due to better diagnosing and counting.

Compare that to the actual conclusions of the study.  I wonder if Kirby read past the press release.

And, of course, Kirby wants to bring this all back to vaccines.

 (It is important to keep in mind that almost every child born in 2000 would have received many vaccines that contained the mercury preservative thimerosal, which was not completely phased out of most – but not all – childhood vaccines until at least 2003.)

Even if it were ultimately found that autism rates are truly rising, and that this rise was due to an environment factors – vaccines would still be a very poor candidate.  There is already sufficient independent evidence against a significant link between vaccines and autism. If vaccines were causing a 5-6 fold increase in autism that would be a huge signal the studies to date would have picked up.

Also, Kirby fails to mention that the same data base used in this latest study is the one that showed that after thimerosal was removed from the childhood vaccine schedule autism rates continued to rise without any change – pretty much destroying the thimerosal hypothesis he clings to.

As usual the most mindless aspect of Kirby’s commentary is his casual and self-serving assumption of moral and intellectual superiority, even over dedicated medical researchers. He writes:

Now, it’s always been easier and more reassuring to tell ourselves that autism was almost purely genetic, that it was always with us at the rate of 1 in 90 men (1 in 60 in New Jersey) and that, gee, weren’t doctors doing a great job these days of recognizing and diagnosis this disorder.

This pathetic groupthink has helped create hugely lopsided funding priorities in autism, where genetic studies get lavishly funded, while environmental ones are lucky to even pick up the dollar scraps left behind.

It is cheap and easy to portray and hard-won consensus built upon years of research and evidence as “groupthink.” Also, Kirby appears to have insufficient familiarity with the real world or medical research to understand that grants are not earned and careers not made by following the herd. There are many researchers tackling these tough questions from many angles and perspectives. Young researchers hoping to find a niche for themselves are more likely to question dominant beliefs.

In fact, while I disagree with Hertz-Picciotto in her bottom line interpretation of the evidence, I think it is a very healthy thing for researchers with a minority opinion to challenge the majority. This happens all the time. But, of course, the burden is on her to make her case.

Kirby insists that the scientific mainstream disagrees with him, not because maybe they understand the research better, but because they are afraid of the truth. They want to avoid any research that could ultimately point back to vaccines. But this is just conspiracy-mongering self-righteous nonsense.  And it is a huge non-sequitur.

The notion that scientists disagree with someone because scientists are generally unimaginative and afraid of the truth is huge red flag. This is the mantra of the crank.

Conclusion

This latest study is interesting, but was too limited in scope to significantly alter the evidence as a whole. I would not be surprised if some portion of the increase in autism diagnoses were due to environmental factors. But I don’t think current evidence lends much support to this notion either. The current state of evidence strongly suggests that the dominant reason for the increase in numbers is due to changes in diagnostic behavior.

There are many similar epidemiological questions in the world of medicine. I am content to let the chips fall where they may, and will gladly alter my opinion as new evidence comes in. The same does not appear to be true for the Kirby’s of the world. The autism question in particular is mired in a fake controversy promulgated by an ideological anti-vaccine movement that causes no end of mischief.

___________________________________

References:

Hertz-Picciotto, Irva a,b; Delwiche, Lora a. The Rise in Autism and the Role of Age at Diagnosis. Epidemiology. 20(1):84-90, January 2009.

Bishop DV, Whitehouse AJ, Watt HJ, Line EA. Autism and diagnostic substitution: evidence from a study of adults with a history of developmental language disorder. Dev Med Child Neurol. 2008 Mar 31

Chakrabarti S, Fombonne E. Pervasive developmental disorders in preschool children: confirmation of high prevalence. Am J Psychiatry. 2005 Jun;162(6):1133-41.

Fombonne E. Epidemiology of autistic disorder and other pervasive developmental disorders. J Clin Psychiatry. 2005;66 Suppl 10:3-8.Click here to read

Jick H, Kaye JA. Epidemiology and possible causes of autism. Pharmacotherapy. 2003 Dec;23(12):1524-30.

