There is no question that the incidence and prevalence of autism are on the rise. Starting in the early 1990s and continuing to today, there has been a steady rise in the number of children diagnosed with autism. Prior to 1990 the estimates of autism prevalence were about 3 per 10,000. The most recent estimates from the CDC and elsewhere now have the number at about 100 per 10,000, or 1%.
The burning question is – why are the rates increasing steadily? There are those, particularly in the anti-vaccine community, who conclude that the increase in prevalence is a real biological effect – an epidemic – and is evidence for an environmental cause (which they believe is vaccines, even though the scientific evidence does not support this position). However, the evidence strongly suggests that the rising prevalence of autism is largely an artifact of broadening the diagnosis and increased surveillance.
It should be noted that the data cannot rule out a small true increase in autism prevalence. Some hypothesize that increasing maternal and paternal age are contributing to the incidence of autism, but I will leave that question for another post.
A new study now adds significant support to the surveillance hypothesis – Ka‐Yuet Liu, Marissa King, and Peter S. Bearman from Columbia University, publishing in the American Journal of Sociology, report that the risk of being diagnosed with an autism spectrum disorder (ASD) correlates with social proximity to another family with a child with an ASD diagnosis. For those interested in this topic, the full paper is worth a read. While it gets technical at times, the authors do an excellent job of reviewing this topic in detail.
Over the past two plus years of the existence of Science-Based Medicine (SBM) we have been highly critical of the National Center for Complementary and Alternative Medicine (NCCAM) – going so far as to call for it to be abolished. We are collectively concerned that the NCCAM primarily serves as a means for promoting unscientific medicine, and any useful research it funds can be handled by other centers at the NIH.
So we were a bit surprised when the current director of the NCCAM, Josephine Briggs, contacted us directly and asked for a face-to-face meeting to discuss our concerns.
That meeting took place this past Friday, April 2nd. David Gorski, Kimball Atwood and I met with Dr. Briggs, Deputy Director Dr. John Killen, Karin Lohman PhD (Director, Office of Policy, Planning, and Evaluation) and Christy Thomsen (Director, Office of Communications and Public Liaison).
Dr. Briggs very graciously began the meeting by telling us that she and her staff have been reading SBM and they find our arguments to be cogent and serious. She shares many of our concerns, and feels that we are an important voice and are having an impact. She then essentially turned it over to us to discuss our primary concerns regarding the NCCAM.
We were prepared for this.
A new study published in PLOS Biology looks at the potential magnitude and effect of publication bias in animal trials. Essentially, the authors conclude that there is a significant file-drawer effect – failure to publish negative studies – with animal studies and this impacts the translation of animal research to human clinical trials.
SBM is greatly concerned with the technology of medical science. On one level, the methods of individual studies need to be closely analyzed for rigor and bias. But we also go to great pains to dispel the myth that individual studies can tell us much about the practice of medicine.
Reliable conclusions come from interpreting the literature as a whole, and not just individual studies. Further, the whole of the literature is greater than the sum of individual studies – there are patterns and effects in the literature itself that need to be considered.
A panels of bloggers from SBM will be taking part in the Northeast Conference on Science and Skepticism – NECSS 2010, April 17th beginning 10:00AM in New York.
There will be a 70 minute panel discussion moderated by John Snyder and featuring David Gorski, Kimball Atwood, Val Jones, and myself – Steven Novella. The topic of discussion will be the infiltration of pseudoscience into academic medicine.
This will be part of a full day of science featuring other excellent speakers, including James Randi, D. J. Grothe, Steve Mirsky, George Hrab, and Julia Galef. There will also be a live recording of the wildly popular science podcast, The Skeptics’ Guide to the Universe.
Go to www.NECSScon.org to register.
In the Wall Street Journal last week was a particularly bad article by Melinda Beck about acupuncture. While there was token skepticism (by Edzard Ernst, of course, who is the media’s go-to expert for CAM), the article credulously reported the marketing hype of acupuncture proponents.
Toward the end of the article Beck admits that “some critics” claim that acupuncture provides nothing more than a placebo effect, but this was followed by the usual canard:
“I don’t see any disconnect between how acupuncture works and how a placebo works,” says radiologist Vitaly Napadow at the Martinos center. “The body knows how to heal itself. That’s what a placebo does, too.”
That is a bold claim, and very common among CAM proponents, especially acupuncturists. As the data increasingly shows that acupuncture (and other implausible treatments) provides no benefit beyond placebo, we hear the special pleading that placebos work also.
