Researchers at Duke University recently published that some smokers are genetically pre-disposed to the physical addiction found in nicotine. They characterized smokers their genome. So if your DNA code looks like this, you'll struggle with quitting; but if it looks like that, you may have no trouble quitting.
Well now, Mahler and de Wit have published a fascinating article in PloS One, that looks at the second part of the addiction, but from the same genetic standpoint. Let me explain this behavioral or classic conditioning before I get too far ahead.
Classical or Pavlovian conditioning is characterized by the association of a response with a neutral stimulus. The association develops because it is paired with a significant stimulus that does bring about a specific response. For example, his dogs began to salivate when given food. He then introduced the neutral stimulus which was the bell. The bell and food became paired to the salivating response. Hence, the conditioned stimulus (bell) brought about a conditioned response (salivation).
So with a smoker, lets say he smokes a cigarette with coffee in the morning and then again after dinner. The coffee-drinking by itself does not trigger the smoker to want a cigarette at first. But the coffee drinking eventually becomes paired with smoking. Now the smoker drinks a cup of coffee while at work and suddenly finds himself craving a cigarette. He now has a new conditioned stimulus (coffee) the triggers a conditioned response (cigarette craving).
These researchers actually found what they call a "cue-reactive phenotype" among smokers who are more sensitive to conditioned stimuli than others. This means, they are more likely to develop classic conditioning cues to neutral stimuli. As a side note, they also point out that the subjects who rated as having stronger behavioral triggers for smoking, also had stronger triggers for food craving too.
This isn't necessarily earth shattering news, but it does help us realize the importance of conditioning on smoking cessation (and diet too, I suppose). It cannot be overlooked when developing a method to stop smoking. Many would-be ex-smokers relapse because they underestimate, or never consider, the environmental cues that often trigger the smoking response.
