Biological factors may be involved in development of ADHD

Biological factors may be involved in the development of Attention-deficit/hyperactivity disorder (ADHD), according to new research by scientists from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s College London.

ADHD is characterised by attention difficulty, hyperactivity, and impulsiveness. It is one of the most common and disabling psychiatric conditions in childhood and adolescence, affecting around 5 per cent of children and 2.5 per cent of adults. Progress in understanding the biological basis of the disorders has been slow and insufficient treatment options are available.

Although previous research has documented the importance of environmental and genetic risk factors, the mechanisms underlying the association between these risk factors are unclear.

This new King’s study, published in Molecular Psychiatry, suggests that DNA methylation - a chemical process that moderates the expression of genes - is linked to ADHD in later life.

The researchers analysed methylation levels across the genome at birth and age seven and ADHD trajectories from age seven to 15 in over 800 young people from the Avon Longitudinal Study of Parent and Children (UK).

The authors found that DNA methylation at birth, across a number of genes, was associated with a high and chronic trajectory of ADHD traits in children. Most of these genes were involved in brain development processes and metabolism of fatty-acids.

However, none of them were still linked via DNA methylation at age seven, suggesting that birth may be a critical period for these genes to be associated with later ADHD traits.

Dr Edward Barker, senior author of the paper from the Department of Psychology at the IoPPN, King’s College London, said: ‘Our results suggest that there may be time-specific developmental pathways under which ADHD traits develop.'

Esther Walton, lead author of the paper, added: 'This may help to identify proper timing and targets of intervention including, but not limited to, dietary supplements related to fatty-acid metabolism.'

Notes to editors

Paper reference: Walton, E at al. (2016) Epigenetic profiling of ADHD symptoms trajectories: a prospective, methylome-wide study Molecular Psychiatry doi:10.1038/mp.2016.85.

For further media information please contact Jack Stonebridge, Press Officer, Institute of Psychiatry, Psychology & Neuroscience, King’s College London jack.stonebridge@kcl.ac.uk/ 020 7848 5377.