How common is ADHD?

Estimates vary, both between and within different countries, but ADHD is one of the most commonly-diagnosed behavioural disorders in children and young people.³

• Studies in the UK suggest that ADHD occurs in an estimated 5% of school aged-children.² This means that the average UK classroom will include at least one child with ADHD
• Studies in the United States report higher rates of ADHD,⁴ possibly due in part to the use of different criteria to diagnose ADHD in the US
• ADHD is diagnosed in more boys than girls, by a ratio of at least three to one⁵
• Up to two-thirds of children with hyperactivity disorders continue to have problems into adulthood⁶