Rutter M. Incidence of autism spectrum disorders: changes over time and their meaning. Acta Paediatr. 2005 Jan;94(1):2-15.Click here to read

Paul T. Shattuck. The Contribution of Diagnostic Substitution to the Growing Administrative Prevalence of Autism in US Special Education. PEDIATRICS Vol. 117 No. 4 April 2006, pp. 1028-1037

Taylor B. Vaccines and the changing epidemiology of autism. Child Care Health Dev. 2006 Sep;32(5):511-9.Click here to read

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35 responses so far

35 Responses to “Is the Rise In Autism Rates Real?”

  1. sonicon 08 Jan 2009 at 4:47 pm

    We know the diagnostic behavior has changed radically-both with doctors and parents.
    It would be wise, therefore, to rule that out as an explanation of increase before moving on. One flawed study would not rule that out. More needs to be known and it may take time for the data to come in and the real situation to become apparent.
    This is such an emotional subject- but the truth often requires more patience than emotion allows—

  2. SDRon 08 Jan 2009 at 5:13 pm

    Thanks for writing on autism from a science-based perspective. Having spent more than a year working with autistic students, it hurts to see all the bullshit and myth that surrounds it. Especially with issues like vaccine paranoia, it doesn’t help them, it only hurts them

  3. Elisheva Levinon 08 Jan 2009 at 5:17 pm

    This is very interesting. I tend to lean toward the idea that those artifacts that were not (yet?) investigated may indeed close the numbers gap for the UC Davis research. I think investigations of the genetics of autism linked to the differences we see in brain development will be very fruitful in the coming years, and also provide us with avenues for interventions to educate and socialize these children.

    At the same time, as a parent of two children, (one of whom has Autism), I did notice that both of them had neurological symptoms following a particular set of vaccinations in which a number were given at once, raising the bolus of thimerosol to which their nervouse systems were exposed. In my daughter’s case, this happened at age 6 with boosters. In my son’s case at age 2, when a large number of vaccinations were given at once because he had missed the 18 months boosters due to illness. In both cases, my children’s symptoms caused me to sit up and take notice. However, the consent sheets I signed never informed me that a mercury compound was being injected into my children as part of the vaccine. As a biologist, I would never have consented to exposing either child to any mercury compound unneccesarily. And at both times, which were prior to my son’s diagnosis, I had very little knowledge of autism.

    In effect, my children and I were unwitting subjects in a very large, uncontrolled experiment to which we did not give informed consent. If this had been an actual human trial, no IRB would have allowed it to proceed.

    Do I think that the vaccinations caused my son’s autism? No. There is quite a lot of evidence from my children’s family tree that genetics played a large role. And looking back, certain signs of autism were present in my son before the vaccinations were given.

    However, there is enough evidence that thimerosol causes cell damage, even in skin cells (so that topically applied medications with this mercury compound have been taken off the market), that I do not think that we should dismiss out of hand that a large bolus could affect a vulnerable developing nervous system, and possibly exacerbate developmental anomalies associated with autism (and possibly other genetically induced neurological disorders as well).

    I agree that the Kirby’s of this world are unwilling to change their maps of reality to match incoming evidence. However, I would like to present a different viewpoint about why this may be so.

    I think the distrust that many parents feel about vaccinations comes from the fact that the public was not adequately informed that a heavy metal known to cause neurological damage and other cell damage was a component of government-required vaccinations. Further, when questions about this preservative were raised, the first response of the CDC was to keep information from the public (the people paying for all of this) in order to protect the vaccination programs. A noble goal, perhaps, but an arrogant one that assumed that non-scientists, as well as scientists who are parents, are completely unable to make reasonable decisions about how to deal with the dilemma.

    I continued to have vaccinations adminstered to both children, however, I have specifically requested and paid for non-batch vaccinations that do not use heavy-metal preservatives. This is a reasonable solution to the problem given what we know about the benefits of vaccinations.

    As a scientist, and one working in the field of autism, as I watch this political controversy unfold, I am reminded that the first obligation of a scientist is that of integrity. Non-scientists will rightly refuse to believe any conclusions we make if they see that we are willing to obscure information for political reasons.
    And at the practical level, the public a right to accurate information from goverment agencies because they pay the bills.

  4. MarkMarijnissenon 08 Jan 2009 at 5:28 pm

    What a nice post. It was nice to read how a scientific study gets distorted and abused by the press and people like Kirby. I always know popular media over simplify and distort science, but I never make efforts to seek the complete story.

