Study on controversial treatment for autism 'scuppered' by U.S. health officials

Plans to conduct a study in the U.S. on a controversial treatment for autism have been 'scuppered' by government health officials.

The study by the National Institute of Mental Health (NIMH) intended to examine the effectiveness of a type of treatment advocated by some autism activists as alternative medical therapy for children with the condition.

The treatment called chelation is a therapy in which a man-made amino acid, called EDTA, is added to the blood - it has previously been used to treat victims of heavy metal poisoning.

The NIMH has canceled the study on the grounds that at present the resources are better directed to testing other potential therapies for autism spectrum disorders.

Chelation therapy has been rejected by the majority of the scientific community as it is based on the theory that autism is triggered by exposure to mercury present in childhood vaccines.

There has an abundance of research on the topic and medical experts have dismissed the idea that mercury used in a vaccine preservative causes autism - nevertheless some parents of autistic children continue to strongly believe it does.

According to the U.S. Centers for Disease Control and Prevention (CDC), since 2001, apart from some influenza vaccines, the mercury-containing preservative has not been used in routine childhood vaccines.

The NIMH study was given initial permission to proceed in 2006 but the government body now says it is not pursuing the additional review required to begin the study and no subjects have been recruited for a clinical trial.

The NIMH says on the basis of new scientific data presented in February 2007, an NIH Institutional Review Board reassessed the risk-benefit ratio of the proposed study and decided there was no clear evidence for direct benefit to the children who would participate in the chelation trial and that the study presents more than a minimal risk.

According to the NIH for the study to proceed, additional government approval was required and it was decided not to pursue this.

A study published last year linked EDTA used in the treatment to lasting brain problems in rats.