Unless you're a genius, it'd be downright impossible to succeed at a school like Vanderbilt while supporting a drug habit. But then again, if you were a genius, you probably wouldn't be doing drugs in the first place.
There is a small drug scene on campus, so if you really need to find drugs, I'm sure you wouldn't have too much difficulty. The poison of choice on Vanderbilt's campus, however, is alcohol. Like any university, there are problems with binge drinking, but if you're smart enough to get into Vanderbilt, then you're smart enough to make your own decisions.