A STUDY published in the Lancettoday has found direct evidence that attention-deficit/hyperactivity disorder (ADHD) is a genetic condition. The disorder, which makes children restless, impulsive and easy to distract, has often been attributed to boldness, bad parenting or a high sugar diet.
The research by a team of scientists in Cardiff University concluded that ADHD is a brain development disorder. The study involved genetic analysis of DNA from 366 children with the disorder and 1,047 without the condition. The researchers found that children with the disorder were much more likely to have small DNA segments duplicated or missing than the other children.
The researchers also found significant overlap between these segments and those linked to autism and schizophrenia. The research suggests there may be a shared biological basis to autism and the disorder.
The research team said their findings should help clear up misunderstandings about the disorder so that affected individuals and their families would encounter less stigma.
Lead investigator Prof Anita Thapar said that, too often, people dismissed the disorder as being down to bad parenting or poor diet.
“As a clinician, it was clear to me that this was unlikely to be the case. Now we can say with confidence that the disorder is a genetic disease and that the brains of children with this condition develop differently to those of other children.”
She said the study proved that ADHD should be seen as a neurodevelopmental disorder like autism rather than as a behavioural problem. “In the future these findings will help unravel the biological basis of the disorder which in turn will help develop new and more effective treatments.”
The Irish HADD (hyperactivity attention deficit disorder) family support group said it was aware of the genetic link to the condition, through work done in Trinity College Dublin. Its neuropsychiatric genetics research group is involved in a number of studies on ADHD and has found several genes could contribute to the disorder. Chairwoman of the support group Stephanie Mahony said the link with autism was not surprising as parents had found that the disorder seldom presented on its own.
Children diagnosed with the disorder were often found to have co-occurring conditions such as Asperger’s syndrome, dyspraxia or dyslexia. The support group is one of the organisers of a conference on October 16th which will address the links between the disorder and these conditions.
Ms Mahony said parents would welcome any research which dispelled myths about the disorder. “People say they are just bold children, or it’s bad parenting or a lack of discipline and co-operation. I wish that was the case.”
She said 60,000 children in Ireland were living with the disorder but there may be many more undiagnosed cases. Her group is seeking an expansion in diagnostic and support clinics. “Early diagnosis is crucial,” she said.
Prof Michael Fitzgerald, professor of child and adolescent psychiatry at Trinity College Dublin, said children with the disorder and their families faced shocking prejudice and hostility.
He said some people saw the disorder as a “new fangled” American invention to explain away bad behaviour in children but nothing could be further from the truth.
If children with the disorder did not receive the appropriate help, the consequences for their future were very serious, he said.
The rate of the disorder among prisoners was three times higher than in the general population and that an estimated 4 per cent of adults had the condition.
Previous studies have found that the child of a parent with the disorder is more likely to have the condition than other children.
Studies have also found that if one of a set of identical twins has the disorder, the other twin has a 75 per cent chance of having it.
When the disorder is diagnosed, the symptoms in many cases can be successfully managed with a combination of medications and behavioural interventions.
www.hadd.ie provides support for families living with ADHD
