The impact of flavoring on the rewarding and reinforcing value of e-cigarettes with nicotine among young adult smokers.

Objective: Flavored e-cigarette use has risen rapidly, especially among young adults who also smoke cigarettes. We sought to determine whether flavoring enhances the subjective rewarding value, relative reinforcing value, and absolute reinforcing value of an e-cigarette with nicotine compared to an unflavored e-cigarette with nicotine.

Methods: Using a within-subjects design, young adult smokers (n=32) participated in three human laboratory sessions. Session 1 evaluated the rewarding value of flavoring by having participants rate unflavored and flavored e-cigarettes with nicotine. Session 2 assessed the relative reinforcing value of a flavored vs unflavored e-cigarette via a choice task that evaluated the willingness to "work" to hit targets on a computer screen to earn flavored or unflavored e-cigarette puffs. Session 3 measured the absolute reinforcing value of flavored versus unflavored e-cigarettes via a 90-min ad-libitum vaping session where puffs from each e-cigarette were counted.

Results: Subjective reward value was higher for the flavored versus the unflavored e-cigarette (β=0.83, CI 0.35-1.32, p=0.001). Participants worked harder for flavored e-cigarette puffs versus unflavored e-cigarette puffs (breakpoint=5.7; 597 responses versus 127 responses; β=460.733, CI 246.58-674.88, p<0.0001). Participants took twice as many flavored puffs than unflavored e-cigarette puffs (40 vs 23 puffs; IRR=2.028, CI 1.183-3.475, p=0.01).

Conclusions: Flavoring enhances the rewarding and reinforcing value of e-cigarettes with nicotine, and thus their abuse liability in young adult smokers. Further research is necessary to determine whether the use of flavoring in e-cigarettes impacts cigarette smoking behavior among young adults.