Nicotine effects on affective response in depression-prone smokers

Rationale: Comorbidity between cigarette smoking and depression is thought to arise because depression-prone smokers self-administer nicotine to improve mood. Yet little evidence supports this view, and nicotine's effect on positive affect deficiency in depression remains largely unstudied. Objectives: We hypothesized that (1) nicotine would dispel negative affect and enhance positive affect and (2) effects would be stronger for smokers vulnerable to depression, particularly during a depressed state. Materials and methods: Regular smokers (N=165) were recruited from the community: 63 with no history of major depressive disorder (MDD), 61 with recurrent past but no current MDD, and 41 with both current and past MDD. During four sessions, participants smoked either a nicotinized (NIC+) or denicotinized (NIC-) cigarette double blind after experiencing a negative mood induction or while undergoing a positive mood induction. Positive and negative affects were measured at baseline and at two time points after smoking. Results: Previously depressed smokers showed a heightened positive mood response to positive mood induction when smoking a nicotinized cigarette. Nicotine also increased the degree to which positive mood induction dispelled negative mood in depression-vulnerable smokers. Finally, nicotine worsened the negative affect response to negative mood induction for all groups. Conclusion: Self-administering nicotine appears to improve depression-prone smokers' emotional response to a pleasant stimulus.