• Sat, Jan 20 2007

Sure, there’s an autism epidemic (but watch your words): On the semantics of “epidemic,” ancient and modern

This post begins in utero and ends with the topic of why there is no autism epidemic, with mention of the 5th-century Greek physician Hippocrates (as in the Hippocratic Oath) along the way, all in an attempt to make sense of the past week (a week which has ended, more than sadly, with a terrible, terrible tragedy involving a high school student with Asperger’s syndrome) in Autismland. Autism is not only every day, it is everywhere, in the news and, as I wrote on January 18th, there is plenty to talk about—autism as understood in other countries and at other times, and the extent to which we have reason to be optimistic about how much more we know about autism, and how much we can do.

In this sense, autism is “epidemic.”
Vaccine: The Controversial Story of Medicine's Greatest Lifesaver
I do not mean that there is an “epidemic of autism” in the sense that autism is a disease that is being diagnosed in young children at an alarming rate. I mean rather what journalist Arthur Allen refers to as an epidemic of discovery about autism. The ancient Greek physician Hippocrates was the first to use the word “epidemic,” or rather the ancient Greek word epidemios that is the root word of our word “epidemic,” in a medical sense. The original meaning of epidemios is “on/in one’s own country”; epi means “on” and demos means “people” (as in democracy—”power of the people”—which is from the words demos and kratos, “power”). In Homer’s Odyssey, epidemios refers to one “who is back home” and “who is in his own country,” as bacteriologist Paul M.V. Martin and professeur certifiée de lettres classiques Estelle Martin-Granel write in 2,500-year Evolution of the Term Epidemic (Epidemic Infectious Diseases, vol. 12, no. 6, June 2006). It is only with Hippocrates in the fifth century B.C. that epidemios is used in a medical sense.

Hippocrates’ seven-book treatise, Epidemics, uses the word to refer to something that “spreads” on and among the people; to “groupings of syndromes or diseases, with reference to atmospheric characteristics, seasons or geography, and sometimes propagation of a given syndrome in the human population.” Hippocrates’ use of the term epidemios is to emphasize the extent to which a pattern of symptoms is pervasive in a human population at a certain time; there is no sense in Hippocrates of epidemios as indicating the severity of a disease.
Hippocrates, Volume I: Ancient Medicine (Loeb Classical Library, No. 147)
Martin and Martin-Granel suggest that our contemporary confusion of “epidemic” with a term like “plague” may stem more from the description of the “famous Plague of Athens” in 430 BC in the midst of the Greek historian Thucydides’ account of the Peloponnesian War. While noting that high death rate for this disease (25% in one group of soldiers), they note that

The large number of symptoms and of possible and probable causes rules out the possibility of an epidemic in the modern sense of the term. Instead, the Plague of Athens seems to have been the appearance of a large number of diseases that affected the population at the same time. Plague therefore has the same meaning here as epidemic in the works of Hippocrates. These 2 terms have been used in association or confused throughout history.

“Plague” and “epidemic” have continued to be “used in association or confused” in regard to autism, to the extent that they have become synonyms. While one could say that autism is “epidemic” in the sense of the ancient Greek word that the prevalence of autism is higher than it has ever been (1 in 166)–that is, that autism is “upon the people” or “upon the population” more than it ever has been before, the modern meaning of “epidemic” (as Martin and Martin-Granel write, “a disease that affects a large number of people with a recent and substantial increase in the number of cases”) is decidedly different from the ancient one; this is indeed Caroline Rodgers’ definition of autism as a “global epidemic” in an article in the Winter 2006 issue of Midwifery Today.

