The first aim was to characterize progression of craving, withdrawal/NA, and PA over the course of 24 hours of abstinence in moderate and heavy smokers. The final model with regions of significant group difference is shown in Figure 1A. The best fitting model describing the progression of craving over the course of Day 1 was a cubic polynomial. All growth parameters were found to significantly vary across individuals (p’s < 0.001) and were estimated as random effects. Further, group was found to moderate all growth parameters (Group × Hours: B = 1.83, p < 0.01; Group × Hours2: B = –0.51, p < 0.01, and Group × Hours3: B = 0.03, p < 0.01). Post-hoc tests revealed significant group differences in craving between 1 and 4 hours after the last cigarette (simple effect of Group: p’s < 0.05) such that heavy smokers had significantly greater craving as compared to moderate smokers only for the period of 1 to 4 hours of abstinence. In sum, craving was found to increase more quickly in heavy smokers such that heavy smokers reported greater craving 1–4 hours after the last cigarette.
