Evidence has shown a rapid surge of e-cigarette use among college students in the United States. The National College Health Assessment (NCHA) has underscored this concerning rise, noting that the prevalence of use in past 30 days jumped from 4.9 % in 2015 to 12.6 % in 2019 (American College Health Association, 2019). The health consequences of using e-cigarettes have been well-documented in previous research, including short-term adverse effects such as immune system dysfunction and long-term effects such as lung and heart diseases (Callahan-Lyon, 2014, Marques et al., 2021). Despite the evidence on the rising prevalence and the harmful health impacts of e-cigarette use, there remains a paucity of research specifically addressing the use reasons and their associations with dependence risks among college students.

E-cigarette dependence is an emergent concern, especially among the college student population. One study that investigated the e-cigarette use knowledge of college students reported moderate e-cigarette dependence among college e-cigarette users (McLeish, Hart, & Walker, 2022). Another study conducted among young individuals in California revealed that approximately 11.7 % of those using e-cigarettes reported experiencing at least one symptom of dependence on e-cigarettes (Vogel et al., 2020). Practically, the Penn State Electronic Cigarette Dependence Index (PSECDI), a well-validated scale, has been adopted to measure e-cigarette dependence, providing behavioral and psychological aspects such as frequent use, craving, and withdrawal symptoms (Foulds et al., 2015, Piper et al., 2020). The literature has shown that increased frequency of e-cigarette use and experiencing withdrawal symptoms not only increase the risk of health consequences but also present challenges to cessation efforts (Garey et al., 2019). For instance, a qualitative study on young adults' e-cigarette use discovered that dependent individuals often faced withdrawal symptoms, such as anxiety and fatigue, during their efforts to quit, which resulted in unsuccessful quit attempts (Simpson et al., 2021). Thus, addressing e-cigarette dependence among college students holds significant public health implications for the development of effective cessation programs and interventions.

Understanding the reasons for e-cigarette use is crucial, as it provides deeper insights into potential intervention points to prevent the development of dependence. Also, it is particularly important to focus on college students, given that the college environment presents unique opportunities for exposure to various substances (Weitzman & Nelson, 2004), potentially cultivating behaviors that can persist in the long run. Therefore, such a gap in literature underscores the urgent need for a comprehensive longitudinal study to better understand the e-cigarette use reasons and subsequent dependence among college students.

While previous research has explored the reasons for and frequency of e-cigarette use, there remains a gap in the literature when it comes to linking the reasons for use with dependence. For instance, Patrick et al. (2016) investigated the reasons for e-cigarette use among 4,066 youth using data from the Monitoring the Future study. The authors found that common reasons for using e-cigarettes included experimental purposes, good taste, relaxation, and being hooked. The study also reported that frequent users often use e-cigarettes because of their good taste. Although this study highlighted the significant reasons for e-cigarette use, yet it did not explore the associations between e-cigarette use and dependence. In addition, a cross-sectional study of 1,244 young adults conducted during the COVID-19 pandemic found that reasons for use such as vaping to relax were associated with a higher likelihood of increased vaping due to COVID-19 (Parks, Fleischer, & Patrick, 2022). While these studies have established an understanding of the reasons and associated e-cigarette use patterns such as use frequency, the critical extension to e-cigarette dependence outcomes remains under-researched.

To address the gaps in the literature, this study conducted a prospective longitudinal investigation examining the associations between e-cigarette use reasons and e-cigarette dependence among college students. Specifically, the main research question asks whether the reasons for e-cigarette use predict a higher/lower level of e-cigarette dependence.