Well, thanks to Madara, I just completed my study :p.
The First Level of Addiction:
You constantly think about that person all the time, chase after them and dedicate your life to them... even though the other person doesn't care of acknowledge you.
The Second Level Of Addiction:
Your first level addiction causes you to get really paranoid and pissed off. You get so pissed that you decide that you want to take over the world.
The Third Level of Addiction:
You begin to lose sense of yourself and your goals. Your addiction becomes such a problem that it starts to drive you insane and you start making strange faces and saying the name of thing that causes your addiction.
The Fourth Level of Addiction:
At this stage of addiction, you lose your completely. You become so immersed in your addiction, that you lose the ability to speak and think. All you can say is the name of your addiction and make strange faces.