Does not exist. However, mental weakness does. If you're too much of a pussy that you can't say, " You know what, fuck it, I DON'T want a cigarette." Then you're weak. Addiction is nothing more than you ENJOYING something, don't bring an excuse that you're somehow addicted to it, yeah THAT'S the reason you want to shoot up heroine, or keep eating all those cheeseburgers you fat fuck.Its like the idiots who say addiction is a disease so the the "addicts" can have an excuse or a scapegoat as to why they are too mentally weak to simply stop doing whatever their "addicted" to. Same goes for depression. It's just you being sad, get over it. Shit happens, don't blame some fucking chemical in your brain making you sad. GO DO SOMETHING FUN.