Autism vaccination theory

Overview
There is a popular theory, believed by many parents and a minority of medical professionals and supported by a number of individual cases, that autism may be caused or exacerbated by certain childhood vaccinations – possibly due to the presence of thimerosal, a mercury-based preservative used in the manufacture of vaccines during the 1990s and possibly earlier (it appears that its use began to be phased out in 1999, though it will be at least 2006 before existing thimerosal-bearing stocks are used up or reach their expiration date).

One piece of evidence often brought up in support of this theory is that autism among the Amish (who generally do not use vaccines) is reportedly 1 in 15,000. There are, however, many other factors which could be leading to this low rate. (Is anyone investigating to see what other factors might be at work? Perhaps those factors could help reduce the rate of autism in society at large.)

This theory has been firmly and repeatedly rebutted by the scientific establishment and seems unlikely at this point, but some questions and answers remain to be documented.

Arguments
The only remaining anti-vaccine arguments I am aware of are:
 * 1) People shouldn't be legally forced to accept medications, even if they are truly beneficial, because that puts too much power in political hands. (The determination of benefit may be made scientifically, but politicians often ignore or suppress inconvenient evidence and base their decisions entirely on political considerations.)
 * 2) It may be that certain genetic traits carry a sensitivity to certain drugs, and that this sensitivity doesn't show up in surveys of the general population due to its rarity -- so surveys might show no correlation, but certain populations would still be affected. Autism is genetically-linked, so it could be that people who are predisposed to autism might also be predisposed to be sensitive to the drug. Those who have a family history of autistic traits might still have cause to worry even if most people don't.

Argument #2 is highly speculative and can probably be answered with available data, but I haven't had time to research it.

Argument #1 only applies on a policy level, not as an argument for not vaccinating one's own kids.

--Woozle 13:10, 25 May 2010 (UTC)

Studies
An oft-cited study is Thomas Verstraeten's 2000 study which "found a significant risk for neurological developmental disorders at age 3 months, as babies received increased amounts of thimerosal, and the risk of autism rose 2.48 times greater for infants getting higher amounts of the product, compared to infants who received thimerosal-free vaccines." However, Verstraeten issued another report in 2003 contradicting this conclusion.

Quotes
– Temple Grandin, interview excerpted in The Charlotte Observer on 2010-10-18 I would add to this that it's not clear to me whether the statistical analyses (the ones showing "no correlation") have been looked at in a way which might reveal genetic factors -- e.g. the suspect vaccinations might cause no problems in the overwhelming majority of the population, but in certain families (or, more precisely, where particular genetic factors are present) there might well be a sensitivity -- which wouldn't show up in the data overall because of how small the sensitive population is (it would be smaller than the margin of error in that larger sample) -- see #2 in "Notes" above. --Woozle 20:28, 29 October 2010 (UTC)
 * Q. In recent years, many parents have blamed vaccines for causing autism. That theory has been discredited by recent research. What do you think?
 * A. There's one study that still hasn't been done. There's a type of autism where the child gets language... can say a few words... and then loses it. There's a regression at about 18 months or 2 years. That subgroup needs to be studied separately. Until that study is done, the book is not closed.
 * Q. So you think it's possible vaccines could play a role?
 * A. I'm leaving that open. That study has to be done. I've brought that up with some of the top experts and they get very silent. That's all I'm going to say about it.

Reference

 * Do Vaccines Cause Autism? (About.com)
 * Wikipedia:
 * Thiomersal controversy
 * thimerosal also has details about the controversy
 * MMR vaccine controversy
 * Causes of autism: Vaccines "Although there is no evidence that autism is caused by vaccines or any preservative or additive ever used in vaccines, many parents are concerned about the risks of vaccination due to various unsupported theories related to vaccines..."

Links to file

 * 2007-07-15 Memo warned MMR doctor of research flaw: "The memo was sent to Dr Andrew Wakefield, a researcher at the Royal Free hospital, London. It warned him that the parents of most of the children in his study, investigating alleged links between the vaccine and autism, were litigants seeking compensation from drug companies. The memo said this gave the parents 'a vested interest' in finding a link between MMR and their children's autism."
 * 2007-06-29 Autism and vaccination by Thudfactor
 * 2005-06-20 Deadly Immunity by Robert F. Kennedy Jr.
 * ScienceDaily articles by Dan Olmsted:
 * One in 15,000 Amish: source of the figure used above
 * Absence of Evidence: more specifics about the Amish data
 * The Amish Elephant: how some medical professionals respond