Chelation and Autism Ranking:

Status Research

There are limitations to all of the studies of chelation and autistic individuals identified to date. For example

• Some of the studies had small numbers of participants. One of the studies (Eppright et al, 1996) had a single participant. Three of the other studies (Geier and Geier, 2006; Lonsdale et al, 2002; Patel and Curtis, 2007) had either 10 or 11 participants.
• Some of the studies (such as Blaucok-Busch et al, 2012; Geier and Geier, 2006; Lonsdale et al, 2002; Patel and Curtis, 2007) were open label (the participants and researchers knew who got the treatment) and/or had no comparison control group.
• Some of the studies (such as Eppright et al, 1996; Geier and Geier, 2006; Patel and Curtis, 2007) combined several forms of treatment, making it difficult to evaluate the effectiveness or otherwise of the chelating agent.
• Some of the studies (Eppright et al, 1996; Patel & Curtis, 2007) used anecdotal reports or researcher created questionnaires to measure change instead of using standard outcome measures.
• One of the studies (Lonsdale et al, 2002) did not provide enough detail for us to be able to make a considered assessment of the efficacy of the treatment (stating only that TTFD appears to have a “beneficial clinical effect.”
• Some of the studies (such as Geier & Geier, 2006; Patel & Curtis, 2007) actually reported mixed or negative results which is not necessarily clear from the abstracts or the way that the authors of these studies have represented those results.
• The study by Adams et al (2009) appears to be more robust than other studies (because it was a large randomised controlled trial) but it is still limited by several significant methodological weaknesses.
• There was a high attrition rate, with between a quarter and a third of participants dropping out.
•  It is not clear if parents were truly unaware of which children received DMSA and which children received the placebo during the second phase of the study.
• There is a high likelihood of carry-over effects (both the experimental group and the control group received an initial round of oral DMSA in phase one)
• There is missing data from some of the behaviour checklists, although the ADOS scores were unchanged, which makes it difficult to evaluate the real behavioural effect of the intervention.

According to the Cochrane Review - James et al. (2015) - the study by Adams et al (2009) is actually deeply flawed.

“Only one trial was included in this review, and we judged it to have high or uncertain risk of bias and methodological problems that limited the interpretation of outcomes presented. Of particular concern are the trialists’ questionable data analytical approach and interpretation of findings. It is interesting that trialists found differential directions of heavy metal excretion and change in ASD indices, yet they attempted to convince the reader not to read too much into these differences. Given the deleterious effects of chelation, misinterpretation and misuse of the study of Adams et al to justify the use of chelation for ASD is unethical and potentially places children unnecessarily in harm’s way. Moreover, if these findings are in fact valid, they actually undermine the heavy metal toxicity theory and the rationale for chelation treatment, suggesting that it should not be used in the first place."

For a comprehensive list of potential flaws in research studies, please see ‘Why some autism research studies are flawed’.

Updated

16 Jun 2022

Last Review

01 Dec 2016

Next Review

01 Apr 2023