This is the second of 6 guest posts on infection and chronic disease.
By Rachel Kirby
In light of April being Autism Awareness Month it is only natural that certain topics be brought about in the media. Until now I was not aware of the controversy behind the "risk factors" of autism. Let's begin with the basics. Autism is a brain development disorder that impairs social interaction and communication, and causes restricted and repetitive behavior, all starting before a child is three years old. Having autism may or may not involve all three characteristics. Some may even have symptoms that are independent of the diagnosis, but that can affect the individual or the family. A small fraction of individuals with autism spectrum disorder (ASD) show unusual abilities, such as memorizing an amazing amount of trivia or have extraordinarily rare talents. These are often highlighted in the media. Just this week for example the press covered a story about a girl that has an incredible gift of working with wild animals, as not many others can.
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The discussion on autism becomes messy when you start to discuss the causes. To date nothing has been determined as a specific cause of autism, although many have been suggested. Some more relevant than others. One suggests that autism is linked mitochondrial disease. A child with autism may or may not have mitochondrial disease. Much of what is known about autism suggests that it is a highly heritable disease. Specifically, there is one topic that has been widely published and talked about in media and the scientific community. This is whether or not childhood vaccines have anything to do with the onset of autism. The problem is that there has been an association made because symptoms of autism and the time that children start to get vaccinated are closely related. More specifically mercury that is used in vaccines is the culprit. Many vaccines use a mercury-containing preservative, Thimerosal. When research is done this preservative is often taken out of the vaccines and there is no difference or change in the children that do or do not develop autism. There have been countless studies that have ultimately concluded that there is no correlation between autism and vaccines. The data provide evidence that no correlation exists between the prevalence of MMR vaccination and the rapid increase in the risk of autism over time. The explanation for the marked increase in risk of the diagnosis of autism in the past decade remains uncertain. This is what one study I found had stated. This statement can basically sum up them all. One of the most popular studies, The Lancet article titled "Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children" states that there IS in fact a link between the MMR vaccination and the development of autism. The vaccine community took immediate notice. Concerned parents refused immunization with measles-containing vaccines, and in some parts of the United Kingdom, immunization rates fell. In April of 2004, 10 of the 13 original authors retracted their statements. This was due to controversy in their samples that they had used. Still after this article was published and several other publications state that there is indeed not a correlation between the vaccinations, controversy is still very prevalent.
More recently, the federal government decided to compensate a couple who say that the regular childhood vaccines given to their baby caused her to develop autism. What is interesting about the case is that the government's decision does not say whether or not the vaccines actually caused autism. Their statement was that the vaccines aggravated a "pre-existing" cellular disorder. In my opinion this is opposite EVERYTHING that has been proven in the numerous studies that fail to find any link between vaccines and autism. This of course gives anti-vaccination campaigners reason to keep pushing the issue. Why, if this is false information, give families false hopes? The problem that I see in validating something like this is that this kind of decision undermines any public confidence in the usefulness of vaccines in general, that they do more harm than good. This then leads to a whole new set of issues. That is far to off the topic to get into.
After all of this definitive evidence, there is still a strong belief that this is of the cause of a small subset of autism. Why do families of autistic children or even adults still have so much to say about this? As humans we always want to have a cause or a real reason for something. Diseases or handicaps just don't "happen," in the eyes of most human beings. No mother or family of an autistic child wants to think that this could have been prevented or even that it was their fault. So it's only natural to look for anything and everything that could be a possible cause of their child's disease, and looking that a foreign substance being injected into their bodies only seems like a reasonable answer. I'm not saying that either the family's are wrong or that the scientific evidence is right or wrong or even that this argument is far from over but why fuel something that is being deemed "wrong" scientifically by saying very publicly that it is being given some credibility as this new federal court decision has done.
Rachel works at the hospital in the Pediatric Hematology/Oncology department as a research assistant, assisting with a Cord Blood Stem Cell study. She is planning to apply to the College of Public Health to obtain a degree in Environmental and Occupational Health. She ultimately would like to work in or with the CDC.
Wakefield AJ et al. 1998. "Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and
pervasive developmental disorder in children." Lancet. 351:637-41. Link.
Kaye JA et al. 2001. Mumps, measles, and rubella vaccine and the incidence of autism recorded by general practitioners: a time trend analysis. BMJ. 322:460-463. Link
Rachael, you say "Many vaccines use a mercury-containing preservative, Thimerosal. When research is done this preservative is often taken out of the vaccines and there is no difference or change in the children that do or do not develop autism."
Do you have evidence or references that show removal of thimerosal from vaccines used for research while using it in mass distribution ? This sounds like conspiratorial behaviour, but it's probably just research being done to test and prepare the Thimerosal free vaccines now in use.
I understand that Thimerosal has been taken out of almost all U.S. childhood vaccines, with no change in autism diagnostic rates. Do you have evidence that this is not so?
The Wakefield 1998 study has been thouroughly disproven. The Autisim Omnibus Case's testimony provided much evidence that Wakefield 1998 was meaningless. See for example Orac's Autism Omnibus articles http://scienceblogs.com/insolence/2007/06/the_autism_omnibus_the_differ…
davidp, I read that to mean that research was done examining what happened when thimerosal was removed, and they didn't find a link to autism. I think it was just wording in a confusing manner.
This is a tough topic to cover; it's clear you're well aware of the contreversy and have merely tried to bring light to a theory that may not get the sound discussion it deserves. Good work.
So if thimerosal has no effect on autism rates, what are the more promising suspects that can account for the increase in this disorder?