Attention deficit hyperactivity disorder: overdiagnosed or diagnoses missed?

The prevalence of attention deficit hyperactivity disorder is about 5% of the child population, and it carries risks for mental health, educational and personal dysfunction, antisociality and death. The diagnosis in practice is made with remarkable differences in frequency between nations. Low rates in the UK, by comparison with research estimates, suggest that the condition may often be missed in clinical practice; the reasons are considered.