Can the gateway hypothesis, the common liability model and/or, the route of administration model predict initiation of cannabis use during adolescence? A survival analysis--the TRAILS study

Age of onset of cannabis use and substance use problems: A systematic review of prospective studies

BACKGROUND

The association between the age of cannabis use (CU) onset and substance use (SU) problems has been extensively studied, yet findings remain inconsistent.

AIMS

This systematic review aimed to examine prospective studies on the association between age of CU onset and later SU problems, controlling for key individual, social, and SU-related risk factors.

METHODS

PsycINFO, Web of Science and PubMed were searched for studies published between January 2000 and December 2024. Studies were included if they: 1) were prospective; 2) measured CU onset during adolescence; 3) measured CU or SU problems after CU onset, 4) examined whole plant or phytocannabinoids. Studies were excluded if they exclusively focused on high-risk samples. Risk of bias was assessed using the Risk of Bias in Non-randomised Studies-of Interventions tool. The review was registered with PROSPERO, number CRD42022332092.

RESULTS

Sixteen studies met eligibility criteria. Earlier age of CU onset was associated with CU disorder (CUD) and CU negative consequences, with mixed findings for other SU problems (e.g., alcohol). CU frequency accounted for a significant portion of the risk for CU negative consequences, but the association with CUD remained independent of frequency. Only one study had low risk of bias, while seven had some concerns, and eight had a high or very high risk of bias.

CONCLUSIONS

Findings suggest that early age of CU onset is a specific risk factor in the development of CUD, but not other SU problems. Prevention approaches should aim to delay the onset and reduce the frequency of CU among youth to reduce risk of the development of CUD.

Identifying predictors of multi-year cannabis vaping in U.S. Young adults using machine learning

INTRODUCTION

Increasing number of current cannabis users report using a vaporized form of cannabis and young adults are most likely to vape cannabis. However, the number of studies on cannabis vaping is limited, and predictors of cannabis vaping among U.S. young adults remain unclear. Previous studies on cannabis vaping have known limitations, as they (1) relied heavily on regression-based approaches that often fail to examine complex and non-linear interactive effects, (2) focused on examining cannabis vaping initiation but not on its use over multiple years, and (3) failed to account for recreational cannabis legalization (RCL) status.

METHODS

This study was a secondary analysis of the restricted use files of the Population Assessment of Tobacco and Health Study, Waves 4-6 (December 2016-November 2021). A two-stage machine learning approach, which included Least Absolute Shrinkage and Selection Operator (LASSO) and Classification and Regression Tree (CART), was used to identify predictors of multi-year cannabis vaping while accounting for state-level RCL status among a representative sample of U.S. young adults.

RESULTS

Stratified CART created a five-terminal-node prediction model for states with RCL (split by cannabis use, cigarette use, bullying behavior, and ethnicity) and a different five-terminal-node prediction model for states without RCL (split by cannabis use, heroin use, nicotine vaping, and hookah use).

CONCLUSIONS

Characteristics predicting multi-year cannabis vaping appear to differ from those of cannabis vaping initiation. Results also highlight the importance of accounting for RCL status because predictors of cannabis vaping may differ for individuals living in states with and without RCL.

A Bivariate Twin Study of Lifetime cannabis Initiation and Lifetime Regular Tobacco Smoking Across Three Different Countries

Regular cigarette smoking and cannabis consumption are strongly positively related to each other, yet few studies explore their underlying variation and covariation. We evaluated the genetic and environmental decomposition of variance and covariance of these two traits in twin data from three countries with different social norms and legislation. Data from the Netherlands Twin Register, FinnTwin12/16, and the Minnesota Center for Twin Family Research (total N = 21,617) were analyzed in bivariate threshold models of lifetime regular smoking initiation (RSI) and lifetime cannabis initiation (CI). We ran unstratified models and models stratified by sex and country. Prevalence of RSI was lowest in the Netherlands and prevalence of CI was highest in Minnesota. In the unstratified model, genetic (A) and common environmental factors (C) contributed substantially to the liabilities of RSI (A = 0.47, C = 0.34) and CI (A = 0.28, C = 0.51). The two liabilities were significantly phenotypically (rP = 0.56), genetically (rA = 0.74), and environmentally correlated in the unstratified model (rC = 0.47and rE = 0.48, representing correlations between common and unique environmental factors). The magnitude of phenotypic correlation between liabilities varied by country but not sex (Minnesota rP ~ 0.70, Netherlands rP ~ 0.59, Finland rP ~ 0.45). Comparisons of decomposed correlations could not be reliably tested in the stratified models. The prevalence and association of RSI and CI vary by sex and country. These two behaviors are correlated because there is genetic and environmental overlap between their underlying latent liabilities. There is heterogeneity in the genetic architecture of these traits across country.

Investigating the associations of age of initiation and other psychosocial factors of singular alcohol, tobacco and marijuana usage on polysubstance use: analysis of a population-based survey in Jamaica

OBJECTIVES

This study aimed to examine concurrent polysubstance use of alcohol, tobacco and marijuana and determine correlations with access to marijuana, friend and familial drug use habits, risk perception and the age of initiation associated with the singular use of these substances.

DESIGN

A secondary data analysis.

SETTING

Used the Jamaica National Drug Prevalence Survey 2016 dataset.

PARTICIPANTS

Involved the entire dataset comprising 4623 randomly selected respondents between 12 and 65 years old.

OUTCOME MEASURES

Primary outcome: concurrent polysubstance use recorded as using two or more of alcohol, tobacco and marijuana. Predictor variables include risk perception and age of initiation of singular alcohol, tobacco and marijuana use, ease of marijuana access and family and friend alcohol and illegal drug use.

RESULTS

Approximately 58%-66% of respondents commenced singular alcohol, tobacco or marijuana use under 17. Participants commencing marijuana use at 11 years and under and between 12 and 17 were 3.346 and 4.560 times more likely to report past month concurrent polysubstance use (p=0.030 and p<0.001). Respondents who did not believe that smoking tobacco sometimes (p=0.049), and smoking marijuana sometimes and often was harmful, had increased odds of concurrent polysubstance use (p=0.047 and p<0.001, respectively). Respondents who indicated access to marijuana as easy were significantly more likely to report past month concurrent polysubstance use compared with those who reported access as difficult (p=0.002). Participants who indicated that friends or family members get drunk and take illegal drugs were associated with 1.722 and 1.864 increased odds of reporting past month concurrent polysubstance use (p=0.004 and p=0.017, respectively).

CONCLUSIONS

Decreased perceived risk, childhood and adolescent age of initiation and easy access to marijuana were significantly associated with polysubstance use among Jamaicans. The influence of friends and family members' drug and alcohol use behaviours on individuals developing polysubstance use habits further endorses the need for interventions.

Testing the cannabis gateway hypothesis in a national sample of Spanish adolescents

BACKGROUND

The gateway hypothesis holds that the use of legal substances (i.e., tobacco and alcohol) increases the risk of initiating in cannabis use which, in turn, increases the chances of using other illegal substances. The validity of this hypothesis has been the subject of intense debate in recent years, finding sequences with a different order. Moreover, this pattern has been scarcely studied in Spain, where characteristics related to cannabis use are meaningfully different to other countries. This study aims to examine the gateway effects of cannabis towards other legal and illegal substances in Spanish adolescents.

MATERIAL AND METHODS

Data were obtained from the Ministry of Health in Spain, through a representative survey of addictive behaviors of 36,984 Spanish adolescents (M_age = 15.7, SD = 1.2, 51.4% females).

RESULTS

Lifetime cannabis use increased the likelihood of later legal substance use, both tobacco (OR = 2.0; 95%CI 1.81, 2.22) and alcohol (OR = 1.93; 95%CI 1.61, 2.31), as well as illegal substances (OR = 5.36; 95%CI 4.80, 5.98) and polysubstance (OR = 18.24; 95%CI 14.63, 22.73). Early age of cannabis use onset significantly increased the likelihood of subsequent legal and illegal substance use (ORs between 1.82 and 2.65).

CONCLUSIONS

These findings confirm and expand the available evidence on cannabis as a gateway substance. These results can help to drive preventive strategies for substance use in Spanish adolescents.

