I'm sorry for the delay in getting back to you, but some other people were giving you answers that would be better then mine.
PANIC is good at showing the entire focus on your next fix, no matter what. If a heroin addict needs a fix bad enough, they'll sacrifice their children, their significant other, their parents, whoever. And from their point of view, they know that each high won't be as good as the one before, but they'll constantly chase that first high.
Rehab is a tough thing to do. I had clients who went into rehab, and decided quickly that prison was a better alternative. But heroin addicts end up approaching rehab differently then most addicts. They actually survive rehab fairly well, once they've detoxed, and are great at mouthing the party line.
But once they get back on the streets, heroin sings to them, calling them. And they succumb, knowing it isn't going to work.
Coming out of prison nearly everybody is pretty clean. Even if you're getting drugs behind the walls, it's hard to remain under the influence. Prisons spend a lot of effort in helping to set up inmates to avoid drugs when they are released.
Despite prisons being smoke-free, nearly every inmate who is a smoker resumes the habit within 24 hours of being released. It's the least successful drug intervention that law enforcement makes. In my experience, the next least successful intervention that prison makes is heroin, followed closely by meth. I haven't had a junkie that stayed clean for longer then a couple of months after being released, despite knowing they would be drug tested.
Compare this to alcoholics, who frequently can use prison to turn their lives around. Or pot heads. Or to a lesser extent, coke heads.
Best of luck,
Jim Clark-Dawe