MMR Conspiracy Theorists: The Power of Fear
Yesterday, The Lancet posted the following retraction of the MMR vaccine/autism article that started the whole vaccine/autism kerfluffle.
Following the judgment of the UK General Medical Council’s Fitness to Practise Panel on Jan 28, 2010, it has become clear that several elements of the 1998 paper by Wakefield et al. are incorrect, contrary to the findings of an earlier investigation. In particular, the claims in the original paper that children were “consecutively referred” and that investigations were “approved” by the local ethics committee have been proven to be false. Therefore we fully retract this paper from the published record. [click for original source]
I don’t want to go into the history of the “controversy” (see wikipedia for that) but I’ll summarize it in brief: Dr. Andrew Wakefield (et al.), in 1998, wrote a paper in The Lancet whereby he claimed (and showed evidence supporting this claim, mind you) that the mercury-based preservative in the Measles/Mumps/Rubella (MMR) vaccine caused a bowel problem he called “autistic enterocolitis” which then quickly led to autism in these twelve children. Panic ensued.
In 2004, ten of the paper’s co-authors retracted their support for Wakefield’s conclusions, and between 1998 and 2004, researchers spent millions on epidemiological studies of the vaccine and autism finding no evidence, but the damage was done. The two things I will discuss here are 1) speculation on why this misinformed theory was so appealing to young mothers, and 2) why people still believe it despite a staggering amount of evidence to the contrary, including a full retraction.
Dr. Wakefield’s motives are speculated on elsewhere. Suffice to say that a major, unrevealed conflict of interest existed with a group that was suing the makers of the vaccine claiming it caused autism in their children due to what is now firmly understood to be a spurious coincidence (autism presents initially, as far as a parent can tell, near the same time the child goes in for the MMR vaccine). The science has been resoundingly debunked, and multiple studies show that not vaccinating your children is what puts them at real risk. At the time of publication, however, the article must have seemed like a major breakthrough that could save a lot of families the heartache of raising an autistic child.
Given the state of things in 1998, it would be reasonable for a new mother to be afraid of the MMR vaccine. You might not trust new medical research, and you might understand that clearly not every child that gets the vaccine gets autism, but the quality of life difference for a mother raising an autistic child versus a non-disabled child must be immense, to say nothing of the quality of life for the child. In 1998, most new mothers had never heard of a case of measles in the developed world. The calculation of risk would lead to a logical conclusion: Avoid the MMR vaccine.
So it is understandable that, at the time, the MMR/autism meme spread like the plague. But then, why were lawsuits against vaccine manufacturers for all manner of disorders going on for 20 years previous to the Wakefield study?
Over the next six years, over 100 studies were undertaken to assess this risk (see the wikipedia article, linked above, for a references list). They found no link between the MMR vaccine and autism. Given the two competing hypotheses — that the MMR vaccine causes an enterocolitis that causes autism, or that children are vaccinated at around the same time as autism presents — the evidence mounted to indicate that the latter hypothesis was more likely.
Science speaks in the language of more likely. But there are three facts that, for practical purposes, prove that the MMR vaccine does not cause autism. First, Wakefield et al. (1998) was debunked. The temporal association was debunked and their PCR results were found to be contaminated, leading to the conclusion that their detection of measles virus in LP samples was falsified. Second, detection of, diagnosis of and services for autism improved at around the same time the MMR vaccine Wakefield studied was introduced, leading to a spurious epidemiological correlation. Third, by 2004, over 100 studies had demonstrated no link between MMR and autism.
The conspiracy theorists’ reply was, of course, that these studies had detected no link — that does not mean that there is nothing to detect. The old “absence of evidence / evidence of absence” retreat is a return to arguments from authority: Because this cannot be proven not to exist by my own standards of evidence, which are impossible to meet; and I say it does exist, regardless of the fact that my methods, results and conclusions have been shown to be incorrect (and in some cases, invented); you have to take me seriously.
