Attention Deficit Hyperactivity Disorder (ADHD) - Debate in Western Australia

Following is an excerpt from a radio program transcript on ABC Radio Australia, Saturday 19 June 2004. The interviewer Natasha Mitchell is talking with Dr David Hay, an adhd researcher from Curtin University in Western Australia, who heads up the Australian Twin ADHD study.

The really interesting thing here is Dr Hay's research, which indicates a strong genetic component to adhd.

"Professor Hay runs one of the world's largest twin studies into ADHD and his results suggest that the disorder has a strong genetic or biological basis. And his team is recognised for confirming that ADHD in fact exists on a continuum.

David Hay: All of us are sometimes inattentive, all of us are sometimes fidgety, but it's the person who is so inattentive, who is so hyperactive that it messes up their life at home, at school, at work, with peer relationships. That's what makes up ADHD and that's what we mean by a 'continuum', we're making a decision. We have to say, someone who's got this range of symptoms, we have to give them a label and have to give them help.

Natasha Mitchell: Well there's considerable debate about the line in the sand and we can come to that in a moment, but what is the genetic contribution to that line in the sand?

David Hay: It's very strong. One thing we've gone on to do in the last few years is to actually identify that there are generally distinct types of ADHD.

Many of your listeners will think of ADHD as being the hyperactive kid, because that's what you see on television; it makes a good story. But in fact the child who's purely hyperactive and impulsive is the rarest type of ADHD. The more common type is the child who's got the hyperactive impulsive symptoms and inattention. And the most common type is the inattentive type, and we've shown in fact that these represent three distinct genetic groupings and that's an important observation itself, it gives some backing to the diagnostic system we make. But the genetic component is very strong, I mean I've worked in behaviour genetics for something like 30 years and I've never come across any behaviour that's as genetic as ADHD. And the genes are where we would expect them to be. ADHD and the stimulant medication affects a chemical in the brain called dopamine and we now have four or five genes which are replicated in many studies throughout the world which affect ADHD. So we've got a large genetic component and we've honed in on some specific genes."
http://www.abc.net.au/rn/science/mind/stories/s1132023.htm