I don't think that's true, though I fully admit there's some sample bias (including the fact that I'm senior, as croshan points out). I know a lot of people that do drugs, I had no trouble observing that when I was in grad school, and people talk to me quite a bit about life issues.
To add a counterpoint - there isn't anything on the line in grad school when sharing stories of drug use... completely different ballgame in the professional world. I've only had one coworker where we mutually admitted to smoking weed and that was because we were talking about music and each threw out a couple names that, well, I don't think there are too many sober people listening to it and we both happened to live in Colorado. In my 6 years that's one person I've told about a drug that is legal where we live - god forbit I tell them about my LSD, coke, nitrous, MDMA, etc usage as benign and recreational as it is. I'd open up about pretty much anything else before that - family issues/etc aren't going to get me fired for discussing
