I have worked for a mental health institute treating addiction and associated problems. There is no way to engage with clients or have people that suffer from it participate in open forum discussions like social media. Maybe it's an option to niche it with a related but not the same theme like: things you can do the stay mentally fit tips Tweet channel (I like short names you see). Not associating it directly get's attention and people not bothered to participate in discussions like: how not to feel dead tired and empty when not working tips. This is a prelude state to becoming a client so its prospecting nevertheless.
A more seen and practical alternative is to start expert communities with doctors and other experts that post and interact in a community for example about staying mentally fit. It's a double edge sword as the experts can build online authority and people in real need for medical attention can linger and interact around general items like news clippings on new treatments etc. Why not send a PM to the doc that was discussing e-cigarettes about you not being able to quit smoking pot?
communities recommended:
Social Media Strategies (Google+) with 133K members, high quality posts and moderation
https://plus.google.com/u/0/communities/100354381402619402956
And of course my very own community on everthing Google + marketing:
https://plus.google.com/u/0/communities/114482540072196914877
But i'ts in Dutch but he where else do I get a change to mention it once i a while on all these EN media:)