Even setting aside the absence of evidence fallacy, invoking it is ridiculous: The preponderance of evidence gathered by scientists in this case is actually evidence of absence. If you examine a blood sample, you can prove that it does not contain measles virus just as conclusively as you can prove that it does not contain Faygo. Same with urine samples and CSF samples. And epidemiological studies similarly provide evidence of absence: One study examined the case of Japan, which introduced the vaccine and then stopped administering it. The study demonstrated clearly that introduction of the MMR vaccine does not lead to an increase in autism, and that removal of the vaccine does not lead to a decrease in autism.
The Lancet began hearing commentary on Wakefield et al., including learning of Dr. Wakefield’s conflict of interest; and they made accusations against the study in 2004. At this time, the controversy was becoming major international health news. The preponderance of evidence was against the Wakefield conclusions. So why would educated people — doctors, celebrities, and (dare I say it?) bloggers — continue to voice concerns about the vaccine?
The Power of Fear
As I mentioned before, the prospect of spending 18 years trying to raise a child with autism is terrifying, if not totally unbearable. It works like a twisted version of Pascal’s Wager with a living hell (in the terrified mind of a new parent). That may be a bit hyperbolic, but the essence of my point stands: Why take a tiny risk, even if a hundred studies said not to worry about it, when the consequences are so dire?
Unlike Pascal, the rebuttal is not so simple. We need to invoke game theory. This logic is similar to the Diner’s Dilemma, for the math people that read this. A new parent can choose to eschew the MMR vaccine, gaining a very miniscule supposed improvement in their and their child’s quality of life if and only if everyone else does not eschew the MMR vaccine. Because if a large enough population goes unvaccinated, measles, mumps and rubella will reappear. Or, in the case of the Diner’s Dilemma, if everyone in the group orders the overpriced lobster, everyone will pay full price for it in the end.
Now imagine that the expensive dish is only a teeny tiny bit better than the cheap dish, and way out of your price range… but you have six billion people to split the cost with…
The power of fear is the essence of myth.
In Why God Won’t Go Away, Newburg, d’Aquili, and Rause find the origins of myth in the brain, and in its response to uncertainty and fear. Humans, it turns out, are terrible at evaluating probabilities — especially very small ones. (This is where Pascal’s Wager gets its power.) Time comes for your child to have the vaccine. First, they would explain, the binary operator of our left brain turns your situation into a binary question: “Do I give my child the vaccine?” Second, something called the causal operator follows the chain of consequences from each one: “If I give my child the vaccine, I could be causing autism in my child.” The right brain freaks out about this, because that’s where imagination and emotion reside. The visual-spatial processor in the brain conjures pictures of short yellow busses and a child writhing uncomfortably in his mother’s hug. The other alternative is less horrific-sounding: “If I do not give my child the vaccine, my child could contract measles if he ever encounters a carrier.” The right brain tries to imagine a scenario where your child would ever meet someone with measles. How many people have you heard of with measles? So it does the best it can and comes up with nothing more realistic than being captured by Somali pirates, which of course, would be bad for a lot of non-viral reasons, too.
So those three brain structures (right brain emotion and imagery; left brain binary operator and causal operator) conspire to create the myth of the guilt-riddled mother stuck raising an emotionally stunted, autistic child, always wondering if he could have been “normal” if only mom had believed the alarmists.
Newburg, d’Aquili, and Rause (as well as Hitchens) note that this tendency to misunderstand probabilities and mix imagination and emotion with left-brain reasoning is why we have God in the first place. Death is frightening, and the voices of authority can offer a pleasant alternative to the emotionally-charged image of a lonely, decomposing corpse. But I digress.
So we’re bad at uncertainty. Bad at small probabilities. Bad at reasoning without emotion interfering. Luckily for public health, the medical community is pretty good at those things, and they’ve been working hard to shed some light and truth on the MMR vaccine issue. Yesterday’s Lancet retraction was a long time coming, but I’m glad for it all the same.