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Onset Of Opportunity To Use Cannabis And Progression From Opportunity To Dependence: Are Influences Consistent Across Transitions?

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... A previous online survey by our research group found that 40.8% of a sample of Australian medical cannabis users met criteria for DSM-5 CUD [15] in the preceding 12 months, compared with an estimated 32% lifetime prevalence among the general population of cannabis-using Australians [24]. The risk factors associated with CUD among recreational users have been studied extensively and include: (i) cannabis use variables such as frequency or quantity of cannabis use [25][26][27][28][29][30] or age of first use or regular use [31][32][33][34][35]; (ii) other drug use, especially tobacco [26,27,31,[36][37][38][39][40]; (iii) psychopathology including mood [27,29,31,36,39,[41][42][43] and externalising disorders [29,39,[44][45][46][47][48][49], criminality and social deviance [26,36,37,41], and psychosis [47]; (iv) personality factors such as neuroticism and impulsivity [29,35,50]; (v) environmental factors such as exposure to peer/sibling/spousal parental drug use [29,35,39,44,46,[51][52][53], bullying [54], family dysfunction (e.g. marital discord, low parental monitoring or domestic violence) [29,35,37,41,43,54,55] or adverse events in childhood (e.g. ...
... A previous online survey by our research group found that 40.8% of a sample of Australian medical cannabis users met criteria for DSM-5 CUD [15] in the preceding 12 months, compared with an estimated 32% lifetime prevalence among the general population of cannabis-using Australians [24]. The risk factors associated with CUD among recreational users have been studied extensively and include: (i) cannabis use variables such as frequency or quantity of cannabis use [25][26][27][28][29][30] or age of first use or regular use [31][32][33][34][35]; (ii) other drug use, especially tobacco [26,27,31,[36][37][38][39][40]; (iii) psychopathology including mood [27,29,31,36,39,[41][42][43] and externalising disorders [29,39,[44][45][46][47][48][49], criminality and social deviance [26,36,37,41], and psychosis [47]; (iv) personality factors such as neuroticism and impulsivity [29,35,50]; (v) environmental factors such as exposure to peer/sibling/spousal parental drug use [29,35,39,44,46,[51][52][53], bullying [54], family dysfunction (e.g. marital discord, low parental monitoring or domestic violence) [29,35,37,41,43,54,55] or adverse events in childhood (e.g. ...
... A previous online survey by our research group found that 40.8% of a sample of Australian medical cannabis users met criteria for DSM-5 CUD [15] in the preceding 12 months, compared with an estimated 32% lifetime prevalence among the general population of cannabis-using Australians [24]. The risk factors associated with CUD among recreational users have been studied extensively and include: (i) cannabis use variables such as frequency or quantity of cannabis use [25][26][27][28][29][30] or age of first use or regular use [31][32][33][34][35]; (ii) other drug use, especially tobacco [26,27,31,[36][37][38][39][40]; (iii) psychopathology including mood [27,29,31,36,39,[41][42][43] and externalising disorders [29,39,[44][45][46][47][48][49], criminality and social deviance [26,36,37,41], and psychosis [47]; (iv) personality factors such as neuroticism and impulsivity [29,35,50]; (v) environmental factors such as exposure to peer/sibling/spousal parental drug use [29,35,39,44,46,[51][52][53], bullying [54], family dysfunction (e.g. marital discord, low parental monitoring or domestic violence) [29,35,37,41,43,54,55] or adverse events in childhood (e.g. ...
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Introduction: Prior research has examined the prevalence and correlates of cannabis use disorder (CUD) in people who use cannabis; however, these are poorly described for people using cannabis for medical reasons. Methods: Data came from a 2018 to 2019 online, anonymous, cross-sectional survey of Australians reporting using either illicit or licit cannabis for medical reasons within the past year. Included were questions on demographics, current and lifetime patterns of cannabis use, clinical conditions for which medical cannabis was used, and individual criteria for CUD and cannabis withdrawal syndrome. Bayesian Horseshoe logistic regression models were used to identify covariates associated with meeting CUD DSM-5 conditions for any-CUD (≥2/11 criteria) and moderate-severe-CUD (≥4/11). Results: A total of 905 participants were included in the analysis. The majority (98%) used illicit cannabis products. Criteria for any-CUD criteria were met by 290 (32.0%), and 117 (12.9%) met criteria for moderate-severe-CUD. Tolerance (21%) and withdrawal (35%) were the most commonly met criteria. Correlates with the strongest association with CUD were inhaled route of administration [odds ratio (OR) = 2.96, 95% credible interval 1.11, 7.06], frequency of cannabis use (OR = 1.24, 1.11-1.35), proportion of cannabis for medical reasons (OR = 0.83, 0.74, 0.94), frequency of tobacco use (OR = 1.10, 1.03, 1.17), age (OR = 0.75, 0.64, 0.90) and pain as main clinical indication (OR = 0.58, 0.36, 1.00). Discussion and conclusions: Prevalence of CUD in medical cannabis users appears comparable to 'recreational' users, with many similar correlates. CUD was associated with using cannabis to treat mental health rather than pain conditions and inhaled over other routes of administration.
... As access to the drug is a prerequisite of actual use, adolescents who had increased opportunity to use cannabis (eg, being offered cannabis) were more likely to initiate use and progress into cannabis dependence. 27,[32][33] Although perceived availability has been implicated as an important intervention target, 34 few studies have examined its association with various ages of cannabis initiation groups, which is the focus of the present study. ...
