Examining Age as a Potential Moderator of Response to Reduced Nicotine Content Cigarettes in Vulnerable Populations

Abstract

Introduction: Young adults (aged 18-24 years) have a higher smoking prevalence than younger and older age groups and young adulthood is an important developmental period during which long-term behavior patterns like cigarette smoking are established. The aim of the current study was to examine how young adult smokers with additional vulnerabilities to smoking respond to reduced nicotine content cigarettes.

Methods: This is a secondary analysis of a double-blind, within-subject experiment conducted with 169 cigarette smokers recruited from populations with comorbid psychiatric conditions or socioeconomic disadvantage assessing acute effects of research cigarettes varying in nicotine content (0.4, 2.4, 5.2, 15.8 mg/g). Participants were dichotomized by chronological age (18-24 vs. ≥25 years). Across 14 laboratory sessions effects of nicotine content were examined on measures of relative reinforcing efficacy (Cigarette Purchase Task [CPT] and Concurrent Choice testing), subjective effects, craving/withdrawal, and smoking topography. Repeated measures analysis of variances were used to examine potential moderating effects of age.

Results: Young adults exhibited lower demand for reduced nicotine content cigarettes than older adults across three of five CPT indices (ps < .05). No differences by age were observed on other measures of reinforcing efficacy, subjective effects, craving/withdrawal, or smoking topography where effects generally decreased as an orderly function of decreasing nicotine content (ps <.05).

Conclusion: Overall, these findings suggest that reducing the nicotine content of cigarettes would decrease the addiction potential of cigarette smoking in young adult smokers as much or perhaps more than older adult smokers from populations at increased vulnerability to smoking, addiction, and smoking-related health consequences.

Implications: Reducing the nicotine content in cigarettes to lower addiction potential of smoking has been proposed as a means to improve overall population health. It is imperative to examine how young adults may respond to a nicotine reduction policy. We saw minimal evidence that age moderates acute response and where there was evidence it was in the direction of reduced nicotine content cigarettes having less addictive potential among young versus older adults (eg, steeper decreases in demand for very low nicotine content cigarettes among young versus older adults). Overall, a nicotine reduction policy has the potential to reduce smoking across age groups.

Figure 1.

Demand Indices from the Cigarette Purchase Task simulating demand for cigarette smoking at escalating price. Error bars represent 95% confidence intervals (CIs). Data points not sharing a letter differ significantly by dose within age group (p < .05). Panel A represents mean values by age group (18–24 vs. ≥ 25 years old) at each dose for maximum expenditure per cigarette. Panel B represents mean values by age group (18–24 vs. ≥ 25 years old) at each dose for price per cigarette at which smoking rate begins decreasing proportionate to increasing price (Maximum Price). Panel C represents mean values by age group (18–24 vs. ≥ 25 years old) at each dose for Breakpoint, or price per cigarette at which smoking rate decreases to 0. Analyses included session order, project, CPD, and FTND as covariates. FTND = Fagerström Test for Nicotine Dependence.

Figure 2.

Upper panel: mean proportion of choices allocated to all possible 2-dose comparisons across the four nicotine dose cigarettes (0.4, 2.4, 5.2, 15.8 mg/g tobacco) across Phase 2 choice sessions within each age group (18–24 vs. ≥ 25 years old). Lower panel: mean proportion of choices across Phase 3 sessions within each age group (18–24 vs. ≥ 25 years old). Data points represent mean proportion of choices allocated to the different nicotine dose cigarettes. Error bars represent ± SEM. No significant differences observed by age were noted. Analyses included session order, project, CPD, and FTND as covariates. FTND = Fagerström Test for Nicotine Dependence.