Study Casts Doubt On Vaccine-Autism Link

(AP)  A new study from Italy adds to a mountain of evidence that a mercury-based preservative once used in many vaccines doesn't hurt children, offering more reassurance to parents.

In the early 1990s, thousands of healthy Italian babies in a study of whooping cough vaccines got two different amounts of the preservative thimerosal from all their routine shots.

Ten years later, 1,403 of those children took a battery of brain function tests. Researchers found small differences in only two of 24 measurements and those "might be attributable to chance," they wrote in the February issue of the journal Pediatrics, which was released Monday.

Only one case of autism was found, and that was in the group that got the lower level of thimerosal.

Autism is a complex disorder featuring repetitive behaviors and poor social interaction and communication skills. Scientists generally believe genetics plays a role in causing the disorder; a theory that thimerosal is to blame has been repeatedly discounted in scientific studies.

"Put together with the evidence of all the other studies, this tells us there is no reason to worry about the effect of thimerosal in vaccines," said the new study's lead author, Dr. Alberto Tozzi of Bambino Gesu Hospital in Rome.

The debate over thimerosal and autism has been much stronger in the United States than in Italy, Tozzi said. But the researchers recognized a chance to examine the issue by going back to the children who had taken part in the 1990s whooping cough research.

Randomization sets the new study apart. The random assignment of children rules out the chance that factors other than thimerosal, such as education or poverty, caused the results.

Thimerosal, used in some vaccines to prevent the growth of bacteria and fungus, hasn't been in U.S. childhood vaccines since 2001, except for certain flu shots. Italy and other European nations began removing it in 1999. U.S. health officials recommended the removal of thimerosal as a precaution and to reduce the overall exposure of children to mercury.

Safety regulations still require multi-dose vials of vaccines to contain some type of preservative to prevent the spread of infection from contaminated vials.

The study, funded by the U.S. Centers for Disease Control and Prevention, drew praise from outside experts.

"It's yet another well done, peer-reviewed research study that has demonstrated there is no risk of any neurodevelopmental outcomes associated with thimerosal in vaccines," said epidemiologist Jennifer Pinto-Martin of the University of Pennsylvania.

"This becomes the fourth study to look for subtle signs of mercury toxicity and show the answer was 'no,"' said Dr. Paul Offit, chief of infectious diseases at the Children's Hospital of Philadelphia, the author of a book on autism research and the co-inventor of a rotavirus vaccine.

Tozzi said comparing children with no exposure to thimerosal could have improved the study. "However, if thimerosal were a cause of harm, it is likely that this effect would increase with the administered dose," he said.

The children received either 62.5 micrograms or 137.5 micrograms of ethyl mercury from all their shots during their first year of life. Thimerosal breaks down as ethyl mercury in the body. Before the reduction of thimerosal in the United States, the maximum exposure for infants was 187.5 micrograms of ethyl mercury.

The researchers found the children in both groups scored, on average, in the normal range on 11 tests of memory, attention, motor skills and other brain functions.

Those 11 tests included 24 measured outcomes. Small, but statistical differences were found for only two of those areas, and only for girls. The girls with higher exposure scored worse on a finger-tapping test with their dominant hands, and on a vocabulary test in which they were asked to name common objects.

There was no difference in boys on those outcomes or others. Researchers also found no difference in tic disorders. And the one autism case found in the lower-intake group was likely a chance finding, Tozzi said.

[AJPBSCH]

Cool Thymerosal doesn't cause autism - it only causes brain damage (in girls) - phew, and for a moment I was worried.

Extra for experts: Then marginally over a thousand children were tested (out of thousands) and only one had autism - why didn't they pick the autistic kids? Seriously the conclusions of this study are as useful as the one where a handful of kids "proved" coeliac and autism weren't linked - when (against the odds) one of the autistic kids showed up with gluten intolerance.

[garbosmed]

Since it isn''t your field, I''ve posted a few studies, including the one that caused the Ip (Japan) study conclusions to be withdrawn. The current theory that clinicians and researchers are finding strong evidence for is that the thimerosal, squalene, aluminum and vaccine viruses (alone or interacting) cause a cascading effect that crashes the immune systems in certain children who are vulnerable due to genetic predisposition, weak mitochondrial function, or existing environmental insult. Another recent study showed that aluminum adjuvant increases permeability of the blood-brain barrier, leaving tissue more susceptible to the toxic insults of mercury and to viral invasion.

This is important for all of us, because it may show that what was once safe for most people (vaccines) now is no longer due to rising environmental levels of mercury and other toxins. Or it might show that it is the rising levels of vaccines themselves that is the problem. Or that giving Hep B shots within hours of birth might not be such a swell idea, that it might be better to check the infant for such conditions first. Either way, it is imperative that we continue to study the vaccine-autism/immune disorder connection.

[rational_1]

Ridiculous to think that one wouldn''''t compare IQ tests with people who don''''t drink alcohol at all, isn''''t it? And yet that''''s what this study does.
Posted by Garbosmed at 01:32 PM : Jan 29, 2009

Yes, I see your point and it does come down to saying it''s an all-or-none thing. Either 62.5 ug is sufficient to produce maximal impairment on all the neuropsychological parameters they tested (and an extra 75 ug of ethylmercury does absolutely nothing), or neither is doing anything that they could detect. I have a hard time believing that all 24 of the neuropsychological tests that they performed had identical or near-identical sensitivities to ethylmercury such that none of them could be worsened by an additional 75 ug of the compound. But you''re right that a zero-dose cohort would have strengthened the study. Now getting back to my old MMR references, that''s exactly what was done in some of those studies: they compared autism rates after removal of thimerosal from the MMR vaccine and did not see a decrease in autism incidence. There''s a zero-thimerosal group in those studies.

