A new study confirms that impaired detoxification can lead to toxic heavy metal accumulation in the brains of autistic children, providing insight into the cause of autism. The research also reveals why some children in recent studies responded favorably to heavy metal DMSA chelation therapy.[2-4]
The study examined 52 autistic children, aged three to 12, 40 of whom were nonverbal and 12 verbal. The autistic children were compared to a control group composed of 30 normally developing, healthy children. The children were scored on the severity of autism and social impairment using well-accepted standardized tests. Mercury and lead levels were measured in red blood cells.
How detoxification was measured
Detoxification capacity was measured using two blood tests: one to determine the activity of an essential detoxifying enzyme, glutathione-S-transferase (GST), and one to determine plasma levels of alpha-tocopherol, a form of vitamin E that is a signaling molecule and plays an important role in protecting against the toxic effects of mercury and lead. Reduced GST activity and depleted vitamin E are two critical factors related to poor detoxification, noted the researchers.
Autistic kids found to be “poor detoxifiers” with higher levels of lead and mercury
Results showed that the patients with autism had significantly higher lead and mercury levels and lower GST activity and vitamin E concentrations compared with the controls, indicating impaired detoxification. Mercury and lead levels were increased by 36.58% and 43.34%, respectively, while GST and vitamin E levels decreased by 50.71% and 43.18% percent, respectively. The reductions in the essential detoxifying enzyme GST and vitamin E can explain the poor detoxification in children with autism, leading to the mercury and lead toxicity, the researchers noted.
Results also clearly showed that the higher the patients’ levels of heavy metals and the lower their GST activity and vitamin E levels, the more severe their social and cognitive impairment. Children with severe social and cognitive impairment had remarkably higher levels of mercury and lead and remarkably lower GST activity compared with those with milder abnormalities.
Overall, these results combined with results of previous studies suggest that heavy metal toxicity plays a role as a cause of autism and that autistic patients are “poor detoxifiers” who are unable to readily excrete toxic substances such as mercury and lead when they reach certain levels, concluded the researchers.
The cause of the impaired detoxification appears to be at least partially based on genetic susceptibility. Several studies have reported that some children with autism express subtle changes (called single nucleotide polymorphisms [SNPs]) in genes involved in the detoxification of environmental toxins like mercury and lead. More than 100 such genes may be involved in increasing autism risk.
If poor detoxification is really an underlying cause of autism, how do we treat it?
Successful autism treatment could occur by either reducing lead and mercury levels or by activating GST activity and significantly increasing vitamin E levels, said the researchers. In addition to supplementing with vitamin E, they recommended carnosine and selenium supplements to help decrease the burden of heavy metal toxicity. Supplements like n-acetyl-cysteine (NAC) can also be used to increase glutathione levels, while oral DMSA chelation therapy for autism, discussed in part 2 , can be used to directly reduce mercury and lead levels.[2-4]