  5. Karl Withakayon 08 Jan 2009 at 6:37 pm

    Another thing the “autism is environmental” zealots seem to be overlooking is that if autism truly is on the rise, then the cause of autism must also be on a corresponding/proportional rise as well. If every year, the number of individuals in a given age group increases by X %, there should be a corresponding/proportional increase in the cause/trigger of autism, otherwise, you would expect the numbers to level off when the cause/trigger levels off.

    One thing that could explain the continued rise in autism diagnoses rather well is the firestorm effect related to increased surveillance and diagnostic substitution, etc. In a firestorm, the heat from the fire heats the air around the fire, which then rises due to its lower density. This brings in fresh air, which fans the fire, causing it to burn hotter, heating the surrounding air more, causing it to rise and bring it new fresh air even faster in a run away effect- a firestorm feeding on itself.

    Autism has perhaps become a firestorm diagnosis.

  6. Oracon 08 Jan 2009 at 7:30 pm

    In other words, 20 years ago a child may have been diagnosed with a non-specific speech disorder, and today they would be diagnosed with autism, so-called diagnostic substitution as was found by Bishop in 2008.

    Yes, this paper dropped the ball in not adequately controlling for diagnostic substitution. If I recall correctly, the overall percentage of children in the system with neurodevelopmental disorders has been fairly steady. If the true prevalence of autism were truly rising this dramatically, then we would expect the overall caseload to increase. What is probably really happening is that the same kids who need help are simply being diagnoses as autistic instead of mentally retarded or schizophrenic, as they may have been 20 years ago. After all, there wasn’t even a DSM category for Aspergers and other autism spectrum disorders (such as pervasive developmental disorder, not otherwise specified) before the early 1990s. There was autism, and there was everything else.

  7. HHCon 08 Jan 2009 at 11:10 pm

    Current patterns of state funding makes the use of the autism category more commercialized. The category is not assigned by better diagnosticians but ones wanting more bucks for programing. After all, medical nosology is a specialty. The proper use of the Diagnostic and Statistical Manual requires specialized training. Grass root programs have workers with basic skills in dealing with clients, not highly specialized clinical training. Before the movement for special funding for autism, states funded mental retardation and mental illness separately. Later dual diagnosis, MR/MI became acceptable. Many autistic behaviors are standard in severe mental retardation.

    I would look for rising Amercian statistics in alcoholism and drug usage to explain an increase in autism, if there truly is a genetic basis. Domestic violence statistics would point in the direction of a cultural/environmental factor in autism.

  8. wertyson 09 Jan 2009 at 12:19 am

    One factor which has been in the literature for a while, and which doesn’t seem to come up in these discussions is the effect of assisted fertilisation techiques on Cerebral Palsy and ASD rates. The data are inconsistent but this is an abstract of a new systematic review from Scandinavia which shows the association is possibly real, though unclear.

    http://www.ncbi.nlm.nih.gov/pubmed/19124707?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum

    There are other negative systematic reviews, but given the meteoric rise in use of assisted fertility treatments in developed countries this is worth bearing in mind as well as simpler explanations such as environmental triggers (which really have been investigated to death without any real associations being identified.)

  9. weingon 09 Jan 2009 at 12:21 am

    If there really is an increase in autism, one environmental factor to consider is the use of oral contraceptives by the mothers during courtship. This would predispose them to favor partners with similar HLA types to themselves who are more likely carriers of mutations they themselves carry and allow recessive traits like autism to manifest.

  10. andyschwabon 09 Jan 2009 at 4:38 am

    One thing people consistently forget is that Autism was only really positively identified by Kanner in the 1940′s, although many, myself included, could argue he stood on the shoulders of giants such as Bleuler and Gaspard-Itard.

    Essentially Autism as a diagnosable condition is very much in it’s infancy, and let’s not forget it’s very much a buzz word at the moment- as much as parents crave achievement, wealth and fulfillment for their neuro-typical children, they seek closure, a label and an explanation for those who aren’t so lucky. This is entirely conjecture on my part, but can we be certain that every child with a withdrawn nature, communication deficit or any other difficulty be diagnosed with an Autistic Spectrum Disorder for the sake of ease and closure? Whilst my reasons for thinking this are entirely anecdotal it would further explain the consistently increasing diagnoses.

    I have never been convinced of the vaccines arguement, and even the title of UC Davis’ paper has an ‘I’m right, your wrong, shut up’ feel to it. Whilst that doesn’t prove everything he’s saying is wrong, it scarcely argues against it.