“The pervasive use of prenatal ultrasound, which can cause potentially dangerous thermal effects” is presented as a cause of autism by Rodgers (I posted previously about autism and ultrasound on November 14, 2006.) Rodgers cites numerous research studies concerning damage “consistent with that found in the brains of people with autism” in the brains of mice whose pregnant mothers had been exposed to ultrasound, as well as birth defects that have been shown to be the result of “elevated maternal or fetal body temperatures” (Rodgers cites a 2004 warning from the FDA concerning a rise in temperature in tissue from ultrasound; she also notes how the use of saunas and hot tubs can elevate maternal body temperature). She refers to studies of autism in twins and asks “could this increased twin risk factor [for autism] have to do with the practice of giving mothers with multiple gestations more ultrasounds than those expecting single births” and calls for more “serious consideration” to be given to the effects of prenatal ultrasound, over and beyond genetics. She cites research discounting an MMR/autism link and also a mercury/autism link, and points out that, even though thimerasol has been eliminated from childhood vaccines, “ASD increases are between 10 to 17 percent every year.”

This is Rodger’s explanation for what she refers to as a “global autism epidemic”:

Statistics on the increase of autism worldwide among industrialized nations show that it has emerged in just the last few decades across vastly different environments and cultures. What do countries and regions with climates, diets and exposure to known toxins as disparate as the US, Japan, Scandinavia, Australia, India and the UK have in common? No common factor in the water, air, local pesticides, diet or even building materials and clothing can explain the emergence and relentless increase in this serious, life-long neurodevelopmental disorder.

What all industrial countries do have in common is the quiet yet pervasive change in obstetrical care: All of them use routine prenatal ultrasound on pregnant women.

Rodgers goes so far as to point out that FDA approval of an “eight-fold increase in the potential accoustical output of ultrasound equipment” in 1993—with (as she writes) an increase in the potential for “overheating” of the fetus’s tissues in utero—happens “during the same period of time the incidence of autism increased nearly 60-fold.” Can this somewhat simultaneous occurrence of increased use of ultrasound equipment and a rise in the “incidence of autism” be, she asks, “merely coincidental”?

Rodgers’ question here is rhetorical; her thesis is indeed to make a case for ultrasound as a potential cause of autism. But correlation does not imply causation. Rodgers does not take into account the changes in the criteria for autism in the DSM-IV in 1994, changes which significantly broadened the criteria for an autism diagnosis, and, indeed, the evoluation of our understanding about autism from the time Leo Kanner first described what he called “infantile autism.” Like Michael Waldman’s theory that TV causes autism (which fueled some fervid discussion in Autismland), the suggestion of a link between autism and ultrasounds is a finding without a theory.

Ultrasounds are not, indeed, the only source of elevated maternal body temperature cited by the Midwifery Today article; “hot tubs, steam rooms, saunas and maternal fevers” are also cited. I would further note that elevated maternal body temperature was once associated with the very formation of the fetus. The ancient Greek medical writer Hippocrates, in his On the Nature of the Child—an account of ancient views of embyrology—indeed notes that heat “dries and hardens” or gives shape to the developing fetus; Hippocrates elsewhere writes that the bones are formed by a process of condensing (pachunetai) as a result of having been heated (thermainome). That is, without the fetus being heated, it would not form properly at all; would indeed have “defects.”

Today, ancient medical theories such as Hippocrates’ are often readily discounted for their seeming ridiculousness (such as the philosopher Aristotle’s noting in his The History of Animals that women are “deformed men,” or Hippocrates’ own noting in “The Nature of the Child” that a young woman aborted her fetus by jumping strenuously up and down). Contemporary theories about the aetiology of autism, and various treatments for autism, have often led me to suspect that, when it comes to trying to grapple with and to understand something like autism, we are just as susceptible today to believe in theories of questionable underpinnings.

Such as, whether the mercury-based preservative thimerasol has caused an “epidemic of autism.”

Such as, that there is an “epidemic of autism.”

