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,vertical farming towers racks 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, 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. As such, these results reflect self-reported symptoms, and the extent to which they generalize to psychiatric diagnoses is unclear. Future work utilizing structured clinical interviews are warranted to identify diagnoses associated with conventional and ecigarette use. This is first the investigation to characterize adolescent psychiatric comorbidity in an era when the extensive popularity of e-cigarettes in youth is now clearly established. The current data are of use for policy and tobacco and mental illness intervention by elucidating a sub-population based on mental health status that may be at higher risk for use of traditional and emerging tobacco products. Describing patterns of psychiatric comorbidity between different forms of tobacco product use in teens provides clues to practitioners on assessment and intervention. For instance, these findings suggest that if a teen is a dual user or conventional cigarette smoker,vertical growing systems she or he may be more likely to have comorbid mental health problems than teens who use e-cigarettes only; practitioners should thus make mental health assessment a priority such populations. Similarly, these findings suggest that teens with mild levels of emotional pathology may nonetheless be at elevated likelihood of ecigarette use and should be asked by practitioners about their e-cigarette use patterns, particularly given recent evidence that teens who use e-cigarettes are more likely to initiate combustible tobacco product use.. These results also raise the possibility that adolescents with more severe and pervasive mental health problems could be more vulnerable to factors that increase risk of initiation of e-cigarettes and dual use in teen populations. Some of these risk factors could be targeted via regulation or intervention .
The current results may also have implications for patterns of comorbidity that are likely to arise in the future. Namely, emotionally-healthier individuals who previously might be deterred from using any tobacco products may now be at risk for uptake of e-cigarettes or other emerging products. Furthermore, individuals with certain behavioral comorbidities may be more prone to use multiple products, which may alter the trajectory of future conventional cigarette smoking in patterns that remain to be seen. Rope, as a constraint or a weapon, plays a role in a significant proportion of violent crimes . For example, if sisal rope is found at a crime scene, and a suspect has sisal rope in his possession, a possible link is present between the suspect and the crime. Natural fibers that have traditionally been used for rope manufacture include Gossypium spp. , Cannabis sativa L. , Agave sisalana Perrine , and Musa textilis Ne . Other natural fibers, such as Linum usitatissimum L. and Corchorus olitorus L. , have also been used to make rope. Although ropes of synthetic fibers, such as polypropylene, polyethylene, polyester and polyamide, have become more prevalent, natural fiber rope is still imported from countries outside the U.S. . While microscopy is currently used to match cut ends of a rope and to analyze the cellular composition of ropes in order to help in identifying rope types, DNA analysis may be another method to identify the types of rope. Natural fiber rope primarily consists of fiber cells, which at maturity are typically dead and no longer have a nucleus or other cytoplasmic organelles containing DNA. However, the crude fiber extraction process, which involves crushing stems or leaves to isolate fiber bundles, may allow parenchymal, collenchymal, and epidermal cells that have nuclei or cytoplasmic organelles to remain attached to the fibers. These cells may contain DNA, allowing analysis of the rope components. DNA analysis requires that DNA be extracted, a particular gene be copied by polymerase chain reaction , and the amplified DNA fragments be identified, either through restriction analysis or base sequence. The main objectives of this project were to see if DNA could be obtained from rope and if so, to develop techniques to differentiate between ropes of hemp, sisal, abaca, flax, and jute. In this research, the gene that was chosen for analysis was a plastid gene for a protein known as ribulose bisphosphate carboxylase ⁄ oxygenase large subunit . The rbcL gene was chosen because it is plant specific, present in multiple copies per cell, and present in all plant species . The plant specificity of the rbcL gene was important because contaminating DNA from animals or fungi could be eliminated. The strong conservation of the rbcL gene among plant species allowed the gene to be amplified by PCR with one set of primers, while base pair variations allowed the different ropes or plants to be identified.The main objectives of this project were to see if DNA could be obtained from rope and used to differentiate between ropes made from flax, sisal, abaca, hemp, and jute. While there has been a considerable amount of work with plants in forensic science , no work using DNA analysis to identify the plant material comprising rope has been previously reported. The experiments in this research demonstrated that parenchyma cells accompany the rope fibers during the crude fiber extraction process, and that DNA, presumably from the parenchyma cells, is present and can be obtained from rope samples. The identity of the DNA that was extracted from the rope was shown to be species specific and was matched to DNA from plants identified by experts, such as dried plants obtained from a herbarium and fresh samples from greenhouses. In most cases, the results of the restriction analysis from rope samples matched the results predicted from the sequences of well-identified plant species. For some rope samples, the results were not as expected, but discrepancies could be shown to result from mis-identification of the rope by the manufacturer or by the inclusion of fibers of more than one species.