The first nicotine product tried is associated with current multiple nicotine product use and nicotine dependence among a nationally representative sample of U.S. youths

This study examines the demographic factors associated with youths' first product tried (i.e., cigarettes, e-cigarettes, cigars, hookah, or smokeless tobacco). This study also evaluates whether the first product tried is associated with future nicotine product use (i.e., no use, single product use, and multiple product use) and nicotine dependence. Participants were 1999 youths (ages 12-17 years) who had ever tried a nicotine product and completed the Population Assessment of Tobacco Health study's Wave 1 (2013-2014) and Wave 4 (2016-2018) assessments. Two separate multinomial logistic regression models examined the association between 1) demographic factors and the first product tried at Wave 1 and 2) the first product tried at Wave 1 and past-30-day product use status at Wave 4. A two-part multivariable model examined the association between the first product tried and nicotine dependence, with part 1 modeling the presence (or absence) of any symptom of dependence and part 2 modeling the degree of dependence among those with any symptom of dependence. The first product tried was associated with sex, race, urbanicity, and parent education. First trying smokeless tobacco (vs. e-cigarettes) was associated with a greater likelihood of multiple product use (vs. no use and vs. single product use). Regarding the degree of nicotine dependence (n = 713), first trying smokeless tobacco (vs. e-cigarettes) was associated with higher nicotine dependence scores among those with any symptom of dependence. Youths who first try smokeless tobacco (vs. e-cigarettes) may be at higher risk for future multiple product use and more symptoms nicotine dependence. Research should explore tailored interventions for smokeless tobacco users.

Within-person associations of escalated electronic nicotine delivery systems use with cigarette, alcohol, marijuana and drug use behaviors among US young adults

AIMS

Most extant evidence has addressed between-person differences, short-term or cross-sectional associations of electronic nicotine delivery systems (ENDS) use with other substance use, the majority focusing on current rather than escalated use. The present study aimed to examine within-person changes in escalated ENDS use and their associations with individual and combined substance use over a 6-year period.

DESIGN, SETTING AND PARTICIPANTS

This study used a longitudinal cohort design with US young adults. A generalized linear mixed-model approach was employed to fit a series of weighted logistic regression models. Data were drawn from waves 1-5 of the Population Assessment of Tobacco and Health (PATH) study in the United States. Of the 9110 young adults at baseline, aged 18-24 years, a total of 5042 individuals had matched data across all five waves of assessments.

MEASUREMENTS

Escalated ENDS use was computed by subtracting the number of days of ENDS use within the past 30 days at wave w - 1 from that at wave w and coded as 1 = escalated, if the value was greater than zero (otherwise, coded as 0 = not escalated).

FINDINGS

Escalated ENDS use gradually decreased over time, with the lowest prevalence at wave 4 (4.0%) but sharply increasing at wave 5 (8.4%). Escalated ENDS use was associated with increased odds of using each substance (binge drinking, marijuana use, marijuana vaping, prescription and illicit drugs) and different combinations of polysubstance use between cigarette smoking, binge drinking and marijuana use (Ps < 0.05). In addition, sweet/fruit flavor use (versus menthol/mint) was associated with increased likelihood of reporting co-use of cigarettes and marijuana.

CONCLUSIONS

In the United States, the prevalence of young adults using electronic nicotine delivery systems appears to have increased steadily between 2013 and 2019, although the rate of increase may have started to accelerate in recent years. Escalated electronic nicotine delivery systems use and time-lagged established electronic nicotine delivery systems use appear to be prospectively associated with individual and combined substance use, particularly between cigarettes, alcohol and marijuana. Among established electronic nicotine delivery systems users, sweet/fruit flavor appears to be associated with increased risk of co-using cigarettes and marijuana.

Exploring associations of adverse childhood experiences with patterns of 11 health risk behaviors in Chinese adolescents: focus on gender differences

PURPOSE

Adolescents exposed to adverse childhood experiences (ACEs) are at increased risk for health-compromising behaviors. However, few studies have investigated how ACEs correlate with patterns of health risk behaviors (HRBs) during adolescence, a crucial developmental period. The aim was to extend the current knowledge about the relationship between ACEs and HRB patterns among adolescents, and to explore gender differences.

METHODS

A multi-centered population-based survey was conducted in 24 middle schools in three provinces across China between 2020 and 2021. A total of 16,853 adolescents effectively completed anonymous questionnaires covering exposure to eight ACE categories and 11 HRBs. Clusters were identified using latent class analysis. Logistic regression models were utilized to test the association between them.

RESULTS

There were four classes of HRB patterns: "Low all" (58.35%), "Unhealthy lifestyle" (18.23%), "Self-harm" (18.42%), and "High all" (5.0%). There were significant differences between HRB patterns in terms of the different numbers and types of ACEs in three logistic regression models. Specifically, compared to "Low all," different types of ACEs were positively associated with the three other HRB patterns, and there were significant trends toward increase in the three latent classes of HRBs with higher ACEs. In general, females with ACEs had a higher risk of "High all" except sexual abuse than males.

CONCLUSION

Our study comprehensively considers the association between ACEs and aggregation categories of HRBs. The results support efforts to improve clinical healthcare, and future work may explore protective factors based on individual, family, and peer education to mitigate the negative trajectory of ACEs.

Longitudinal effects and environmental moderation of ALDH2 and ADH1B gene variants on substance use from age 14 to 40

Alcohol use and dependence are strongly affected by variation in aldehyde dehydrogenase (ALDH2) and, to a lesser extent, alcohol dehydrogenase (ADH1B) genes. We use this genetic variation with an adoption design to test the causal role of alcohol use on other drug use, as well as the moderating role of adoptive parent, sibling, and peer alcohol use. Longitudinal models were run on 412 genotyped adopted individuals of East Asian ancestry with multiple assessments between ages 14 and 40. We found robust associations between alcohol frequency, quantity, and maximum drinks and ALDH2, but not ADH1B, status. The magnitude of the ALDH2 protective effect increased with age, particularly for maximum drinks, though estimates were smaller than previously reported in ancestrally similar individuals in East/North-East Asian countries. These results suggest that sociocultural factors in Minnesota may reduce the protective effects of ALDH2. We found that peer alcohol use, but not parent or sibling use, predicted adopted offspring's use, and that these environmental influences did not vary by ALDH2 status. Finally, we did not find strong evidence of associations between ALDH2 status and tobacco, marijuana, or illegal drug use, contrary to expectation if alcohol serves as a gateway to use of other drugs.

Trends in the sequence of initiation of alcohol, tobacco, and marijuana use among adolescents in Argentina and Chile from 2001 to 2017

BACKGROUND

Variation in drug policies, norms, and substance use over time and across countries may affect the normative sequences of adolescent substance use initiation. We estimated relative and absolute time-varying associations between prior alcohol and tobacco use and adolescent marijuana initiation in Argentina and Chile. Relative measures quantify the magnitude of the associations, whereas absolute measures quantify excess risk.

METHODS

We analyzed repeated, cross-sectional survey data from the National Surveys on Drug Use Among Secondary School Students in Argentina (2001-2014) and Chile (2001-2017). Participants included 8th, 10th, and 12th grade students (N = 680,156). Linear regression models described trends over time in the average age of first use of alcohol, tobacco, and marijuana. Logistic regression models were used to estimate time-varying risk ratios and risk differences of the associations between prior alcohol and tobacco use and current-year marijuana initiation.

RESULTS

Average age of marijuana initiation increased and then decreased in Argentina and declined in Chile. In both countries, the relative associations between prior tobacco use and marijuana initiation weakened amid declining rates of tobacco use; e.g., in Argentina, the risk ratio was 19.9 (95% CI: 9.0-30.8) in 2001 and 11.6 (95% CI: 9.0-13.2) in 2014. The relative association between prior alcohol use and marijuana initiation weakened Chile, but not in Argentina. On the contrary, risk differences (RD) increased substantially across both relationships and countries, e.g., in Argentina, the RD for tobacco was 3% (95% CI: 0.02-0.03) in 2001 and 12% (95% CI: 0.11-0.13) in 2014.