... Opportunities to use cannabis may change as a function of developmental transitions, including moving from one school or neighborhood to another, or change in the youth's peer environment. 33 The perception of cannabis as easily available could be a distal pathway leading to eventual drugs involvement. 27,33,34 The findings suggest that interventions aimed to increase adult supervision in both home and school settings may reduce early initiation of use. ...
... 33 The perception of cannabis as easily available could be a distal pathway leading to eventual drugs involvement. 27,33,34 The findings suggest that interventions aimed to increase adult supervision in both home and school settings may reduce early initiation of use. ...
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BACKGROUND Prevention of early age initiation of cannabis use is a national priority, highlighting the importance of identifying cannabis‐specific attitudes, norms, and perceived behavioral control in relation to initiation age. METHODS Data were from the NEXT Generation Health Study, a national longitudinal sample of US adolescents followed from 10th grade (N = 1850). Cannabis‐specific attitudes, norms, and perceived behavioral control were assessed at 10th grade. Age of first use was reported retrospectively 2‐3 years after high‐school and participants were categorized as early initiators (<14 years; 3.8%), high‐school (HS) initiators (14‐18 years; 35.6%), post‐HS initiators (>18 years; 8.3%), or never users (52.3%). RESULTS Relative to never users, early initiators were more likely to endorse pro‐use attitudes (AOR [adjusted odds ratio] = 2.39, 95% confidence interval [CI] = 1.27‐4.50), less disapproving parental attitudes toward use (AOR = 2.50, 95% CI = 1.45‐4.28), higher cannabis use among friends (AOR = 3.81, 95% CI = 2.21‐6.60), and higher ease of access (AOR = 2.10, 95% CI = 1.14‐3.87); HS initiators were similarly more likely to report less disapproving attitudes toward use (AOR = 1.55, 95% CI = 1.25‐1.91), higher cannabis use among friends (AOR = 2.81, 95% CI = 2.18‐3.65), and higher ease of access (AOR = 1.66, 95% CI = 1.21‐2.28). CONCLUSIONS Earlier cannabis initiation was associated with more favorable cannabis attitudes, subjective norms, and perceived behavioral control, highlight these variables as potential intervention targets.
... Once initiation of use has occurred, individuals will vary in frequency of cannabis use, with the increased frequency associated with increased likelihood for the development of cannabis dependence (Chen et al. 1997). Considering the sources of variation in progression through the stages of cannabis use, and the extent to which influences consist across different stages can provide insight into the aetiology of CUD (Hines et al. 2015a(Hines et al. , 2016. ...
... Alternatively, genetic influences associated with other behaviours may be influencing progression through the stages of cannabis use. Previous research has identified conduct disorder influences transitions to cannabis use opportunity, and from the opportunity to dependence (Hines et al. 2016). This is in line with existing research demonstrating the consistent influence of conduct disorder on drug use Storr et al. 2011;Reboussin et al. 2015), and genes relating to conduct disorder and involvement with deviant peers (Gillespie et al. 2009a) are plausible candidates for the shared genetic liability between age of opportunity and the development of cannabis abuse/dependence. ...
... Cannabis opportunity, the frequency of use, and abuse/ dependence show a moderate effect of the unique environment (0.35, 0.26, and 0.22, respectively), but the correlation between unique environmental influences on the opportunity and the later stages of drug use were non-significant. This may reflect measurement error (Plomin et al. 2013) but is in line with existing research demonstrating the pattern of environmental factors associated with progression between specific stages of drug use differs between transitions (Sartor et al. 2007;Belsky et al. 2013;Hines et al. 2016). For example, childhood and early adolescent factors have been shown to be uniquely associated with cannabis opportunity, whereas escalating other drug use factors is uniquely associated with the development of cannabis dependence (Hines et al. 2016). ...
Article
Background The genetic component of Cannabis Use Disorder may overlap with influences acting more generally on early stages of cannabis use. This paper aims to determine the extent to which genetic influences on the development of cannabis abuse/dependence are correlated with those acting on the opportunity to use cannabis and frequency of use. Methods A cross-sectional study of 3303 Australian twins, measuring age of onset of cannabis use opportunity, lifetime frequency of cannabis use, and lifetime DSM-IV cannabis abuse/dependence. A trivariate Cholesky decomposition estimated additive genetic (A), shared environment (C) and unique environment (E) contributions to the opportunity to use cannabis, the frequency of cannabis use, cannabis abuse/dependence, and the extent of overlap between genetic and environmental factors associated with each phenotype. Results Variance components estimates were A = 0.64 [95% confidence interval (CI) 0.58–0.70] and E = 0.36 (95% CI 0.29–0.42) for age of opportunity to use cannabis, A = 0.74 (95% CI 0.66–0.80) and E = 0.26 (95% CI 0.20–0.34) for cannabis use frequency, and A = 0.78 (95% CI 0.65–0.88) and E = 0.22 (95% CI 0.12–0.35) for cannabis abuse/dependence. Opportunity shares 45% of genetic influences with the frequency of use, and only 17% of additive genetic influences are unique to abuse/dependence from those acting on opportunity and frequency. Conclusions There are significant genetic contributions to lifetime cannabis abuse/dependence, but a large proportion of this overlaps with influences acting on opportunity and frequency of use. Individuals without drug use opportunity are uninformative, and studies of drug use disorders must incorporate individual exposure to accurately identify aetiology.
