Well, there are plenty of studies showing that a lot of psychiatric drugs do more harm than good. In fact, the FDA is making Ritalin producers put another warning label on the product now.
Frankly, playing with brain chemistry is a very dangerous thing and we take it far too lightly. The flip side of the whole thing is you breed an attitude in modern culture that you will find all the answers to your problems in a pill (and don't think for a second that there aren't people out there that will prescribe you with whatever will make you feel better and fatten their own wallets in the process)...
Is Tom Cruise crazy? Sure, he's a Scientologist. But even a Scientologist can get one right every once in a while.