August 18, 2016

expert reaction to study investigating unhealthy diet in pregnancy and associated epigenetic changes linked to ADHD in children

A group of researchers publishing in Journal of Child Psychology and Psychiatry have investigated prenatal high-fat and high-sugar diets, epigenetic markers and their relationship with ADHD in 164 children and report an association between an ‘unhealthy’ prenatal diet and higher ADHD symptoms.

Dr Neel Kamal, consultant community paediatrician, Royal College of Paediatrics and Child Health, said:

“This approach of looking at diet rich in sugar and fat during pregnancy is novel and promising. The findings cited are plausible explanation of influencing genes through IGF2DNA methylation. Further research along these lines will be helpful.”

Prof. John Stein, Emeritus Professor of Physiology, University of Oxford, said:

“This study, though preliminary, is very exciting.  It demonstrates yet again how prescient Jean Golding was to found ALSPAC.  Rijlaarsdam et al. show that persistent conduct problems up to 13 years later in children whose mothers ate too much fat and sugar in pregnancy may partly result from excessive methylation, hence silencing, of IGF2, but only if this silencing causes them ADHD.  IGF2 is an important growth factor in early development of the brain.  These associations are somewhat tenuous and certainly do not prove that sugar and fat can cause conduct problems, but all the more interesting because this site on chromosome 11 has already been linked with ADHD and dyslexia.  It should be possible to distinguish the roles of excess sugar and different fats; this will be important because omega 3 and omega 9 fats have been associated with improved brain development, and saturated fats are now thought to be not as harmful as used to be argued.”

Dr Max Davie, Mental Health Lead, Royal College of Paediatrics and Child Health, said:

“This is a very interesting paper, which provides powerful suggestive information about a correlation between maternal diet and ADHD symptoms.

“It demands replication, and testing the hypothesis that improving diet may improve these symptoms would be a useful next step.

“However, it does have some limitations. It applies to a fairly small subset of children, and so may not apply to the broader population with ADHD. It makes reasonable attempts to correct for confounding factors, but this is never easy, and it may be that the mothers with a worse diet are more impulsive by nature, and hence find it hard to resist unhealthy options, and this inherited tendency is, at least in part, responsible for the presence of ADHD symptoms in their children.

“At present, this is not a study that would change my clinical practice, but if intervention studies resulting from this work show that nutritional support in pregnancy can have an effect then we should take any opportunity that we can to help.”

Prof. Eric Taylor, Emeritus Professor of Child & Adolescent Psychiatry, Institute of Psychiatry, Psychology & Neuroscience, King’s College London, said:

“The background is that we already know there to be an association between high fat/sugar diets in pregnancy and behaviour problems in the children. But an association does not mean that the diet causes the later problem. This study sets out to test an important idea about the processes involved: that an unhealthy diet alters the baby’s DNA in a way that might lead to brain changes and later ADHD problems.

“The results are suggestive, not definitive. The study did not find a direct link between an unhealthy diet and later ADHD. It did, however, find that in a subgroup of children who had early behaviour problems there was evidence for associations between the unhealthy diet in pregnancy and DNA methylation, and between the DNA methylation and ADHD symptoms. It was not a large effect, and it did not affect all children, but it is a valuable lead to future research.

“Parents of children with ADHD should not take from this work that their diet was responsible for their children’s problems. There are many causes of ADHD, and usually many small influences are at work together. It is not usually possible to argue back from the problem to any single cause. But the research adds strength to the existing public health message that pregnant women should be able to get a healthy diet.”

‘Prenatal unhealthy diet, insulin-like growth factor 2 gene (IGF2) methylation, and attention deficit hyperactivity disorder symptoms in youth with early onset conduct problems’ by Rijlaarsdam et al. published in Journal of Child Psychology and Psychiatry on Thursday 18th August. 

Declared interests

Dr Neel Kamal: No conflicts of interest

Prof. John Stein: No conflicts of interest.

Dr Max Davie: No conflicts of interest.

Prof. Eric Taylor: I don’t have current financial interests to declare. But it should be noted that: I am a retired child psychiatrist, in the past I have conducted funded research on food influences on ADHD, I have been a member of previous groups developing ADHD guidelines, e.g. for NICE, and I once edited the journal in which this paper appears