September 30, 2010

Possible Genetic Causes Of ADHD Discovered

Scientists at the UK's Cardiff University report they have discovered evidence that attention-deficit/hyperactivity disorder (ADHD) is a genetic condition--a discovery that could help find better ways to treat the ailment and exonerate parents often blamed for poor child rearing.

Writing in the medical journal The Lancet, Dr. Nigel M. Williams of the Cardiff School of Medicine and his colleagues found that children who were diagnosed with ADHD were more likely to have small segments of their DNA missing or duplicated than those who did not suffer from the hyperactivity disorder.

They also discovered genetic variants similar to those found in autism and schizophrenia, according to a university press release, "proving strong evidence that ADHD is a neurodevelopmental disorder--in other words, that the brains of children with the disorder differ from those of other children."

As part of their research, the Cardiff experts reviewed the genomes of 366 children who had been clinically diagnosed as ADHD-positive, and compared the results to 1,000 control samples. They discovered that 15% of those in the ADHD group had, according to BBC News Health Correspondent Jane Dreaper, "large and rare variations in their DNA," versus just 7% in the control group.

The most affected area was found on chromosome 16, which according to the university's press release has previously linked to psychiatric disorders including schizophrenia.

"We hope that these findings will help overcome the stigma associated with ADHD," Cardiff University Professor Anita Thapar said in a statement. "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."

ADHD, which according to the university's press release causes children to be "excessively restless, impulsive and distractible, and experience difficulties at home and in school," affects one out of every 50 children in the UK and an estimated 8% to 10% of American school kids. The research was financially sponsored by Wellcome Trust, along with additional support from Action Medical Research, the Medical Research Council and the European Union.

"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,' Reuters reporter Kate Kelland wrote in an article on Thursday. "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," Philip Asherson of the Institute of Psychiatry King's College London, told Kelland.


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