Reply #22: It's been done.

[Igel]

There are some significant differences between autistic brains and normal brains ("normal" used to mean within 1 standard deviation of the mean).

It's been done to death, so to speak.

There are a lot of brain chemistry differences. More importantly, there are some structural differences--structural differences that pretty much have to originate pre-birth, even though they continue to develop after birth (the entire humongous pre/post-birth transition is vastly overrated--some systems come on line, others shut down, but much of the body doesn't really care how the oxygen, glucose, amino acids, etc., etc., got into the bloodstream).

The Hg/autism connection has two main problems: First, eye-tracking shows whether or not kids are at the more dire end of the autism spectrum at 3-4 months of age in many cases, if not earlier. That's before nearly every vaccination--and usually when the soon-to-be-heartbroken parents would swear that their kid's developing perfectly normally. In fact, when they were told during the course of the study they adamantly denied it--even though the earlier the intervention starts the better. The limiting factor in eye-tracking is whether the kids can focus and have sufficient control over their eye muscles. Austistic and normal kids simply have different sets of interests even at 3 months: The normal kids seek out faces, both novel and familiar; the autistic kids simply don't care, human, doorknob, it's all equally interesting (or not). To solve part of the problem using a kind of brute-force method you'd need to find some enterprising fmri folks to image neonates' brains--or even brains in utero--so they could track the tykes later. The only problem would be sample size. Autism isn't all that common, and they'd probably need a few dozen autistic brains in the sample with no way of IDing them a priori. At an autism rate of what--0.2%?--they'd need to image 10,000 or more neonates. The funding would have to be out of this world. It would never pass the human research protocols committee.

Second, those holding the Hg/vaccination link to be true made a probably false assumption about organic Hg's behavior in the human body. Methyl mercury is retained and has a fairly long biological half-life. It takes a long-time for it to be removed from the bloodstream and tissues. Ethyl mercury pretty much washes right out at the levels induced by vaccinations, at a rate something like 1000 times faster than methyl mercury. (Yes, that was a bit of a shock to the researchers involved.) Thimerosal is a kind of ethyl mercury. In other words, the window of exposure to Hg from something like thimerosal is much, much smaller than assumed. The result would be that you'd expect to find a lot *more* autism than you do, with a different distribution, and a different frequency over time, since the methyl mercury background concentrations in the population would provide at least as much, if not more, exposure to Hg.