Hyperactive children may suffer from genetic disorder, says study
Parents of hyperactive children should not be blamed for failing to bring up their offspring properly, according to scientists who today publish evidence that the condition is genetic.
Children with attention deficit hyperactivity disorder (ADHD) find it hard to concentrate and can be wild and uncontrollable both at home and at school. Controversy has raged around the drug most widely used to calm such children, Ritalin, which is of the amphetamine family. In the US, such drugs became popular among families who wanted their lively (non-ADHD) boys to do better in class, while in the UK they were tagged chemical coshes. Meanwhile, parents have often tacitly been blamed for lack of discipline or giving their children a sugar and additive-laden diet.
But today the furore around ADHD moves into a different space. Researchers, funded not by drug companies but by the Wellcome Trust and other bodies, are publishing the results of a study which for the first time identifies genetic changes in children diagnosed with ADHD.
And the particular DNA markers they found are in the same area of the brain as genetic variants linked to autism and schizophrenia. That means, say the authors of the paper in the Lancet, that ADHD would be better classified as a neurodevelopmental disorder than a behavioural problem.
"We hope that these findings will help overcome the stigma associated with ADHD," said Professor Anita Thapar from the MRC Centre in Neuropsychiatric Genetics and Genomics at Cardiff University, one of the authors.
"Too often, people dismiss ADHD 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 ADHD is a genetic disease and that the brains of children with this condition develop differently to those of other children."
One in 50 children is affected by ADHD, and while it used to be thought that they grow out of it, many continue to have problems in adult life.A genetic link has been suggested for some time, but not proven. Past investigations have shown that ADHD is more likely in a child who has a parent that suffers from the disorder, and that if one twin has ADHD, the other twin has a 75% chance of also having it.
But the study has found the first direct evidence by analysing DNA samples from 366 children diagnosed with ADHD, aged five to 17, and 1,047 children without the condition. They found the children with ADHD were more likely to have certain small segments of DNA either duplicated or missing than the other children. Although this finding was limited to 16% of all the children with ADHD, they say it is highly likely the rest have other genetic variants that have not yet been identified.
The researchers point out that they have not found a single gene that is responsible for the condition, and environmental circumstances will also be part of the picture – although as yet they do not know what those are. "ADHD is a very complex disorder which will have a number of different causes. A number of different genetic factors will be involved along with other, non-genetic factors," said Dr Kate Langley, another of the authors.
The findings will not be used for diagnosing ADHD, they add, but they result in new treatments. The stimulant drugs most commonly used to control the symptoms have been around since the 1950s.ADHD support groups warmly welcomed the findings, which they said would make life easier for families.
"This is indeed extremely welcome news of clear evidence to confirm that attention-deficit/hyperactivity disorder (ADHD) is indeed a brain development disorder with closer links to autism than was previously thought," said Simon Hensby of Adders, an online information organisation.
drive from www.guaridan.co.uk
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