... Although global metaanalyses estimate the prevalence of physical and sexual abuse to be minimal to moderate severity (22), childhood physical and sexual abuse in childhood are both public health concerns given their association with negative outcomes across the life course (23). In relation to cannabis use and dependence, a study breaking down risk factors by stages of drug use found a relationship between CSA and exposure to cannabis, but not progression to dependence (24). Studies of these risk factors for illicit drug use have contradictory findings, with physical abuse more strongly associated than sexual abuse in some studies (25,26), while others show the opposite relationship (27). ...
... Adolescent cannabis use is a necessary step in the progression to the development of cannabis abuse/dependence (24), and is a commonly identified risk factor for anxiety, depression and psychosis (9,50). The results of the present review add to the evidence that preventing adolescent cannabis use may be a viable intervention target for reducing risks of these negative outcomes amongst those experiencing early adversities such as physical and sexual abuse. ...
Article
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Background: Among adolescents, cannabis use is a health concern due to associations with drug addiction and mental health disorders across the life course. It has been shown that childhood maltreatment is associated with drug addiction in adulthood. However, a better understanding of the relationship between maltreatment and drug use may improve targeted prevention and interventions. The aim of this systematic review is to describe the association between exposure to childhood maltreatment, specifically physical and sexual abuse, with adolescent cannabis use. Methods: A systematic search strategy was applied to Embase, PsycINFO, and Ovid MEDLINE(R) databases. Methods followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Abstract and title screening was performed to identify papers which reported an estimate of the association between childhood physical or sexual abuse and adolescent cannabis use. Full text screening of each paper was performed, and data were extracted and study quality assessed. Weighted means meta-analysis was performed on studies reporting odds ratios as effect estimates. Results: Of 8,780 screened articles, 13 were identified for inclusion. Eight papers received a quality rating score indicating lower risk of bias. Eleven papers reported the relationship between childhood sexual abuse and adolescent cannabis use; effect estimates ranged from AOR 0.53–AOR 2.18 (weighted mean OR 1.29, 95% CI 1.08–1.49). The relationship between childhood physical abuse and adolescent cannabis use was reported in 7 papers; effect estimates ranged from AOR 1.25–AOR 1.87 (weighted mean OR 1.39, 95% CI 1.12–1.66). Differences in the strength of the evidence were observed by the method of exposure ascertainment, and there was some evidence of differences in association by gender, age of cannabis initiation, and the severity of the abuse. Conclusions: This systematic review indicates childhood physical or sexual abuse may increase risk of adolescent-onset cannabis use. Few studies considered variation in timing of onset, or by gender. Adolescent cannabis use precedes is strongly associated with increased risk of negative mental health outcomes; further exploration of adolescent cannabis use's place on the causal pathway between childhood abuse and adult mental health problems is warranted to improve intervention.
... That is, the association between ad exposure and marijuana use is contingent on availability: Low availability can deter the translation of positive attitudes (as often instilled by marijuana ads) into behavior (Smith & Swinyard, 1983). This is consistent with emerging literature that shows that availability and realistic use opportunities can explain marijuana use trajectories (Burdzovic Andreas & Bretteville-Jensen, 2017;Hines et al., 2016;Wagner & Anthony, 2002). This interaction can further depend on age. ...
... It is specifically aimed at understanding the conditions under which marijuana advertisement exposure is associated with increased marijuana use in adolescents. More specifically, in line with recent works on the roles of realistic use opportunities and availability in affording marijuana use (Burdzovic Andreas & Bretteville-Jensen, 2017;Hines et al., 2016;Wagner & Anthony, 2002), I sought to examine whether perceived ease of access to marijuana and age can attenuate the association between marijuana ad exposure and past-year marijuana use. The descriptive findings (Table 2) demonstrate that older teenagers (10th grade, typically 15-16 years old) experience stronger peer pressure to use marijuana, believe that it is easier for them to get marijuana, and report more past-year instances of marijuana use, compared to younger students (8th grade, typically 13-14 years old). ...
Article
This study theorizes and tests moderators (perceived availability of marijuana and age-group) of the association between adolescents’ frequency of marijuana ad exposure and past-year marijuana use. To test this model, I analyzed national survey data from 9,024 American adolescents with hierarchical regression techniques. Results showed that being a male (95% confidence interval [CI] for unstandardized regression coefficient [0.06, 0.16]) and peer pressure (95% CI [0.04, 0.14]) were positively associated with past-year marijuana use, and father education (95% CI [−0.11, −0.06]) was negatively associated with it. Perceived ease of access (95% CI [0.18, 0.22]), ad exposure (95% CI [0.03, 0.14]), and age (95% CI [0.16, 0.27]) were positively associated with past-year marijuana use. Importantly, the associations of perceived ease of access and age with past-year marijuana use were significantly larger than that of ad exposure. Age (95% CI [0.00, 0.15]) and perceived ease of access (95% CI [0.01, 0.07]) independently strengthened the ad exposure to use association. There was a significant three-way interaction (95% CI [0.01, 0.12]) showing that age increases the positive influence of perceived ease of access on the marijuana ad exposure to past-year marijuana use association. An exploratory analysis further revealed that male adolescents are more strongly influenced by perceived ease of access compared to females. Based on the findings, I suggest that approaches for reducing perceived marijuana availability and for implementing age-specific interventions are promising avenues for prevention programs aimed at decreasing marijuana use in adolescents.