    The UC Davis’s of this world would be better served researching properly and accepting that co-relation and causation are not necessarily one and the same (which really does seem to be the centrepoint that everything else revolves on for them). As an Autism professional I doubt very much that vaccines have anything to do with Autism- but I, like pretty much everyone else here, am perfectly open to new ideas so long as they are properly researched. To date this theory has not been, and until it is their argument will lack credibility and people like myself will not, as Davis puts it ‘move on’.

  11. passionlessDroneon 09 Jan 2009 at 9:02 am

    Hi Weing –

    If there really is an increase in autism, one environmental factor to consider is the use of oral contraceptives by the mothers during courtship. This would predispose them to favor partners with similar HLA types to themselves who are more likely carriers of mutations they themselves carry and allow recessive traits like autism to manifest.

    Very interesting line of thought. Nicely done.

    - pD

  12. [...] NeuroLogica delves into the controversy surrounding the rise in autism rates [...]

  13. daedalus2uon 09 Jan 2009 at 4:33 pm

    I completely agree that the vaccine idea is wrong and is a dead end. It is driven by lawyers and quacks due to greed, not by science based on facts and logic.

    The problem with the idea that oral contraceptives might be related to autism is that there is evidence for a negative correlation between oral contraceptive use and autism.

    http://www.pediatrics.org/cgi/content/full/107/4/e63

    Other things that correlate negatively with autism (from this paper) include smoking and vaginal infection. Things that correlate positively with autism include uterine bleeding, Rh incompatibility, induced labor, prolonged labor, precipitous labor and hyperbilirubinaemia.

    A final common pathway in all of these is basal NO level. Oral contraceptive containing estrogens cause the release of NO via activation of the estrogen receptor. Infections cause expression of iNOS and raise NO levels. Carbon monoxide binds to heme and so has some cross-talk with NO on some heme containing enzymes (such as guanylyl cyclase).

    Hemoglobin is the sink for NO, so uterine bleeding would reduce NO levels, Rh incompatibility causes hemolysis of fetal erythrocytes and free hemoglobin is ~600x more effective at NO destruction that is hemoglobin in erythrocytes. The neuroanatomy characteristic of people with ASDs starts in the first trimester when those structures of the brain are first formed.

    There are a number of other factors that also correlate positively and negatively with autism, and those factors correlate negatively and positively with NO status. I recently presented a poster on low NO as the final common pathway in ASDs. When I have time I will post it as a blog.

    Some single gene mutations (such as the MeCP2 deletion observed in Rett Syndrome) may cause autism-like symptoms by causing metabolic stress (which lowers NO levels). In Rett Syndrome this may result because women are mosaic because one X chromosome is inactivated and because the missing MeCP2 gene is one of her X chromosomes. Loss of MeCP2 causes aberrant readout of DNA methylation, and will cause mosaic organs to be out of “sync” metabolically. That leads to metabolic stress, and the generic response to metabolic stress is to lower NO levels. In mouse models of Rett Syndrome, the phenotype has been produced with surprising fidelity, and is resolved by restoring MeCP2 activity. A resolution that is reminiscent of the transient resolution of autism symptoms during acute fever (which I think is due to NO from iNOS, see my blog of a year ago).

  14. theoon 09 Jan 2009 at 11:36 pm

    @ Karl Withakay: That’s so obvious – I’m very annoyed for not thinking of it before.

  15. weingon 10 Jan 2009 at 7:00 am

    daedalus2u,
    There goes that hypothesis down the drain. I wasn’t aware that a study of oral contraceptive use during the courtship stage by the mother and subsequent autism had already been done.

  16. HHCon 10 Jan 2009 at 9:39 am

    Autistic behaviors are also present in mentally retarded / organic
    brain damaged patients with syphillis or within families that inbreed.

