Expectancies and reasons for use of e-cigarettes among young adults: A longitudinal analysis.

Use of electronic cigarettes, or e-cigarettes, has increased exponentially in recent years. Mechanisms that might underlie this increase include expectancies and reasons for e-cigarette use. This study was designed to identify and evaluate changes in expectancies and reasons for e-cigarette use among young adults over time and to determine whether such changes were associated with changes in e-cigarette use. Data for these analyses were collected from a sample of 137 young adult e-cigarette users who completed electronic surveys 5 times over a 12-month period. Results yielded five e-cigarette use expectancy and reason factors: Affect-Related Reasons, Social Reasons, Positive Social Expectancies, Positive Internal Expectancies, and Negative Expectancies. Linear mixed models showed that Negative Expectancies significantly increased over time (p = .004), whereas Affect-Related Reasons significantly decreased over time (p = .001). Additional linear mixed models indicated that, whereas both frequency and quantity of e-cigarette use decreased over time, changes in Positive Internal Expectancies were positively associated with changes in frequency of e-cigarette use (p = .032) and changes in Positive Social Expectancies were positively associated with changes in both frequency (p = .007) and quantity (p = .026) of e-cigarette use. These findings suggest that young adults' expectancies and reasons for using e-cigarettes fluctuate over time, and changes in expectancies seem to be longitudinally associated with changes in e-cigarette use. Positive expectancies for e-cigarette use represent targets for clinical, prevention, and intervention efforts. (PsycINFO Database Record (c) 2019 APA, all rights reserved).