The number of cigarettes a person smokes in a day or a week is no indication of how difficult it will be for them to quit smoking. If you want to kick the habit and can’t, that’s a sure sign for Difranza that you are addicted to nicotine.
MRIs of the brains of smokers show that nicotine activates billions of receptors, releasing chemicals such as serotonin, dopamine and dozens of other chemicals that fire up other nerves, creating a cascading effect.
That is why Difranza thinks that true nonaddicted smokers make up a fraction of people who smoke — about 5 percent. The brain is changed by nicotine, he says, and harbors memories of the smoking experience.
via ‘Chippers’ Challenge Concepts Of Smoking Addiction : NPR.