Any good Doctor will not test your child or send them to be tested until they are 6 years old. I believe to many children are being put on these drugs that cause side effects and hurt there health.With out thinking about down the line what it will do to them.And looking at everything that is going on with children these days,with School ,home life,parents getting divorces and times be hard on everyone these days.
There are other things that look like adhd ,but Doctors don't look at these things and Parents don't know about them. I know I didn't .Until now.
My Son has Seizures after being on these drugs and now I have to watch him have Seizures every day ,and the Medicines for his Seizures has not stopped them and he also had Surgery last June to have what they call the VNS chip put in to try and help.
So now I worry about my Son dieing instead of being hipper. And yes he is still hipper from time to time and doesn't always know he is doing it because of the Seizures. I would rather have him back the way he was before the Seizures Started.
And Seizures can look like a child has add or adhd and even bipolar and some even look like they have autism.
The one thing I have done to help my son with his learning is he is now home Schooled for two hours a day by a teachers from the School where we live and they are great and have done more for him in a short period of time than any other Teachers have.And I give him Vitamin B6 and Omega 3-6-9 every day and you can tell if he doesn't have it . And sure he has his bad days just like we all do and because of his Seizures.
So children should have there brain's check first by having a EEG and blood work up to make sure everything is normal by seeing and talking to a Neurologist ,not all Seizures can be seen learned that also.
Hope this helps you and others.
Good ol Wikipedia has a pretty good description. You can also go to the top of this page and hit the ADHD link and get more info.
Most schools don't test till 1st grade, but that is beginning to change due to the knowledge that the sooner a child gets help, the better it is for the child.