The 'overlap' between somatic conditions and those with a more behavioural or psychological set of characteristics is of great interest to many. When such associations become apparent, and bearing in mind the old mantra 'correlation does not imply causation', it offers a potentially unique window on how body and brain are linked and how affecting one system may affect the other. A previous post discussing the beta-blocker--autism study kinda hinted at the common thread on this blog: a potential anti-hypertensive effect might impact on cognitive organisation/ability (with the caveats that I am not in anyway condoning the use of any pharmaceutic for anything or offering medical advice).
I was therefore suitably interested when this study by Niederhofer (full-text)* cropped up on the PubMed radar on the possible overlap between ADHD-like symptomatology and an over-representation of coeliac (celiac) disease (CD); indeed also what happened to behavioural symptoms when a gluten-free diet was installed. The crux of the study was that in the population studied presenting with ADHD-type symptoms according to Hypescheme (n=67), fifteen percent showed markers for coeliac disease. When I say markers, I am talking about serological testing for anti-gliadin and anti-endomysial antibodies, of which there is still some debate about the best way to diagnose coeliac disease (see NICE guidelines here). Compared with the estimated general population rates of CD, anywhere from 0.1% - 2%+, the 14.9% presented in this study is Roger Moore as James Bond eyebrow lifting (I can't actually believe that there is a Facebook group for this) bearing in mind the small participant group included in the current study. Sir Roger might also lift an eyebrow at the results of the gluten-free trial undertaken following CD diagnosis, where behavioural manifestations seemed to show an improvement when on diet.
Despite the easy-to-pick flaws in the experimental design used, these results comes as little surprise. In previous posts I talked about the possible relationship between coeliac disease and autism and case studies like this one from Stephen Genuis which suggested that adopting a gluten-free diet might have behavioural connotations as well as physical ones, at least for some. The related research from Lidy Pelsser and colleagues on diet and ADHD might also tie in; although one has to caution about the lack of data on the presence of CD in the Pelsser cohort.
What is perhaps more important is what a gluten-free diet might actually be affecting in terms of behaviour. I tried (tried!) to make a case for gluten affecting the attention and hyperactivity comorbid aspects of autism in this post which is perhaps not a million miles away from what the current study is (I think) saying. The logical step in this argument is that any effect from diet in cases of autism might be mediated through such behavioural parameters; so affecting peripheral aspects to the condition potentially might impact on core aspects and the triad, sorry, dyad, of presentation. This is perhaps a theme that needs to be explored with greater assiduity throughout autism intervention research: what is intervention actually targeting?
Outside of such speculations, this study confirms one thing: ADHD like many other developmental conditions is complex and not necessarily rooted entirely in the old noggin. There may be a requirement to screen for coeliac disease when a diagnosis of ADHD is given... too much, yes/no?
To finish, and in tribute to the best James Bond ever (Connery was good, but Moore edged it), nobody does it better... or if you prefer, the Me First and the Gimme Gimme version.. [raise eyebrow and look to camera making some witty remark like 'I think he got the point'].
* Niederhofer H. Association of attention-deficit/hyperactivity disorder and celiac disease: a brief report. Prim Care Companion CNS Disord. 2011: 13(3)