Dual use of conventional and e-cigarettes is also common in adolescents , raising the possibility that some adolescents may use e-cigarettes to substitute for conventional cigarettes in situations where smoking is restricted. Indeed, school bathrooms and staircases are among the most common places adolescents report using e-cigarettes . Given that adolescents with mental health symptoms are more prone to nicotine dependence , these populations could be more likely to initiate use of e-cigarettes to bridge situations when they are not able to smoke, which ultimately could perpetuate the over-representation of smoking among individuals with mental health problems. While research has yet to characterize the psychiatric comorbidity with patterns of conventional and e-cigarette use in adolescents, a recent study of Hawaiian adolescents found that alcohol/marijuana use and other psychosocial risk factors were highest in dual users, moderate in e-cigarette only users, and lowest in non-users . Most pairwise comparisons involving conventional cigarette only users were not significant in that study, perhaps limited by reduced statistical power due to the smaller size of this group . Given these findings, stratification of psychiatric comorbidity across dual use, single-product use, and non-use in adolescents is plausible. The current study characterized the mental health of adolescents who reported ever using ecigarettes, conventional cigarettes, both, or neither. To provide a wide-ranging picture of psychiatric comorbidity, traditional syndrome-based indices of various depressive, manic, anxiety, and substance use disorders were administered. Consistent with NIMH’s Research Domain Criteria Initiative ,greenhouse benches we also assessed several transdiagnostic phenotypes implicated in multiple internalizing and externalizing psychopathologies and conventional cigarette use .
Up to this point, data on the psychiatric comorbidity associated with ecigarette and dual use is virtually absent, leaving unclear as to how the mental health of these two groups compare to conventional cigarette users and non-users. Given that conventional cigarettes and e-cigarettes have both similarities and differences , whether the patterns of psychiatric comorbidity are similar or different between e-cigarette only users and conventional cigarette users is unclear. As the first study to comprehensively characterize psychiatric comorbidity in adolescent e-cigarette and dual use, this study may yield data that is important to tobacco policy by identifying adolescent populations that are psychiatrically vulnerable and potentially at risk for use of traditional and emerging tobacco products. Such data could highlight the need to protect psychiatrically vulnerable adolescents from tobacco product use take via targeted tobacco product regulation and behavioral health prevention programming for this populations. This report is based on a cross-sectional survey of substance use and mental health among 9 th grade students enrolled in ten public high schools surrounding Los Angeles, CA, USA. The percentage of students eligible for free lunch within each school on average across the ten schools was 31.1% . Students not in special education or English as a Second Language programs were eligible . Of the students who assented to participate , 3,383 provided active parental consent and enrolled in the study. In-classroom paper-and-pencil surveys were administered across two 60-minute data collections during the fall of 2013, conducted less than two weeks apart. Some students did not complete all questionnaires within the time allotted or were absent for data collections , leaving a final sample of 3310.
The University of Southern California Institutional Review Board approved the protocol. Based on patterns of lifetime use, the sample was divided into: use of neither electronic nor conventional cigarettes ; use of conventional cigarettes only ; use of electronic cigarettes only ; use of electronic and conventional cigarettes . Primary analyses used generalized linear mixed models that accounted for clustering of data within school, in which the 4-level cigarette use group variable was a categorical regressor variable and a mental health indicator was the outcome variable, with separate models for each outcome. GLMM specified binary and continuous distributions for the lifetime substance use status and mental health quantitative outcomes, respectively. Because of skewed distributions on the three substance use problems measures, Poisson distributions were specified for these outcomes. For outcomes with omnibus groups differences, we conducted follow up pairwise contrasts using an adjusted p-value, correcting for study-wise false discovery rate of 0.05. GLMMs were adjusted for gender, age, ethnicity, and highest parental education; missing data on covariates were accounted for by dummy coding a ‘missingness’ variable to allow inclusion in analyses. Results are reported as standardized effect size estimates . As illustrated in Table 2, there were omnibus differences across the four groups for all outcomes. Pairwise contrasts indicated that adolescents who used conventional cigarettes only reported worse mental health than non-users and e-cigarette only users on multiple internalizing emotional syndromes and transdiagnostic phenotypes . On these internalizing emotional outcomes, the conventional cigarettes only and dual use groups did not significantly differ. For some internalizing outcomes , e-cigarette only users had higher elevations than non-users, but lower problem levels than conventional only or dual users. Relative to non-users, use of either product was related to the externalizing phenotypes of poorer inhibitory control and impulsivity.
