ADHD and Learning Difficulties | Action Medical Research | Children's Charity

Learning disability and Attention Deficit Hyperactivity Disorder - genetic role

This research was completed on 16 March 2010

Published on 31 January 2007

Around one child in every 100 suffers both a learning disability and a psychiatric disorder, such as attention deficit hyperactivity disorder (ADHD).1,2,3 Little is known about what causes this distressing combination of problems. Researchers are striving to reveal possible genetic causes, to help improve diagnosis, clarify children’s needs and promote development of new treatments.

What's the problem and who does it affect?

Feeling isolated and misunderstood

Three in 100 children have a learning disability.2 Some 30 to 50% of children with learning disabilities also have a psychiatric disorder,1,3 such as ADHD. But their psychiatric problems are often missed. Even when they are noticed, many standard treatments are less effective than usual, or cause greater side effects.

Children with learning disabilities and ADHD typically experience very severe learning problems. They are also extremely hyperactive and impulsive, and have difficulties concentrating. Some children remain dependent on their families for their whole lives – the most severely affected may need help with even the most basic things, such as washing, eating and getting dressed. Many aspects of day-to-day life can be highly stressful for these children and their families. Family life can be disrupted, school can be very hard for children who are able to attend, and friendships can be problematic. In fact, the whole family can become isolated.

Even activities that ought to be enjoyable, such as going on holiday, or to a birthday party, can seem impossible – partly because many parents worry that other people won’t understand their child’s behaviour.

What is the project trying to achieve?

Getting down to some neglected research

A number of genes have already been linked to ADHD, in extensive studies of children with this disorder. But the vulnerable group of children who also have learning disabilities have often been excluded from these studies, even though they are 8 times more likely to suffer from ADHD.1,4

So, in this project, researchers are studying genetic material in blood samples from 50 children who suffer from both ADHD and learning disabilities. They are looking for genetic factors that might cause the children’s ADHD, particularly variations in the number of copies of certain genes. The team is checking whether the children’s parents also carry any of the genetic irregularities that they detect in this study.

What are the researchers' credentials?

Project LeaderProfessor A Thapar FRCPsych, PhD
Project team
  • Dr Nigel M Williams PhD
  • Prof Michael J Owen PhD FRCPsych FMEDSci
  • Prof Michael C O’Donovan MBChB PhD FRCPsych
  • Dr Kate Langley, PhD
LocationDepartment of Psychological Medicine, Cardiff University
Other locations
  • University Hospital of Wales, Cardiff
DurationTwo years
Grant awarded31 October 2006
Start date17 March 2008
End date16 March 2010
Grant amount£124,719.00
Grant codeSP4198

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The Cardiff Neuropsychiatric Genetics group is a world-class team undertaking cutting-edge research into the genetic basis of mental disorders that result from problems within the brain, or with its development. The team has new laboratories, equipped with up-to-date technology and has close links with local children’s services.

The quality of the research is strengthened by the close working relationship of team members. They have been undertaking internationally renowned studies together, and generating exciting findings, for the last 15 years. The team includes clinicians and researchers with expertise in child psychiatry, child psychology and molecular genetics. The team is also collaborating with colleagues who specialise in diagnosing genetic illnesses.

Who stands to benefit from this research and how?

A better understanding of children’s problems

Researchers aim to reveal, for the first time, possible genetic causes of ADHD in children with learning disabilities. If they are successful, and a large number of children share the same genetic irregularities, then it would make sense to develop genetic tests for these irregularities. This may improve diagnosis and enable families of children who are tested to benefit from appropriate counselling and advice from clinical genetics services. Researchers hope their work will help raise awareness of the fact that many children with learning disabilities also have psychiatric problems, such as ADHD.

This raised awareness, along with the possible future availability of genetic tests, may mean doctors are more likely to spot the children’s ADHD. The project team hopes that the children, and their families, would then receive more support – from the healthcare system, social services and schools, for example Finally, researchers hope their work will also provide clues as to the biological origins of the problems faced by children with learning disabilities and ADHD, which, in the longer term, may lead to better methods of treatment and prevention.


  1. Simonoff E. Children with psychiatric disorders and learning disabilities. BMJ 2005;330(7494):742-3.
  2. Wechsler, D. Wechsler Intelligence Test for Children: UK, 3rd Edition; Psychological Corporation: London.
  3. Dykens EM, Hodapp RM. Research in mental retardation: toward an etiologic approach. J Child Psychol Psychiatry 2001;42(1):49-71.
  4. Epstein MH, Cullinan D, Polloway EA. Patterns of maladjustment among mentally retarded children and youth. Am J Ment Defic 1986;91(2):127-34.
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