  17. MindDocon 10 Jan 2009 at 11:07 am

    I am a school psychologist, and therefore responsible for diagnosing school-age children with a variety of disorders, including those on the autistic spectrum. Even with my awareness of “fad” diagnoses (why isn’t anyone obsessing over the AD/HD increase?, and don’t get me started on teens being labeled bipolar…), I still find myself diagnosing kids with Asperger’s, even those as old as 13, far more than I would expect based on my training. An overlooked factor I am curious about (in addition to what has been addressed here), is a comparison with a drop in per-student funding. Let me explain: a student hoping to receive Special Education Services requires a diagnosis. As school funding dries up slowly, classes get larger. That odd kid in the back with questionable hygiene and no friends? He’s not getting the direct attention he needs in the early elementary years to keep up with the material… he keeps spacing out. Now he’s in 7th grade, getting mostly D’s and F’s, but he can dismantle and reassemble a computer without any help. Maybe early intervention with some of these kids eliminates the need for a label and services, but there are now 31 kids in the room, and the teacher (whose training to deal with a student like this is, while improving, minimal) just wants him gone. I get a referral, test him until we can’t stand each other, and get him into the Special Ed. funding pool with a label of Asperger’s. Make no mistake: he definitely qualifies; it’s just that maybe if he had had social skills training and other interventions (including parent education) in K-2nd grades, I would never get that referral. Not to mention that the gold standard in Psych. research and testing is certainty to the .05 level! I can be wrong 5% of the time and call myself a great psychologist. Just something to think about. The anti-vaccine people think it’s like diagnosing diabetes, but they have NO clue how subjective and variable the whole process can be. By the way, if parents disagree with my findings, they can refuse to sign any documentation, and the kid does NOT get services. This is not even close to pure medicine (which itself is far from perfect).

  18. daedalus2uon 10 Jan 2009 at 11:49 am

    There are many things that will cause “autism-like” behaviors. There are a few dozen or more single or multi gene deletions that cause autism-like behaviors. In utero thalidomide exposure will cause it, anti-epileptics will too, so will several different maternal viral infections. Maternal exposure to stress while in utero is strongly linked to autism too. Social isolation increases autism behaviors in humans and also in primates. Social isolation in rodents epigenetically programs decreased NO levels in the brain.

    The question of “are these all autism” is still open. There is tremendous heterogeneity among populations diagnosed with autism and with autism-like symptoms. Individuals with autism can have quite variable behaviors also. The diagnosis is only from behaviors. When those behaviors reach a clinical threshold is completely arbitrary. As behaviors, they are only diagnosed by the subjective decision of the clinician diagnosing the behaviors.

    Every cause that I have been able to find documentation for does couple to NO physiology and produces a reduction in NO levels/signaling. The pathways that are affected are also regulated by NO and are skewed in a low NO direction. Stress causes a prompt reduction in NO levels and many of the stress mediated pathways are triggered and regulated by that low NO.

    HHC, interesting that you mention syphilis. I have not heard that before. Do you have a link? Before antibiotics were developed, the standard of care for neurosyphilis was fever therapy, inducing malaria and letting the patient go through about 10 cycles of fever before curing the malaria with quinine. This is reminiscent of the paper on resolution of autism symptoms with fever by Zimmerman. I blogged about that a year ago.

  19. stewarton 10 Jan 2009 at 2:08 pm

    I scanned the paper. Unfortunately, they do not review the large number of studies that do provide evidence for diagnostic substitution – the proportion of children needing services is relatively constant, but the specific labels change over time. There’s no mention of Shattuck, or Wing & Potter, or the large discrepancies between states in autism diagnoses, but the similar proportions of children needing services.
    I recommend the paper by Gernsbacher, Dawson & Goldsmith (2005), for a more reasonable look at this.
    http://www.psychologicalscience.org/pdf/cd/autism_epidemic.pdf

    I think it would e instructive to go into an old psychiatric hospital, look at the patient records from 50 or 100 years ago, and compare the modern diagnoses with those provided at the time.

  20. Josephon 10 Jan 2009 at 2:27 pm

    The theoretical problems of the study, like not considering diagnostic substitution, can be more broadly explained as a failure to consider awareness as a factor. Obviously, it’s not enough to consider diagnostic criteria changes and such. If there’s zero awareness, no one gets diagnosed.

    I’ve written a theoretical critique of the paper and I’ve also looked at its numbers.

