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Gluten and ADHD: Is There a Link?

By: Peter Olins, PhD on September 18, 2012.

Preliminary research studies have suggested that there might be a link between gluten and ADHD (attention deficit hyperactivity disorder). In the latest work by H. Niederhofer, he found a high incidence of celiac disease among patients with ADHD. When these newly-diagnosed celiacs were placed on a gluten-free diet, they reported a significant decrease in ADHD symptoms. However, due to limitations of the study, it is still too soon to conclude if the there is a cause-and-effect relationship between gluten and ADHD. This work adds to the growing evidence suggesting that celiac disease can involve neurological effects in the brain.

The Search for Treatments for ADHD

Over the past 10 years there has been an explosion in the incidence of ADHD, both in children and adults (Ref. 1). Little is known about the causes of ADHD, and it is not clear if it is a single condition or a collection of conditions. It is clear, however, that there is a strong genetic component (Ref. 2). Psychoactive drug treatment can be effective for some, but there are obvious concerns about side-effects and long-term safety, especially in children. This has understandably led some parents to seek other “remedies”, including dietary intervention, even though the evidence for these may be weak.

In this article, I discuss a recent study by H. Niederhofer which explores a possible link between ADHD and celiac disease (Ref. 3). The study involved 67 ADHD patients in Italy, over the period of 2004 to 2008; their ages ranged from 7 to 42 years (mean age, 11.4). The “Hypescheme Questionnaire” was used to assess ADHD: this is a broad survey of different behavioral and social factors, not limited to the current psychological diagnostic criteria for ADHD (“DSM-IV”).

Ref. 1: Garfield C.F., et al. Trends in attention deficit hyperactivity disorder, ambulatory diagnosis and medical treatment in the United States, 2000-2010. Acad. Pediatr. 2012 Mar;12(2):110-6. Epub 2012 Feb 10.

Ref. 2: Larsson H., et al. Childhood attention-deficit hyperactivity disorder as an extreme of a continuous trait: a quantitative genetic study of 8,500 twin pairs. J. Child Psycho.l Psychiatry. 2012 Jan;53(1):73-80. doi: 10.1111/j.1469-7610.2011.02467.x. Epub 2011 Sep 16.

Ref. 3: Niederhofer H. Association of Attention-Deficit/Hyperactivity Disorder and Celiac Disease: A Brief Report. Prim. Care Companion CNS Disord. 2011;13(3). pii: PCC.10br01104. doi: 10.4088/PCC.10br01104 PMCID: PMC3184556

Higher Prevalence of Celiac Disease in Patients With ADHD

All ADHD patients were also tested for the presence of celiac disease, based on the presence of endomysial antibodies. A remarkable fraction (about 15%) of the patients entering the study were also found to have celiac disease. This is about 15-fold higher than the prevalence of celiac disease in the general population.

Celiac Patients Reported an Improvement in Symptoms of ADHD on a Gluten-Free Diet

All 10 newly-diagnosed celiac patients were moved to a gluten-free diet for 6 months, and their Hypescheme rating was assessed before and after the new diet. Patients (or their parents) reported an improvement in their behavior and functioning, which was statistically significant.

Behavioral Studies are Challenging to Perform

Clinical studies on the treatment of psychological conditions are notoriously difficult: they are particularly prone to the “placebo effect”, in which the subject or observer wants to believe that there has been an improvement. The only way to eliminate these concerns is to perform large, “double-blind” studies, in which neither the subject nor observer is aware if a treatment has been given or not.

Association Does Not Mean “Cause and Effect”

It’s a common misconception that just because two things are associated, one must cause the other. Indeed, it’s well known that celiac disease is often a associated with a variety of other conditions, such as autoimmune diseases. However, contrary to much of what can be found on the Internet, there is very little evidence that the cause of celiac disease (a sensitivity to dietary gluten) is also the cause of these other conditions. Another way to look at this is to examine hypertension and obesity—two conditions that are often associated. It is known that a high salt diet can contribute to hypertension, but there is no reason to think that salt triggers obesity!

A Gluten-Fee Diet is Not a Test of the Role of Gluten in a Disease!

It is hard to conduct clinical trials on the effect of gluten. For example, simply changing from a conventional diet to a gluten-free one is NOT a valid test for the possible role of gluten. Since gluten is present in so many common foods, a gluten-free-diet (GFD) differs vastly from a conventional diet and lifestyle; so that even if a change is observed, it could just as easily be caused by the drastic shift in diet or lifestyle, rather than anything to do with gluten itself. In addition, it’s very hard for subjects (or their parents) to be unaware if they are on a GFD.

The best way to test the role of gluten would be to start with all subjects consuming a GFD, and then add back pure gluten just to some of them. Unfortunately, very few trials involve this kind of rigor. In the case of patients with celiac disease, there are also ethical concerns about deliberately administering gluten, which is toxic to celiacs. (In contrast, clinical trials normally involve testing whether a drug decreases someone’s symptoms, rather than increasing them!).

Limitation of the Niederhofer Study

  • Patients making a transition from a conventional diet to a GFD were assessed for ADHD using a questionnaire, which inevitably involves a large subjective component. In the case of children with ADHD, parents responded to the questionnaire. The parents were obviously also involved in the change of diet.
  • The study was not designed to eliminate the possibility of a simple “placebo effect”.
  • Only the patients found to have celiac disease were tested for a possible effect of a GFD.
  • The study only involved a small number (10) of celiac patients.

Summary and Comments

  • In this study, people with ADHD were much more likely (about 15-fold) to have celiac disease than the general population.
  • Newly-diagnosed celiac patients reported a reduction in ADHD symptoms after going on a GFD.
  • One thing should be stressed: if a parent suspects that their child might have celiac disease, since gluten consumption is necessary for a clear diagnosis, it is unwise for the child to be put on a GFD before investigating the possibility of celiac disease with their pediatrician.
  • Changing to a GFD is also not a decision to be taken lightly, since this is hard to maintain over a lifetime, and can make it harder to achieve balanced nutrition. In the case of children, the added stigma of being on a special diet can also impose extra emotional and social burdens.
  • While there is evidence to suggest an association between ADHD and gluten, it is too early to conclude that there is a cause-and-effect relationship between consuming gluten and ADHD.

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