Autism Street

Once in a while, a drop of skepticism can be found in an ocean of belief.

Lately, I’ve noticed some good questions being posited in online autism discussions about whether or not chelation can work, in spite of the fact that it’s thought that most available chelators probably don’t cross the blood-brain barrier.
 
Essentially, the questions being asked concern current chelators’ ability to remove heavy metals from the brain. Despite assertions that heavy metal toxicity is a main aspect of autism, questions along the lines of, “although known chelators can remove heavy metals from other body tissues, how can chelation work to affect autism if it can’t remove heavy metals from the brain?” are rightfully placed.
 
Good on those people for raising very valid questions and showing some skepticism.

Do chelators remove mercury from the brain?

I’ve seen this aspect addressed by an astute internet forum poster (quoted with permission):

These are excellent questions that deserve answers when considering chelation.

If anyone knows of evidence that refutes any of my statements below, please post (there may be some, but I didn’t find it). I am not a medical professional, but then neither are those on this forum who promote the use of chelation, so I might as well give it a go…

1. There is no definitive evidence that any of the commonly-used chelators even cross the blood-brain barrier of humans.

2. There is no evidence that any of these chelators are removing heavy metals from the brains of children.

3. There is no evidence that even if these did cross the bb barrier, and even if these did transport heavy metals out of the brain, that this would improve neurocognitive functioning, nor that damage to the brain via heavy metal poisoning is “reversible.”

4. There have been questions raised (though not answered) — if chelators did indeed cross the b/b — regarding the possible “redistribution” of heavy metals in the body to the brain.

5. Using chelators often involves the assumption that heavy metals (specifically mercury) are the root cause of autism, and that the removal of heavy metals will remove the autism.

There exists assumption upon assumption upon assumption in regard to chelation and autism. We just don’t know if chelating a child will result in improvement, but what little science there is does not point in the direction of improvement, and certainly not in the direction of any “reversal” of neurological damage caused by heavy metals.

Here is some info in regard to the neurocognitive improvement (actually the lack thereof) in regard to the chelation of lead (an example):

Effect of Chelation Therapy on the Neuropsychological and Behavioral Development of Lead-Exposed Children After School Entry

Link: http://pediatrics.aappublications.org/cgi/content/full/114/1/19

But, is heavy metal in the brain even an issue in autism?

Remeber that although the subject of how chelation can even work is being asked about, assertions that heavy metal toxicity is a main aspect of autism are not uncommon. I’d like to address such assertions as well.

As was communicated by that insightful poster, “If anyone knows of evidence that refutes any of my statements below, please post (there may be some, but I didn’t find [them]). I am not a medical professional, but then neither are [many] on [internet] forum[s] who promote the use of chelation, so I might as well give it a go…”

6. There is no definitive evidence that autistic children have any more mercury in the brain, or body burden for that matter, than non-autistic children.

Note: Mercury=autism proponents often point to a study by Bradstreet et al. which claimed to show autistic children excreted more mercury following chelation with DMSA than controls. However, that study has  potentially critical flaws - It reported mercury excretion as a ratio to creatinine following first morning (spot) urine collections. The potential problems with this are:

A) Ratioing to creatinine could be very problematic, especially so in autistic children. Without reporting the actual creatinine values, there is no way to know “how much” mercury was excreted at all. The only thing you can determine is how much mercuy per gram of creatinine was excreted, which tells you nothing about quantity excreted.

Consider the following example: Joe has some wallets. Each wallet contains 5 “one-dollar” bills per “twenty-dollar” bill. If he dumps out his wallets into a bowl, how much money (in “one-dollar” bills) ends up in the bowl?

B) A spot collection might as well tell nothing compared to a 24-hour collection. Since excretion of urinary metabolites and heavy metals can vary greatly througout a 24-hour period (and so can urine volume), a 24-hour collection is the best way to determine “how much” mercury is excreted on a daily basis.

Consider the following example. Joe has some wallets. Each wallet contains 5 “one-dollar” bills per “twenty-dollar” bill in the morning. He dumps out his wallets into a bowl. He goes to the bank and refills his wallets. In the afternoon, each wallet contains 3 “two-dollar” bills per “ten-dollar” bill, and he dumps out the wallets into the bowl. He goes to the bank to refill his wallets one more time. That evening, each wallet contains 1 “five-dollar” bill per “fifty-dollar” bill, and he dumps the wallets into the bowl. How much money in 1’s, 2’s, and 5’s ended up in the bowl?

