Psychological therapies, like Cognitive Behavioral Therapy (CBT), are often used to treat anxiety disorders, especially in children, and are an effective treatment option for many patients. About 65 percent of children are free of their anxiety following treatment—leaving 35 percent of children who still experience some degree of anxiety even after they participate in CBT. So what separates the former group from the latter? Which factors are involved in whether a patient responds to CBT? In our study, we explored how psychological therapy, such as CBT, may be linked to changes on a biological level and how this might differ from person to person.
Factors That Influence Our Biology
Recent research has found that the environment can influence gene regulation and that biological changes can occur in response to certain experiences. Here are a few key biological processes that are important for our study:
- DNA Methylation. This is a biological process that involves adding methyl groups to specific points in the DNA code, and usually leads to reduced gene activity. Unlike the DNA sequence (which stays the same across the lifespan), these additions vary and can change with time, disease, and even following certain environmental event, such as trauma.
- The Serotonin Transporter. The Serotonin Transporter is involved in signaling in the brain and has been implicated in anxiety and depression for many years. Genetic differences in this region are linked to individuals’ responses to their environment, how susceptible they are to negative circumstances, and how much they benefit in positive situations. Interestingly, it has also been suggested that DNA methylation in the region is particularly influenced by environmental factors.
While we understand that genetic variations in the Serotonin Transporter gene may be related to how well patients respond to CBT, no one has examined whether changes in DNA methylation levels in the gene are associated with response to CBT. In this study, we tried to determine whether response to CBT could be linked to biological changes by examining DNA methylation in the Serotonin Transporter gene.
How Children’s DNA Respond to Therapy
Our study, known as the Genes for Treatment (GxT ) Project, was a large, multi-site study of children with anxiety disorders. The study aimed to identify factors that influence how individuals respond to CBT. Using DNA samples collected from cheek swabs, DNA methylation levels at the Serotonin Transporter promoter region (the starting point of a gene) were measured before treatment began, and again after treatment ended. We found the following results:
- Children who responded to treatment had increased in DNA methylation after therapy.
- Children who did not respond to treatment had decreased in DNA methylation after therapy.
We classified children as “treatment responders” if they were free of all anxiety disorders at a follow-up session with their clinical psychologist, six months after treatment had ended. These results suggest that biological factors may be linked to an individual’s response to therapy.
Biological Changes With Psychological Outcomes
Measuring the effects of therapy can be a challenging undertaking. However, our results provide evidence that change following psychological therapy is linked to change at a biological level. We cannot determine whether these biological changes are causing—or are a result of—changes in anxiety symptoms. However, we did see that changes in DNA methylation during treatment were associated with the child’s outcome at their follow-up session, rather than their response immediately after the therapy had finished. This suggests that the DNA methylation changes are happening before the changes at the psychological level.
While there is still much to learn about how psychotherapy is linked to our biology, this research provides preliminary evidence that our biology may be involved in our response to psychological treatments, such as CBT.
Sources
Roberts, S., Lester, K. J., Hudson, J. L., Rapee, R. M., Creswell, C., Cooper, P. J., Eley, T. C. (2014). Serotonin transporter methylation and response to cognitive behaviour therapy in children with anxiety disorders. Translational Psychiatry, 4, e444. doi: 10.1038/tp.2014.83
Susanna Roberts is a Ph.D. student at King’s College London. She received her BSc Biology with Psychology from Queen Mary, University of London, and her MSc in Social, Genetic and Developmental Psychiatry from King’s College London. Susanna is completing her Ph.D. under the supervision of Professor Thalia Eley and Dr Chloe Wong at King’s College London, where her Ph.D. research focuses on genetic and epigenetic factors associated with response to psychological therapies such as CBT.
Thalia C. Eley, Ph.D., is Professor of Developmental Behavioural Genetics at the Social, Genetic and Developmental Psychiatry Centre at the Institute of Psychiatry, Kings College London. She directs the Emotional Development, Intervention and Treatment lab (EDITlab). Her work combines behavioural genetics with developmental psychology.
Using both quantitative and molecular genetic approaches she has focused on two main themes within her research. First she has examined the role of gene-environment interactions on the development of anxiety and depression, work for which she was awarded the Lilly-Molecular Psychiatry Award for the best original research submitted by a young investigator (2004). Second, she has considered the role of cognitive biases in the development of anxiety and depression in the context of genetically sensitive designs. At present her twin research includes ongoing analyses of her longitudinal twin study, G1219. She is also working on the transmission of anxiety and depression from parents to children using the “Children of Twins” approach. Her molecular work currently focuses on two projects exploring the role of specific genetic markers in response to psychological therapies, including cognitive-behaviour therapy for child anxiety and exposure therapy for adult phobias. The first paper from the child anxiety study was awarded the Macquarie University Research Excellence Award, 2011.
Professor Eley studied psychology at Cambridge University, and completed her PhD at the Institute of Child Health, University College London. For her doctoral work, she conducted a twin study of emotional development. Publications from this study led to being awarded the Spearman Medal (for outstanding published work in psychology within 10 years of graduation), from the British Psychological Society. After that time she was funded by two fellowships from the UK Medical Research Council and is now Professor of Developmental Behavioural Genetics.