... Although global metaanalyses estimate the prevalence of physical and sexual abuse to be minimal to moderate severity (22), childhood physical and sexual abuse in childhood are both public health concerns given their association with negative outcomes across the life course (23). In relation to cannabis use and dependence, a study breaking down risk factors by stages of drug use found a relationship between CSA and exposure to cannabis, but not progression to dependence (24). Studies of these risk factors for illicit drug use have contradictory findings, with physical abuse more strongly associated than sexual abuse in some studies (25,26), while others show the opposite relationship (27). ...
... Adolescent cannabis use is a necessary step in the progression to the development of cannabis abuse/dependence (24), and is a commonly identified risk factor for anxiety, depression and psychosis (9,50). The results of the present review add to the evidence that preventing adolescent cannabis use may be a viable intervention target for reducing risks of these negative outcomes amongst those experiencing early adversities such as physical and sexual abuse. ...
... An emerging literature focusing on the exposure to use opportunities shows this indeed to be the necessary initial step predicating any future drug use and associated problems [17,19,20,22]. Although cannabis remains the most commonly used drug [23], not all individuals are equally likely to be exposed to cannabis. ...
... However, the likelihood of use given the use opportunity is relatively high for cannabis [29,30], especially for those receiving repeated use offers [31]. The related studies show that youth faced with use opportunities were more likely to remain cannabis-free if they did not have additional high-risk characteristics such as alcohol and tobacco use, delinquency or drug-using peers [22,[32][33][34]. ...
Article
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Abstract Aims To examine adolescent cannabis use -- both at the national and individual level -- by deconstructing it into its necessary conditions of realistic use opportunities and willingness to use the drug given such opportunities. Design Nationally-representative, repeated cross-sectional survey. Setting Norway. Participants A total of 8,818 16-year olds who participated in the European School Survey Project on Alcohol and Other Drugs (ESPAD) in 2007, 2011, and 2015. Measurements Adolescent reports concerning their lifetime “cannabis use” and “possibilities to use cannabis” were used to assess: a) overall cannabis use, b) exposure to realistic cannabis use opportunities, and c) cannabis use among those exposed to use opportunities. Logistic regression models were used to estimate national trends since 2007 in these indicators, and to identify individual-level factors associated with cannabis use vs. non-use among youth exposed to concrete use opportunities. Findings Prevalence of lifetime cannabis use remained stably low averaging 6.4% across the three surveys. Lifetime exposure to cannabis use opportunities significantly decreased (ORESPAD Assessment = .90, 95%CI .84 - .07, p = .006), yet cannabis use among adolescents with such opportunities steadily increased (ORESPAD Assessment = 1.17, 95%CI 1.03 - 1.34, p = .02) since 2007. After controlling for a range of other risk factors, abstinence from alcohol intoxication and cigarette use, as well as the perceptions of even infrequent cannabis use as risky remained the factors most robustly associated with lower likelihood of cannabis use among youth with realistic use opportunities. Conclusions Approaches accounting for realistic use opportunities proved critical in our understanding of underage cannabis use, both at the national and individual level, and may be informative for development of prevention strategies in the era of cannabis liberalization. In addition, delineation of realistic opportunities from behaviors conditioned upon such opportunities is generalizable to a range of public health issues.
... Irrespective of the drug constituents 81,82 , only a minority of cannabis users become addicted; therefore, other factors must predict vulnerability. Concurrent tobacco use has been identified as a risk factor in several studies [128][129][130] , as have early adolescent onset and frequent (especially daily) use 128,131 . Males typically have an earlier opportunity to use cannabis, a greater risk of addiction and a faster progression from first opportunity of use to addiction 64,128,129 . ...
... Concurrent tobacco use has been identified as a risk factor in several studies [128][129][130] , as have early adolescent onset and frequent (especially daily) use 128,131 . Males typically have an earlier opportunity to use cannabis, a greater risk of addiction and a faster progression from first opportunity of use to addiction 64,128,129 . These findings are consistent with normative data from European treatment services: the mean age of first treatment is 24 years; the mean age at first cannabis use is 16 years; and 83% of treated individuals are male 70 . ...
Article
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In an increasing number of states and countries, cannabis now stands poised to join alcohol and tobacco as a legal drug. Quantifying the relative adverse and beneficial effects of cannabis and its constituent cannabinoids should therefore be prioritized. Whereas newspaper headlines have focused on links between cannabis and psychosis, less attention has been paid to the much more common problem of cannabis addiction. Certain cognitive changes have also been attributed to cannabis use, although their causality and longevity are fiercely debated. Identifying why some individuals are more vulnerable than others to the adverse effects of cannabis is now of paramount importance to public health. Here, we review the current state of knowledge about such vulnerability factors, the variations in types of cannabis, and the relationship between these and cognition and addiction.
... 40,41 In the current study, cigarette use was associated with incident CUD among those without cannabis use but not among those with cannabis use. These results are consistent with past literature in which cigarette use was associated with a faster transition from cannabis use to cannabis dependence among 3,824 Australian adult twins and siblings, 42 while in contrast, cigarette use was not associated with the transition to cannabis dependence among 600 Dutch adults reporting frequent (ie, ≥ 3 days per week) cannabis use at baseline. 43 It may be that cigarettes exert a greater influence on the transition from no cannabis use to CUD than the transition from cannabis use to CUD. ...
