Cause of Autism Part III

Cause of Autism Part III

Vaccine theory

Controversial research by Andrew Wakefield in the UK that was published in The Lancet in the February 1998 issue, dubbed the "Wakefield Study", suggested a possible link in cause of autism and the MMR vaccine. The original research has come under criticism, largely due to an alleged conflict of interest on Wakefield's part. In March 2004, almost all of the paper's authors retracted its "interpretation" section, which claimed a potential link between pervasive developmental disorders and "possible environmental triggers".

Critics have claimed that Wakefield's study contains many obvious flaws, including an inability to recognize bias in his sample. In October 2005, a study by the respected Cochrane Library said, on the basis of 31 pieces of research into the possible side effects of MMR, that it found no association between MMR and autism. Several independent groups, including the National Academy of Sciences, have also conducted investigations and concluded that the evidence does not support a link.

One study by Gillberg and Heijbel in 1998 examining the prevalence of autism in children born in Sweden from 1975 to 1984 found no difference in the prevalence of autistic children born before the introduction of the MMR vaccine in Sweden and those born after the vaccine was introduced. Another study, conducted by Madsen and other researchers in 2002, studied all children born in Denmark from January 1991 through December 1998. There were a total of 537,303 children in the study; 440,655 of the children were vaccinated with MMR and 96,648 were not. The researchers did not find a higher risk of autism in the vaccinated than in the unvaccinated group of children.

Research in the U.S. has suggested a similar link between autism and the DPT vaccine, although this is not referenced. However, contrary to early claims from Wakefield, it is doubtful that a large majority of autism cases would come from this vaccine. Despite all the evidence to the contrary, controversy surrounding autism and vaccines continues to this day, and many polls, such as the autism coach poll, which involved only 15 respondents, show vaccines as the most popular theory currently on the etiology of autism among parents of autistic children.

Dr Mark Geier and his son, David Geier have published eleven peer-reviewed studies on the possible link between autistic spectrum disorders and childhood vaccines (TCVs). In their first study, they compared the number of complaints associated with TCVs, administered between 1992 and 2000, to the number of complaints resulting from a thimerosal-free vaccine administered between 1997 and 2000. The children who received greater amounts of ethylmercury from TCVs were more likely to have a complaint filed with the Vaccine Adverse Event Reporting System (VAERS). Further studies by the Geiers yielded similar results. In 2006, the Geiers published an article , "Early Downward Trends in Neurodevelopmental Disorders Following Removal of Thimerosal-Containing Vaccines", which contends that recent data confirms a reduction in autism diagnoses corresponds directly with the removal of TCVs from childhood vaccination schedules.

US health agencies have uniformly rejected the conclusions of the Geiers' studies, and one of the Geiers' articles was the subject of heavy criticism by the American Academy of Pediatrics. Geier says public health officials are "just trying to cover it up."

On the other hand, a report prepared by the staff of the Subcommittee on Human Rights and Wellness, House Committee on Government Reform, Chaired by Dan Burton, was published in the Congressional Record in May, 2003, stated:

"However, the Committee upon a thorough review of the scientific literature and internal documents from government and industry did find evidence that thimerosal did pose a risk. Thimerosal used as a preservative in vaccines is likely related to the autism epidemic. This epidemic in all probability may have been prevented or curtailed had the FDA not been asleep at the switch regarding the lack of safety data regarding injected thimerosal and the sharp rise of infant exposure to this known neurotoxin. Our public health agencies’ failure to act is indicative of institutional malfeasance for self-protection and misplaced protectionism of the pharmaceutical industry."
In a controversial article in June 2005, Robert F. Kennedy, Jr. described research suggesting that it is not the vaccines themselves, but a mercury-based preservative called thiomersal, used in some vaccine preparations (although not MMR), that may be a cause of autism. Kennedy argues that autism was first observed in children who were born around the time of introduction of thiomersal into mass-produced vaccines, and that the incidence of autism in the United States is well correlated with the amounts of thiomersal children receive during their first two years of life. Kennedy also noted that the there is a low reported incidence of autism in the Amish, who do not immunize their children. Kennedy states that is an exception, the rare child who was immunized.However, the CDC has described a link between thiomersal and autism as 'unlikely'.

In 1999 the Public Health Service (including the CDC, FDA, and NIH) recommended that thiomersal no longer be used in vaccine preparations. While it was by 2005 utilized in only a very few childhood vaccines, it has not been established that autism rates have dropped significantly. The CDC and some medical organizations continue to assert that no available evidence supports a causal link between thiomersal and autism. Critics have in turn claimed that the CDC analysis demonstrates deliberate bias in the CDC research.

For example, an analysis by Madsen et al. in Demark noted that the incidence of autism remained fairly constant while thiomersal was being phased out and started to rise beginning in 1991, even after thimerosal was discontinued in 1992. Critics of this analysis point out that the methodology was biased. Dissenters to the Denmark data point out a significant increase in autism rates among children whose childhood vaccines contained thiomersal. However, in Madsen et al.'s study, the amount in the vaccinations actually decreased while autism rates increased (specifically, during the period 1961–1970, infants had received a total of 400 µg of thiomersal by the age of 15 months, and during the period 1970–1992, infants had received a total of 250 µg at 10 months of age).

The California Department of Developmental Services (DDS), considered to have the best reporting system for autism in the US, has reported unprecedented decreases in the caseload increase. The caseload increase went from 734 during the second quarter of 2005 to 678 during the third quarter of 2005, a 7.5% decline in one quarter. Note that the total caseload handled by the state is still increasing, but the recent trend points to a deceleration in the trend. For example, from the 2nd to the 3rd quarter of 2004, the caseload went from 25,020 to 25,769 (a increase of 749 clients). Between the 1st and 2nd quarter of 2004, the caseload increased from 24,297 to 25,020 (a increase of 723 clients).

These variations have led to speculation that removal of thiomersal from vaccines in California is starting to pay off. Others point out they are unremarkable and may simply be an indication that the awareness curve is starting to level off, and that the rate of caseload increase should be expected to decrease to population growth levels (1.6% annual) eventually. Caseload increase between 2004 and 2005 was about 10%.

A study published in the March 2006 issue of the Journal of American Physicians and Surgeons (JPANDS) by Dr. Mark Geier claimed to show that "new cases" of autism in California dropped as much as 35% following removal of thimerosal from vaccines. However, the study did not document incidence drops, and its definition of "new cases" is known to be flawed.

A study published in May 2006 by Dr. Mark Geier et al. indicates that the trends of newly diagnosed neurodevelopmental disorders (NDs) such as autism reported to VAERS "correspond directly to the expansion and subsequent contraction of the cumulative mercury dose to which children were exposed from TCVs through the U.S. immunization schedule."

A study due to be published in July 2006 claims that the MMR vaccinations are definitely not the cause of autism and Asperger Syndrome.

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