A new study of children with anxiety disorders suggests that response to cognitive-behavioural therapy (CBT) is influenced by many genetic variants of small effect - rather than any individual gene.

The research, led by scientists from King's College London and published in the British Journal of Psychiatry, is the first to explore the impact of DNA variants across the entire genome on CBT response.

CBT is one of the leading treatments for anxiety and depression in the UK, following considerable investment in the past five years. It is especially popular in treating anxiety disorders in children, although around 40 per cent of those receiving therapy remain anxious once the course of treatment finishes.

The study of 980 children undergoing CBT for anxiety disorders, at 11 therapy centres across the world, sought to identify DNA variants that predict who will respond well to CBT.

Scientists from King's analysed the association between single nucleotide polymorphisms (SNPs) and changes in symptom severity during CBT. SNPs are DNA differences (polymorphisms) between individuals in the 3 billion nucleotide base pairs of DNA - steps in the spiral staircase of the double helix of DNA that make up the human genome. Each SNP represents a difference in a single nucleotide base pair, and these SNPs account for inherited differences between people.

Contrary to previous research, which has not looked genome-wide, they did not identify any individual SNPs or variants with large effects on treatment response. This suggests that response to CBT may be influenced instead by many variants with small effects, a pattern that has been seen in genome-wide studies of many behavioural traits.

The study's first author, Jonathan Coleman from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King's College London, said: 'Although this study doesn't identify any specific variant affecting CBT response, it provides us with some important initial ideas. Childhood anxiety has severe, negative impacts in later life, and if we can understand how the genome influences the way children respond to CBT, we can help inform parents and children seeking the best way to relieve their anxiety.'