ADHD

30 September 2010

ADHD kids are missing DNA

Children with attention deficit hyperactivity disorder (ADHD) are twice as likely to have missing or extra chromosomes than children without ADHD, a study has found.

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Children with attention deficit hyperactivity disorder (ADHD) are twice as likely to have missing or extra chromosomes than children without ADHD- the first evidence that the disorder is genetic, a new study says.

British researchers compared the genomes of 366 white British children from five to 17 years old with ADHD, to those of more than 1,000 similar children without the disorder.

The study

The scientists focused on a sequence of genes linked to brain development that has previously been connected to conditions like autism and schizophrenia.

In children without ADHD, about 7% of them had deleted or doubled chromosomes in the analysed gene sequence. But among children with the disorder, researchers discovered about 14% had such genetic alterations.

Scientists also found that 36% of children with learning disabilities in the study had the chromosomal abnormalities, compared to those with a normal IQ.

Chunks of DNA missing

"This is the first time we've found that children with ADHD have chunks of DNA that are either duplicated or missing," said Anita Thapar, a professor at the MRC Centre in Neuropsychiatric Genetics and Genomics at Cardiff University who was one of the study's authors.

She said the findings are too early to affect diagnosis or treatment and are only applicable to people of European Caucasian descent because studies have not been done yet on other ethnicities.

Millions affected

The condition is estimated to affect millions of children around the world, and scientists have long thought the disorder has a genetic component.

US experts estimate that ADHD affects from 3 - 5% of school-age children in the United States. There are no figures for developing nations.

The study was paid for by Action Research, Baily Thomas Charitable Trust, the Wellcome Trust, Britain's Medical Research Council and the European Union. It was published online in the medical journal The Lancet.

Peter Burbach, a professor of molecular neuroscience at University Medical Centre Utrecht in the Netherlands, was surprised some of the genetic defects found for ADHD were identical to ones for autism and schizophrenia. He was not connected to the Lancet research.

Environment a possible cause

"There's a great chance the environment is modifying these genes," Burbach said, adding the genes could lead to several brain disorders, depending on things like the child's upbringing and other genetic factors.

He also thought scientists might eventually be able to reverse ADHD.

"This is not a structural abnormality in the brain, it's just the last phase of development that's gone wrong," he said. "It could be the brain just needs to be fine-tuned."

Philip Asherson, a professor of molecular psychiatry at the Institute of Psychiatry at King's College London, said the study only dealt with a subset of people with ADHD and said the environment should still be considered a cause.

In the case of some Romanian orphans, Asherson said there was proof that severe deprivation at an early age can lead to ADHD or other neurological problems.

Asherson said the medical world was still years away from being able to correct ADHD.

"The study doesn't tell us a lot about what's going on in the brains of people with ADHD," he said. "If we can find out more about these genes and how they affect brain development, that may give us inroads, but it's hard to say when that will be."

(Sapa, September 2010) 

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ADHD Expert

Dr Renata Schoeman has been in full-time private practice as a general psychiatrist (child, adolescent and adult psychiatry) since 2008, currently based in Oude Westhof (Bellville). Renata also holds appointments as senior lecturer in Leadership (USB) and as a virtual faculty member of USB Executive Development’s Neuroleadership programme. She serves on the advisory boards of various pharmaceutical companies, as a director of the Psychiatric Management Group (PsychMG) and is the co-convenor of the South African Society of Psychiatrist (SASOP) special interest group for adult ADHD, and co-founder of the Goldilocks and The Bear Foundation (www.gb4adhd.co.za) She is passionate about corporate mental health awareness and uses her neuroscience background to assist leaders in equipping them to become balanced, healthy and dynamic leaders that take their own and their team’s emotional, intellectual, social health and physical needs into account. Renata is academically active and enjoys research and collaborative work, has published in many peer-reviewed journals, and has presented at local and international congresses. She is regularly invited to present at conferences and to engage with the media. During her post-graduate studies, she trained at Harvard, Boston in neurocognition and neuroimaging. Her awards include, amongst others, the Young Minds in Psychiatry award from the American Psychiatric Association, the Discovery Foundation Fellowship award, a Thuthuka award from the NRF, and a MRC Fellowship. She also received the Top MBA student award and the Director’s award from USB for 2015. She was a finalist for the Businesswomen’s Association of South Africa’s Businesswoman of the Year Award for 2016, and received the Excellence in Media Work award from SASOP during 2016.

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