  21. jruchon 10 Jan 2009 at 2:55 pm

    An understanding of ones own bias is always important. I read a lot of speculative filling in the blanks in these posts in dismissing the unexplained 90% rise in autism identified by the study. I suspect that in finding that the ‘“inclusion of milder cases” resulted in a 56% increase in diagnoses’, the study has in fact controlled for shifting diagnosis. Severe cases of autism are difficult to miss because of their symptoms unmistakable impact on all aspects of life. A six year old who does not speak, is not potty trained, has autism related sensory issues, stims, and has an unmistakable lack of normal social interaction will not leave a doctors office or enter a school without raising flags. This is the group that is hurt the most by dismissing the potential role of environmental factors on a genetic predisposition. If the unknown and therefore dismissed corresponding environmental influence continues to be ignored, then I think we can expect to increasingly find that future children who would have otherwise gone on to be engineers or scientists mild cases of aspergers are going to end up with full blown autism, yet I have no doubt that “mainstream” thought will continue to cite better awareness as the cause. The big duh being that a problem as severe as classic autism creates its own awareness, much as 131 cases of measles in the first half of this year created awareness. In the same way that you would not blame the rise of something as serious and obvious as measles on awareness, you should not blame the rise of unmistakable classic or regressive autism on awareness.

    The rise in the diagnose of manageable forms of autism should be separated from the rise of the more severe forms as both a matter of priority and a matter of precision in this question.

  22. HHCon 10 Jan 2009 at 8:31 pm

    daedalus2u, Sorry, I do not have a internet link. Most likely my patients had fever therapy at the state run facilities in the Midwest.

  23. daedalus2uon 10 Jan 2009 at 11:56 pm

    HHC, fever therapy hasn’t been used in over 50 years.

    Autism can occur with zero brain damage. In my opinion symptoms reminiscent of autism associated with brain damage should be called “autism-like” and not autism.

  24. arthurgoldenon 11 Jan 2009 at 5:04 am

    A. Dr. Novella writes in his blog entry:

    In other words, 20 years ago a child may have been diagnosed with a non-specific speech disorder, and today they would be diagnosed with autism, so-called diagnostic substitution as was found by Bishop in 2008.

    I agree with Dr. Novella that this is very likely.

    Then, Orac comments on the above statement and the comment includes:

    What is probably really happening is that the same kids who
    need help are simply being diagnoses as autistic instead of
    mentally retarded or schizophrenic, as they may have been
    20 years ago. After all, there wasn’t even a DSM category for
    Aspergers and other autism spectrum disorders (such as
    pervasive developmental disorder, not otherwise specified)
    before the early 1990s.

    I agree with Orac on his entire comments including the above quote that this is very likely. I would like to add some more detailed comments.

    B. On a new blog on “Autism” on the “change.org” website (which was confused by many people as being part of the more recently established website “change.gov” of the President-Elect Barak Hussein Obama transtion team), there is a blog entry on “What is Autism?” that linked to the actual language of DSM-IV and for the first time I noticed that 3 of the 5 categories of the broadened “autism spectrum” contained caveats about Schizophrenia as follows:

    Diagnostic Criteria for 299.80 Asperger’s Disorder:

    “Criteria are not met for another specific Pervasive Developmental Disorder or Schizophrenia.”

    299.80 Pervasive Developmental Disorder Not Otherwise Specified (Including Atypical Autism):

    “…criteria are not met for a specific Pervasive Developmental Disorder, Schizophrenia, Schizotypal Personality Disorder, or Avoidant Personality Disorder.”

    Diagnostic Criteria for 299.10 Childhood Disintegrative Disorder:

    “The disturbance is not better accounted for by another specific Pervasive Developmental Disorder or by Schizophrenia.”

    C. At the end of the blog entry on “What is Autism?”, there are listed two references “For more information.” The first is to a CDC webpage that starts with a very short statement that happens to be “What is Autism?” and in the last sentence of the first of two paragraphs states “An ASD begins before the age of 3…” with ASD being the abbreviation for Autism Spectrum Disorder. Although my own son Ben was not diagnosed until he just turned 5 in early 1977 (under the old much narrower definition of autism) by Peter B. Rosenberger M.D. pediatric neurologist at Massachusetts General Hospital, his developmental history before age 3 was still fresh information and met the criteria without question. Although the CDC webpage states an ASD begins before the age of 3, the above 3 categories with the caveat about Schizophrenia do not mention onset by age 3.

