Monday, November 2, 2009

Direct from the Researcher

Another week, another amazing LEND opportunity!

The center that hosts "my" LEND program has an ongoing brown-bag research-seminar series where distinguished researchers come in for one-hour presentations on their ongoing work. One of the LEND assignments involves attending one of these presentations each semester and reporting back. My interdisciplinary team (with an autism focus) chose to attend last Friday's presentation: “Gene x Environment Interactions Contributing to Autism: Lessons Learned from the UC-Davis Center for Children’s Environmental Health and Disease Prevention,” presented by Dr. Isaac Pessah.

Little did I know when we signed up at the beginning of the semester to attend this talk, that Dr. Pessah would be discussing an article that would go online as a pre-pub just a week and a half before, and already be getting the blogospheric once-over right before we got to hear him in person!

The article in question is Blood Mercury Concentrations in CHARGE Study Children with and without Autism. The authors are Irva Hertz-Picciotto, Peter G. Green, Lora Delwiche, Robin Hansen, Cheryl Walker, and Isaac N. Pessah; and the sponsoring institution is the MIND Institute of UC-Davis.

Quick detour about the MIND Institute -- this is an organization whose co-founders were parents of children with autism, searching for a cure and ready to lay the blame with vaccines. (See All Things Considered transcript from Jan. 20, 2003). Since its inception, the MIND Institute has focused on environmental considerations in autism. They operate from the position that the rise in autism prevalence can not be entirely accounted for by changing definitions, diagnostic substitution, and increased awareness/education.

Given that background, it's not at all surprising to see a study comparing mercury concentrations in the blood of children with and without autism.

The conclusions might not be expected, though.
Conclusions: After accounting for dietary and other differences in Hg exposures, total Hg in blood was neither elevated nor reduced in CHARGE Study preschoolers with AU/ASD as compared with unaffected controls, and resembled those of nationally representative samples.

They used a substantial sample of preschoolers on the autism spectrum, plus two control groups: one group with non-autism developmental disabilities, and one typically-developing group. They interviewed mothers to determine household and medical and dietary exposures to mercury.

It turned out that the biggest contributor to blood mercury levels in all groups was fish consumption. Once you account for fish consumption, there were no significant differences in blood mercury levels between groups. In fact, before controlling for fish consumption, the blood mercury levels for the autism group were actually lower than the other groups. Because the ASD kiddos ate less fish!!

Sullivan over at LeftBrain/RightBrain does a fine parsing of the study and the various online reactions to it. I won't try to re-do a job that's been already well-done!

For me, it's rather a thrill to be hearing first-hand, right from the mouth of one of the actual study authors, that the ASD kiddos had similar blood-mercury levels, and any differences were pretty much all about the fish. Now, this doesn't say anything directly about mercury and autism causation. The authors are very straightforward about that. Still it's another useful counterweight to what has become an insidious public perception. It's not the thimerosal, folks!!

P.S. You may have noticed that the title of Dr. Pessah's talk was about genes & environment. He also addressed a second paper, not yet publicly available, that delved deeper into genetic complexity than my poor notes were able to keep straight in the absence of being able to refer to the actual PowerPoint slides! When the paper actually comes out, I might take a whack at it. Or it still might turn out to be pretty much beyond my ken.


mama edge said...

Wow, what a wonderful front seat of the theater you had! And bravo to the researcher for putting aside his biases and using the scientific method to test (and invalidate) his hypotheses. It gives me hope that science will prevail over hyperbole, someday.

Anonymous said...

I'm sure you will do fine - when the paper finally comes out.

We are in sync with our posts you mentioning "Gene x Environment Interactions" and me on Nature vs. Nurture.

Thank you for posting this. Powerful stuff.


Name dropper.


datri said...

Hooray for science!

It won't change the minds of those who are firmly entrenched in the anti-vax movement tho. I'm sure they'll come up with some conspiracy theory.

Telemommie said...

This is really interesting as the mercury theory always hangs over the heads of us "Autism Parents." Also proud to see UC Davis doing this work as an alum.