CONCLUSION

Diverging trends in risk ratios and risk differences highlight the utility of examining multiple measures of association. Variation in the strength of the associations over time and place suggests the influence of environmental factors. Increasing risk differences indicate alcohol and tobacco use may be important targets for interventions to reduce adolescent marijuana use.

Longitudinal effects of adverse childhood experiences on substance use transition patterns during young adulthood

BACKGROUND

Few studies have investigated how adverse childhood experiences are associated with substance use patterns during young adulthood, a crucial developmental period.

OBJECTIVE

The objective of this study was to extend current knowledge on the association between adverse childhood experiences and patterns of substance use among young adults. We also sought to understand how current mental health status and biological sex influences these patterns.

PARTICIPANTS AND SETTING

The current study utilized wave 8-wave 11 data of a longitudinal cohort study (N = 2880).

METHODS

We used latent transition analysis (LTA) to understand stability and transition patterns of substance use across participants who reported adverse childhood experiences (ACEs+) versus those who did not (ACEs-). Latent class regression was used to assess contemporaneous effects of mental health and sex on classes over time.

RESULTS

Both groups had similar patterns of substance use emerge at each timepoint: High all; Binge, tobacco, cannabis; and Steady/increasing binge drinking. ACEs+ had a higher proportion of youth in the High all class and much higher stability in this class, compared to the ACEs- group. Those in the ACES+ group were less likely to transition out of a riskier class. Mental health and sex showed differential effects across ACEs groups.

CONCLUSION

Results point to increased risk of polysubstance use, including opioids and prescription medications, among those who reported adverse childhood events. Future work may explore protective, malleable, factors that may confer reduced risk of long-term polysubstance use.

Relationships between patterns of cannabis use, abuse and dependence and recent stimulant use: Evidence from two national surveys in Ireland

Background and objectives

Epidemiological studies show that the use of cannabis is related to the use of other illicit drugs, including stimulants such as cocaine and ecstasy. However, few studies have examined how patterns of cannabis use relate to the use of stimulants. In this research we determined relationships between patterns of cannabis use and recent stimulant use, drawing on data from two large nationally representative surveys. We also explored how frequency of cannabis use relates to stimulant use and whether subjects with a cannabis use disorder (CUD)–defined as cannabis abuse or dependence–are more likely to be recent users of cocaine or ecstasy.

Materials and methods

We analysed data from Ireland’s 2010/11 and 2014/15 National Drug Prevalence Surveys,which recruited 5,134 and 7,005 individuals respectively, aged 15 years and over, living in private households. We included only those people who reported some past cannabis use. Multivariable logistic regression analysis was used to examine associations between patterns of cannabis use and recent stimulant use.

Results

Among survey participants who had used cannabis in the last month, 17.9% reported recent cocaine use, while almost one-quarter (23.6%) reported recent ecstasy use. There was a significant linear relationship between patterns of cannabis use and recent use of cocaine, ecstasy or any stimulant, with last month cannabis users displaying greater odds (OR = 12.03, 95% CI: 8.15–17.78) of having recent stimulant use compared to last year (OR = 4.48, 95% CI: 2.91–6.91) and former (reference) cannabis users. Greater frequency of cannabis use in the last 30 days was also significantly related to the use of stimulants. In addition, results demonstrated an association between CUD and recent use of cocaine or ecstasy (OR = 2.28, 95% CI: 1.55–3.35).

Conclusions

Findings from this study suggest a relationship between patterns and frequency of cannabis use and recent use of stimulants and an association between CUD and stimulant use. As the use of cannabis with stimulants may increase the risk of negative health consequences, education in community and medical settings about polydrug use and its increased risks may be warranted.

Relationships between age at first substance use and persistence of cannabis use and cannabis use disorder

Background

From a secondary prevention perspective, it is useful to know who is at greatest risk of progressing from substance initiation to riskier patterns of future use. Therefore, the aim of this study was to determine relationships between age at first use of alcohol, tobacco and cannabis and patterns of cannabis use, frequency of use and whether age of substance use onset is related to having a cannabis use disorder (CUD).

Methods

We analysed data from Ireland’s 2010/11 and 2014/15 National Drug Prevalence Surveys, which recruited 5134 and 7005 individuals respectively, aged 15 years and over, living in private households. We included only those people who reported lifetime cannabis use. Multinomial, linear and binary logistic regression analyses were used to determine relationships between age of substance use onset and patterns of cannabis use, frequency of use and having a CUD.

Results

When compared to former users, the odds of being a current cannabis user were found to be reduced by 11% (OR = 0.89; 95% CI: 0.83, 0.95) and 4% (OR = 0.96; 95% CI: 0.92, 1.00) for each year of delayed alcohol and cannabis use onset, respectively. Among current users, significant inverse linear relationships were noted, with increasing age of first use of tobacco (β = − 0.547; P < .001) and cannabis (β = − 0.634; P < .001) being associated with a decreased frequency of cannabis use within the last 30 days. The odds of having a CUD were found to be reduced by 14% (OR = 0.86; 95% CI: 0.78, 0.94) and 11% (OR = 0.89; 95% CI: 0.82, 0.98) for each year of delayed tobacco and cannabis use onset respectively in analyses which examined survey participants aged 15–34 years.

Conclusions

Among people who report past cannabis use, it is those with a more precocious pattern of early use of substances, including alcohol, and especially tobacco and cannabis, who are more likely to report ongoing, heavy and problematic cannabis use. Secondary prevention initiatives should prioritise people with a pattern of very early onset substance use.

Cigarette Smoking Behavior a Gateway to Opium Use Disorder: A Mendelian Randomization Analysis

Gateway hypothesis presumes that using a psychotropic drug can increase the probability of using another drug. The study was to assess whether cigarette smoking is a gateway drug for subsequent opium use. Mendelian randomization (MR) analysis was applied to test and estimate the size of causal effect of cigarette smoking on opium use. The CHRNA3 rs1051730 polymorphism was used as an instrumental variable. A population-based case control study in the setting of Fasa Cohort Study was carried out using 477 cases and 531 controls based on their opium use status at the baseline of cohort study. The logistic two stage estimator method was applied. The Number of cigarettes smoked per day was associated with opium use (OR 1.17, 95% CI 1.15-1.19). In the MR analysis, rs1051730 T alleles were associated with increased risk of opium use among ever smokers (OR 5.73, 95% CI 1.72-19.07) however there found no evidence of association among never smokers. In instrumental variable analysis, showed that on average smoking every 1 more cigarette per day increases the odds of opium use by 1.17 (OR 1.17, 95%CI:1.14-1.19). The MR analysis found a positive finding on the relationship between cigarette smoking and opium use which supports the gateway hypothesis. It adds new information to the gateway theory regarding the relation of cigarette smoking and drug use, and increases our understanding of the importance of tobacco control for prevention of opium addiction.

Changes from 2017 to 2018 in e-cigarette use and in ever marijuana use with e-cigarettes among US adolescents: analysis of the National Youth Tobacco Survey

AIMS

To examine changes from 2017 to 2018 in e-cigarette use and ever marijuana use with e-cigarettes among US adolescents.

DESIGN

Analysis of data from the 2017 and 2018 National Youth Tobacco Survey (NYTS), cross-sectional surveys of US middle school (grades 6-8) and high school (grades 9-12) students.

SETTING

United States.

PARTICIPANTS

US adolescent population from middle school, with mean age = 12.7 [standard deviation (SD) = 1.0] years, and high school, with mean age = 16.1 (SD = 1.3) years.

MEASUREMENTS

Analysis of e-cigarette use and ever use of marijuana with e-cigarettes according to frequency of use and smoking status, comparing 2017 with 2018. Frequent smoking and e-cigarette use was defined as use for ≥ 20 of the past 30 days.