    D. I believe it is very likely (please note that I am no longer certain about anything concerning autism so I am stating “it is very likely”) a large part of rise in “autism” (when what is really meant is the much broader ASD) is that while many more people meet the criteria of ASD, a competent medical doctor who would have to have the specialty of being a psychiatrist to determine that “the disturbance is not better accounted for … by Schizophrenia.” Concerning the differential diagnosis between ASD and Schizophrenia, I realize that I am not a psychiatrist, psychologist or neurologist, but I have extensive experience of being involved with both adults with a diagnosis of ASD and adults with a diagnosis of Schizophrenia and as adults I find many of them cannot be differentiated by me. While a diagnosis of ASD might be more socially acceptable than a diagnosis of the mental illness of Schizophrenia, there are proven medicines for treating Schizophrenia and it might be very dangerous for an individual to believe they have an ASD when they really have Schizophrenia. Until very recently, I did not believe that it really mattered so much but there is some very recent biological theories which seems to me to have a solid foundation in scientific research about the differences, found in:

    http://www.sfu.ca/biology/faculty/crespi/pdfs/115-Crespi&Badcock2008.pdf
    “Psychosis and Autism as Diametrical Disorders of the Social Brain”
    by Bernard Crespi and Christopher Badcock
    BEHAVIORAL AND BRAIN SCIENCES (2008) 31, 241–320

    which was recently discussed in The New York Times at:

    http://www.nytimes.com/2008/11/11/health/research/11brain.html?e
    In a Novel Theory of Mental Disorders, Parents’ Genes Are in Competition
    By BENEDICT CAREY published: November 10, 2008
    “Two scientists, drawing on their own powers of observation and a creative reading of recent genetic findings, have published a sweeping theory of brain development that would change the way mental disorders like autism and schizophrenia are understood….”

    E. Although this blog entry of Dr. Novella seems to be focusing on the diagnosis of children, a lot of the rise in autism rates is among very high functioning adults (many of whom seem to have their own blogs), some of whom are self-diagnosed. Even for those who were diagnosed at the age of early thirties in the early 1990s by some unnamed psychologist using the new broader definition of ASD, where is the qualified medical doctor – psychiatrist – who determined it was not really Schizophrenia?

    F. Now concerning the diagnosis of autism instead of mental retardation, I agree it is most likely happening too. However, unlike Schizophrenia which has known medical treatments (which may be ignored to the great harm of the person wrongly diagnosed with ASD), I personally see much less of a problem of confusing autism with mental retardation. If anyone feels it makes a significant difference, I would appreciate the information. I await further comments.

    Arthur Golden of Jerusalem Israel

  25. HHCon 11 Jan 2009 at 11:53 am

    daedalus2u, Yes, your time frame for fever therapy perfectly matches my work experience. In fact, the staff historian where I began my work claimed that we were working with patients which were born during the syphilis epidemics. Babies were left by parents at the hospital for a lifetime of care.

  26. Elisheva Levinon 11 Jan 2009 at 3:02 pm

    Daedelus2u, I have a question concerning this statement:

    “Things that correlate positively with autism include uterine bleeding, Rh incompatibility, induced labor, prolonged labor, precipitous labor and hyperbilirubinaemia”

    A few of these–uterine bleeding, induced labor, and precipitous labor–are also associated with Pre-eclampsia. Also, bleeding during the first trimester and second trimester of pregnancy has been associated with later ASD diagnosis, and this as well is seen pregnancies that become pre-eclamptic. Is there any link between pre-eclampsia and later ASD diagnosis? I have heard talk that there is, but I have not seen confirmation. And could pre-eclampsia also be associated with your NO hypothesis?

  27. son 11 Jan 2009 at 4:12 pm

    …and what role NO has in “vitamin” D regulation, as vitamin D is also implicated in pre-eclampsia.

    /S

    E.g.
    Fischer et al, Metabolism of vitamin D3 in the placental tissue of normal and preeclampsia complicated pregnancies and premature births. Clin Exp Obstet Gynecol. 2007;34(2):80-4.

    Bodnar et al, Maternal vitamin D deficiency increases the risk of preeclampsia. J Clin Endocrinol Metab. 2007 Sep;92(9):3517-22. Epub 2007 May 29.

  28. HHCon 11 Jan 2009 at 6:01 pm

    Arthur Golden of Jerusalem, Israel,

    You may be interested in learning about the work of Dr. Ralph Reitan. The Reitan-Indiana Neurological Test Battery was developed to evaluate children from 5 to 8 years old. The Halstead-Reitan Neurolpsychological Test Battery for Adults is extremely useful. A complete neuropsychological evaluation is
    required before using the DSM for diagnosis. SHALOM.

