Study finds first evidence that ADHD is genetic

LONDON Thu Sep 30, 2010 4:54am EDT

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LONDON (Reuters) - British scientists have found the first direct evidence attention deficit/hyperactivity disorder (ADHD) is a genetic disorder and say their research could eventually lead to better treatments for the condition.

Researchers who scanned the gene maps of more than 1,400 children found that those with ADHD were more likely than others to have small chunks of their DNA duplicated or missing.

Anita Thapar, a professor psychiatry at Cardiff University who led the study, said the findings should help dispel the myths that ADHD is caused by bad parenting or high-sugar diets.

"This is really exciting because it gives us the first direct genetic link to ADHD. 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," she told reporters at a briefing about the findings.

ADHD is one of the most common child mental disorders and is estimated to affect around 3 to 5 percent of children globally. It is seen far more often in boys than in girls.

Children with ADHD are excessively restless, impulsive and easily distracted, and often experience difficulties at home and in school. There is no cure, but the symptoms can be kept in check by a combination of medication and behavioral therapy.

Millions of people take ADHD drugs including Novartis's

Ritalin, known generically as methylphenidate, Johnson & Johnson's Concerta, Shire's Adderall and Vyvanse and Eli Lilly's

Strattera. Global sales of ADHD drugs were around $4 billion dollars in 2009, according to pharmaceutical analysts at Deutsche Bank in London.


Thapar said the findings would help unravel ADHD's biological basis, "and that's going to be really important in the future to develop new and much more effective treatments."

But experts stressed that the DNA findings were unlikely to lead the development of a genetic test for ADHD, since a complex mix of genes and environment are likely to be the cause.

"It is not clear that this will yet lead to a diagnostic test, but may well open up new avenues for understanding the neurobiology of the disorder," said Philip Asherson of the Institute of Psychiatry King's College London.

The study also showed an overlap between the deleted or duplicated DNA segments, known as copy number variants (CNVs), and genetic variants linked to the brain disorders autism and schizophrenia -- providing what the scientists said was "strong evidence" that ADHD is a neurodevelopmental condition.

The Cardiff team analyzed the genomes of 366 children with ADHD and compared them with 1,047 samples from children without ADHD to try to find variations in their genetic make-up.

The findings, published in The Lancet medical journal, showed that rare CNVs were almost twice as common in children with ADHD compared to the other children.

Nigel Williams, who also worked on the study, noted the significant overlap between CNVs found in children with ADHD and regions of the gene map which are known to influence susceptibility to autism and schizophrenia.

He said the most marked overlap was found at a particular region on chromosome 16 which has been linked to schizophrenia and other major psychiatric disorders and spans a number of genes, including one known to play a role in brain development.

"We have seen a clear genetic link between these segments and other brain disorders," he said. "These findings give us tantalizing clues to the changes that can lead to ADHD."

(Editing by Ralph Boulton)

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Comments (10)
judyvg wrote:
I believe ADHD is very much linked with what children ingest. One of my children had all the symptoms of ADHD and life was really hard, trying to deal with her.

Not wanting her to have Ritalin, or similar, I searched for natural ways to help her. I came across the book entitled “E For Additives” by Maurice Hanssen. In the book, are to be found a list of food additves and their side effects. There is also a list of additives which are linked to hperactivity, I determined to cut these from my child’s diet. This was not easy for these additives are found in a lot of processed food. It entailed a lot of home cooking. and a lot of food label reading.

Nevertheless, in a matter of a few weeks, my child’s behaviour changed dramatically. She had no more ADHD symptoms and thus there was a positive change in her behaviour. I can only say the advice in the book was spot on.

Sep 30, 2010 7:31am EDT  --  Report as abuse
Cru wrote:
I thought we already knew this? I guess someone was right.

Being restless probably saved many a caveman from being eaten or gored.

Sep 30, 2010 10:15am EDT  --  Report as abuse
Ready2Puke wrote:
What a load of manure. Correlation does not prove causation! The fact that here in the US there is a high correlation between the sale of strawberry ice cream and the salaries of teachers doesn’t mean if we decrease the sale of strawberry ice cream teachers will be driven in to poverty. The fact that chromosomes are present or missing in children with ADHD may or may not mean they are any closer to causing ADHD than the sale of strawberry ice cream does on driving the salaries of teachers up or down. This sort of research may point the way toward something but at the level described it means precious little. In addition I believe geneticists are finding that gene expression is more important than the configuration of the genes.

Sep 30, 2010 10:46am EDT  --  Report as abuse
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