This of course is not a straightforward issue, and certainly less so as there has been some confusion with other more provable learning difficulties.

The notion of ADHD was introduced around the time that laws were passed in Europe and the USA regarding children's regular attendance at school.

Now, school is an artificial environment for all of us, but especially children. Made to sit for many hours each day absorbing usually written or oral material. It was found that some children did not concentrate. In fact they displayed symptoms of distraction and disruption.

Once, children who did the above were described differently. Some were considered more energetic than their classmates. Some were dreamers. These often developed into highly intelligent, creative adults who contributed on a high level to human society. The list of such individuals is endless. Psychiatry unfortunately tends towards reductionism and therefore reduces all behaviour it comes across, and deems unusual, as illness. Its next step tends to be the use of drugs.

Papers I've looked at on the Lancet, the accessible ones from overseas such as from New Zealand, indicate the possibility of social prejudice among professionals in the diagnosis of children as young as 6.