Article
Objective: The current study prospectively investigated the relationship between cigarette use and the initiation of, persistence of, and relapse to cannabis use disorder (CUD) 3 years later among adults in the United States. Methods: Analyses included respondents who completed Waves 1 and 2 of the National Epidemiologic Survey on Alcohol and Related Conditions (2001-2002 and 2004-2005, respectively) and responded to questions about cigarette use, cannabis use, and CUD (n = 34,653). CUDs were defined by DSM-IV criteria using the Alcohol Use Disorder and Associated Disabilities Interview Schedule-Diagnostic Version IV. Multivariable logistic regression models were used to calculate the odds of CUD initiation, persistence, and relapse at Wave 2 by Wave 1 cigarette use status. Analyses were adjusted for sociodemographics, psychiatric disorders, nicotine dependence, and alcohol and other substance use disorders. Results: Cigarette use at Wave 1 was associated with initiation of CUD at Wave 2 among those without Wave 1 cannabis use (adjusted odds ratio [AOR] = 1.62; 95% CI, 1.35-1.94) but not among those with Wave 1 cannabis use (AOR = 1.00; 95% CI, 0.83-1.19). Cigarette use at Wave 1 was also associated with persistence of CUD at Wave 2 among those with CUD at Wave 1 (AOR = 1.63; 95% CI, 1.30-2.00) and relapse to CUD at Wave 2 among those with remitted CUD at Wave 1 (AOR = 1.23; 95% CI, 1.09-1.45). Conclusions: Among adults, cigarette use is associated with increased initiation and persistence of and relapse to CUD 3 years later. Additional attention to cigarette use in community prevention and clinical treatment efforts aimed at reducing CUD may be warranted.
... Several specific factors, such as gender, race and age at onset of cannabis use, were previously shown to be associated with changes in the odds of transition from cannabis use to DSM-IV cannabis abuse or dependence [4,11,12]. Furthermore, while there is some evidence suggesting that childhood abuse, parental loss and childhood maltreatment may increase the odds of transition to DSM-IV cannabis abuse or dependence [13], the extent to which these above-mentioned factors play a role in the transition from cannabis use to DSM-5 CUD is unknown. ...
Article
Introduction and aims: It has been previously reported that more than 34% of individuals who use cannabis may qualify for a diagnosis of DSM-IV cannabis abuse or dependence throughout their lifetime. The introduction of the DSM-5 cannabis use disorder (CUD) diagnostic criteria reflects several intrinsic changes in the perception of substance use disorders. However, little is known about the probability of transition from cannabis use to CUD over time nor about the sociodemographic and clinical correlates associated with this transition. Design and methods: Participants were individuals ≥18 years interviewed in the National Epidemiologic Survey on Alcohol and Related Conditions-III in 2012-2013. Measurements included univariable and multivariable discrete-time survival analyses performed to examine the association between previously reported cannabis dependence predictors and the hazards of transitioning from cannabis use to CUD. Survival plots assessed the probability of transition from cannabis use to CUD over time since age of first use and differences in probability between predictor levels. Results: Among lifetime cannabis users (N = 11 272), lifetime probability of transition to CUD was approximately 27%. A higher probability of transition from cannabis use to CUD was observed in the following: men, participants belonging to an ethnic minority group, early-onset cannabis users and individuals who reported experiencing three or more childhood adverse events. Discussion and conclusions: This is the first study to explore transition from cannabis use to the DSM-5 CUD diagnosis. The current study identified specific predictors of this transition, which may assist in targeting at-risk populations.
... Self-medication theories explain that people with mental disorders choose specific drugs depending on the interaction between the psychopharmacologic action of the drug and the dominant painful feelings with which they struggle. Moreover, psychosocial risk factors are also related to this comorbidity, including parenting styles and norms regarding drug use, childhood sexual abuse, unemployment, and peer pressure (Danielsson, Lundin, Agardh, Allebeck, & Forsell, 2016;Hines et al., 2016;Kosty et al., 2015;Lehn et al., 2007). ...
Article
Objective: The objective of this study was to compare psychiatric comorbidity and consumption-related variables in ADHD patients seeking treatment for cocaine, cannabis, or both. Method: Assessment was conducted using European Addiction Severity Index (EuropASI), Conners’ Adult ADHD Diagnostic Interview (CAADID), Structured Clinical Interview for DSM Disorders (SCID), Adult Self-Report Scale (ASRS), Wender Utah Rating Scale (WURS), Barratt Impulsiveness Scale-11 (BIS-11), and FIDI, with statistical analyses of analysis of variance (ANOVA), Student’s t test, chi-square test, and multinomial regression model. Results: In total, 1,538 patients with substance use disorder (SUD) were evaluated for ADHD; 239 (15.5%) had ADHD, with cannabis 41, cannabis/cocaine 36, and cocaine 74. Men represented 80%, with mean age of 32.9 ± 10 years. Significant variables were—in bivariate analysis—more years of cannabis use in cannabis group and younger age for cocaine use disorder in cannabis/cocaine group, and—in multivariate analysis—lifetime anxiety disorder and younger age at onset of any SUD in cannabis group and working affected scale in cannabis and polysubstance use in cannabis/cocaine group. Conclusion: Groups with cannabis use had higher severity. ADHD features were similar in all groups. The assessment of ADHD and comorbid disorders is important.
... Although there are more than 160 million Cannabis users in the world, no pharmacological therapy currently available is considered adequate for the treatment of symptoms caused during the withdrawal syndrome. The known effects of withdrawal syndrome, which occur when drug use is deprived and disappear with the reintroduction of Δ9-THC [60], favor the recurrence of use by users attempting to stop. The main compounds that have activity on the cannabinoid receptor and mechanisms related to Cannabis withdrawal syndrome are as follows. ...
