Smoking patterns and stimulus control in intermittent and daily smokers

Abstract

Intermittent smokers (ITS) - who smoke less than daily - comprise an increasing proportion of adult smokers. Their smoking patterns challenge theoretical models of smoking motivation, which emphasize regular and frequent smoking to maintain nicotine levels and avoid withdrawal, but yet have gone largely unexamined. We characterized smoking patterns among 212 ITS (smoking 4-27 days per month) compared to 194 daily smokers (DS; smoking 5-30 cigarettes daily) who monitored situational antecedents of smoking using ecological momentary assessment. Subjects recorded each cigarette on an electronic diary, and situational variables were assessed in a random subset (n=21,539 smoking episodes); parallel assessments were obtained by beeping subjects at random when they were not smoking (n=26,930 non-smoking occasions). Compared to DS, ITS' smoking was more strongly associated with being away from home, being in a bar, drinking alcohol, socializing, being with friends and acquaintances, and when others were smoking. Mood had only modest effects in either group. DS' and ITS' smoking were substantially and equally suppressed by smoking restrictions, although ITS more often cited self-imposed restrictions. ITS' smoking was consistently more associated with environmental cues and contexts, especially those associated with positive or "indulgent" smoking situations. Stimulus control may be an important influence in maintaining smoking and making quitting difficult among ITS.

Figure 1. Cigarette consumption by day of week for daily smokers (DS) and intermittent smokers (ITS).

Error bars are standard errors.

Figure 2. Cigarette consumption by time of day for (a) daily smokers (DS) and (b) intermittent smokers (ITS).

Cigarettes consumed within each time block were averaged across all days of the week. Error bars are standard errors. Both means and standard errors are estimated using GEE analysis. Note that the span of y-axes differ between the two panels, with that for DS five times greater than that for ITS; the different axes are necessary to better illustrate the magnitude of the changes within each group.

Figure 3. Modeled associations between mood measures and changes in the probability of smoking (vs. randomly-selected non-smoking occasions).

Data are presented as changes relative to the average probability of smoking, for daily smokers (DS) and intermittent smokers (ITS) separately, because the absolute probability is influenced by the sampling scheme for smoking and non-smoking occasions, which differs between groups. The mood scales presented are (a) Positive Affect; (b) Arousal; (c) Inattention. All mood scores are standardized factor scores scaled to M = 50, SD = 10. In each case, the range of the mood score represents the range encompassing approximately 95% of the observed scores.