Ah the Medication debate, an old one still waged today by psychiatrists and psychologists and ultimately the difficulty in settling it lies in a great flaw in the study of human behaviour: Correlation without knowing causation.
To give an example: A depressed person may be lacking in certain chemicals, but is the depression a result of those chemicals or are there less chemicals because something is making the brain depressed, therefore it produces less. Are you actually treating, or just getting the poor sap too high to notice? And does it matter?
The problem is a lot of psychiatry/psychology is about symptoms, not causes. Whereas with most diseases and the like we can definitely say "yep, this little bugger is causing the problem". Not so in psych, where if a person matches the symptoms, they have the condition. Unfortunately, since we can't say what causes the condition finding the correct treatment can be difficult.
Is it a natural hormone imbalance? Is it learned behaviour? Does their life just generally suck? Do they just drink too much damn coffee? Are they on heroine without us knowing? All of the above? Who knows?
Personally until we know the cause I'm hesitant to claim medication, therapy or a combination are truly recommendable. Wikipedia says ADHD has multiple competing theories, and since the damn ethics rules won't just let people grab a bunch of babies, cut into their brains, and start messing with their hormone levels and how they are parented and the like which means it's going to be a long time before we can have definitive answers on that one -.-
Though if medication at least makes the person bearable to be around and/or productive, then maybe it's better for society if they are just kept in a state of permanent drugged-up-ness?