Autism Street

By Do’C and Interverbal

Introduction

Back in November of 2007 we wrote an article about a recent paper by DeSoto & Hitlan. Also, Dr. DeSoto has since published a FAQ about the paper at her university website.

The intention of our original article was a critical look at what this paper had to offer to those interested in autism research. When we first read the DeSoto & Hitlan, 2007 paper, we noticed several issues that concerned us greatly.

There seemed to be some gray areas and even overt errors that should be addressed. In our opinion, these errors range in form, from overstatements about cited articles, assertions for which no appropriate supporting science was presented, and reliance on older publications that were not subjected to the process of peer-review, to citation of a paper that does not appear to support the assertion for which it was cited in the first place. We also looked at the statistics in some detail.

Is it appropriate for a couple of bloggers to try to tackle peer-reviewed research? We would answer, “yes”, in some cases, bloggers can address academic articles in a critical sense. And while we would certainly agree that blogs are similar to non-peer-reviewed journals (in that they lack the safety net of formal peer-review) we also think that judgment should be based on what is said, not by whom it is said. DeSoto & Hitlan make this exact same point in their FAQ page about the article on their website.

What is more, we do not think that DeSoto & Hitlan are “junk scientists” nor do we encourage that view. DeSoto & Hitlan deserve respect, first as people and then as scientists. However, despite this, we think they made several important mistakes (including some that merit formal correction), and it is this aspect specifically, and not DeSoto & Hitlan’s abilities, that we call into question.

We (Do’C and Interverbal) do not have an agenda aside from advocating for crystal clear science in autism. We want transparency, we want logic, and we want careful empiricism. While it is no secret that we take a skeptical position in regard to biomedical “autism treatments” and claims of a real increase in autism, this is because we have been so careful to “keep up” with the research literature in these areas. In other words, this is our opinion that evolved over time in response to the science. If the science changes, then our general opinions will also change. Regardless of whether or not we disagree with others, we do not commonly refer to them as “idiots”. We think it’s likely that DeSoto & Hitlan have a very similar agenda to the one we espouse. Once and again, the issue here is and should be, the actual arguments - not the people doing the arguing.

It’s our opinion that the distinction between statistical significance and the authors’ term “marginally significant” was not clear. In addition, DeSoto & Hitlan attempted to justify their interpretation by noting how important it is that researchers understand what is “behind the rise in autism”. No epidemiological evidence was provided to support the assertion that there is any rise in the true prevalence of autism itself.

Following our article, a fairly lengthy discussion in the comments ensued. This discussion included a response from Dr. DeSoto. While her response contains some clarification, and points out potential errors on our part, it also provides some additional detail and assertions about the mistakes we mentioned above. It seems to us, that some of Dr. DeSoto’s FAQ page may interest Autism Street readers too. We’ll take a look at all of these things, but before we do, we’re going to acknowledge some minor errors on our part.

Erratum: Relevant Publications List

One of the apparent concerns raised by Dr. DeSoto in her response to our article, was the fact that we did not present the complete list of all relevant publications, nor did we focus on the fact that an error existed in the original work by Ip et al.

“We hope that “DoC,” and others are remembering that an error was discovered in another authors’ work about autism (which the original authors have determined likely occurred during typing – see their correction as well as the editor in chief’s explanation of how the error occurred, which are published in the same issue of JCN).”

While we were not necessarily interested in this aspect of the DeSoto & Hitlan paper, nor are we interested in DeSoto & Hitlan’s motivation for publishing (correction of an existing error is reason enough), we acknowledge that a more complete relevant publication list would probably have been beneficial to most readers, and include it here.

It should be noted that errors in the original work of Ip et al. were first discovered by DeSoto & Hitlan, and the journal editor was then made aware of those discovered errors.

Relevant publications

Ip P, Wong V, Ho M, Lee J, Wong W
Mercury exposure in children with autistic spectrum disorder: case-control study
J Child Neurol 2004 19: 431-4.

