Marc Joseph Nutrition - Blog

In a recent study published in the journal Neuropediatrics, researchers observed that higher blood mercury levels were significantly associated with Attention Deficit Hyperactivity Disorder (ADHD).

Specifically, the case control study examined 52 children with ADHD (44 boys, mean age=7) along with a control group. Researchers found:

• significantly greater blood mercury levels in the children with ADHD than the control group (18.2 vs. 11.6 nmol/L)
• that children with blood mercury levels greater than 29 nmol/L (27% of the children studied) had nearly 10 times the risk of having ADHD

Mercury is not the only heavy metal associated with ADHD. As mentioned in an earlier blog post (One-third of ADHD Cases May be Tied to Lead, Smoking), lead exposure may also be a potential cause.

Whether mercury, lead, or another heavy metal may be involved, it’s important to use an appropriate diagnostic test. A blood test is not necessarily a good choice. Heavy metals tend to clear from the blood over the course of several months. So, if exposure to heavy metals is in large, infrequent doses (e.g., through a vaccine preservative), a blood test wouldn’t necessarily reveal an elevated level unless the test were done right after the exposure.

Also, even if the exposure were low-level and chronic (e.g., mercury fillings, fish consumption), blood levels may not be high. The blood test, though, doesn’t tell you anything about what amount of metals are being retained by the body’s tissues and organs — and that’s what you really care about most.

A challenge test using a chelation substance, like DMSA, is sometimes used to try get a better understanding of tissue levels. But it’s not accurate either. The test may tell you that you have high metal levels, but a negative test result doesn’t necessarily mean that you have low levels. It just means that the chelation substance didn’t pull any metals with that challenge dose. Think of it like a miner going into mine in search of gold. He scrapes the walls for a bit and finds no gold. Does that mean there’s no gold in the mine? Mmmm, no.

A better test for chronic, long-term heavy metal exposure or acute exposures that occurred more than a couple of months ago is a hair test. This test can help to reveal disordered essential mineral transport, which is a hallmark sign of heavy metal toxicity. The heavy metals displace and disrupt the normal use of essential minerals in the body (e.g., zinc, magnesium, calcium, etc.), including the deposition of these minerals into the hair.

You can read more about approaches for dealing with heavy metal toxicity and ADHD here and here.

This entry was posted on Wednesday, February 7th, 2007 at 6:57 pm and is filed under ADD/ADHD, Mercury. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.