FINDINGS

Past 30 days e-cigarette use was reported by 33.1% [95% confidence interval (CI) = 29.1-37.4%] of ever/no past 30 days smokers, 68.6% (95% CI = 64.1-72.7%) of past 30 days smokers and 7.2% (95% CI = 6.3-8.2%) of never smokers in 2018 and by 19.3% (95% CI = 16.1-23.1%), 53.0% (95% CI = 46.9-58.9%) and 3.3% (95% CI = 2.7-4.4%) in 2017, respectively (all P < 0.001). Prevalence of past 30 days e-cigarette use was higher among frequent smokers (69.8%, 95% CI = 62.3-76.5% in 2018; 53.8%, 95% CI = 44.1-63.2% in 2017, P < 0.001) and lower among never smokers. Most of the latter were infrequent users, while frequent and daily e-cigarette use was 18- and 24-fold lower compared with ever smokers, respectively. Approximately half of past 30 days and 70% of frequent e-cigarette users reported ever marijuana use with e-cigarettes in both years. Past 30 days smokers were more likely to report past 30 days e-cigarette use [odds ratio (OR) = 15.79, 95% CI = 12.58-19.83 in 2018; OR = 16.11, 95% CI = 12.44-20.86 in 2017) compared with adolescents reporting no past 30 days smoking.

CONCLUSIONS

Among US adolescents, e-cigarette use increased in all smoking groups in 2018 compared with 2017. Frequent and daily e-cigarette use was far lower in never-smokers compared with ever-smokers. High prevalence of ever marijuana use with e-cigarettes was observed.

Tobacco Use and Parental Monitoring-Observations from Three Diverse Island Nations-Cook Islands, Curaçao, and East Timor

Tobacco use among adolescents is a global problem of public health importance. This study examined the profile of differences and similarities in adolescent tobacco use, and the role of parental monitoring activities among adolescents in three island nations of varying economic status: Cook Islands, Curaçao, and East Timor. Using nationally representative data we conducted regression modeling to determine the effect of four types of parental monitoring activities on tobacco use. Within a recall period of 30 days prior to being surveyed, 29.7% of students in East Timor, 21.6% in Cook Islands, and 13.1% in Curaçao reported having smoked cigarettes and/or used tobacco in other forms during 1 or more days during the preceding 30 days. Lower rates of parental monitoring as measured by four variables (parental understanding of problems and worries; knowing about how free time was being spent; going over things without approval; and checking to see if homework was done) were associated with higher percentages of adolescent tobacco use. Taken together the results underscore the need for increased parental involvement in programs which are designed to reduce tobacco use among adolescents.

Changes in the Order of Cigarette and Marijuana Initiation and Associations with Cigarette Use, Nicotine Vaping, and Marijuana Use: U.S. 12th Grade Students, 2000-2019

This study (a) examined changes in marijuana and cigarette initiation sequencing and (b) considered implications of such changes for prevention efforts by examining associations between initiation sequencing and current adolescent substance use. Analyses used 2000-2019 cross-sectional data from the national Monitoring the Future (MTF) study (78,252 U.S. 12th grade students). Models examined trends in six distinct patterns of initiation order, and multivariable associations between order of initiation and 30-day cigarette and marijuana use prevalence, cigarette and marijuana use frequency among users, and nicotine and marijuana vaping prevalence. While the percentage of students initiating neither cigarettes nor marijuana increased, increases also were observed in marijuana-only initiation (the fastest-growing pattern) and initiation of marijuana before cigarettes; these increases were accompanied by a significant decrease in cigarette-only initiation. Cigarette use prevalence and frequency were highest among students initiating cigarettes before marijuana; marijuana use prevalence and frequency were highest among students initiating marijuana before cigarettes. Cigarette and marijuana prevalence, as well as marijuana frequency, were lowest among students initiating only a single substance. Nicotine vaping was less prevalent among students initiating a single substance versus both substances, but no significant differences were observed in nicotine vaping prevalence between those initiating only cigarettes versus only marijuana. Implications of these findings for prevention efforts are discussed in the frameworks of both the common liability model and route of administration model.

Pattern of Methamphetamine Use and the Time Lag to Methamphetamine Dependence

OBJECTIVES

Use of methamphetamine (MA) commonly co-occurs with the use of other substances. The present study aims to examine substance initiation patterns of other substances, including alcohol, nicotine, inhalants, and cannabis (OTH), in MA users and its consequence on the time lag of MA dependence.

METHODS

Sociodemographic, environmental, and clinical data were obtained from MA users at a Thai substance treatment center. The Semi-Structured Assessment for Drug Dependence and Alcoholism was employed to diagnose drug dependence.

RESULTS

Of 991 MA users, 52.6% were males, and the average age was 26.8 ± 7.1 years. The mean age of first MA use (18 years) was greater than the mean age of first use of alcohol (17 years), nicotine (16 years), and inhalants (15 years) (P < 0.001), but was comparable with the mean age at the first use of cannabis (P > 0.05). Family history of MA use and nicotine dependence were associated with early MA onset. Participants who used MA as their first drug (MA>OTH) were more likely to be female and less likely to smoke intensely and to be exposed to severe traumatic events than those who used MA later than other substances (OTH>MA). The time lag from age at onset of MA use to MA dependence was shorter in OTH>MA than in MA>OTH (3 vs 5 years; χ = 5.7, P = 0.02, log-rank test).

CONCLUSIONS

A higher proportion of women was observed in MA>OTH than in OTH>MA. The use of other substances before MA increases the individual's vulnerability in shortening the interval between age at onset of MA use and MA dependence in a substance treatment cohort.

Is smoking heaviness causally associated with alcohol use? A Mendelian randomization study in four European cohorts

Background

Observational studies have shown that tobacco and alcohol use co-occur, but it is not clear whether this relationship is causal.

Methods

Using data from the Avon Longitudinal Study of Parents and Children (ALSPAC) and UK Biobank, we used observational methods to test the hypothesis that smoking heaviness increases alcohol consumption. Mendelian randomization (MR) analyses were then used to test the causal relationship between smoking heaviness and alcohol consumption using 55 967 smokers from four European studies [ALSPAC, The Nord-Trøndelag Health Study (HUNT), the Copenhagen General Population Study (CGPS) and UK Biobank]. MR analyses used rs1051730/rs16969968 as a genetic proxy for smoking heaviness.

Results

Observational results provided evidence of an association between cigarettes per day and weekly alcohol consumption (increase in units of alcohol per additional cigarette smoked per day = 0.10, 95% confidence interval (CI) 0.05 to 0.15, P ≤ 0.001 in ALSPAC; and 0.48, 95% CI 0.45 to 0.52, P ≤ 0.001 in UK Biobank). However, there was little evidence for an association between rs1051730/rs16969968 and units of alcohol consumed per week across ALSPAC, HUNT, CGPS and UK Biobank (standard deviation increase in units of alcohol per additional copy of the risk allele = –0.004, 95% CI –0.023 to 0.016, P=0.708, I² = 51.9%). We had 99% and 88% power to detect a change of 0.03 and 0.02 standard deviation units of alcohol per additional copy of the risk allele, respectively.

Conclusions

Previously reported associations between smoking and alcohol are unlikely to be causal, and may be the result of confounding and/or reverse causation. This has implications for public health research and intervention research.

The Relationship Between Tobacco and Cannabis Use: A Review

BACKGROUND

Based on the prevalence and health implications of tobacco and cannabis use, aiming to reduce their use, especially among youth, is a sound objective at both the individual and public health level. A proper understanding of the relationships between tobacco and cannabis use may help to achieve this goal.

OBJECTIVES

To review the relationships between tobacco and cannabis use.

METHODS

A selective review of the literature.

RESULTS

We present an overview of the motivations for tobacco and cannabis use, and their perceived harmfulness. The article then reviews the gateway theory, reverse gateway theory, route of administration theory, and common liability theory. We describe the link between co-use and dependence symptoms, and the substitution phenomenon between tobacco and cannabis use. Three forms of simultaneous use-mulling, blunt smoking, and chasing-and their impacts are explained. We summarize the impact of tobacco use on cannabis (and vice versa) treatment outcomes, and, finally, review new treatments that simultaneously target tobacco and cannabis dependence. Most of the literature reviewed here relates to substance use among adolescents and young adults.

CONCLUSIONS

The use of tobacco and cannabis-two of the most widely used substances around the world-are strongly intertwined in several respects. Both health professionals and researchers should have well-informed views on this issue to better evaluate, understand, inform, and provide care to their patients.

