Discussion
The present study tested whether a laboratory stressor could augment the ability of a memory updating procedure to decrease cigarette use. While our predictions for the cue-based intervention were not supported, two hypotheses about the stressor were. First, during phase 1 of the intervention, greater craving and physiological responses were observed following exposure to the stressor as compared to the control task. Second, and more importantly, during the weeks following the intervention, larger decreases in cigarette use were seen in stress versus control group participants.The failure to reproduce the effect of a previous smoking cue-based intervention on cigarette use [The stress-based intervention reduced cigarette use but not craving and physiological responses during the follow-up sessions. This too differed from studies using cue-based memory updating interventions [Interestingly, the control procedure also conferred some benefit. Across groups, we observed decreased nicotine dependence scores, increased motivation to quit smoking, and decreased cigarette use. While this may in part be a byproduct of study participation (e.g., placebo or Hawthorne effect), it may also reflect individual differences in responsiveness to the intervention. Just as the stress task may not have been equally stressful to all participants, for some, the control arithmetic task may have been stressful. These individual differences in stress reactivity may account for the correlations between physiological responding at intervention and changes in cigarette use. Across all participants, greater decreases in cigarette use correlated with greater phase 1 systolic BP responses and greater decreases in systolic BP during phase 2. Systolic BP responses could potentially reflect both the reactivation of craving-related processes and the efficacy of the intervention.While this study was originally conceived as a memory updating paradigm, other interpretations are plausible. One possible interpretation is that phase 2 alone led to decreased cigarette use. However, although extinction procedures (often in the form of exposure therapy) can produce transient reductions in cigarette use [A more plausible alternative interpretation may be that the stress procedure enhanced extinction. Although no studies (to our knowledge) have investigated behavioral stress induction on extinction (as in the current study), cortisol has been used to induce a stress state. In fear-related studies, elevated stress hormones during extinction learning (either endogenously or through prior cortisol administration) can further reduce fear responses post-extinction and at follow-up [While it is not possible to determine which mechanism (i.e., memory updating or enhanced extinction) is involved, the present study nonetheless provides, to our knowledge, the first evidence that a single-session stress-based intervention can reduce cigarette use in non-treatment seeking smokers. Future studies may wish to examine neurobiological underpinnings and clarify differences between enhanced extinction and memory updating.