An experimental evaluation of e-cigarettes in young adults: Reinforcement enhancement and devaluation by nicotine - Project Summary/Abstract
One concern about e-cigarettes is their abuse potential; however, we know of no systematic study of
this in a young adult population. Abuse-liability assessments traditionally include the analysis of
positive subjective effects and of self-administration, but these may fall short of accurately
characterizing the abuse potential of tobacco products because recent preclinical studies indicate
some of nicotine's abuse liability is due to the ability of nicotine to enhance the rewarding effects of
non-drug reinforcers. However, only recently have reports of reinforcement enhancement emerged
with human adult tobacco smokers. Furthermore, recent data from our rodent laboratory has
demonstrated that a secondary consequence of reinforcement enhancement by nicotine is reinforcer
devaluation; when non-pharmacological reinforcers are experienced in the presence of nicotine, and
then in the absence of nicotine, their reinforcing value diminishes well-below their pre-nicotine
exposure levels. Our rodent data suggest that reinforcer devaluation is not related to physical
symptoms of withdrawal. If these results can be applied to human use of nicotine, they would suggest
that in order for the world of natural reinforcers to retain their motivational value, they need to be
experienced in the continual presence of nicotine. Therefore, reinforcement (a) enhancement and (b)
devaluation may work in unison to escalate use of nicotine-containing products. Most importantly, our
data suggest reinforcement enhancement and devaluation can occur prior to the onset of physical
dependence associated with daily smoking. Thus, these two processes may be especially important
in the young adult population, which is the age period during which the transition from occasional-to-
habitual tobacco/nicotine use occurs.
Reinforcement enhancement and devaluation will be evaluated in the proposed experiment by
exposing a young-adult population of tobacco experimenters to e-cigarettes. These young adults will
self-administer one of three doses of nicotine (0, 6, or 12 mg/ml) during several laboratory sessions.
Changes in reinforcer efficacy resulting from nicotine exposure will be evaluated by testing changes
in video-game behavior. Video games are an ecologically valid and potent reinforcer for this particular
population, and we believe video gaming may be particularly sensitive to nicotine's reinforcing-
enhancing effects. Furthermore, to examine whether nicotine delivered by e-cigarettes produces
some of the psychological effects that are characteristic of tobacco cigarettes, changes in (i) general
hedonic pleasure, (ii) cognitive performance, and (iii) nicotine withdrawal will be assessed during the
laboratory sessions. Data from this battery of psychological tests may provide information on whether
these variables (i-iii) moderate or mediate changes in reinforcer efficacy.
