(Press-News.org) Research published today provides the first direct evidence that attention-deficit/hyperactivity disorder (ADHD) is a genetic condition. Scientists at Cardiff University found that children with ADHD were more likely to have small segments of their DNA duplicated or missing than other children.
The study also found significant overlap between these segments, known as copy number variants (CNVs), and genetic variants implicated in autism and schizophrenia, 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.
The research, published today in the journal The Lancet, was largely funded by the Wellcome Trust, with additional support from Action Medical Research, the Medical Research Council and the European Union.
"We hope that these findings will help overcome the stigma associated with ADHD," says Professor Anita Thapar. "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 is one of the most common mental health disorders in childhood, affecting around one in 50 children in the UK. Children with ADHD are excessively restless, impulsive and distractible, and experience difficulties at home and in school. Although no cure exists for the condition, symptoms can be reduced by a combination of medication and behavioural therapy.
The condition is highly heritable – children with ADHD are statistically more likely to also have a parent with the condition and a child with an identical twin with ADHD has a three in four chance of also having the condition. Even so, until now there has been no direct evidence that the condition is genetic and there has been much controversy surrounding its causes, which some people have put down to poor parenting skills or a sugar-rich diet.
The team at Cardiff University analysed the genomes of 366 children, all of whom had been given a clinical diagnosis of ADHD, against over 1,000 control samples in search of variations in their genetic make-up that were more common in children with the condition.
"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," explains Dr Nigel Williams. "These findings give us tantalising clues to the changes that can lead to ADHD."
The researchers found that rare CNVs were almost twice as common in children with ADHD compared to the control sample – and even higher for children with learning difficulties. CNVs are particularly common in disorders of the brain.
There was also significant overlap between CNVs identified in children with ADHD and regions of the genome which are known to influence susceptibility to autism and schizophrenia. Whilst these disorders are currently thought to be entirely separate, there is some overlap between ADHD and autism in terms of symptoms and learning difficulties. This new research suggests there may be a shared biological basis to the two conditions.
The most significant overlap was found at a particular region on chromosome 16 which has been previously implicated in schizophrenia and other major psychiatric disorders and spans a number of genes including one known to play a role in the development of the brain .
"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," explains Dr Kate Langley. "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."
Dr John Williams, Head of Neuroscience and Mental Health at the Wellcome Trust, which has supported Professor Thapar's work for ten years, says: "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."
INFORMATION:
To see Professor Anita Thapar and Dr Nigel Williams discussing this research, visit: http://www.youtube.com/watch?v=3NlaekvCZ48
END
A particularly aggressive childhood cancer can be fought successfully with far less chemotherapy than previously believed, avoiding harmful side effects caused by cancer drugs.
The 96 percent survival rate found in an eight-year clinical trial at the University of California, San Francisco, stands to change the approach toward fighting intermediate-risk – stage three and stage four – neuroblastoma. Neuroblastoma attacks the network of cells that control the body's response to stress, known as the sympathetic nervous system, and affects 650 children in the United States ...
Many researchers have studied the relationship between the increase in sales of new antidepressants in recent decades and a simultaneous decline in the suicide rate. In a study based on figures from the Nordic countries, researchers at the Norwegian Institute of Public Health found no evidence that increased sales of the new medicines could be linked to a lower suicide rate. The researchers also did not find any relationship between reduced sales of the older and more toxic antidepressants and a reduction in suicide rates.
The suicide rate has been declining since the ...
Severe sepsis, a disease characterised by a sudden drop in blood pressure and progressive organ dysfunction following infection, remains one of the most common causes of mortality in intensive care units worldwide. Even under the best possible medical conditions, mortality rates range between 30 and 70%. A research team from the Instituto Gulbenkian de Ciência, Portugal, led by Miguel Soares, found that free heme, released from red blood cells during infection, is the cause of organ failure, leading to the lethal outcome of severe sepsis. Moreover this team found that the ...
The key to the stability of any building is its foundation, but it is difficult to test some building sites in advance – such as those on the moon. New research from North Carolina State University is helping resolve the problem by using computer models that can utilize a small sample of soil to answer fundamental questions about how soil at a building site will interact with foundations.
"If you are going to build a large structure, you have to run a lot of tests on the building site to learn how the soil will behave in relation to the building's foundation," says Dr. ...
Athens, Ga. – A new University of Georgia study suggests that mothers who consume a diet high in trans fats double the likelihood that their infants will have high levels of body fat.
Researchers, whose results appear in the early online edition of the European Journal of Clinical Nutrition, found that infants whose mothers consumed more than 4.5 grams of trans fats per day while breastfeeding were twice as likely to have high percentages of body fat, or adiposity, than infants whose mothers consumed less than 4.5 grams per day of trans fats.
The researchers investigated ...
In an advance that may give brewers powerful new ability to engineer the flavor and aroma of beer — the world's favorite alcoholic beverage — scientists are publishing the most comprehensive deciphering of the beer's "proteome" ever reported. Their report on the proteome (the set of proteins that make beer "beer") appears in ACS' monthly Journal of Proteome Research.
Pier Giorgio Righetti and colleagues say they were inspired to do the research by a popular Belgian story, Les Maîtres de l'Orge (The Brew Masters), which chronicles the fortunes of a family of brewers over ...
Traces of crude oil that linger on the shores of Alaska's Prince William Sound after the Exxon Valdez oil spill remain highly biodegradable, despite almost 20 years of weathering and decomposition, scientists are reporting in a new study. Their findings, which appear in ACS' semi-monthly journal Environmental Science & Technology, suggest a simple approach for further cleaning up remaining traces of the Exxon Valdez spill — the largest in U.S. waters until the 2010 Deepwater Horizon episode.
Albert D. Venosa and colleagues note that bacteria, evaporation, sunlight, and ...
Garlic has "significant" potential for preventing cardiomyopathy, a form of heart disease that is a leading cause of death in people with diabetes, scientists have concluded in a new study. Their report, which also explains why people with diabetes are at high risk for diabetic cardiomyopathy, appears in ACS' bi-weekly Journal of Agricultural and Food Chemistry.
Wei-Wen Kuo and colleagues note that people with diabetes have at least twice the risk of death from heart disease as others, with heart disease accounting for 80 percent of all diabetes-related deaths. They are ...
In a real-life "back to the future" story, scientists today reported that the sustainable, environmentally-friendly process that gave birth to plywood a century ago is re-emerging as a "green" alternative to wood adhesives made from petroleum. Speaking at a meeting of the American Chemical Society, they described development of new soy-based glues that use a substance in soy milk and tofu and could mean a new generation of more eco-friendly furniture, cabinets, flooring, and other wood products.
"Protein adhesives allowed the development of composite wood products such ...
Drug manufacturers have been adjusting to strict new government standards that limit the amount of potentially harmful impurities in medicine, according to the cover story of the current issue of Chemical & Engineering News (C&EN), ACS' weekly newsmagazine. The impurities are "genotoxic," capable of damaging the DNA in genes.
C&EN Senior Correspondent Ann Thayer notes that internationally accepted regulations long have limited the levels of impurities permitted in prescription drugs. But guidelines have not covered so-called genotoxic impurities (GTIs), substances that ...
