yeah articles talking about this has been around a few years. A major problem would be side effects, including emotional. (nothing is free)
I'm sure there would be plenty of people that once they got a taste of it, would illegally dope themselves up as much as they could until they are really messed up.
Hopefully they'd be smart enough to stop though.
Also, these drugs would doubtfully increase intelligence directly, just the capacity to store more information and recall it, or to increase concentration.
We're supposed to be living on mars, wearing tin foil unitards, and have flying cars by now, might I remind.