Former playboy model Jenny McCarthy has written a piece appearing on CNN's website regarding her suspicions that the chemicals in vaccines are implicated in the development of autism. You see, McCarthy has a child who was diagnosed with autism some years ago. McCarthy has since become a proponent of a movement in the autism community claiming that the etiological origin of autism can be traced to vaccines given during the second year of life.
In her piece, McCarthy states that a recent federal court "conceded" that vaccines "may be" implicated in the development of autism. If only the federal court is made up of scientists rather than lawyers!
Apparently, there is a considerable number of parents who have joined McCarthy, armed with little scientific data, making wild and speculative claims of conspiracy between the government, doctors, and the pharmaceutical industry in hiding the risks of vaccination. At first, their fingers pointed towards the mercury compound thiomersal that was used as a anti-bactericide in vaccines. When panel after panel of scientific organizations determined that there was absolutely no evidence of thiomersal's relation to autism arose, the vaccinations themselves were blamed.
I'm not buying the argument. Most scientists claim that the link between vaccines and autism is a myth, and I believe them over the former playmate of the year. As cognizant organisms, we tend to seek out connections between events. It so happens that vaccines are given around 15 months of age, and it is around this time that the symptoms of autism begin to emerge. It is easy to point one's finger at vaccines and claim that they cause autism because the mechanisms underlying how vaccines work and how autism develop are poorly understood, either by the general public or most scientists. Many children are safely vaccinated and do not develop autism. Children who do not get vaccinated out of autism fears are threatened by far more life-threatening illnesses such as influenza or tetanus.
In part, the reason people may believe in a link between autism and mercury is that recent years have seen a dramatic rise in diagnoses of autism, as well as an increase in the use of thiomersal-based vaccines. However, to make this interpretation is to fall victim to a common logical fallacy cum hoc ergo propter hoc (Latin for "with this, therefore because of this"). It is more commonly known as mistaking correlation for causation.
In my research methods course, I tell my students that I have incontrovertible evidence that consuming chicken decreases murderous rage. You see, I conducted a study in which I examined statistics published by the U.S. Federal government's Department of Agriculture and the Bureau of Justice. You can get the data yourself here and here. What you find on the one page is that chicken consumption has increased from the period between 1996-2005. On the other page, you find that murder rates have been sharply declining over that same period. Thus, eating chicken somehow reduces murder. Right?
Here is a graph of the relationship. You can see a clear negative relationship between per capita chicken consumption in pounds, and the murder rate per 100,000 people. The correlation is strong, at .84.
Of course, this is all a bunch of horse manure. Why? Because especially over time, many things increase or decrease, such as the amount of chicken people eat (due to health concerns) and the murder rate (due to a decrease in the use of crack cocaine). If you took the correlation between my age during the years and either of these variables, you would find significant correlations because my age increased while chicken consumption increased or murders decreased. Just because something correlates with something else doesn't mean one causes the other.Likewise, the use of a vaccine and changes in the diagnostic category of autism (i.e., more children mistakenly diagnosed before as mentally disabled now receiving the "correct" diagnosis of autism) can make it look like there is a causal relationship between the two, when in reality there is only a coincident relationship.
The problem I have is that far more people probably respect and follow the flawed logic of the former playboy playmate of the year than doctors and scientists at the National Institutes of Health, the Center for Disease Control, and the World Health Organization. These parents might avoid vaccinating their children, who may then acquire a disease like encephalitis, which could permanently damage the child's brain.
Remarkably, in this article, McCarthy writes that her child has recovered from autism and is developing normally! After lambasting the medical establishment for not rushing to her door to inquire, she attributes her child's recovery based to the dietary and socialization regiments.
Now I'm no expert in autism. What I really think is happening here is that children who are completely normal are being diagnosed as autistic when they are just going though a stage in which they are not developing 'normally.' They grow out of this stage and end up normal people because they were always normal, but that a frenzied crew of 'experts' have rung the alarm bell over autism and that many children are being misdiagnosed as autistic when in reality they are just developing on a different path than other children.
Autism is not cancer or HIV in which you can take a biopsy or blood sample and know to a high degree of accuracy whether the person actually has the disease. (But see my former post on problems with this in respect to HIV). Autism is nosologized as a set of behaviors that must be interpreted by doctors and parents, and there is no way of seeing autism in a microscope or on an assay. So in a culture of fear over raising children fueled by experts wanting to be experts (McCarthy being one of them as the author of a parenting guide), you end up with 'experts' who have made virtual careers over developing dietary interventions, intervention schemes, and the like, which low and behold work for children who never had autism in the first place, and were just kids going through an unusual developmental trajectory. These diets and regiments may or may not work for those who truly have the affliction of autism, but they always work 100% of the time for normal kids misdiagnosed with autism.
Don't get me wrong - I'm not denying that autism exists, and I have seen many children diagnosed with autism. A difficult child myself, I used to bang my head on the ground and had a strange fascination with the drain spout of the washing machine, which would fill the basement sink with bubbly water. My mother, who is a social worker trained to diagnose mental illnesses, often says I would have been diagnosed with autism. True, had I not been born in 1976, but in 1996, at the height of the epidemic.
In sum, I don't mean to belittle McCarthy or her family's experience. I am sure these years have been difficult for her and her son. But I think that people in the limelight should realize that the mass of people may take the wrong message. Do we need children dying of rabies because their parents are afraid of vaccinations? I think not.
