14 DAY TRIAL // A new study concluded that ADHD is a genetic disorder after scientists discovered that children who suffer from it, have more small segments of their DNA duplicated or missing, compared with other children.
The study carried by scientists at Cardiff University, also found that between these segments there was a serious overlap, known as copy number variants or CNVs, as well as genetic variants appearing in autism and schizophrenia, and this proves that the attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder.
The researchers analyzed the genomes of 366 children with a clinical diagnosis of ADHA, against more than 1,000 control children.
Dr Nigel Williams explained that “children with ADHD have a significantly higher rate of missing or duplicated DNA segments compared to other children and we have seen a clear genetic link between these segments and other brain disorders.
“These findings give us tantalizing clues to the changes that can lead to ADHD,” he added.
Also rare CNVs were almost twice as frequent in children with ADHD, and for those who had difficulties in learning, the numbers were even higher.
CNVs are very common in disorders of the brain and as scientists found overlaps between CNVs in children with ADHD and areas of the genome that influence susceptibility to autism and schizophrenia, they suggested that there could be a common biological basis to autism and ADHD.
The most serious overlap was found on a certain part of the chromosome 16, involved in schizophrenia and other psychiatric disorders.
Dr Kate Langley says that “ADHD is not caused by a single genetic change, but is likely caused by a number of genetic changes, including CNVs, interacting with a child's environment.
“Screening children for the CNVs that we have identified will not help diagnose their condition.
“We already have very rigorous clinical assessments to do just that,” she added.
The problem is that people did not know that ADHD is a genetic disease, so they assumed that the condition was caused by a poor diet and bad parenting.
Professor Anita Thapar says that she hopes that the ADHD associated stigma will disappear, as “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.”
ADHD affects a child in 50 in the UK, and affected children are extremely restless, distracted, impulsive and they have difficulties at home and in school.
Currently, there is no cure for this condition, but the symptoms can be improved by mixing medication and behavioral therapy.
Aldo, this disorder is inherited, and children with ADHD are likely to have a parent with the condition.
Dr John Williams, Head of Neuroscience and Mental Health at the Wellcome Trust, has supported Professor Thapar's work for ten years.
He says that “these findings are testament to the perseverance of Professor Thapar and colleagues to prove the often unfashionable theory that ADHD is a brain disorder with genetic links.
“Using leading-edge technology, they have begun to shed light on the causes of what is a complex and often distressing disorder for both the children and their families.”
The research was largely funded by the Wellcome Trust, with support from Action Medical Research, the Medical Research Council and the European Union, and was published today in the journal The Lancet.