No studies have examined the longitudinal relationship between e-cigarette use and elevated depressive symptoms among young adults. The main objective of the current study was to establish a potential bi-directional relationship between e-cigarette use and elevated depressive symptoms among college students in Texas, across a 1 year period of time. A survey of 5445 college students in Texas was conducted with 6-month and 1-year follow-ups. A longitudinal cross-lagged model was used to simultaneously examine the bi-directional relationships between current, or past 30-day, e-cigarette use and elevated depressive symptoms across the three study waves. Depressive symptoms were measured using a 10-item Center for Epidemiologic Studies Depression Scale (CES-D) with a cutpoint of ≥ 10 to measure elevated depressive symptoms. Covariates included baseline age, gender, college type (2- or 4-year), and other alternative tobacco products used. E-cigarette use did not predict elevated depressive symptoms at 6-month and 1-year follow-ups. However, depressive symptoms predicted e-cigarette use at both 6-month and 1-year follow-ups. The current study indicates that depressive symptoms predict subsequent e-cigarette use and not vice versa. Future studies are needed to replicate current findings and also further establish the mechanisms for causality, which could inform Food and Drug Administration regulatory planning. There has been recent evidence for cross-sectional associations between e-cigarette use and elevated depressive symptoms and mental health problems. There have been no studies examining these associations using longitudinal designs. This study established a temporal relationship, such that elevated depressive symptoms predicted e-cigarette use 6 months later among college students. Future research is needed to establish the mechanisms of association as well as causality.

Objectives: We examined differences in the characteristics of youth non-users, cigarette-only, e-cigarette-only, and dual e-cigarette and cigarette users. Methods: Using weighted, representative data, logistic regression analyses were conducted to examine differences in demographic characteristics and tobacco use behaviors across tobacco usage groups. Multiple linear regression analyses were conducted to examine differences in harm perceptions of various tobacco products and perceived peer use of e-cigarettes by tobacco usage group. Results: Compared to non-users, dual users were more likely to be white, male, and high school students. Dual users had significantly higher prevalence of current use of all products (except hookah) than e-cigarette-only users, and higher prevalence of current use of snus and hookah than the cigarette-only group. Dual users had significantly lower harm perceptions for all tobacco products except for e-cigarettes and hookah as compared to e-cigarette-only users. Dual users reported higher peer use of cigarettes as compared to both exclusive user groups. Conclusion: Findings highlight dual users' higher prevalence of use of most other tobacco products, their lower harm perceptions of most tobacco products compared to e-cigarette-only users, and their higher perceived peer use of cigarettes compared to exclusive users.

Students become increasingly disconnected from their schools across the middle school years, but little is known about the factors contributing to changes in school connectedness. This study examined the time-invariant and time-varying roles of depressive symptoms and externalizing problems in trajectories of student-perceived school connectedness across the middle school years. Three yearly waves of data were collected from 296 students beginning in the sixth grade. Hierarchical linear modeling results indicated that school connectedness declined across time. Initial levels of adjustment problems at school entry were concurrently associated with lower levels of connectedness. Initial levels of externalizing problems did not account for rate of decline, but elevated levels of externalizing problems across the middle school years were associated with lower concurrent levels of connectedness. Surprisingly, initial levels of depressive symptoms predicted a slower rate of decline in connectedness for boys. Findings highlight the detrimental associations between adjustment problems and school connectedness.