  29. daedalus2uon 11 Jan 2009 at 6:53 pm

    Yes, preeclampsia is associated with low NO. The association is very strong, endothelial dysfunction (low NO in the endothelium), sleep disordered breathing. Preeclampsia is associated with heart disease, elevated BMI, hypertension, diabetes and the metabolic syndrome.

    The factors in the HELLP syndrome (hemolysis, elevated liver enzymes, low platelet count) are tied in with NO in that free hemoglobin (from lysed red blood cells) destroys NO ~600 times faster than does hemoglobin in RBCs. Elevated liver enzymes are a sign of low NO, and can be decreased by increasing basal NO levels (unpublished data). NO inhibits platelet aggregation and oxidative stress and low NO makes platelets and RBCs more sticky.

    What is interesting is that placental metabolic stress seems to be pretty unique to humans. Other mammals don’t have it to the same extent as humans do. This is highly speculative, but that may be to purposefully induce low NO to cause neuronal hyperplasia and may be part of why humans have such uniquely large brains.

    I see gestational diabetes as a sign of metabolic stress too, a feature to try and get more glucose to cells too far from a capillary. I have a recent blog on regulation of the vasculature by NO, and low NO is going to increase the capillary spacing. NO also regulates the number of mitochondria, and if cells don’t have enough mitochondria and switch some of their ATP production from oxidation to glycolysis, it takes 19 times more glucose to make ATP via glycolysis than by oxidation. Switching 5% of ATP from oxidation to glycolysis requires twice as much glucose. Glucose transport is active, with the “important” concentration being the concentration adjacent to the cell taking it in (not the value in bulk blood). If glucose demand goes up and capillary spacing gets farther apart due to low NO, the only way physiology can adapt is by increasing blood glucose levels. The cells closest to the capillary get enough and the cells too far don’t get enough (because the intervening cells consume it). The cells closest stop taking up extra glucose (glucose resistant) and stop taking up insulin (become insulin resistant) to leave glucose and insulin for the cells farther from a capillary. This is why tighter control of blood glucose leads to higher mortality. The glucose level that is important isn’t in bulk blood, it is in the extravascular space next to the cells taking it up.

    There is cross-talk between vitamin D and NO signaling.

    http://www.jbc.org/cgi/content/full/277/15/13294

    mediated through zinc finger transcription factors. Zinc finger transcription factors are the largest class of transcription factors in humans, ~900. These authors previously found that NO isn’t important only in removing Zn from the zinc finger protein, but is also necessary for removing Zn from metallothionein, which is the normal physiological reservoir of Zn to put it on the Zn finger protein in the first place. It may take higher levels of vitamin D to achieve the same signaling when basal NO levels are compromised.

  30. [...] not account for the rise in autism diagnoses in the US. For example, the recent UC Davis study (even though I disagree with their conclusions) eliminated immigrants from the data base and showed they represented a very small [...]

  31. RickKon 14 Jan 2009 at 9:53 pm

    Are we seeing a drop in other diagnoses, like schizophrenia, that offsets any of the rise in autism? If a big part of the problem is a change in definition, wouldn’t we see a drop in “old definition” cases to offset some of the rise in autism diagnoses?

  32. HCNon 15 Jan 2009 at 12:32 am

    Rickk, check out the plots on this blog:
    http://www.autismstreet.org/weblog/?p=297

    See the straight line?

  33. RickKon 15 Jan 2009 at 6:02 pm

    HCN – that’s very striking. Thank you.

    Are there other states or national stats that show similar relationships between a rise in autism and an offsetting decrease in other diagnoses?

  34. HCNon 15 Jan 2009 at 7:08 pm

    I don’t think so, California seems to have the largest consistent database. If you browse the http://autismnaturalvariation.blogspot.com/ website you will find some discussion on the other studies. There are some that show changes in diagnostic criteria and research in what diagnosis older residents in institutions would now get.

  35. [...] as proof that autism rate rises can’t be explained by increased diagnosis, doesn’t exactly say what they claim it does, as Steve Novella notes: The key to putting this study into context is the phrase “other [...]

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