|Photo via Wikimedia Commons|
I know this is one of those areas that gets everyone all riled up, but I ran across the a study earlier this month and thought the results were interesting and worth pointing out. Just a quick note before I start, if you are one of the people who see the M word used in an article about autism and get all bent out of shape, I would ask that you ignore that part of it and consider the other the other findings. So, without further ado..
The study in question looked for and found a possible relationship between the levels of trace and toxic elements and the severity of autism in children. The trace elements in question are copper, zinc, magnesium, and selenium while the toxic elements are lead and mercury.
The researchers looked at hair and nail samples from a total of 95 children. These children were divided into four groups - a typical (control) group with 50 children, and a low functioning group (LFA) with 15 children, a medium function group (MFA) with 15 children, and high function group (HFA) that also had 15 children. The children were placed in their groups by their score on the Childhood Autism Rating Scale (CARS) test, a older but still valid test for autism. Children in the HFA group had a score on the CARS of 15-30, MFA was 30-45, and LFA was 45-60. The children lived in India and were between the ages of 4 and 12. The groups were matched on age as well as gender.
The researchers analyzed the samples and found that there were significant relationships between the severity of autism and the measured level of these elements. In general, children with more severe autism had higher levels of copper, lead, and mercury and lower levels of selenium and magnesium. Zinc was the exception as there wasn't a significant relationship between severity and the level measured. However, children in the LFA group did show a significant decrease in zinc when compared to the control group.
Since these relationships are easier to visualize rather than read, I am including some graphs below that show the mean values for each group for each sample type (hair and nail). Most of the values below reached the threshold for significance ( p < 0.01 or p < 0.001) but not all of them did (Zinc in hair and nails for MFA and LFA as well as lead in nails for MFA and HFA did not).
There are two caveats to keep in mind as you look at the charts.
First, these data points do not "prove" that autism is caused by any specific thing. They only show a relationship between the level measured and a severity of autism. Or to put it a different way, the relationship here is between the level measured in hair or nails and the score on the CARS test. Although on the flip side, CARS is a decent test and can distinguish between autism and pdd-nos, so it should be an acceptable way of determining severity.
Second, there is no data about why the numbers look the way they do. All of the children were from the same general area but that does not mean that they all come from the social or economic background. It is also entirely possibly that these differences could be caused by differences in diet between the groups
However, it is my feeling that these results do reflect the reality of what can happen in certain children with autism. As a case in point, all of my own children show an elevated (almost toxic) level of copper, a low level of zinc (2 of 3 were zinc deficient), and low levels of selenium.
Lakshmi Priya, M. D., & Geetha, A. (2010). Level of Trace Elements (Copper, Zinc, Magnesium and Selenium) and Toxic Elements (Lead and Mercury) in the Hair and Nail of Children with Autism. Biological trace element research. doi: 10.1007/s12011-010-8766-2.