Smoking in the absence of nicotine: Behavioral, subjective and physiological effects over 11 days

Aims: Sensorimotor stimuli associated with tobacco smoking influence smoking behavior; however, current research has focused almost exclusively on the effects of brief, laboratory-based exposure to smoking-related stimuli. The purpose of this experiment was to characterize the effects of smoking stimuli delivered in the absence of nicotine over an extended (11-day) exposure. Design, setting and participants: Thirty adult regular smokers participated in an in-patient study. After assessing preferred brand smoking, participants were assigned randomly to one of three groups corresponding to subsequent smoking conditions: nicotine-containing cigarettes, de-nicotinized cigarettes or no smoking. Measurements: Measures of smoking reinforcement, subjective effects, physiological effects, withdrawal/craving and puff topography were taken repeatedly during both periods of free access and controlled assessments during abstinence. Findings: Daily de-nicotinized cigarette use declined immediately by 1.7 cigarettes/day compared to the preferred brand baseline and declined by another 3.5 cigarettes over time; participants smoking de-nicotinized cigarettes also demonstrated a 31% decline in the number of puffs earned on a progressive ratio, a measure of the motivation to smoke, during the study. Subjective ratings of smoking were largely negative throughout the study in the de-nicotinized group, while the nicotine-containing condition reported increasingly positive subjective effects with repeated exposure. Acute craving suppression following smoking remained evident throughout the study regardless of nicotine content. Conclusions: These effects highlight the importance of non-nicotine sensorimotor stimuli as determinants of the maintenance of smoking behavior and suggests that extinction of conditioned reinforcement in the absence of nicotine progresses slowly.