Historical trends in the grade of onset and sequence of cigarette, alcohol, and marijuana use among adolescents from 1976-2016: Implications for "Gateway" patterns in adolescence

INTRODUCTION

In the past decade, marijuana use prevalence among adolescents has remained relatively steady while cigarette and alcohol prevalence has declined. We examined historical trends in: average grade of onset of marijuana, alcohol, and cigarette use by 12^th grade; proportion who try alcohol/cigarettes before first marijuana use, among those who use by 12^th grade; and conditional probability of marijuana use by 12^th grade after trying alcohol/cigarettes.

METHODS

Data were drawn from 40 yearly, cross-sectional surveys of 12^th grade US adolescents. A subset of students (N = 246,050) were asked when they first used each substance. We reconstructed cohorts of substance use from grade-of-onset to determine sequence of drug use, as well as probability of marijuana use in the same or later grade.

RESULTS

Average grade of first alcohol and cigarette use by 12^th grade increased across time; e.g., first cigarette increased from grade 7.9 in 1986 to 9.0 by 2016 (β=0.04, SE = 0.001, p < 0.01). The proportion of 12^th grade adolescents who smoke cigarettes before marijuana fell below 50% in 2006. Each one-year increase was associated with 1.11 times increased odds of first cigarette in a grade after first marijuana (95% C.I. 1.11-1.12). Among those who initiate alcohol/cigarettes prior to marijuana by 12^th grade, the probability of subsequent marijuana use is increasing.

CONCLUSION

Marijuana is increasingly the first substance in the sequence of adolescent drug use. Reducing adolescent smoking has been a remarkable achievement of the past 20 years; those who continue to smoke are at higher risk for progression to marijuana use.

E-cigarette use is associated with other tobacco use among US adolescents

OBJECTIVES

To examine whether tobacco initiation via e-cigarettes increases the likelihood of subsequent tobacco use among a large representative sample of US adolescents.

METHODS

This study is a retrospective longitudinal analysis from a representative sample of US middle and high school students (n = 39,718) who completed the 2014 and 2015 National Youth Tobacco Survey. The adjusted odds ratios of lifetime and current use of tobacco use were estimated by logistic regression analysis while controlling for important socio-ecological factors associated with tobacco use.

RESULTS

E-cigarette initiators were more likely to report current use of cigarettes (AOR 2.7; 1.9-4.0, p < 0.001), cigars (AOR 1.7; 1.2-2.4, p < 0.01), or smokeless tobacco (AOR 3.1; 2.2-5.4, p < 0.001), and lifetime use of the same products as well. Also, lifetime and current use of e-cigarettes significantly increased the likelihood of cigarettes, cigars, and smokeless tobacco use.

CONCLUSIONS

Initiation of tobacco via e-cigarette, lifetime, and current use of e-cigarettes are associated with higher odds of lifetime and current use of cigarettes, cigars, and smokeless tobacco. Collectively this suggests e-cigarettes may lead to an increased use of tobacco among adolescents.

Maternal and paternal cannabis use during pregnancy and the risk of psychotic-like experiences in the offspring

Cannabis use continues to increase among pregnant women. Gestational cannabis exposure has been associated with various adverse outcomes. However, it remains unclear whether cannabis use during pregnancy increases the risk for offspring psychotic-like experiences. In this prospective cohort, we examined the relationship between parental cannabis use during pregnancy and offspring psychotic-like experiences. Comparisons were made between maternal and paternal cannabis use during pregnancy to investigate causal influences of intra-uterine cannabis exposure during foetal neurodevelopmental. This study was embedded in the Generation R birth cohort and included N = 3692 participants. Maternal cannabis exposure was determined using self-reports and cannabis metabolite levels from urine. Paternal cannabis use during pregnancy was obtained by maternal report. Maternal cannabis use increased the risk of psychotic-like experiences in the offspring (OR_adjusted = 1.38, 95% CI 1.03-1.85). Estimates were comparable for maternal cannabis use exclusively before pregnancy versus continued cannabis use during pregnancy. Paternal cannabis use was similarly associated with offspring psychotic-like experiences (OR_adjusted = 1.44, 95% CI 1.14-1.82). We demonstrated that both maternal and paternal cannabis use were associated with more offspring psychotic-like experiences at age ten years. This may suggest that common aetiologies, rather than solely causal intra-uterine mechanisms, underlie the association between parental cannabis use and offspring psychotic-like experiences. These common backgrounds most likely reflect genetic vulnerabilities and shared familial mechanisms, shedding a potential new light on the debated causal path from cannabis use to psychotic-like phenomena. Our findings indicate that diagnostic screening and preventative measures need to be adapted for young people at risk for severe mental illness.

Predictors of initiation of nicotine, alcohol, cannabis, and cocaine use: Results of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC)

BACKGROUND AND OBJECTIVES

There may be substantial overlap in the risk factors for substance use and substance use disorders (SUD). Identifying risk factors for substance use initiation is essential for understanding the etiology and natural history of SUD and to develop empirically-based preventive interventions to reduce initiation.

METHODS

Analyses were done on Wave 1 participants of the National Epidemiological Survey of Alcohol and Related Conditions (NESARC) (n = 43,093). Estimates of the cumulative probability of substance use initiation were obtained separately for nicotine, alcohol, cannabis, and cocaine. Survival analyses with time-varying covariates were implemented to identify risk factors for substance initiation.

RESULTS

The lifetime cumulative probabilities of substance initiation were 45.5% for nicotine, 82% for alcohol, 19.6% for cannabis, and 6.4% for cocaine. Among respondents with lifetime nicotine use, 50% had used it by age 15.3, whereas for alcohol, cannabis, and cocaine the respective ages were 17.8, 16.6, and 19.8. Previous use of another substance, being male, having a cluster B personality disorder, family history of SUD, and being separated, divorced, or widowed increased the risk of use of all the substances assessed, whereas social anxiety disorder and some personality disorders were associated with specific substances.

DISCUSSION AND CONCLUSIONS

Although the age of substance use initiation varies by substance, in more than 50% of cases initiation of use occurs in the first two decades of life. Although most risk factors for substance use initiation are common across substances, some are substance-specific.

SCIENTIFIC SIGNIFICANCE

This information may help in the development of empirically-based preventive interventions. (Am J Addict 2018;27:477-484).

Drug use among youth: National survey data support a common liability of all drug use

The prevalence of substance use disorders in adults is higher if substance use is initiated during adolescence, underscoring the importance of youth substance use prevention. We examined whether the use of one substance by adolescents is associated with increased risk for using any other substance, regardless of use sequences. In 2017 we examined data from 17,000 youth aged 12-17 who participated in the 2014 National Survey on Drug Use and Health, a sample of nationally representative data on substance use among the U.S. civilian, noninstitutionalized population aged 12 or older. Descriptive analyses and multivariable logistic regression models were applied. After controlling for age, sex, and race/ethnicity, compared with youth without past-month marijuana use, youth with past-month marijuana use were 8.9 times more likely to report past-month cigarette use, 5.6, 7.9 and 15.8 times more likely to report past-month alcohol use, binge use, or heavy use (respectively), and 9.9 times more likely to report past-month use of other illicit drugs. The prevalence of past-month use of cigarettes, marijuana, and other illicit drugs was significantly higher among past-month alcohol users compared with youth without past-month alcohol use, and increased as intensity of alcohol use rose. Among past-month cigarette smokers, the prevalence of marijuana, other illicit drugs, and alcohol use were each significantly higher than youth without past-month cigarette use. Youth marijuana use, cigarette smoking, or alcohol consumption is associated with other substance use. This finding has importance for youth prevention, supporting a message no use by youth of any substance.

The Association Between Smoking and Electronic Cigarette Use in a Cohort of Young People

PURPOSE

Electronic cigarette (e-cigarette) use is associated with smoking initiation among young people; however, it is also possible that smoking is associated with e-cigarette initiation. This study explores these associations among young people in Great Britain.