And, if there is indeed no “epidemic of autism,” the question to ask is: Why do many still think there is one? Why is it so hard to say that
Unstrange Minds: Remapping the World of Autism

……. there is no real epidemic……If there is no real epidemic, we might just have to admit that no one is to blame. Their desire is understandable. But we cannot find real solutions if we’re basing our ideas on false premises and bad science. (Roy Richard Grinker, Unstrange Minds: Remapping the World of Autism, p. 171)

Why does living with “autism every day” cause one to think that “autism is epidemic”?

There is still plenty to talk about whether or not there is an autism epidemic and rather than distract ourselves with “false premises and bad science,” best to get to work teaching and learning from the autistic children and persons who are right here among us, this week, today, and now. And that’s something we need no debate about.

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  • Julia

    Ultrasound?

    ::eyeroll::

    Firstborn – 1 ultrasound; no doubt in anyone’s mind that he’s autistic, if they have any experience with autistic people and he’s observed for 15 minutes.

    Twins – 5 ultrasounds; not quite so obvious that either is on the autism spectrum. (I’m pretty sure she is, not quite so sure about him.)

    Man, I sure love playing “provide the anecdotal evidence that the theory may be wrong” game! :D I think I’m batting about .925 on shooting things down at this point….

    (Or is that mean of me?)

  • Tracey

    I’m with Julia on this one. I have three children–only my youngest is autistic, but I received the same number of ultrasound tests for all three pregnancies at the same doctor’s office with the same machine. My oldest is almost 16 and my youngest is 6. |According to this theory, Tom Cruise and Katie Holmes’ daughter should have the most profound case of autism because they owned an ultrasound machine and used it whenever they felt like it. I think the medical community that buys into this theory had better watch little Suri like hawks!

  • Caroline Rodgers

    I read with interest Kristina Chew’s critique of my article, “Questions about Prenatal Ultrasound and the Alarming Increase in Autism.” Chew points out that “Rodgers does not take into account the changes in the criteria for autism in the DSM-IV in 1994 . . . which significantly broadened the criteria for an autism diagnosis.” It seems that Chew is not aware that all of the changes in the DSM concerning autism have been scientifically analyzed, along with 54 surveys on the prevalence of autism in the United States and the United Kingdom. The result was published in 2004 in the Public Health Reports article, “What’s Going on? The Question of Time Trends in Autism.” The author, Mark F. Blaxill, took into account every change in the Diagnostic and Statistical Manual of Mental Disorders (DSM-MD) concerning autism spectrum disorders (ASD), and concluded “. . . taking into consideration changing definitions, ascertainment bias, and case-finding methods, [the comparison] provides strong support for a conclusion of rising disease frequency” which it identified as a 10-fold increase in ASD in the United States, calling it “an urgent public health concern.”
    Chew correctly states that correlation does not imply causation, but given that prenatal ultrasound has been proven to cause neurodevelopmental problems in mammals under experimental conditions that can be repeated, it seems cavalier to dismiss the potential risk posed by ultrasound to human fetuses.
    My article was based on published studies, not anectodal information. Obviously, prenatal ultrasound does not cause autism in every case, but there is enough evidence to warrant further study, at the least. The risk factors for prenatal ultrasound are complex and involve the amount of heat generated by the exam (which varies, according to the equipment used, duration of the exam and the exact placement of the transducer) and the developmental stage of the fetus. The sex of the fetus is also a risk factor, as boys are more likely than girls to be affected, so that mixed-sex fraternal twins would not necessarily have the same outcomes.
    Although many babies subjected to prenatal ultrasound have no apparent ill effects, in view of the many unexplained birth defects, the risk versus benefit should be seriously considered by expectant mothers and their medical practitioners.

  • http://www.autismvox.com Kristina Chew, PhD

    Many thanks to Caroline Rodgers for responding to my critique of her article about an autism-ultrasound connection, and for citing Mark Blaxille’s What’s going on? The question of time trends in autism; a PDF file of the entire article is available here via the website of Safe Minds, whose executive board Mark Blaxill is a member of, and whose focus on the potential harmful effects of mercury and thimerosal is well-known.