But is that true? It turns out there is a literature on the placebo effect itself, and the evidence suggests that placebos generally do not work.
A question that arises often when discussing the optimal role of science in medicine is the precise role of plausibility, or prior probability. This is, in fact, the central concept that separates (for practical if not philosophical reasons) science-based medicine (SBM) from evidence-based medicine (EBM).
The concept featured prominently in the debate between myself and Dr. Katz at the recent Yale symposium that Kimball Atwood recently discussed. Dr. Katz’s treatment of the topic was fairly typical of CAM proponents, and consisted of a number of straw man derived from a false dichotomy, which I will describe in detail below.
I also recently received (I think by coincidence) the following question from an interested SBM reader:
What would Science Based Medicine do if H. pylori was not known, but a study showed that antibiotics given to patients with stomach ulcers eliminated symptoms? I assume that SBM wouldn’t dismiss it outright saying that it couldn’t possibly be helping because antibiotics don’t reduce stomach acid. I assume a SBM approach would do further studies trying to discover why antibiotics work. But, in the meantime, would a SBM practitioner refuse to give antibiotics to patients because he doesn’t have a scientific explanation as to why it works?
This is the exact type of scenario raised by David Katz during our discussion. He claimed that strict adherence to the principles of SBM would deprive patients of effective treatments, simply because we did not understand how they work. This is a pernicious straw man that significantly misconstrues the nature of plausibility and its relationship to the practice of medicine.
One of the basic principles of science-based medicine is that a single study rarely tells us much about any complex topic. Reliable conclusions are derived from an assessment of basic science (i.e prior probability or plausibility) and a pattern of effects across multiple clinical trials. However the mainstream media generally report each study as if it is a breakthrough or the definitive answer to the question at hand. If the many e-mails I receive asking me about such studies are representative, the general public takes a similar approach, perhaps due in part to the media coverage.
I generally do not plan to report on each study that comes out as that would be an endless and ultimately pointless exercise. But occasionally focusing on a specific study is educational, especially if that study is garnering a significant amount of media attention. And so I turn my attention this week to a recent study looking at acupuncture in major depression during pregnancy. The study concludes:
The short acupuncture protocol demonstrated symptom reduction and a response rate comparable to those observed in standard depression treatments of similar length and could be a viable treatment option for depression during pregnancy.
The House of Commons Science and Technology Committee (STC) has released a report, Evidence Check 2: Homeopathy, in which they recommend that the NHS stop funding homeopathy. The report is a rare commodity – a thoroughly science-based political document.
The committee went beyond simply stating that homeopathy does not work, and revealed impressive insight into the ethical, practical, and scientific problems caused by NHS support for an implausible and ineffective pseudoscience.
The STC formed in October of 2009, and this is their second report. The goals of the STC itself are significant step forward:
The purpose of Evidence Check is to examine how the Government uses evidence to formulate and review its policies.
We certainly can use more of that.
This week on Science-Based Medicine I wrote an article about a new study looking at the onset of autism symptoms, showing that most children who will later be diagnosed with autism will show clear signs of autism at 12 months of age, but not 6 months. This is an interesting study that sheds light on the natural course of autism. I also discussed the implications of this study for the claim that autism is caused by vaccines.
Unfortunately, I made a statement that is simply wrong. I wrote:
Many children are diagnosed between the age of 2 and 3, during the height of the childhood vaccine schedule.
First, this was a vague statement – not quantitative, and was sloppily written, giving a different impression from the one I intended. I make these kinds of errors from time to time – that is one of the perils of daily blogging about technical topics, and posting blogs without editorial or peer-review. Most blog readers understand this, and typically I will simply clarify my prose or correct mistakes when they are pointed out.
However, since I often write about topics that interest dedicated ideologues who seek to sow anti-science and confusion, sometimes these errors open the door for the flame warriors. That is what happened in this case.
Understanding the natural history of a disease is an important framework to have. It not only is critical for prognosis, but also informs us about diagnostic and screening strategies, is important to assessing interventions, and provides clues to causation.
There has been much debate about the early course of autism, specifically the earliest age at which autism may be detected. At present scientific evidence suggests that autism is dominantly genetic, and so researchers expect that there may be early signs of autism even in infancy. Traditionally, however, autism is not diagnosed until age 2-3, when parents bring their children to medical attention, or when signs are detected on routine well-child visits or in day-care.
Retrospective studies, largely involving review of home movies, have suggested that autism can be diagnosed as early as 6-12 months, suggesting that parental report is not an adequate screen because subtle signs are hard to detect without rigorous observation.