That's the finding of a study, appearing in the September issue of Nicotine and Tobacco Research, that focused on 20 heavy smokers. They were given drugs that either increased or decreased their brain's dopamine levels. Dopamine is a neurotransmitter that affects motor function and is believed to affect emotion.
Animal studies show nicotine causes dopamine release in brain areas linked to feelings of pleasure.
This new study found that when the smokers were given the dopamine-mimicking drug bromocriptine, they smoked less than when given a drug that impedes the effects of dopamine.
Bromocriptine is used to treat Parkinson's disease, some tumors and menstrual problems.
"Overall, these results imply that smoking behavior can be manipulated within the same subjects in opposite directions by alternately stimulating and blocking dopamine, which strongly suggests the importance of dopamine in reinforcement from cigarette smoking," says lead researcher Nicholas H. Caskey, of the Veterans Affairs Greater Los Angeles Healthcare System and the Neuropsychiatric Institute at UCLA's David Geffen School of Medicine.