A high-fat, high-sugar diet during pregnancy may be linked to ADHD in children with behavioural problems in early life, according to new research.

The study, led by scientists from King's College London and the University of Bristol, suggests that expectant mothers may be able to reduce the risk of ADHD symptoms by avoiding unhealthy foods.

The findings repeat conclusions drawn by earlier research, but also provide further explanation of the processes involved.

Early-onset conduct problems tend to occur in tandem with ADHD, and both can also be traced back to similar prenatal experiences, such as maternal distress or poor nutrition.

In this new study, published today in the Journal of Child Psychology and Psychiatry, 83 children with early behavioural issues were compared to 81 children with low levels of conduct problems.

The participants were all members of the Bristol-based “Children of the 90s” cohort that has been supporting longitudinal research since 1991.  

The researchers assessed how the mothers' nutrition affected IGF2, a gene involved in fetal development and the brain development of areas implicated in ADHD.

The study found that poor prenatal nutrition, comprising high fat and sugar diets, was associated with greater change to IGF2 in both groups of children.

Higher IGF2 methylation was also associated with stronger ADHD symptoms in children between the ages of 7 and 13, but only for those who showed an early onset of behavioural problems.

Dr Edward Barker from King's College London said: “Our finding that poor prenatal nutrition was associated with higher IGF2 methylation highlights the critical importance of a healthy diet during pregnancy.

“These results suggest that promoting a healthy prenatal diet may ultimately lower ADHD symptoms and conduct problems in children. This is encouraging given that nutritional and epigenetic risk factors can be altered.”

The research also points to the need to examine more specific types of nutrition, Barker said.

“For example, the types of fats such as omega 3 fatty acids, from fish, walnuts and chicken are extremely important for neural development.

“We already know that nutritional supplements for children can lead to lower ADHD and conduct problems, so it will be important for future research to examine the role of epigenetic changes in this process.”