Addiction Potential of Cigarettes With Reduced Nicotine Content in Populations With Psychiatric Disorders and Other Vulnerabilities to Tobacco Addiction

Abstract

Importance: A national policy is under consideration to reduce the nicotine content of cigarettes to lower nicotine addiction potential in the United States.

Objective: To examine how smokers with psychiatric disorders and other vulnerabilities to tobacco addiction respond to cigarettes with reduced nicotine content.

Design, setting, and participants: A multisite, double-blind, within-participant assessment of acute response to research cigarettes with nicotine content ranging from levels below a hypothesized addiction threshold to those representative of commercial cigarettes (0.4, 2.3, 5.2, and 15.8 mg/g of tobacco) at 3 academic sites included 169 daily smokers from the following 3 vulnerable populations: individuals with affective disorders (n = 56) or opioid dependence (n = 60) and socioeconomically disadvantaged women (n = 53). Data were collected from March 23, 2015, through April 25, 2016.

Interventions: After a brief smoking abstinence, participants were exposed to the cigarettes with varying nicotine doses across fourteen 2- to 4-hour outpatient sessions.

Main outcomes and measures: Addiction potential of the cigarettes was assessed using concurrent choice testing, the Cigarette Purchase Task (CPT), and validated measures of subjective effects, such as the Minnesota Nicotine Withdrawal Scale.

Results: Among the 169 daily smokers included in the analysis (120 women [71.0%] and 49 men [29.0%]; mean [SD] age, 35.6 [11.4] years), reducing the nicotine content of cigarettes decreased the relative reinforcing effects of smoking in all 3 populations. Across populations, the 0.4-mg/g dose was chosen significantly less than the 15.8-mg/g dose in concurrent choice testing (mean [SEM] 30% [0.04%] vs 70% [0.04%]; Cohen d = 0.40; P < .001) and generated lower demand in the CPT (α = .027 [95% CI, 0.023-0.031] vs α = .019 [95% CI, 0.016-0.022]; Cohen d = 1.17; P < .001). Preference for higher over lower nicotine content cigarettes could be reversed by increasing the response cost necessary to obtain the higher dose (mean [SEM], 61% [0.02%] vs 39% [0.02%]; Cohen d = 0.40; P < .001). All doses reduced Minnesota Nicotine Withdrawal Scale total scores (range of mean decreases, 0.10-0.50; Cohen d range, 0.21-1.05; P < .001 for all), although duration of withdrawal symptoms was greater at higher doses (η2 = 0.008; dose-by-time interaction, P = .002).

Conclusions and relevance: Reducing the nicotine content of cigarettes may decrease their addiction potential in populations that are highly vulnerable to tobacco addiction. Smokers with psychiatric conditions and socioeconomic disadvantage are more addicted and less likely to quit and experience greater adverse health impacts. Policies to reduce these disparities are needed; reducing the nicotine content in cigarettes should be a policy focus.

Figure 1.. Concurrent Choice Testing

A, Mean proportion of choices allocated to all possible 2-dose comparisons across the 4 nicotine dose cigarettes (0.4, 2.4, 5.2, and 15.8 mg/g of tobacco) across six 3-hour 2-dose concurrent choice sessions. Data points represent mean proportions of choices allocated to the different nicotine dose cigarettes and across participants and populations; error bars, SEM. Dose pairs are ordered to show those with largest to least preference differences going from left to right. B, The mean proportion of choices allocated to the 15.8-mg/g dose when it was available at the same response effort (fixed-ratio of 10 responses) as the 0.4-mg/g dose (phase 2; left) and when it was available at different response effort (progressive ratio starting at 10 responses that incremented upward to a maximum of 8400 responses) compared with the 4-mg/g dose (fixed-ratio 10) (phase 3; right). Phase 2 and phase 3 are described in the Procedure subsection of the Methods section. Data points represent means across participants and sessions (phase 3); error bars, SEM. ^aStatistically significant difference at P < .05 after Bonferroni correction.

Figure 2.. Results From the Cigarette Purchase Task (CPT) Simulating Estimated Demand for Each of the Different Nicotine Content Cigarettes at Escalating Prices

A, Overall demand (estimated consumption levels across prices ranging from $0 to $40 per cigarette). Data points represent means across participants; shaded areas, 95% CI in the best lines. B-F, Data points represent means across participants; error bars, SEM. Demand intensity indicates estimated consumption at $0 price (range, 0-100, with higher scores indicating greater consumption when cigarettes are free); maximal expenditure, estimated maximal expenditure participants were willing to incur for smoking in 1 day (range, 0-1600, with higher scores indicating greater expenditure); maximal price, estimated price at which demand begins to decrease proportional to price increases (range, 0-40, with higher scores indicating a greater cigarette unit price associated with unit elasticity for cigarettes); breakpoint, estimated price at which participants would quit smoking rather than incur its costs (range, 0-60, with higher scores indicating a greater cigarette unit price associated with discontinuation of smoking); and α, estimated overall sensitivity of demand to price increases (range, 1.096⁻²⁰ to 1, with higher scores indicating greater sensitivity to cigarette unit price increases). Data points not sharing a symbol differ significantly (P < .05) after Bonferroni correction.