There are substances to enhance any performance, you ever notice the ads during a golf broadcast?
Any advantages from traditional anabolic steroids would seem to be marginal at best, and likely not worth the risk for most considering - except in the area of injury rehab, I suppose.
However, there are (or will be) substances that artificially improve a golfer's performance; one's that help control your mind's state seem like they could help.
I'm not even going to pretend to know how prevalent usage currently is at any level.