A Novel Abuse Liability Assessment of E-Cigarettes in Young Adults II: Reinforcement Enhancement and Follow-Up Assessment

A double-blind study was performed to test the abuse liability of electronic nicotine delivery systems (ENDS) in young adults; in particular, the influence of nicotine on reward sensitivity was assessed. A total of 53 healthy nonusers participated in experimental sessions during which they played a video game made available on a progressive ratio schedule of reinforcement and self-administered nicotine via ENDS. Participants were randomized into one of three groups. Two groups received either a dedicated concentration of nicotine (6 and 12 mg) or a placebo, and whether they received the placebo or their dedicated nicotine dose was randomly determined on a session-by-session basis to mask the sequencing of drug administration. The third group received only a 0 mg (placebo) vaping device during all sessions. In comparison to all placebo conditions, nicotine-induced reward sensitization was evidenced on behavioral measures of video game reinforcement, but not subjective appraisals of the vaping experience. A 1-month follow-up survey provided evidence that reinforcement enhancement by nicotine predicts increased abuse liability of ENDS.