A 2003 paper in the International Journal of Toxicology suggests the answer is yes. A Baton Rouge doctor named Amy Holmes, who herself had an autistic child, wondered if mercury was involved. She tested the hair of a series of autistic children from her practice and found, to her surprise, that they had less mercury in their hair than other children. Then she and two other scientists did a well-controlled comparison of normal and autistic children that confirmed her original observation. These are the data in the 2003 paper. Here is its abstract:
Reported rates of autism have increased sharply in the United States and the United Kingdom. One possible factor underlying these increases is increased exposure to mercury through thimerosal-containing vaccines, but vaccine exposures need to be evaluated in the context of cumulative exposures during gestation and early infancy. Differential rates of postnatal mercury elimination may explain why similar gestational and infant exposures produce variable neurological effects. First baby haircut samples were obtained from 94 children diagnosed with autism using Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM IV) criteria and 45 age- and gender-matched controls. Information on diet, dental amalgam fillings, vaccine history, Rho D immunoglobulin administration, and autism symptom severity was collected through a maternal survey questionnaire and clinical observation. Hair mercury levels in the autistic group were 0.47 ppm versus 3.63 ppm in controls, a significant difference. The mothers in the autistic group had significantly higher levels of mercury exposure through Rho D immunoglobulin injections and amalgam fillings than control mothers. Within the autistic group, hair mercury levels varied significantly across mildly, moderately, and severely autistic children, with mean group levels of 0.79, 0.46, and 0.21 ppm, respectively. Hair mercury levels among controls were significantly correlated with the number of the mothers’ amalgam fillings and their fish consumption as well as exposure to mercury through childhood vaccines, correlations that were absent in the autistic group. Hair excretion patterns among autistic infants were significantly reduced relative to control. These data cast doubt on the efficacy of traditional hair analysis as a measure of total mercury exposure in a subset of the population. In light of the biological plausibility of mercury’s role in neurodevelopmental disorders, the present study provides further insight into one possible mechanism by which early mercury exposures could increase the risk of autism.
The abstract omits the most important piece of information: There was little or no overlap between the hair mercury of the control and autistic groups. (It is hard to tell exactly, the data are badly plotted.) Given the size of the two groups, this is highly persuasive. The abstract also omits the basic conclusion: In autistic children, a mechanism that gets rid of mercury is broken. As a result, they get poisoned by levels of environmental mercury that would otherwise be safe.
Holmes started treating autistic children by (a) giving them a compound that tends to bind to mercury and form a compound that is excreted and (b) reducing their mercury exposure. The results of this treatment have been very impressive. As children get older, it becomes less effective. Here are details:
We currently have over 500 autistic patients under treatment with DMSA ranging in age from 1 to 24 years old. In general, we do not expect to see any behavioral, language, or social improvements until at least some of the CNS mercury has been removed. As of 1/15/01, we had 85 patients who had finished DMSA alone and had completed at least 4 months of DMSA + lipoic acid. The results of treatment in these patients are presented below:
Once lipoic acid is added, we usually track mercury excretion via tests of fecal mercury. We have noticed a large dependence of excretion on age of patient with the younger patients excreting much more mercury than the older patients. We think this difference in rapidity of excretion may explain the differences in response between the various age groups.
We have 6 patients, all 1 to 2 years of age who are finished with treatment by measurements of urinary and fecal mercury excretion. These 6 patients are “normal” by parent reports and repeat psychological testing. We have no children over the age of 2 who are finished with treatment. The rapidity of excretion seems to decrease markedly with each additional year of age. There are several children, mostly in the younger age groups, who have made remarkable progress to the point of being able to be mainstreamed in school, but who are still have some “oddities” of behavior — none of these children have completed treatment yet.
Addendum. A new TV series ( Eli Stone, rated B+ by Entertainment Weekly ) will consider this issue. According to the NY Times TV reporter, “Reams of scientific studies by the leading American health authorities have failed to establish a causal link between the [mercurcy-containing] preservative and autism.”