METHODS

A longitudinal survey of 1,152 11- to 18-year-olds was conducted with baseline in April 2016 and follow-up between August and October 2016. Logistic regression models and causal mediation analyses assessed whether (1) ever e-cigarette use and escalation were associated with smoking initiation (ever smoking at follow-up) among baseline never smokers (n = 923), and (2) ever smoking and escalation were associated with e-cigarette initiation (ever e-cigarette use at follow-up) among baseline never e-cigarette users (n = 1,020).

RESULTS

At baseline, 19.8% were ever smokers and 11.4% were ever e-cigarette users. Respondents who were ever e-cigarette users (vs. never users, 53% vs. 8%, odds ratio [OR] = 11.89, 95% confidence interval [CI] = 3.56-39.72) and escalated their e-cigarette use (vs. did not, 41% vs. 8%, OR = 7.89, 95% CI = 3.06-20.38) were more likely to initiate smoking. Respondents who were ever smokers (vs. never smokers, 32% vs. 4%, OR = 3.54, 95% CI = 1.68-7.45) and escalated their smoking (vs. did not, 34% vs. 6%, OR = 5.79, 95% CI = 2.55-13.15) were more likely to initiate e-cigarette use. There was a direct effect of ever e-cigarette use on smoking initiation (OR = 1.34, 95% CI = 1.05-1.72), and ever smoking on e-cigarette initiation (OR = 1.08, 95% CI = 1.01-1.17); e-cigarette and smoking escalation, respectively, did not mediate these effects.

CONCLUSIONS

Among young people in Great Britain, ever e-cigarette use is associated with smoking initiation, and ever smoking is associated with e-cigarette initiation.

National Trends in Substance Use and Use Disorders Among Youth

OBJECTIVE

To examine trends in the 12-month prevalence of patterns of substance use and substance use disorders (SUDs) among US youth during 2002 through 2014.

METHOD

Data were from 288,300 persons 12 to 17 years old who participated in the 2002 to 2014 National Surveys on Drug Use and Health. Descriptive analyses and bivariable and multivariable logistic regressions were applied.

RESULTS

During 2002 through 2014, among US youth, the 12-month prevalence of any substance use decreased by 27.1% (from 43.2% to 31.5%); among youth users, the 12-month prevalence of SUDs decreased by 28.9% (from 27.0% to 19.2%), and the ratio of substance dependence to abuse decreased from 2.2 to 1.6. Multiple substance use was common and was associated with SUDs. During 2002 through 2014, the prevalence of using marijuana and alcohol only, using marijuana only, and having marijuana use disorders only increased, whereas most other trends were downward. Increases in age at first substance use were associated with downward trends in any substance use. Upward trends in age at first substance use, youth and parental strong disapproval of cigarette use, and youths' seatbelt-wearing prevalence and downward trends in substance use patterns were associated with the downward trend in SUDs among youth users.

CONCLUSION

The 12-month prevalence of any substance use among youth and SUDs among youth users decreased during 2002 through 2014. Postponing age at first use of any substance is critical among youth in the United States. Future research is needed to better understand the interrelations between specific risk and protective factors, age at first substance use, substance use patterns, and SUDs among youth users.

Endocannabinoid Signaling and the Hypothalamic-Pituitary-Adrenal Axis

The elucidation of Δ9-tetrahydrocannabinol as the active principal of Cannabis sativa in 1963 initiated a fruitful half-century of scientific discovery, culminating in the identification of the endocannabinoid signaling system, a previously unknown neuromodulatory system. A primary function of the endocannabinoid signaling system is to maintain or recover homeostasis following psychological and physiological threats. We provide a brief introduction to the endocannabinoid signaling system and its role in synaptic plasticity. The majority of the article is devoted to a summary of current knowledge regarding the role of endocannabinoid signaling as both a regulator of endocrine responses to stress and as an effector of glucocorticoid and corticotrophin-releasing hormone signaling in the brain. We summarize data demonstrating that cannabinoid receptor 1 (CB1R) signaling can both inhibit and potentiate the activation of the hypothalamic-pituitary-adrenal axis by stress. We present a hypothesis that the inhibitory arm has high endocannabinoid tone and also serves to enhance recovery to baseline following stress, while the potentiating arm is not tonically active but can be activated by exogenous agonists. We discuss recent findings that corticotropin-releasing hormone in the amygdala enables hypothalamic-pituitary-adrenal axis activation via an increase in the catabolism of the endocannabinoid N-arachidonylethanolamine. We review data supporting the hypotheses that CB1R activation is required for many glucocorticoid effects, particularly feedback inhibition of hypothalamic-pituitary-adrenal axis activation, and that glucocorticoids mobilize the endocannabinoid 2-arachidonoylglycerol. These features of endocannabinoid signaling make it a tantalizing therapeutic target for treatment of stress-related disorders but to date, this promise is largely unrealized. © 2017 American Physiological Society. Compr Physiol 7:1-15, 2017.

The genetic relationship between cannabis and tobacco cigarette use in European- and African-American female twins and siblings

BACKGROUND

Use of cigarettes and cannabis frequently co-occurs. We examine the role of genetic and environmental influences on variation in and covariation between tobacco cigarette and cannabis use across European-American (EA) and African-American (AA) women.

METHODS

Data on lifetime cannabis and cigarette use were drawn from interviews of 956 AA and 3557 EA young adult female twins and non-twin same sex female full siblings. Twin modeling was used to decompose variance in and covariance between cigarette and cannabis use into additive genetic, shared, special twin and non-shared environmental sources.

RESULTS

Cigarette use was more common in EAs (75.3%, 95% C.I. 73.8-76.7%) than AAs (64.2%, 95% C.I. 61.2-67.2%) while cannabis use was marginally more commonly reported by AAs (55.5%, 95% C.I. 52.5-58.8%) than EAs (52.4%, 95% C.I. 50.7-54.0%). Additive genetic factors were responsible for 43-66% of the variance in cigarette and cannabis use. Broad shared environmental factors (shared+special twin) played a more significant role in EA (23-29%) than AA (2-15%) women. In AA women, the influence of non-shared environment was more pronounced (42-45% vs. 11-19% in EA women). There was strong evidence for the same familial influences underlying use of both substances (rA=0.82-0.89; rC+T=0.70-0.75). Non-shared environmental factors were also correlated but less so (rE=0.48-0.66). No racial/ethnic differences were apparent in these sources of covariation.

CONCLUSION

Heritability of cigarette and cannabis use is comparable across racial/ethnic groups. Differences in the contribution of shared and non-shared environmental influences indicate that different factors may shape substance use in EA and AA women.

Marijuana dependence moderates the effect of posttraumatic stress disorder on trauma cue reactivity in substance dependent patients

BACKGROUND

Individuals with posttraumatic stress disorder (PTSD) are at heightened risk for marijuana use. Although extant studies speak to the importance of examining the co-occurrence of PTSD and marijuana use as it relates to a variety of clinically-relevant outcomes, no studies have explored the way in which marijuana use may affect in-the-moment emotional responding among individuals with PTSD. Thus, the purpose of this study was to explore the role of marijuana dependence in the relation between PTSD and subjective and biological emotional reactivity in response to a trauma cue.

METHODS

Participants were 202 patients with and without current PTSD consecutively admitted to a residential SUD treatment facility. Patients were administered diagnostic interviews, and subjective (negative affect) and biological (cortisol) reactivity to a personalized trauma cue were assessed.

RESULTS

Whereas current PTSD was associated with greater subjective emotional reactivity among participants without marijuana dependence, there were no significant differences in subjective emotional reactivity as a function of PTSD status among participants with marijuana dependence. Moreover, marijuana dependent participants (with and without PTSD) reported less subjective emotional reactivity than participants with PTSD and without marijuana dependence. No significant findings were obtained for cortisol reactivity.

CONCLUSIONS

Findings suggest that patients with co-occurring PTSD and marijuana dependence may experience alterations in their emotional processing in response to a trauma cue (i.e., dampening of arousal). Additional research is required to clarify the specific mechanisms through which marijuana use influences emotional reactivity and fear-related emotional processing, as well as how such effects may influence PTSD treatment.