... Globally, substance use disorders contributed to 38 million disability adjusted life years in 2010, these start in early adolescence and peak in early adulthood (20-24 years) and are significantly higher among men than women [4]. Numerous studies have supported the opportunity model of ATOD use [3,[5][6][7][8] and the progression from opportunity to dependence [9]. Youth cannot knowingly begin to use a substance until an opportunity to use occurs, and this opportunity represents an environmental determinant of future use [8]. ...
... In his commentary, Fink extends our argument on the importance of use opportunities [1]-a basic physical requirement for actual use [2][3][4][5][6][7][8]-in examining cannabis use phenomena. We very much agree that 'specific questions about cannabis use opportunities are needed to clarify the mechanisms that… link MMLs [medical marijuana laws] and RMLs [recreational marijuana laws] to population changes in cannabis use' [1]. ...
... Understanding of drug use escalation and dependence benefits from examining the stages of drug use [6], which include opportunity to use, initiation and escalation in frequency of use. Genetic and environmental factors are differentially associated with transition through these stages [6][7][8][9][10][11][12], and speed of transition is emerging as an important area in the study of drug use [13][14][15][16][17][18]. There is thought to be a short period after substance use initiation for implementation of prevention interventions [19], and identifying factors associated with more rapid transitions has implications for the timing of interventions. ...
Article
Introduction and aims: The effect of heroin administration route on speed of transition to regular use is unknown. This paper aims to determine whether the speed of transition from initiation of heroin use to daily heroin use differs by route of administration (injecting, chasing/inhaling or snorting). Design and methods: Privileged access interviewer survey of purposively selected sample of 395 current people who use heroin (both in and not in treatment) in London, UK (historical sample from 1991). Data on age and year of initiation, time from initiation to daily use and routes of administration were collected by means of a structured questionnaire. Generalised ordered logistic models were used to test the relationship between route of initial administration of heroin and speed of transition to daily heroin use. Analyses were adjusted for gender, ethnicity, daily use of other drug(s) at time of initiation, year of initiation and treatment status at interview. Results: After adjustment, participants whose initial administration route was injecting had a 4.71 (95% confidence interval 1.34-16.5) increase in likelihood of progressing to daily use within 1-3 weeks of initiation, compared to those whose initial administration route was non-injecting. Discussion and conclusions: The speed of transition from first use to daily heroin use is faster if the individual injects heroin at initiation of use. Those who initiate heroin use through injecting have a shorter time frame for intervention before drug use escalation. [Hines LA, Lynskey M, Morley KI, Griffiths P, Gossop M, Powis B, Strang J. The relationship between initial route of heroin administration and speed of transition to daily heroin use. Drug Alcohol Rev 2017;00:000-000].
... As the two groups will encompass different social role transitions [4], the contextual factors surrounding their drug use will probably be different. Different stages of cannabis use share influences, but are associated differentially with contextual factors [5]. Further analyses that consider the influences acting immediately on risk for dependence within each class (such as peer use, mental health status changes, and other drug use) should identify differences in the factors underlying CUD risk and develop our understanding of the mechanisms of risk for CUD, as well as areas to target for early intervention. ...
Article
Objective Early onset of alcohol use is associated with an increased risk of substance use disorders (SUD), but few studies have examined associations with other psychiatric disorders. Our aim was to study the association between the age of first alcohol intoxication (AFI) and the risk of psychiatric disorders in a Finnish general population sample. Methods We utilized a prospective, general population-based study, the Northern Finland Birth Cohort 1986. In all, 6,290 15-16-year old adolescents answered questions on AFI and were followed up until the age of 33 years for psychiatric disorders (any psychiatric disorder, psychosis, SUD, mood disorders and anxiety disorders) by using nationwide register linkage data. Cox-regression analysis with Hazard Ratios (HR, with 95% confidence intervals (CI)) was used to assess the risk of later psychiatric disorders associated with AFI. Results Statistically significant associations were observed between AFI and any psychiatric disorder, psychosis, SUDs, and mood disorders. After adjustments for other substance use, family structure, sex and parental psychiatric disorders, AFIs of 13-14 years and ≤12 years were associated with SUD (HR = 5.30; 95%CI 2.38 – 11.82 and HR = 6.49; 95%CI 2.51 – 16.80, respectively), while AFI ≤ 12 years was associated with any psychiatric disorder (HR = 1.59; 95%CI 1.26 -2.02) and mood disorders (HR = 1.81; 95%CI 1.22 -2.68). After further adjustments for Youth Self Report total scores, AFI ≤ 14 was associated with an increased risk of SUD and AFI ≤ 12 with an increased risk of any psychiatric disorder. Conclusions We found significant associations between the early onset of alcohol intoxication, later SUD and any psychiatric disorder in a general population sample. This further supports the need for preventive efforts to postpone the first instances of adolescent alcohol intoxication.
Article
Cannabis is the most commonly used illicit drug in the United States. Over the past decade its use has increased, with young adults/college aged individuals having the highest proportion of users compared to any other age group. Given the high rates of usage in this age group, cannabis use is an important aspect of mental and physical health in college-aged adults. Current evidence indicates that marijuana use, especially early and dose-dependent use, can have significant negative ramifications on general functioning, academic performance, psychiatric wellness, and may be causally related to development of other substance use disorders and risky behaviors. No strong evidence supports marijuana as a beneficial treatment for any psychiatric indication, however there is evidence supporting the use of cannabidiol (CBD) in illnesses such as epilepsy. Providers must be well apprised of the current evidence base for both detecting and treating marijuana use disorder given its increasing prevalence and decreasing perception of risk. Screening of cannabis use disorder and treatment with appropriate therapy is highly important for college mental health.
