Attention Deficit Hyperactivity Disorder (ADHD) is a diagnosis of the American Psychiatric Association (APA, 1994) and describes behavioural symptoms of impulsivity, inattention and hyperactivity.

These symptoms must be presented to such a degree that they significantly interfere with the individual's family and peer relationships, their educational and/or occupational functioning and general day to day activities.

According to current diagnostic criteria there are three types of ADHD seen in children and young people:

1. Hyperactive/impulsive type
2. Inattentive type
3. Combined hyperactive-impulsive/inattentive type

(Hughes and Cooper, 2007)