The best way to answer this is to simply count the 1’s, 2’s, adn 5’s in the bowl at the end of the 24 hours, although it could also be calculated if you know how many 10’s, 20’s, and 50’s, and how many wallets he had.

C) As a possibility, the use of chelators may influence creatinine clearance and skew results reported as a ratio to creatinine.

See the following study for additional detail about spot urinary creatinine excretion:

Spot urinary creatinine excretion in pervasive developmental disorders
Whiteley P, Waring R, Williams L, Klovrza L, Nolan F, Smith S, Farrow M, Dodou K,  Lough WJ, Shattock P.

Link: http://www.blackwell-synergy.com/doi/abs/10.1111/j.1442-200X.2006.02207.x

Going with porphyrins instead of mercury to creatinine ratios?
It would have been nice if Nataf et al. reported actual mercury levels along with the porphyrin levels and had published actual total porphyrin levels over 24 hours, instead of ratioing to creatinine similar to Bradstreet et al.

7. There are no published reference ranges or supporting normative studies (that I am aware of) for determining pediatric mercury toxicity with ASD using methodology that employs provocation with a chelator followed by interpretation of spot urinary measurements of heavy metals expressed as a ratio to creatinine - toxicity is apparently assumed based on comparison to non-provoked method reference ranges.

8. There is no definitive evidence that autistic children are unable to excrete mercury on their own any differently than non-autistic children.

Note: mercury=autism proponents often point to Holmes et al. (First Baby Haircut Study) which claimed to show autistic children had lower hair mercury levels than non-autistic children. Holmes et al. did not demonstrate poor excretion, but in their conclusion, they hypothesized it. Unfortunately, they hypothesized it based on some potentially critical flaws.

A. Holmes et al. did not actually measure mercury exposure. They claimed to have in their conclusion, but if you read the paper carefully, it is easily determined that mercury exposure  was estimated/calculated and not really measured at all. Those estimations are subject to numerous potential errors: simply counting dental fillings instead of actually measuring quantities of dental amalgam (two tiny fillings represent more hypothetical exposure than one large one in their formula which could be the opposite of reality), estimating seafood consumption based on recollection reported years later, and possible exposure of samples during years of uncontrolled storage to name just a few. Nevermind that dental amalgam and seafood consumption are not even representative of the same kind of mercury in Thimerosal. Further reading on these ideas is available from what I think might be an original source.

B. Control subjects in Holmes et al. had unusually high levels (way higher than well-done studies that show very high levels in heavy seafood consumption countries. Autistic subjects did not have low levels of mercury at all (in fact, they had levels higher than the NHANES study which included 1 and 2 year-olds. Overall, I recommend reading up on the Texas Sharpshooter Fallacy.

C. Mercury is not excreted in the hair in the first place. Hair levels are the result of passive uptake of the mercury that’s in the blood. There is no evidence that I am aware of, that mercury in hair is in any way representative of excretion.

D. Many parents have claimed that their kids “can’t detoxify” or “are poor excretors”.

Others have asked something along the lines of, “If autistic people are poor excretors as hypothesized, why don’t autistic people develop real mercury poisoning and or die from it”.

Adams et al. addressed this just this year (sort of) with a study done back in 2002-2003 (at the same time as Holmes et al. and also using the same laboratory). The Adams et al. hair results showed no differences in mercury. Since a portion of the Adams et al. subjects were 3-6 years old (and not 1 or almost 2 like in Holmes et al.) The Adams et al. study seems to hypothesize that if Holmes et al. is somehow right, then autistic children may only be ”poor excretors” temporarily.

This suggests that they are just as good at excreting mercury as non-autistic peers by about age 3 (of course you’ll have to assume, despite any definitive evidence, that they weren’t previously).

Here’s a link to Adams et al.

Let’s short roundup all the points about chelation.

1. No definitive evidence that current chelators even cross the blood brain barrier
2. No definitive evidence that current chelators are removing heavy metals from the brain
3. Even if they did work, no definitive evidence that neurological damage caused by heavy metals would be reversible
4. Chelators might redistribute heavy metals into the brain
5. Heavy metals even causing autism is an assumption, as is that removal equals reversal
6. No definitive evidence that autistic children have more mercury in the brain or body in the first place
7. No definitive published reference ranges or supporting normative studies for current provoked heavy metal toxicity methodology for ASD children
8. No definitive evidence of inability to excrete heavy metals - only hypotheses (”poor excretor”, “temporary poor excretor”)