It is estimated that it affects between 3-5% of children of school age, though other estimates suggest this could be as high as 10% of the school population (Rowland et al. 2002). Fewer children of Hispanic American and African American backgrounds seem to have received a diagnosis of ADHD compared to White Americans, however it is very possibly due to increased poverty and reduced insurance coverage and possibly other cultural issues rather than a true difference with respect to ethnicity. The condition not only affects the US, but also most western countries (e.g. UK, NICE guidelines 2008, rest of Europe) and North Africa. ADHD rates have been found to dramatically increase over the last two decades and the condition is now the most commonly diagnosed in school age children (e.g Mandell et al. 2005; and more recent reports).

ADHD is often seen in Autism Spectrum Disorders (ASD). And like ADHD, ASD rates have also dramatically increased in the last 2 decades.

So what options do we have in response to ADHD, whether this is in association with Autism or not?

The most common answer is Ritalin-like medication. A very large proportion of children diagnosed with the condition receives medication. Children as young as 4 years old are being prescribed drugs. This causes major concerns both in the US and in the UK.

Simple interventions however do exist. Nutrition, particularly with good supplementation of Omega-3 (Richardson et al. 2006), but also dietary modification with exclusion of foods the child is sensitive to (Pellser et al. 2011) have been found to be effective.

It is worth highlighting this latest Lancet study.

The Lancet, Volume 377, Issue 9764, Pages 494 – 503, 5 February 2011.

The study used a number of ADHD rating scales based on parents, teachers (non-blinded) ratings or blinded paediatrician ratings. The strengths are multiple ratings, large sample size (n=50) with matched controls (n=50), overall heterogeneous population representative of the general population of children with ADHD.

What it is important to know is that the restricted diet the children are placed on is not designed based on any allergy test- it is a standard diet that consists of a few hypoallergenic foods, rice, meat, vegetables, pears and water, completed with fruits, potatoes and wheat. The challenge test conducted after 5 weeks on the respondent children consists of either 3 high IgG foods or 3 low IgG foods. Whether or not the foods were of low IgG or high IgG response, there was deterioration of ADHD symptoms upon challenge.

I have been in touch with the Lead author, Dr Lidy Pelsser who clarified that the low Ig G group means Zero IgG level- if this is the case, the group’s conclusions that IgG levels are irrelevant to ADHD symptoms is correct. In my experience of allergy tests though, at least with regard to IgE levels, a low level does not equal to zero or not detectable. A low level is a low detectable level and this can have biological implications.

I have also contacted the lab ImuPro in Australia to get some clarification with regard to their rating of low IgG levels. If Low IgG level are detectable low level, the conclusion on potential relevance of IgG testing would potentially be quite different, until it is proven that response to foods with No IgG at all (i.e. not detectable as opposed to low) also lead to return of ADHD symptoms.

These methodology details are however not very important in the light of the very good outcomes of the restriction diet: see figure 2 of the paper.

Figure 2: Distribution of behaviour scores at start and end of the first phase. Scores according to (A) masked paediatrician ratings and (B) unmasked teacher ratings. To facilitate comparison between the various measures, scores have been standardised as percentages of the maximum score per measure. Bars=maximum and minimum score. Shaded boxes=interquartile range. Horizontal bars within boxes=median. ADHD=attention-defi cit hyperactivity disorder. ARSall=ADHD rating scale total score (maximum score 54). ARSatt=ADHD rating scale inattention score (maximum score 27). ARShyp=ADHD rating scale hyperactivity and impulsivity score (maximum score 27). ODD=oppositional defi ant disorder (maximum score 8).

The authors conclude that a trial diet for a 5-week period should be proposed to every child with ADHD, followed by a challenge procedure to define which food the child would react to.