Scientists in Germany said Thursday they have found compelling evidence of a genetic link to hyperactivity in children, identifying three mutations prevalent in fidgety youngsters.
A research team led by Professor Johannes Hebebrand of the University of Duisburg-Essen in western Germany studied 329 families in which one child had attention-deficit hyperactivity disorder syndrome.
They found that a great majority -- around 70 percent -- had a combination of three mutations in the gene for the so-called dopamine transporter linked to hyperactivity.
"People who have this combination in both copies of the gene have a 2.5 increased ADHD risk. People with only one copy of this variant still have almost twice the risk," Hebebrand said in a statement.
"Of course, this doesn't mean that everyone who has the genetic variants will automatically get the disease."
He noted that even healthy children can have such variations and that it requires several gene mutations happening at once for ADHD to result.
The study provides firmer genetic evidence for the role of the dopamine transporter in hyperactivity than had been found to date, Hebebrand said.
ADHD is the most common psychiatric disorder among children and adolescents, with boys affected three or four times as often as girls.