Grump tank for disgruntled atheists.


In a fit of logodaedaly inspired by a particularly infuriating aginner, I have just coined this term to indicate the mythonuttical belief in a connection between autism and vaccination.

The aginner in question stubbornly and aggressively clings to a variety of idiotic beliefs that run counter to both evidence and expert opinion, and supports these beliefs with a panoply of fallacies of logic. All in all, this aginner provides a fascinating, if infuriating, nutcase study.

One of his collection of unfounded beliefs concerns the empirically invalidated claim that vaccination causes autism. Most of the authors of a 1998 study that postulated a connection based on woefully few study subjects have since retracted their erroneous interpretations, yet the damage was done and the myth continues.

At 12 months of age, infants receive MMR vaccination against viruses that formerly caused illness, debility, and some deaths (measles, mumps, rubella). This also happens to be the age at which signs of early autism are first recognized in some affected infants. Many other events impact an infant in the first year of life, but a single event, such as vaccination stands out by virtue of its singularity and so is noticed even when there is no causative association. This fallacious assumption that correlation indicates causation arises whenever an unusual event precedes an unconnected event. Epidemiologists must study large numbers of cases to tease out any genuine causative associations from serendipitious associations.

"Other larger studies have found no relationship between MMR vaccine and autism.
For example, researchers in the UK studied the records of 498 children with autism born between 1979 and 1998. They found:

  • The percentage of children with autism who received MMR vaccine was the same as the percentage of unaffected children in the region who received MMR vaccine.

  • There was no difference in the age of diagnosis of autism in vaccinated and unvaccinated children.

  • The onset of "regressive" symptoms of autism did not occur within 2, 4, or 6 months of receiving the MMR vaccine.

"Groups of experts, including the American Academy of Pediatrics, agree that MMR vaccine is not responsible for recent increases in the number of children with autism. In 2004, a report by the Institute of Medicine (IOM) concluded that there is no association between autism and MMR vaccine, or vaccines that contain thimerosal as a preservative." (source)

As health professionals have become more informed of autistic symptomatology and are able to recognize milder cases, rates of identification of existing cases have increased. Increased rates of identification do not necessarily indicate increased prevalence.

Research into the etiology of autistic neurobiological disorders continues, but the conditions are almost certainly multifactorial in etiology. Autism subtypes include early onset and regressive (Rett Syndrome, Glutaric Aciduriais). Autism is not a single syndrome and likely results from several different etiologies or combination of pathological mechanisms: genetic, infectious, neurologic, metabolic, immunologic, and environmental.

Vaccines act by priming the immune system to develop a clone of 'memory cells' that can respond rapidly to any exposure to live virus. On first exposure to live virus, the primed memory cells proliferate (as they would otherwise have proliferated on second exposure), pumping out monoclonal antibodies that bind specifically to the virus, enabling the rapid elimination of the infectious agent. The introduction of vaccines has enabled the eradication of smallpox and the virtual elimination of many childhood killers. Happily, vaccination has prevented horrific outbreaks such as the pre-vaccination polio epidemics that paralyzed children for life and forced thousands of children and adults into 'iron lungs'. The image at top left shows iron lungs collect in a gym (courtesy of Rancho Los Amigos National Rehabilitation Center). Image above right courtesy of Ontario March of Dimes.

"Mounting evidence indicates that immune dysfunction along with an environmental pathogen may be factors contributing to the development of some cases of autism. One of the immune deficiencies observed in autism is abnormal T-cell mediated immunity. Another is altered levels of certain classes of antibodies(immunoglobulins), including decreased levels of immunoglobulin A and deficient complement activity, based on the inheritance of a null allele of the C4B gene. In addition to the C4B gene, other genes on chromosome 6 also appear to be associated with autism. In the developing child, genetically determined immune deficiencies might increase the risk for autism in 2 ways: (1) A pathogen or its toxins might damage the brain, and (2) the pathogen might trigger an autoimmune mechanism that would interfere with brain functioning. In the mother, immune deficiency might allow a pathogen to persist in utero, damaging the fetal brain directly or triggering a maternal immune response that creates pathogenesis in the fetal brain." (Immune findings in autism)
These alterations are quite different than the effects observed after immunization.

Labels: , , , , , ,


Post a Comment

Links to this post:

Create a Link

<< Home

. . . launched (sans champagne, alas) 10/22/06