M. Catherine DeSoto and Robert T. Hitlan
Blood Levels of Mercury Are Related to Diagnosis of Autism: A Reanalysis of an Important Data Set
J Child Neurol 2007 22: 1308-1311.

Roger A. Brumback
Note From Editor-in-Chief About Erratum for Ip et al Article
J Child Neurol 2007 22: 1321-1323.

Erratum
J Child Neurol 2007 22: 1324.

Erratum: Statistical Importance

Dr. DeSoto commented:

“It is not even remotely correct to say that most of our concerns were “are mainly statistical in nature”. Our main concern is that false, mistaken data was published.”

We never disagreed with DeSoto & Hitlan’s correction of mistaken data. We agreed with them. It was the aspects in the DeSoto and Hitlan paper beyond the correction of clear mistakes that we focused on. That is why our previous comment was phrased as it was. We now recognize that this may have confusing, we appreciate the chance to clarify.

Erratum: Use of a One-Tailed Test – With Outliers

This erratum first appeared informally in the comments of our original post. It was not part of our main critique. The issue was whether a test of the corrected data was run using a one-tailed test with the outliers kept in. The authors never mention that they ran such a test and Interverbal incorrectly stated that the authors had not run this test. Interverbal has acknowledged this error multiple times now and in several different locations.

Erratum: Comments On Selected Statements

Part of our review of selected statements contained in the DeSoto & Hitlan paper focused a critical eye on their apparent overstatement/misinterpretation of the results of Holmes et al., 2003.

Holmes AS, Blaxill MF, Haley BE.
Reduced levels of mercury in first baby haircuts of autistic children.
Int J Toxicol. 2003; 22:277-285.

DeSoto & Hitlan write:

“In the autistic group, severity of autism was inversely related to hair mercury levels. This means that the more severe autistic cases actually had less excretion of mercury.”

That’s been hypothesized, but it doesn’t mean that at all.

Our criticisms of DeSoto & Hitlan’s interpretation center on the fact that, mercury is not “excreted” in the hair of humans. Although we thought our brief points about the physiological likelihood of active excretion, and the use of the quotation marks around the words “excretion” and “excreted” made it clear that we distinguish it as a specific process, as opposed to inclusive of “any elimination whatsoever” (such as passive uptake during hair formation and resulting bioaccumulation), it became clear from reading the FAQ website published by Dr. DeSoto, that our distinction may not have been clear enough.

It should be noted that references by us to “excretion” and “excreted” indicate a specific and biologically significant, human physiological removal mechanism, and do not simply refer to “any elimination” from the body (such as the case with the known processes of passive uptake and bioaccumulation in human hair).

It should also be noted that no scientific evidence demonstrating that mercury “accumulation” in human hair is related to overall mercury elimination via significant excretory routes (stool and urine, etc.), such that reduced hair “accumulation” indicates reduced “excretion” via the known significant excretory routes, was presented in DeSoto & Hitlan, 2007.

Dr. DeSoto Comments

Following the publication of our article, Dr. DeSoto posted a fairly lengthy comment. You can read it in its entirety here. While her comment contained some points we’ve acknowledged here, it also presents some new problems for Dr. DeSoto’s apparent position. We plan to discuss these in more detail. Although readers in the comments section that followed the original article questioned many of the statements by Dr. DeSoto, she did not reply to them there. We are genuinely appreciative that Dr. DeSoto took the time to comment, though.

Even with our own errata out of the way, there is still a lot of material to cover here, so we’ll at least break things up into sections (possibly two more parts – we’ll just have to see). As always, reader comments and criticism are welcome. At the end of these two or three parts, we’ll provide our conclusion about the DeSoto & Hitlan paper and attempt to answer the question, “Do we think this paper adds to the body of scientific knowledge about autism?”. We’ll also provide a relevant list of additional reading.

Coming next: We’ll look at that FAQ in more detail.