An ordered effect of dual use vs. e-cigarette use only vs. non-use was found for elevations in mania, positive urgency, and anhedonia. An ordered effect of dual use vs. either single product use vs. non-use was also found for lifetime use status and level of abuse/problems for all substances. Given the differences in patterns across internalizing and externalizing and positive-emotion seeking behaviors, syndromes, and traits, we plotted standardized T-scores of the outcomes by conventional/e-cigarette use status separately in the two domains. These figures respectively illustrate general trends of: differentiation of conventional and dual cigarette use from never and e-cigarette use on most internalizing outcomes , and tri-level ordered differentiation of never vs. single product vs. dual use on externalizing outcomes . Analyses of the substance problem outcomes utilizing the overall sample cannot distinguish between substance ever-users who report zero drug/alcohol-related problems and substance never-users. To identify whether e- and conventional-cigarette use status differentiates level of substance problems among substance ever-users, a supplementary analysis of the three substance problem outcomes was conducted that limited each analysis to ever-users of the respective substance using the same GLMM analytic strategy and covariates as the primary analyses with a continuous outcome distribution specified. As in the analysis in the primary sample, these analyses of substance ever-users generally showed an ordered pattern whereby dual tobacco product users reported the highest levels of alcohol, cannabis, and drug problems, followed by single tobacco product users , and then never-users of either tobacco product, respectively . This study is the first to comprehensively examine differences in psychiatric profiles between four different groups based on typologies of tobacco product use: non-users; e-cigarette only users; conventional cigarette only users; and dual users. This novel 4- group comparison is a critical innovation; with changes in the pattern of tobacco product use in the past several years, new typologies of adolescent tobacco product use have emerged, including both e-cigarette and dual use . Given the relative lack of data to suggest that additional psychiatric problems would be associated with e-cigarette vs. conventional cigarette or dual use, it was unclear whether e-cigarette only users would differ from the other user groups in psychiatric comorbidity. This study’s main findings were that: e-cigarette only users reported a level of internalizing mental health problems midway between non-use and conventional cigarette use; and externalizing/substance use comorbidity was extensive and followed an ordered pattern with dual users having the most severe and pervasive comorbidity, followed by single-product users and non-users, respectively. These results are novel and raise an important question as to whether e-cigarette use may be common in ‘lower-risk’ subgroups of the adolescent population who otherwise are not attracted to other tobacco products, like conventional cigarettes. These results are broadly consistent with recent data in adults as well as Wills et al.’s study of psychosocial risk factors and alcohol/marijuana use in Hawaiian 9th/10th graders, growers equipment which found that e-cigarette users were at an intermediate risk status in between non-users and dual users .
In the current sample of Los Angeles 9th graders, a similar pattern of differentiation by dual vs. e-cigarette only vs. non-use is seen that extends across a number of mental health syndromes and transdiangostic phenotypes. The current study also found that conventional cigarette only users have worse internalizing mental health problems than e-cigarette only users. Overall, it is clear that future research and intervention dedicated to comorbidity between use of tobacco products and mental health problems in adolescents should assess and distinguish between use of conventional cigarettes only, e-cigarettes only, and dual use. For eight internalizing emotional disorder symptoms and phenotypes, adolescents who used e-cigarettes only reported an intermediate level of problems which was lower than conventional cigarette only users on seven outcomes and higher than never-users on three outcomes. Prior research suggests that adolescents with better emotional health are more strongly deterred from initiating smoking due to concerns about smoking’s negative effects on health and social acceptability . Thus, emotionally-healthier adolescents may be more willing to use e-cigarettes, which are generally perceived to be more socially acceptable and less harmful than conventional cigarettes . The availability of tobacco products that are perceived as less harmful and more socially acceptable, like e-cigarettes, may lower the threshold of risk for tobacco product experimentation associated with certain mental health problems. Externalizing behavioral comorbidities and mania were elevated in adolescents who used e-cigarettes only versus those who use never used either tobacco product. Adolescents who used conventional cigarettes only also showed this pattern relative to those who never used either tobacco product, which extends prior research on tobacco-psychiatric comorbidity . Moreover, this study provides novel data indicating use of e-cigarettes per se is not universally linked with all types of mental health comorbidities; rather use of e-cigarettes alone is associated more prominently with externalizing problems and less prominently with internalizing problems. A clear gradient was observed in which substance use/problems, mania, and positive urgency that successively increased with the number of tobacco products used . One explanation for these findings is that adolescent cigarette smokers with these comorbidities may be more nicotine dependent and may therefore be motivated to also use e-cigarettes to alleviate withdrawal during times when they cannot smoke . Indeed, these disorders are linked with more severe conventional cigarette dependence . Another explanation is that adolescents with substance use and mania comorbidity who have experimented with ecigarette use may not derive enough reinforcement from e-cigarettes, which may be an important factor given prior evidence that conventional cigarette smokers with these comorbidities report stronger motivation to smoke for positive reinforcement . Because e-cigarettes have provided less reliable nicotine delivery and reinforcement than conventional cigarettes in novice users , adolescents with substance use and mania comorbidities who have tried e-cigarettes may be motivated to subsequently experiment with conventional cigarettes in an effort to find a product that provides stronger and more consistent rewarding effects. An additional perspective is that substance experimentation is driven by a drive for pleasure and means for rebelling against norms , and that teens with externalizing mental health problems are motivated to experiment with a wider array of multiple substances, including e-cigarettes, conventional cigarettes, and other drugs. Further longitudinal evaluation of these hypotheses is necessary and future research should explore whether there is a gradient in the intensity of intervention needed in preventing conventional cigarette smoking and dual use. This study had several strengths, including a comprehensive four-group comparison strategy that distinguished four unique patterns of tobacco product use, broad sampling of mental health syndromes and cross-cutting traits, and utilization of a large, diverse sample. The cross-sectional design does not permit an assessment of the temporal precedence of the mental health problems and the use of conventional/e-cigarettes. Accordingly, this study cannot speak to etiological mechanisms underpinning the link between mental health and tobacco product use. Because the survey did not assess past 30-day e-cigarette use, use frequency and progression in use, persistence of use, and nicotine strength , several aspects regarding the quality and profile of e-cigarette and conventional cigarette use are not addressed in this study. Furthermore, the focus on lifetime use leaves unclear whether findings generalize to brief experimentation or more persistent use patterns. To limit burden on students and class time, brief self-report measures were used.