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ADHD Genetic Research Dr. Philip Asherson, Dr. Jonna Kuntsi and Prof. Eric Taylor Research News The MRC Social Genetic and Developmental Psychiatry Research Centre was established in 1994 with the aim of encouraging collaborative research between investigators from different scientific backgrounds. The Centre is housed within the new SGDP Building that was opened in February 2003 and is based at the Institute of Psychiatry, part of King’s College London. Social, Genetic and Developmental Psychiatry Developmental Theme The Centre’s main Developmental theme leads to research focused on childhood disorders because relatively little is known about them despite their public health importance. However, the developmental perspective involves more than studying children - it is an aetiological approach that investigates when and how disorders emerge and change during development. We believe that such research is essential to result eventually in interventions that prevent the onset of disorders rather than waiting to treat full-blown disorders. The Centre’s approach to development spans the life course. For example, of considerable current interest are adult outcomes of childhood disorders such as ADHD. Genes and ADHD Progress towards identifying the genes involved in ADHD has proceeded rapidly over the last five years. Most interest has focused on genes involved in dopamine pathways in the brain, such as the dopamine transporter gene, which Ritalin and other stimulants bind to, and one of the dopamine receptors called the D4 receptor gene. Evidence for the involvement of both these genes is increasing, although we do not yet understand how exactly changes within these genes increase the risk for ADHD. Other investigators have been looking for regions of the human genome that are shared between siblings (brothers and sisters) that both have ADHD – so called affected sibling pair studies. Two new studies from the US and Holland may lead to the identification of new genes. Both of these studies identify several regions of the genome that may be linked to ADHD and also contain genes that influence reading disability and autism. This raises the possibility that that some genes that influence risk for ADHD also influence other developmental disorders and traits. The IMAGE Project at the Institute of Psychiatry We are very pleased to announce the launch of a major International study called the International Multi-centre ADHD Gene project – the IMAGE project. This new project is an extension of previous work initiated at the SGDP Centre, that brings clinical investigators and molecular geneticists together from across Europe. The National Institute of Health, which is the main funding body in the United States, has provided around $10 million for this research. This makes IMAGE one of the largest research initiatives on ADHD funded anywhere in the world to date. What is the IMAGE Project? The IMAGE Project will gather medical information and DNA from individuals who have ADHD as well as from their brothers, sisters and parents. The idea of this project is to create a resource that can be used both now and in the future to find the genes that cause ADHD. This is an exciting opportunity since the resource will be available to some of the best scientists in the world who want to find the genes involved. The first phase of this project will take five years during which DNA and clinical data will be gathered from 2,000 school age children with ADHD as well as their brothers, sisters and parents. At the same time we will begin to search the human genome - the entire set of human genes - for genes that are linked to ADHD. Who can take part in the IMAGE project? Because this is a family study we will be looking at similarities and differences between siblings. We will be looking for genes that are shared by siblings who both have ADHD. We will also look for genes that are not shared by siblings where one has ADHD and the other does not. Linking ADHD, genes and cognitive processes On specific psychological tests children with ADHD tend to have difficulties inhibiting inappropriate responses and sustaining attention over time. However, when the same tasks are made faster or more rewarding, their performance can improve drastically. By bringing together genetic approaches with research on psychological processes we hope to makes links between genes, ADHD and problems in maintaining optimal states of arousal and attention. We will compare the performance of children with ADHD and their nearest-age siblings on a detailed psychological test battery. Comparing siblings allows us to estimate the size of genetic influences and investigate the contribution of specific genes to ADHD and performance on the psychological tests. Why find genes ? ADHD, hyperactivity and related problems are very common, affecting the lives of many children and adults. The disorder is recognised as one of the most important cause of problems that some children have with their schoolwork and relationships with friends and family. These problems often have long-term consequences so that about two thirds of children diagnosed with ADHD have persistent problems that effect them as adults. By investigating the causes and finding out much more about how genes and environments – nature and nurture – combine together to bring about ADHD, we will be in a far better position to develop the best and most effective approaches to help individuals with ADHD. Finding the genes involved in an important step in this direction since we know that genetic influences on ADHD are particularly important. Mail: IMAGE Project, SGDP Building, Institute of Psychiatry, London, SE5 8AF |
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