Preliminary test of cigarette nicotine discrimination threshold in non-dependent versus dependent smokers

- Minimum discriminable nicotine in tobacco (“threshold”) may inform public policy.
- Nicotine discrimination threshold in cigarettes is similar regardless of dependence.
- Perceptions differentiated threshold vs subthreshold in both groups.
- Puff choice differentiated threshold only for dependent smokers.
- Limiting nicotine to below threshold may discourage dependence onset and maintenance.

BackgroundDespite its potential for understanding tobacco dependence, behavioral discrimination of nicotine via smoking has not been formally examined as a function of nicotine dependence level.MethodsSpectrum research cigarettes were used to compare non-dependent with dependent smokers on the lowest content of nicotine they could discriminate (i.e., “threshold”). Dependent (n = 21; 16 M, 5 F) or non-dependent (n = 7; 4 M, 3 F) smokers were tested on ability to discriminate between cigarettes with nicotine contents of 17, 11, 5, 2, and 1 mg/g, one per session, from an “ultra-low” cigarette with 0.4 mg/g (all had 9-10 mg “tar”). All abstained from smoking overnight prior to sessions, and number of sessions was determined by the lowest nicotine content they could reliably discriminate from the ultra-low on >80% of trials (i.e., ≥5 of 6). Subjective perceptions and cigarette choice behavior were also assessed and related to discrimination behavior.ResultsDiscrimination thresholds (and most perceptions) did not differ between dependent and non-dependent smokers, with median thresholds of 11 mg/g for both subgroups. Yet, “liking” and puff choice for threshold cigarettes were greater in dependent but not non-dependent smokers, while cigarettes with nicotine contents below threshold did not support “liking” or choice in both groups.ConclusionsIn sum, this preliminary study suggests threshold for discriminating nicotine via smoking may not vary by dependence level, and further study is needed to confirm that cigarettes unable to be discriminated are also not reinforcing.