[garbosmed]

Aluminum adjuvant linked to gulf war illness induces motor neuron death in mice
Neuromolecular Medicine, 2007
Christopher Shaw, Ph.D. [Department of Ophthalmology and Program in Neuroscience, University of British Columbia, Vancouver, British Columbia, Canada]
This study demonstrates the extreme toxicity of the aluminum adjuvant used as a preservative in vaccines. Excerpt:
"testing showed motor deficits in the aluminum treatment group that expressed as a progressive decrease in strength measured...Significant cognitive deficits in water-maze learning were observed in the combined aluminum and squalene group...Apoptotic neurons were identified in aluminum-injected animals that showed significantly increased activated caspase-3 labeling in lumbar spinal cord (255%) and primary motor cortex (192%) compared with the controls. Aluminum-treated groups also showed significant motor neuron loss (35%) and increased numbers of astrocytes (350%) in the lumbar spinal cord.

[rational_1]

I think you miss the point in why we are critical of this study.
Posted by Garbosmed at 01:26 PM : Jan 29, 2009

Sorry for the confusion - I was still on Simpsonwood.

I just went to the Pediatrics website and read the Tozzi article first hand rather than relying on the CBS News description. The basis of their conclusions is that there is no dose-dependent (62.5 vs 137.5 micrograms) effect of ethylmercury on any of the neuropsychological parameters they examined. This seems highly unlikely if this compound is a causative agent for these disorders - one would expect a higher frequency of problems with kids exposed to higher doses. It''s analogous to a dose-dependent effect of an antihypertensive in reducing blood pressure - you''d expect a sigmoid-shaped dose-response curve. So, in their study either both concentrations of ethylmercury they tested are already producing maximal effects on the parameters they tested (and are maximal in all not just some, which I find hard to believe) or neither is having any effect. No other interpretation is possible. Ideally the study would have been strengthened with the inclusion of a cohort with no thimerosal exposure but that group doesn''t appear to exist in their study population.

[garbosmed]

Aluminum adjuvant linked to gulf war illness induces motor neuron death in mice
Neuromolecular Medicine, 2007
Christopher Shaw, Ph.D. [Department of Ophthalmology and Program in Neuroscience, University of British Columbia, Vancouver, British Columbia, Canada]
This study demonstrates the extreme toxicity of the aluminum adjuvant used as a preservative in vaccines. Excerpt:
"testing showed motor deficits in the aluminum treatment group that expressed as a progressive decrease in strength measured...Significant cognitive deficits in water-maze learning were observed in the combined aluminum and squalene group...Apoptotic neurons were identified in aluminum-injected animals that showed significantly increased activated caspase-3 labeling in lumbar spinal cord (255%) and primary motor cortex (192%) compared with the controls. Aluminum-treated groups also showed significant motor neuron loss (35%) and increased numbers of astrocytes (350%) in the lumbar spinal cord.

[garbosmed]

Activation of Methionine Synthase by Insulin-like Growth Factor-1 and Dopamine: a Target for Neurodevelopmental Toxins and Thimerosal.
Molecular Psychiatry, July 2004.
Richard C. Deth, PhD [Northeastern University].
This study demonstrates how Thimerosal inhibits methylation, a central driver of cellular communication and development. Excerpt:
"The potent inhibition of this pathway [methylation] by ethanol, lead, mercury, aluminum, and thimerosal suggests it may be an important target of neurodevelopmental toxins."

[garbosmed]

Activation of Methionine Synthase by Insulin-like Growth Factor-1 and Dopamine: a Target for Neurodevelopmental Toxins and Thimerosal.
Molecular Psychiatry, July 2004.
Richard C. Deth, PhD [Northeastern University].
This study demonstrates how Thimerosal inhibits methylation, a central driver of cellular communication and development. Excerpt:
"The potent inhibition of this pathway [methylation] by ethanol, lead, mercury, aluminum, and thimerosal suggests it may be an important target of neurodevelopmental toxins."

[garbosmed]

Uncoupling of ATP-mediated Calcium Signaling and Dysregulated IL-6 Secretion in Dendritic Cells by Nanomolar Thimerosal
Environmental Health Perspectives, July 2006.
Samuel R. Goth, Ruth A. Chu Jeffrey P. Gregg
This study demonstrates that very low-levels of Thimerosal can contribute to immune system disregulation. Excerpt:
1"Our findings that DCs primarily express the RyR1 channel complex and that this complex is uncoupled by very low levels of THI with dysregulated IL-6 secretion raise intriguing questions about a molecular basis for immune dyregulation and the possible role of the RyR1 complex in genetic susceptibility of the immune system to mercury."

[garbosmed]

Thimerosal Neurotoxicity is Associated with Glutathione Depletion: Protection with Glutathione Precursors.
Neurotoxicology, Jan 2005.
S. Jill James, PhD [University of Arkansas].
This recent study demonstrates that Thimerosal lowers or inhibits the body''s ability to produce Glutathione, an antioxidant and the body''s primary cellular-level defense against mercury. Excerpt:
1"Thimerosal-induced cytotoxicity was associated with depletion of intracellular Glutathione in both cell lines...The potential effect of Glutathione or N-acetylcysteine against mercury toxicity warrants further research as possible adjunct therapy to individuals still receiving Thimerosal-containing vaccines."