Early adolescent substance use in Mexican origin families: Peer selection, peer influence, and parental monitoring

BACKGROUND

Because adolescents vary in their susceptibility to peer influence, the current study addresses potential reciprocal effects between associating with deviant peers and use of alcohol, tobacco and other drugs (ATOD), as well as the potential buffering role of parental monitoring on these reciprocal effects.

METHOD

674 children of Mexican origin reported at fifth and seventh grade (10.4 years old at fifth grade) on the degree to which they associated with deviant peers, intended to use alcohol, tobacco or other drugs (ATOD) in the future, and had used controlled substances during the past year. Trained observers rated parental monitoring from video-recorded family interactions at the first assessment.

RESULTS

Youth who intended to use ATODs during fifth grade experienced a relative increase in number of deviant peers by seventh grade, and youth with more deviant peers in fifth grade were more likely to use ATODs by seventh grade. Parental monitoring buffered (i.e., moderated) the reciprocal association between involvement with deviant peers and both intent to use ATODs and actual use of ATODs.

CONCLUSIONS

Parental monitoring can disrupt the reciprocal associations between deviant peers and ATOD use during the transition from childhood to adolescence.

Cannabis use and other predictors of the onset of daily cigarette use in young men: what matters most? Results from a longitudinal study

Background

According to the gateway hypothesis, tobacco use is a gateway of cannabis use. However, there is increasing evidence that cannabis use also predicts the progression of tobacco use (reverse gateway hypothesis). Unfortunately, the importance of cannabis use compared to other predictors of tobacco use is less clear. The aim of this study was to examine which variables, in addition to cannabis use, best predict the onset of daily cigarette smoking in young men.

Methods

A total of 5,590 young Swiss men (mean age = 19.4 years, SD = 1.2) provided data on their substance use, socio-demographic background, religion, health, social context, and personality at baseline and after 18 months. We modelled the predictors of progression to daily cigarette smoking using logistic regression analyses (n = 4,230).

Results

In the multivariate overall model, use of cannabis remained among the strongest predictors for the onset of daily cigarette use. Daily cigarette use was also predicted by a lifetime use of at least 50 cigarettes, occasional cigarette use, educational level, religious affiliation, parental situation, peers with psychiatric problems, and sociability.

Conclusions

Our results highlight the relevance of cannabis use compared to other potential predictors of the progression of tobacco use and thereby support the reverse gateway hypothesis.

Prospective Predictors of Novel Tobacco and Nicotine Product Use in Emerging Adulthood

PURPOSE

The purpose of this study was to investigate whether risk factors for cigarette smoking assessed in adolescence predict the use of novel tobacco and nicotine products (hookah, little cigars, and e-cigarettes) in early emerging adulthood.

METHODS

In a longitudinal study (N = 862), risk factors were measured in middle and high school, and novel product use was measured in emerging adulthood (mean age 22.4 years). Structural equation modeling was used to test a model predicting lifetime use of any of hookah, little cigars, and e-cigarettes in early emerging adulthood from distal predictors (gender, maternal smoking through Grade 8; already tried alcohol, cigarettes, or marijuana by Grade 8; and sensation seeking at Grade 8) and potential mediators (intentions to smoke cigarettes, drink alcohol or smoke marijuana at Grade 9, and smoking trajectory across high school).

RESULTS

The most prevalent novel tobacco product was hookah (21.7%), followed by little cigars (16.8%) and e-cigarettes (6.6%). Maternal smoking, having already tried substances, and sensation seeking each predicted the use of at least one of these products via an indirect path through intentions to use substances and membership in a high-school smoking trajectory.

CONCLUSIONS

Risk factors for cigarette smoking were found to predict novel tobacco use, suggesting that interventions to prevent cigarette smoking could be extended to include common novel tobacco products.

Reasons for recent marijuana use in relation to use of other illicit drugs among high school seniors in the United States

OBJECTIVES

Studies show that illicit cannabis (marijuana) use is related to use of other illicit drugs and that reasons for use are related to frequency of marijuana use. However, research is needed to examine whether specific reasons for marijuana use are associated with use of other illicit drugs.

METHODS

Data from recent marijuana-using high school seniors were examined from 12 cohorts of Monitoring the Future (Weighted n = 6481) to examine whether reasons for recent marijuana use are associated with use of eight other illicit drugs.

RESULTS

Using "to experiment" decreased odds of reporting use of each drug and using to decrease effects of other drugs increased odds of reporting use of each drug. In multivariable models, using marijuana "to experiment" decreased the odds for reporting use of hallucinogens other than LSD and narcotics other than heroin. Using marijuana for "insight" increased the odds for use of hallucinogens other than LSD, and use due to "boredom" increased the odds for reporting use of powder cocaine and hallucinogens other than LSD. Using marijuana to increase effects of other drugs increased odds of reporting use of each of the eight drugs, and using it to decrease other drug effects increased odds of reporting use of crack, hallucinogens other than LSD, and amphetamine/stimulants.

CONCLUSIONS

This study helped identify illicit marijuana users who are more likely to report use of other illicit drugs. Prevention efforts need to focus on students who report certain reasons for marijuana use as they may be at risk for use of other illicit drugs.

Tobacco smoking and cannabis use in a longitudinal birth cohort: evidence of reciprocal causal relationships

BACKGROUND

There is evidence of associations between tobacco and cannabis use that are consistent with both a classical stepping-stone scenario that posits the transition from tobacco use to cannabis use ('gateway' effect of tobacco) and with the reverse process leading from cannabis use to tobacco abuse ('reverse gateway' effect of cannabis). The evidence of direct causal relationships between the two disorders is still missing.

METHODS

We analysed data from the Christchurch Health and Development Study (CHDS) longitudinal birth cohort using advanced statistical modelling to control for fixed sources of confounding and to explore causal pathways. The data were analysed using both: (a) conditional fixed effects logistic regression modelling; and (b) a systematic structural equation modelling approach previously developed to investigate psychiatric co-morbidities in the same cohort.

RESULTS

We found significant (p<0.05) associations between the extent of cannabis use and tobacco smoking and vice versa, after controlling for non-observed fixed confounding factors and for a number of time-dynamic covariate factors (major depression, alcohol use disorder, anxiety disorder, stressful life events, deviant peer affiliations). Furthermore, increasing levels of tobacco smoking were associated with increasing cannabis use (p=0.02) and vice versa (p<0.001) over time.

CONCLUSIONS

Our results lend support to the notion of both of 'gateway' and 'reverse gateway' effects. That is, the association between tobacco and cannabis use arises from a reciprocal feedback loop involving simultaneous causation between tobacco use disorder and cannabis use disorder.

Endocannabinoids and the Endocrine System in Health and Disease

Some of the earliest reports of the effects of cannabis consumption on humans were related to endocrine system changes. In this review, the effects of cannabinoids and the role of the CB1 cannabinoid receptor in the regulation of the following endocrine systems are discussed: the hypothalamic-pituitary-gonadal axis, prolactin and oxytocin, thyroid hormone and growth hormone, and the hypothalamic-pituitary-adrenal axis. Preclinical and human study results are presented.

Cannabis use is a better indicator of poor mental health in women than in men: a cross-sectional study in young adults from the general population

Cannabis use is a known risk factor for a range of mental health problems, but less is known on the association with general mental health. We aim to explore the relationship between cannabis use and general mental health. We did a cross-sectional online survey of 1,929 young adults aged 18-30 years. Participants reported socio-demographic data, substance use and the Symptom Checklist-90 (SCL-90). Monthly cannabis use was associated with a higher total score on the SCL-90, both in a crude (OR 1.94, 95% CI 1.57-2.38) and fully adjusted model (OR 1.48, 95% CI 1.07-2.03). The association between cannabis and mental health was stronger in women and weekly users, and was independent of age at first use of cannabis. We conclude that moderate cannabis use is associated with general mental health problems in young adulthood. This relationship is independent of age at first use and of other risk factors, and is strongest in women.

Routes of administration of cannabis used for nonmedical purposes and associations with patterns of drug use

PURPOSE

Little is known regarding cannabis administration routes for nonmedical use-that is, its delivery methods (e.g., joints, water pipe, food). Therefore, we examined the prevalence rates of different cannabis delivery methods and assessed the relationship of the distinct administration routes with problematic drug use. Subgroups of cannabis users were also investigated (i.e., "pure" cannabis users, previously described as employing a harmless route of administration, and water pipe users, previously described as using a harmful route of administration).