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Purpose The M onitoring Y oung Life styles (MyLife) project was initiated as an integrated quantitative and qualitative prospective investigation of correlates, causes, and consequences of adolescent substance use and other addictive behaviours in Norway. Participants The MyLife cohort was recruited from middle schools in Norway, which were selected from low, medium and high standard of living areas in both rural and urban regions of the country. A total of 3512 eighth, ninth and tenth graders (55% girls) from 33 schools were enrolled in the quantitative project arm (QT), while a total of 120 eighth graders (52% girls) from six schools were enrolled in the qualitative project arm (QL). Findings to date QT baseline was conducted in the fall of 2017, when 2975 adolescents completed an online questionnaire at school during a regular class time. A total of 2857 adolescents participated in the first QT follow-up 1 year later. QL baseline was conducted across the fall semesters of 2014 (one class) and 2015 (five classes), when a total of 118 eighth graders completed face-to-face interviews. QL follow-ups were conducted in the spring of 2015 and fall of 2017 (n=98) for group interviews, and in the spring of 2017 and 2018 (n=95) for individual interviews. In terms of additional data sources, a total of 3035 parents consented to own participation, of which 1899 completed a brief online questionnaire at QT baseline in late 2017. School principals completed brief surveys at the same time. Future plans Both QT and QL arms have planned follow-ups through 2021. Consents were obtained for individual-level linkages of adolescent and parental quantitative surveys to each other, as well as to the information available in multiple national registries and databases. These supplemental data sources will provide key information on additional putative exposures as well as on the long-term health, educational, and social outcomes of the MyLife participants.
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Background and aims: Little is known about how cannabis use over the life course relates to harms in adulthood. The present study aimed to identify trajectories of cannabis use from adolescence to adulthood and examine both the predictors of these trajectories and adverse adult outcomes associated with those trajectories. Design: A latent trajectory analysis of a longitudinal birth cohort (from birth to age 35 years). Setting and participants: General community sample (n=1,065) from New Zealand. Measurement: Annual frequency of cannabis use (ages 15-35); childhood family and individual characteristics (birth to age 16); measures of adult outcomes (substance use disorders ages 30-35; mental health disorders ages 30-35; socioeconomic outcomes at age 35; social/family outcomes at age 35). Findings: A six class solution was the best fit to the data. Individuals assigned to trajectories with higher levels of cannabis use were more likely to have experienced adverse childhood family and individual circumstances. Membership of trajectories with higher levels of use was associated with increased risk of adverse outcomes at ages 30-35. Adjustment of these associations for the childhood family and individual predictors largely did not reduce the magnitude of the associations. Conclusions: In New Zealand, long-term frequent cannabis use, or transition to such use, appears to be robustly associated with diverse harms in adulthood.
Article
Preceding initiation, opportunity to use heroin is the earliest necessary condition for heroin-related outcomes to occur. This study aimed to characterise first heroin use opportunity (prior to initiation) and to identify heroin-related outcomes associated with earlier age at first opportunity. Structured interviews were conducted with 93 opiate substitution treatment clients in UK drug and alcohol treatment clinics. The majority of participants (64.8%) reported initiating heroin use on the same day as being first presented with the opportunity to use heroin. Of those who reported early age at opportunity to use heroin, 77.4% reported this came from friends/partner/family compared with 59.3% of those who reported later opportunities. After adjustment, overdose was found to be more than twice as likely amongst those who reported first opportunity to use heroin at age 17 or under (AOR 2.82 95% CI 1.57–5.05). Findings indicate the early drug use environment is linked to later risk of overdose. Greater consideration of context surrounding heroin use opportunity may indicate mechanisms to disrupt or prevent initiation of heroin use and later drug-related harms. Given short latency to initiation, focus should be placed on preventing initiation of heroin use through injecting.
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During the early 1970s Denise Kandel and her colleagues documented an ‘invariant sequence’ in initiation of drug use: starting with alcohol and tobacco, progressing to cannabis and then to other illicit, or ‘harder’ drugs. This observation, which became known as the ‘gateway sequence’ of drug use, has been influential in policy debates but remains highly contentious, with the area of greatest controversy focusing upon whether cannabis use increases risk causally for initiation of other illicit drugs. While numerous studies have replicated Kandel's initial findings (sequence of onset) and reported that associations between cannabis use and the use of other illicit drugs remain after controlling for potentially confounding factors, the mechanisms underlying these observed associations remain hotly debated. In particular, it is possible that the observed associations are non‐causal but reflect the influence of confounding factors which influence both early‐onset drug use and subsequent progressions. However, research employing a range of techniques to address this issue has been unable to discount the possibility that associations between earlier and subsequent drug use reflect causal processes. This paper reviews Kandel's ongoing contributions to this field, which span 45 years, and discusses both the influence of her work and the controversy that it has aroused.
