Professor Neil Ward believes that mercury may contribute to hyperkinetic disorders. Why?

29 Feb

I’ve been looking through some of the submissions to the Associate Parliamentary Food and Health Forum (FHF) inquiry into diet and behaviour (the PDF of the Report is available online; I did ask if I could post the submissions online, but FHF refused and asked me to advise that people to contact them so that FHF can supply anyone who’s interested with copies of any submissions to the inquiry [1]). I was interested to see that Prof Neil Ward of Surrey University claimed in his submission that “exposure to environmental toxins may contribute to some of the behavioural features of hyperkinetic disorders, especially lead, cadmium, mercury and aluminium.” However, I have struggled to figure out why Ward sees mercury as playing a role in this.

Clearly, mercury poisoning can have really nasty effects. From the tragic events in Minamata in Japan, we know that this can have serious negative symptoms; mercury poisoning can also kill. However, we also know that the symptoms caused – for example, gait and sight disturbances – do not equate to either autism or an hyperkinentic disorder.

Knowing what we know about the symptoms of mercury poisoning, it’s even harder to see why Ward then goes on to recommend a number of the more dubious approaches to Autistic Spectrum Disorders – urinary trace element analysis, a focus on gut permeability and leaky guts, hair mineral testing etc. – to those researching children with hyperkinetic disorders. Ward also takes a rather credulous view towards elimination diets and hyperkinetic disorders:

Atopic children with ADHA have been shown to respond well to elimination diets. The most common foods targeted for elimination are: dairy products, sugar, wheat, eggs, chocolate and salicylate-rich foods, such as; apples, cherries, grapes, berries, tomatoes, and oranges…In some cases it has been shown that the Feingold diet is an effective approach for improving the behavioural problems of ADD/ADHD children.

It is deeply depressing that – after the hypothesis that mercury causes autism has been so thoroughly discredited – there are still attempts to implicate mercury in hyperkinetic disorders. Worryingly, Ward’s submission also looks like it may leave the door open to a range of dubious tests and treatments (from hair mineral testing to potentially harmful elimination diets) for hyperkinetic disorders.

[1] I struggled a bit to get hold of FHF via e-mail (which could be down to problems at my end or there’s) so you may find it more reliable to phone them on 020 72221265

8 Responses to “Professor Neil Ward believes that mercury may contribute to hyperkinetic disorders. Why?”

  1. passionlessDrone March 3, 2008 at 18:22 #

    Hi Jon –

    You might be interested in knowing that clinical studies have shown a relationship between levels of mercury and diagnosis of ADHD. It doesn’t show causation, and is well below the level for ‘poisoning’, but the relationship does seem to exist.

    http://www.ncbi.nlm.nih.gov/pubmed/17177150?ordinalpos=2&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum

    Children with blood mercury level above 29 nmol/L had 9.69 times (95 % CI 2.57 – 36.5) higher risk of having ADHD after adjustment for confounding variables. CONCLUSION: High blood mercury level was associated with ADHD. Whether the relationship is causal requires further studies.

    There are also quite a bit of studies on use of dietary restriction for children with ADHD that have found dietary modification can result in reduced hyperactivity.

    Take care!

    – pD

  2. Joseph March 4, 2008 at 18:35 #

    The abstract of that study says they adjusted for age, parental occupation and gender. Did they not adjust for the most evident counfound of all in this type of study, i.e. fish consumption? This seems quite relevant in ADHD, where fish consumption is often recommended as a form of treatment. See, for example, this.

  3. passionlessDrone March 4, 2008 at 20:18 #

    Hi Joseph –

    I don’t know if they took fish eating into account or not. (?) I thought in Hong Kong everyone was eating crazy amounts of fish. But you do raise an interesting point.

    Go figure, increased levels of lead in the blood have also been found in ADHD.

    http://www.ncbi.nlm.nih.gov/pubmed/17868654?ordinalpos=18&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum

    “RESULTS: Blood lead levels in this sample closely matched US population exposure averages, with a maximum level of 3.4 mug/dL. Blood lead levels were statistically significantly higher in ADHD-combined type than in non-ADHD control (p

  4. Jon March 4, 2008 at 21:55 #

    pD- firstly, links between high lead levels and ADHD-like symptoms seem very plausible (though I’m less convinced as to whether lead plays a significant causal role in ADHD cases in the UK today). I’ve no particular objection to Ward’s claim re. lead – sorry if that wasn’t clear.

    Re. mercury, that one study is rather problematic – small sample (which may not generalise across cultures) and one groups of kids recruited from a hospital (do they eat differently as a result – for example, eat less fish?) Also, as Joseph mentions, there’s the question of what’s raising mercury-levels in the kids with ADHD: increased fish consumption seems a v likely possibility (in the UK, there’s evidence of a correlation between fish consumption and mercury levels). Because of all these issues, I still think that Ward is far overstating the case re. mercury.

