Reinforcement enhancement by nicotine: A novel abuse-liability assessment of e-cigarettes in young adults.

Nicotine can act as a primary positive reinforcer, and as negative reinforcer to relieve withdrawal; we tested whether it can also enhance the reinforcing efficacy of non-drug reinforcers. Young-adult never-users were delivered nicotine via e-cigarette, and a videogame reinforcer was used to test nicotine enhancement. Three dose groups were tested (placebo-only, 6 or 12-mg nicotine), and participants returned to the lab for several sessions over the course of 1 month. Those in the two nicotine-dose groups received placebo on some occasions and nicotine on others; nicotine enhancement of the videogame reinforcer was assessed in a within-subjects fashion by comparing each of the two nicotine groups' dedicated nicotine dose to placebo. In the placebo-only group, progressive-ratio (PR) schedule breakpoints did not alter as a function of videogame exposure, suggesting that the videogame retained its basic-reinforcing properties throughout the study. For the two groups that received nicotine, both doses of nicotine increased PR-schedule breakpoints for the videogame reinforcer relative to the placebo condition. Although nicotine was associated with greater subjective evaluation of the enjoyment of the videogame, it was unrelated to the enjoyment of the e-cigarette device. No evidence was found that nicotine elevated either anhedonia or withdrawal symptoms in the timeframe of the study. The results provide initial evidence that nicotine enhancement, via electronic cigarettes, occurs in non-frequent users of nicotine products and may be a reason they can develop nicotine dependence in the absence of withdrawal and direct effects of nicotine. (PsycInfo Database Record (c) 2021 APA, all rights reserved).