Studies show that caffeine is known to be a stimulant for being awake and alert but this effect may vary from one person to another as everybody has a different body structure. Some people say that they can not start working before a cup of coffee and continue drinking during the day while some others can not even drink even one swallow.
Scientists also claim that caffeine gives energy in adults and it may have positive effects on memory for people with ADHD. Caffeine is said to be useful and effective for brain and if we think that for hundreds of years people drink for ex. coffee or etc. for being awake this is not a new information.
If the child or the adult has an ADHD, of course the prescribed medicines seem to have the priority when it comes to reality, but it is also not proven if the medicines interact with caffeine or not so far. Also there is another fact,it may not be good for children especially when randomly used. Sources:psychcentral.com sciencebasedmedicine.org