    As far as elimination diets go – certainly, it’s very plausible that cutting out, for example, certain food additives may help. However, it was Ward’s credulous support of approaches such as the Feingold diet and salicylate reduction or elimination – which are not evidence-based, and can be harmful – that I was objecting to. I still see these objections as valid.

  5. passionlessDrone March 7, 2008 at 19:58 #

    Hi Jon –

    (Is this Jonathon / i.e., interverbal?)

    Well, I wasn’t trying to make a case for mercury ‘causing’ adhd per se. I just found the paper interesting.

    I am curious why you think Feingold or saliclyate removal could be dangerous. (?)

    As far as not evidence based, I’ve seen many a reference to this paper in 1985 published in The Lancet; reviews indicate that salicylate removal was helpful for a large percentage ADHD participants. Salicylates aren’t mentioned specifically in the abstract, and getting the entire paper online seems to be difficult.

    http://www.ncbi.nlm.nih.gov/pubmed/2857900?ordinalpos=40&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum

    Here is another one I did find that indicates salicylate challenges resulted in reactions in 75% of people that responded well to a few foods diet for reduction in hyperactivity:

    http://grande.nal.usda.gov/ibids/index.php?mode2=detail&origin=ibids_references&therow=420684

    Take care!

    – pD

  6. Jon March 7, 2008 at 22:10 #

    pD- no, I’m not Interverbal. Easy confusion, though, given the name. And yes – that ADHD/mercury papers does look interesting.

    Restricted diets can be harmful in a number of ways. The most obvious being that – if care isn’t taken – those following them can fail to eat a balanced diet and their health can suffer as a result. There’s also the general PITA issue: it’s no fun avoiding lots of foods. If intolerance/allergy is an issue then restricted diets can be very worthwhile; if not, it’s a shame, though.

    Evidence for the Feingold diet is – at best – very patchy. See for example the review here. Evidence re. salicylates is mixed. There’s certainly nothing here that one could confidently base government policy on.

    I should also say that Ward chooses to emphasise an unblinded study instead, and that – to my eyes – the available evidence (or lack thereof) isn’t reflected in his submission to the FHF. I’m very sorry that I can’t just reproduce this submission here – what I’m saying might make more sense if others could read what I’m writing about. If interested, I’d recommend contacting FHF for a copy.

    Jon

  7. navi March 16, 2008 at 17:36 #

    I’m a teeny bit confused.

    Is ADHD/Hyperkinetic disorder considered on the autism spectrum in the UK?

    As the wife of one dx’d with ADHD and the mother of a child with ASD – though also shows signs of ADHD, I’m inclined to think they are not one in the same… It’s kind of hard to understand that my son could have two different presentations of the same disorder, but two different, comorbid disorders is a bit more believable… I know they have some overlapping symptoms, etc, but not that ADHD fits on the spectrum. It definitely wouldn’t fall under current DSM guidelines for ASD, from what I’ve read of them….

    That, and if we add more disorders to the spectrum, we are increasing the prevalence of children on the spectrum… which feeds the fire of the people preaching ‘epidemic’. Especially with prevalence rates of ADHD being 2-18% (http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5434a2.htm)

    I’m mean think of it… a generation rescue ad with 1 in 10,000 in 1983 vs 1 in 5 today. adding ADHD to the spectrum is putting fuel on the fire for scare tactics (current version: http://www.generationrescue.org/pdf/080212.pdf – link nicked from a flickr autism group where I got reamed for attacking the ad, but only by one person)

    blurring the lines of whether ADHD is an autism-related topic also means opening the door of connecting any potential causes of ADHD to be linked as causes of autism. But then some of the biomed people are already doing it, so maybe causes of ADHD are a relevant autism discussion, though a clarification that they are two different disorders would be useful…

    I realize all those that deal with ADHD may be thinking “look at the attention autism is getting! look at the services! people think ADHD kids just need a good kick in the butt; I want an autism diagnosis!” but I think, kids like my son, who may have comorbid diagnoses might end up with – “his form of autism is adhd, which needs fewer services than a traditional autism diagnosis.” While I don’t think my son’s district would ever do that, a lot of districts that are more strapped for cash might. That idea is scary…

    I’d understand, if we came up with some clinical evidence linking the two disorders, beyond what currently exists… (http://www.newsroom.ucla.edu/portal/ucla/UCLA-Geneticists-Find-Location-3612.aspx is the most recent information I found on a cursory search).

    But as it stands, as far as I know, these are two completely different disorders, linked only by a few genes and some overlapping anecdotal symptoms (which also leads me to believe my son’s autism is genetic, since his dad is adhd, and he has some signs of adhd, although he did regress).

    It would be interesting to know if the prevalence of ADHD is greater or not in the autistic population than the typical population…

  8. navi March 16, 2008 at 17:44 #

    ooh, I found one, regarding comorbid ADHD & Autism:

    http://www.ncbi.nlm.nih.gov/pubmed/15206005?dopt=Abstract

    found from
    http://autismnaturalvariation.blogspot.com/2006/08/no-autism-epidemic-update.html

    Very interesting…

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