METHODS

As part of the Cohort Study on Substance Use Risk Factors, 1,763 cannabis users answered questions concerning their drug use (i.e., routes of administration, problematic cannabis use, other illicit drug use). Descriptive statistics, latent class analysis, correlations and t-tests were assessed.

RESULTS

The main administration route was "joints with tobacco"; other routes of administration had prevalence rates from 23.99% to 38.23%. In addition, increasing the number of administration routes was associated with more problematic cannabis use, as well as heavier illicit drug use. Water pipes without tobacco were especially linked to heavy drug use patterns, whereas "pure" cannabis use seemed less harmful.

CONCLUSIONS

Our findings highlighted that diversification in routes of administration can be associated with heavier illicit drug use. This was especially true for water pipe users, whereas "pure" cannabis users, who did not mix cannabis with tobacco, were an exception. Indeed, these results may be useful for future preventive programs, which may need to focus on those who have diversified routes of administration for cannabis.

Legal substance use and the development of a DSM-IV cannabis use disorder during adolescence: the TRAILS study

AIMS

To examine whether early onset of tobacco or alcohol use, and continued use of tobacco or alcohol in early adolescence, are related to a higher likelihood of developing a cannabis use disorder during adolescence.

DESIGN AND SETTING

Data were used from four consecutive assessment waves of the TRacking Adolescents' Individual Lives Survey (TRAILS), a general Dutch population study. TRAILS is an ongoing longitudinal study that will follow the same group of adolescents from the ages of 10 to 24 years.

PARTICIPANTS

The sample consisted of 1108 (58% female) adolescents (mean ages at the four assessment waves are 11.09, 13.56, 16.27 and 19.05 years, respectively)

MEASUREMENTS

Cannabis use disorders were assessed using the Composite International Diagnostic Interview 3.0 (CIDI). Adolescent tobacco and alcohol use were assessed using self-report questionnaires.

FINDINGS

Early-onset tobacco use [odds ratio (OR) = 1.82, confidence interval (CI) = 1.05-3.14, P < 0.05], but not early-onset alcohol use (OR = 1.33, CI = 0.84-2.12, P > 0.05), was associated with a higher likelihood of developing a cannabis use disorder. Similarly, adolescents who reported continued use of tobacco (OR = 2.47, CI = 1.02-5.98, P < 0.05), but not continued use of alcohol (OR = 1.71, CI = 0.87-3.38, P > 0.05), were more likely to develop a cannabis use disorder.

CONCLUSIONS

Early-onset and continued tobacco use appear to predict the development of a cannabis use disorder in adolescence, whereas early onset and continued alcohol use do not.

Concurrent and simultaneous polydrug use: latent class analysis of an Australian nationally representative sample of young adults

BACKGROUND

Alcohol use and illicit drug use peak during young adulthood (around 18-29 years of age), but comparatively little is known about polydrug use in nationally representative samples of young adults. Drawing on a nationally representative cross-sectional survey (Australian National Drug Strategy Household Survey), this study examines polydrug use patterns and associated psychosocial risk factors among young adults (n = 3,333; age 19-29).

METHOD

The use of a broad range of licit and illicit drugs were examined, including alcohol, tobacco, cannabis, cocaine, hallucinogens, ecstasy, ketamine, GHB, inhalants, steroids, barbiturates, meth/amphetamines, heroin, methadone/buprenorphine, other opiates, painkillers, and tranquilizers/sleeping pills. Latent class analysis was employed to identify patterns of polydrug use.

RESULTS

Polydrug use in this sample was best described using a 5-class solution. The majority of young adults predominantly used alcohol only (52.3%), alcohol and tobacco (34.18%). The other classes were cannabis, ecstasy, and licit drug use (9.4%), cannabis, amphetamine derivative, and licit drug use (2.8%), and sedative and alcohol use (1.3%). Young adult males with low education and/or high income were most at risk of polydrug use.

CONCLUSION

Almost half of young adults reported polydrug use, highlighting the importance of post-high school screening for key risk factors and polydrug use profiles, and the delivery of early intervention strategies targeting illicit drugs.

Hookah, cigarette, and marijuana use: a prospective study of smoking behaviors among first-year college women

Better understanding of the temporal sequence of hookah, cigarette, and marijuana use will help to inform smoking prevention efforts. To address this gap in the literature, we assessed all three of these smoking behaviors in a sample of 424 first-year college women. Using a longitudinal design, we investigated whether hookah use predicts initiating/resuming cigarette and/or initiating marijuana use, and whether cigarette and/or marijuana use predicts initiating hookah use. Participants (67% White, M age = 18.1 years) completed nine monthly surveys. The initial (i.e., baseline) survey assessed demographics, sensation-seeking, impulsivity, and pre-college substance use. Follow-up surveys assessed past-month substance use; outcomes were initiating/resuming cigarette use, initiating marijuana use, and initiating hookah use during the first year of college. We controlled for sensation-seeking, impulsivity, binge drinking, and other smoking behaviors in our multivariate logistic regression models. The results showed that (a) pre-college hookah use predicted initiating/resuming cigarette use; (b) pre-college marijuana use predicted initiation of hookah tobacco smoking; and (c) pre-college cigarette use predicted neither hookah nor marijuana initiation. The findings highlight the co-occurrence of smoking behaviors as well as the need for bundling preventive interventions so that they address hookah, cigarette, and marijuana use.

Prevalence and factors associated with the use of illicit substances among male university students in Kuwait

OBJECTIVES

To estimate the prevalence of illicit use of substances and identify the factors associated with illicit drug use among male students in the state-run Kuwait University and private universities in Kuwait.

SUBJECTS AND METHODS

The study was a cross-sectional survey with a sample of 1,587 male students from both private universities (n = 869) and the public (n = 718) Kuwait University in Kuwait. A self-administered questionnaire was used to collect data. Overall lifetime prevalence of substance use was computed with 95% confidence interval. Logistic regression was used to identify the factors influencing substance use, which was adjusted for potential confounders.

RESULTS

The total lifetime prevalence of illicit drug use was 14.4% and the most frequently used illicit substance was marijuana (11%). The substance use in general varied significantly (p ≤ 0.001) between private (18%) and public (10%) universities. Multivariate logistic regression model revealed that drug use was positively associated with age, poor academic performance, high family income, being an only child, divorced parents, and graduation from a private high school.

CONCLUSION

Drug use among male university students in Kuwait was high and requires attention and appropriate intervention. The factors identified with drug use in this study could be utilized to develop appropriate public health policies and preventive measures that may improve the health status of the student population.

The topography of multiple drug use among adolescent Australians: findings from the National Drug Strategy Household Survey

INTRODUCTION AND AIMS

Despite evidence that many Australian adolescents have considerable experience with various drug types, little is known about the extent to which adolescents use multiple substances. The aim of this study was to examine the degree of clustering of drug types within individuals, and the extent to which demographic and psychosocial predictors are related to cluster membership.

DESIGN AND METHOD

A sample of 1402 adolescents aged 12-17 years were extracted from the Australian 2007 National Drug Strategy Household Survey. Extracted data included lifetime use of 10 substances, gender, psychological distress, physical health, perceived peer substance use, socioeconomic disadvantage, and regionality. Latent class analysis was used to determine clusters, and multinomial logistic regression employed to examine predictors of cluster membership.

RESULT

There were 3 latent classes. The great majority (79.6%) of adolescents used alcohol only, 18.3% were limited range multidrug users (encompassing alcohol, tobacco, and marijuana), and 2% were extended range multidrug users. Perceived peer drug use and psychological distress predicted limited and extended multiple drug use. Psychological distress was a more significant predictor of extended multidrug use compared to limited multidrug use.

DISCUSSION AND CONCLUSION

In the Australian school-based prevention setting, a very strong focus on alcohol use and the linkages between alcohol, tobacco and marijuana are warranted. Psychological distress may be an important target for screening and early intervention for adolescents who use multiple drugs.