Friday, July 16, 2010

Newsflash! Vaccines Cause Autism...If You're Scientifically Illiterate

Mark Blaxill and Dan Olmsted are displaying their science illiteracy again over at Age of Autism in an article entitled New Study Shows Vaccines Cause Brain Changes Found in Autism. The article extols the virtues of a newly published study by Laura Hewitson, Brian J. Lopresti, Carol Stott, N. Scott Mason, and Jaime Tomko - Influence of pediatric vaccines on amygdala growth and opioid ligand binding in rhesus macaque infants: A pilot study. The abstract can be found here and the full text can be found for free here.

So, is this study as amazing as Blaxill and Olmsted would have us believe?

Not really. Orac has covered it, as have Steve Novella and Sullivan, so I won't go into a whole lot of detail. Instead, I'll highlight the primary points:
  • Small study population: only 16 monkeys overall
  • Uselessly small control group: 4 monkeys
  • Missing monkeys in the actual data analyzed: only 12 9 monkeys in the experimental group and 2 in the control group (what happened to the other 4 5?), with no explanation why the full population was not used
  • Missing conflict of interest statement: Laura Hewitson has a child involved in the Autism Omnibus hearings, in which a finding of thimerosal-containing vaccines causing autism would enable Hewitson to collect compensation from the National Vaccine Injury Compensation Program
  • Missing author: Andrew J. Wakefield, who was very likely heavily involved in this study (as demonstrated by previous studies based on this macaque population - discussions here, here and here) only appears as a "Thank you" in the acknowledgments section
  • Lack of knowledge on normal macaque amygdala development: Hewitson, et al., show amygdala volume increases in the experimental group (no statistical significance), yet a large decrease in volume in the 2 controls (with statistical significance, though how they got it, I have no clue).  Sullivan mentions that a 2009 study in macaques shows amygdala volume increases akin to what Hewitson found, yet without any vaccination or other invasive procedure (scans only), suggesting that the decreases in the controls is either abnormal or an anomaly stemming from the small sample size
Interestingly, that last point is not to be found anywhere at Age of Autism.  One commenter at Respectful Insolence commented:

A reader at AoA asked: "If no one has studied non-human primate amygdala development, how do we know what 'normal' is? Is it normal to have a decline in amygdala size during development?"

In reply, another reader simply provided a link to the abstract of the paper Sullivan pointed out. [Payne C, Machado CJ, Bliwise NG, Bachevalier J. Maturation of the hippocampal formation and amygdala in Macaca mulatta: A volumetric magnetic resonance imaging study. Hippocampus. 2009 Sep 8]

Since that paper showed that the conclusions of the Hewitson paper (which relied on an anomalous, probably scatter-related decline in amygdala volume in the tiny control group while vaccinated macaques developed normally) are utter nonsense, it's not surprising that the post was quickly deleted. Olmstead and Blaxill can't handle the truth.

If anyone can verify this, please let me know.

With so many flaws, in particular the small control group, that render the study relatively meaningless, one wonders why the University of Pittsburgh's IACUC (Institutional Animal Care and Use Committee) approved the study. If the sample size is going to be so small that no statistically significant or meaningful results can be found, then there is no reasonable justification for subjecting animals to the research. In fact, I sent an e-mail to the university's IACUC asking them these very questions:

My question to the Institutional Animal Care and Use Committee is how such a study was approved? If the control group is so small that no meaningful, statistically significant results can be found, then it is a waste of animals and would seem to constitute unethical use of animals. What justification was presented for the use of infant macaques for this study?

What actions will the university take to prevent such wasteful abuse of animals in future research?

If I hear back, I will write a follow-up.

In the meantime, if anyone has tried commenting at AoA and had their comments censored, please feel free to copy them below, including the date and time you posted them.

2 comments:

  1. Thanks for being a voice of reason. The anti-vaccine crowd pisses me off.

    ReplyDelete
  2. "If anyone can verify this, please let me know."

    I posted that note at Age of Autism in response to another post, which has also been removed. I simply and very briefly quoted the post from "betty watson."

    Betty made this comment at Respectful Insolence: "I was the one who posted the question about 'normal' amygdala development, in hopes of planting a 'seed' of doubt in their readers. I didn't even see the response post with the Payne et al article before they removed it. So far someone has offered that the 'control' group shows us what is normal, and someone has suggested saline offers a protective factor (by shrinking the amygdala). I posted a response playing 'dumb' again, and then posted one with the Payne reference...I'm guessing those won't show up, and my original one will be removed. Time will tell."

    I simply provided a link to the study that proved beyond doubt that the Hewitson study was wrong.

    I later made another comment, which in its entirety was quite like this: "It is normal for the amygdala to increase in size with increasing age in infant humans and infant macaques." That, too, was quickly removed.

    For Age of Autism and SafeMinds, ignorance is power.

    ReplyDelete

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