Attention Deficit Hyperactivity Disorder - which affects boys more than girls and makes them inattentive, highly-impulsive and prone to distraction - is caused by a genetic aberration, scientists in Trinity College have confirmed. ADHD affects between one and three per cent of the population.
The research by TCD's departments of genetics and psychiatry was based on an evaluation of 49 Irish ADHD patients and their parents. It shows that a hereditary variation of what is known as the dopamine transporter gene, or a variation of the gene code adjoining it, is responsible. This causes an abnormality of neurotrans mission in the brain.
The findings pave the way to mapping the errant gene, which could lead to developing a treatment. They show that international research on ADHD and the use of stimulant drugs in its treatment has been "on the right track", according to psychiatrist Dr Michael Fitzgerald, who co-ordinated the work with geneticist Dr Michael Gill.
The findings are published in the latest issue of Molecular Psychiatry. "We are very pleased. This work is genuinely significant in the international context", Dr Fitzgerald said.
The Trinity team also suggests a possible link between ADHD and the "novelty-seeking" personality trait whereby a person may be contrite, impulsive, excitable, quick-tempered and extravagant. The latter, Dr Fitzgerald said, could be manifested in a journalist, for example, who would have hundreds of interesting stories in his head but would never get around to writing any of them.
The findings were welcomed by Mrs Stephanie Mahoney, spokeswoman for the Hyperactive Children's Support Group in Ireland, which assisted in the research. "People with ADHD can have a terrible time. The more recognition the condition gets, the better for a person with ADHD and their families. They are bright children and can contribute a lot."
Mrs Mahoney, who has a son with ADHD, said that, while her son could be "boisterous", he also had an "amazing memory, which needless to say comes in handy".
Some 200 families with children who have ADHD are part of the support group.
"It's hard to diagnose. Children may have only some of the symptoms and can be affected to varying degrees", Mrs Mahoney added. While boys are more commonly affected than girls, there is a big difference in symptoms between the sexes. Boys tend to be boisterous, noisy and attention-seeking, whereas girls tend to be quiet and uninterested.
While ADHD is viewed mainly as a childhood condition, its symptoms can persist into adulthood.