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Background and aims: Parental alcohol use disorders (AUDs) and parental separation are associated with increased risk for early use of alcohol in offspring, but whether they increase risks for early use of other substances and for early sexual debut is under-studied. We focused on associations of parental AUDs and parental separation with substance initiation and sexual debut to (1) test the strength of the associations of parental AUDs and parental separation with time to initiation (age in years) of alcohol, tobacco and cannabis use and sexual debut and (2) compare the strength of association of parental AUD and parental separation with initiation. Design: Prospective adolescent and young adult cohort of a high-risk family study, the Collaborative Study on the Genetics of Alcoholism (COGA). Setting: Six sites in the United States. Participants: A total of 3257 offspring (aged 14-33 years) first assessed in 2004 and sought for interview approximately every 2 years thereafter; 1945 (59.7%) offspring had a parent with an AUD. Measurements: Diagnostic interview data on offspring substance use and sexual debut were based on first report of these experiences. Parental life-time AUD was based on their own self-report when parents were interviewed (1991-2005) for most parents, or on offspring and other family member reports for parents who were not interviewed. Parental separation was based on offspring reports of not living with both biological parents most of the time between ages 12 and 17 years. Findings: Parental AUDs were associated with increased hazards for all outcomes, with cumulative hazards ranging from 1.19 to 2.71. Parental separation was also an independent and consistent predictor of early substance use and sexual debut, with hazards ranging from 1.19 to 2.34. The strength of association of parental separation with substance initiation was equal to that of having two AUD-affected parents, and its association with sexual debut was stronger than the association of parental AUD in one or both parents. Conclusions: Parental alcohol use disorders (AUDs) and parental separation are independent and consistent predictors of increased risk for early alcohol, tobacco and cannabis use and sexual debut in offspring from families with a high risk of parental AUDs.
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Adolescent substance use is of considerable public health importance. This narrative review provides a brief background to genetically informative research methodologies and highlights key recent literature examining the interplay between genetic and environmental influences in the etiology of substance use. Twin studies have quantified the magnitude of genetic and environmental influences, and more recently, co-relative and Children of Twin designs have shown environments can moderate heritability. Studies have identified a number of specific gene variants (e.g. OPRM1, DRD4, 5HTTLPR) that interact with parenting and peer influence, and the effectiveness of interventions may vary by genotype. However, little research has taken into account the stage-sequential nature of substance use. This may obscure important differences in the genetic and environmental influences, and their interplay, at the stages of escalation to problem use. Future research needs to build on existing methodologies to disentangle the complexities of progression in adolescent substance use.
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Background: As drugs remain ubiquitous and their use increasingly viewed as socially normative, vulnerable population groups such as adolescents face continued and growing risk. A better understanding of the factors that discourage individuals from initiating drug use, particularly in enabling scenarios, is therefore needed. This study aims to identify individual, interpersonal and school-contextual factors associated with resistance to using drugs in the presence of a drug use opportunity among adolescents in Bogotá, Colombia. Methods: Data are analyzed from 724 school-attending adolescents (15.1 years, SD=1.3) who have had an opportunity to use drugs. Schools were selected in a multistage probability cluster sample. Random intercept multilevel logistic regression models were implemented to estimate the effect of individual, interpersonal and school-contextual level variables on the likelihood of resisting using drugs. Results: Drug use resistance was observed in less than half (41.4%) of those students who experienced an opportunity to use drugs. Drug use resistance was strongly associated with having experienced a passive drug use opportunity (AOR = 3.1, 95% CI = 2.0, 4.9), the number of drugs offered (AOR = 0.7, 95% CI = 0.6, 0.8) and family factors such as not having a drug-using first-degree relative (AOR = 2.3, 95% CI=1.2, 4.3) and a high degree of parental supervision (AOR = 1.9, 95% CI = 1.0, 3.2). Conclusions: A large proportion of students who experienced a drug-use opportunity did not initiate drug use despite living in a context of high drug availability and social disorganization. The findings highlight the need for effective family-based drug use prevention interventions within the Colombian context.
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Aims To determine the degree to which cigarette smoking predicts levels of cannabis dependence above and beyond cannabis use itself, concurrently and in an exploratory four-year follow-up, and to investigate whether cigarette smoking mediates the relationship between cannabis use and cannabis dependence. Methods The study was cross sectional with an exploratory follow-up in the participants’ own homes or via telephone interviews in the United Kingdom. Participants were 298 cannabis and tobacco users aged between 16 and 23; follow-up consisted of 65 cannabis and tobacco users. The primary outcome variable was cannabis dependence as measured by the Severity of Dependence Scale (SDS). Cannabis and tobacco smoking were assessed through a self-reported drug history. Results Regression analyses at baseline showed cigarette smoking (frequency of cigarette smoking: B = 0.029, 95% CI = 0.01, 0.05; years of cigarette smoking: B = 0.159, 95% CI = 0.05, 0.27) accounted for 29% of the variance in cannabis dependence when controlling for frequency of cannabis use. At follow-up, only baseline cannabis dependence predicted follow-up cannabis dependence (B = 0.274, 95% CI = 0.05, 0.53). At baseline, cigarette smoking mediated the relationship between frequency of cannabis use and dependence (B = 0.0168, 95% CI = 0.008, 0.288) even when controlling for possible confounding variables (B = 0.0153, 95% CI = 0.007, 0.027). Conclusions Cigarette smoking is related to concurrent cannabis dependence independently of cannabis use frequency. Cigarette smoking also mediates the relationship between cannabis use and cannabis dependence suggesting tobacco is a partial driver of cannabis dependence in young people who use cannabis and tobacco.
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Cannabis is the most widely used illicit drug throughout the developed world and there is consistent evidence of heritable influences on multiple stages of cannabis involvement including initiation of use and abuse/dependence. In this paper, we describe the methodology and preliminary results of a large-scale interview study of 3,824 young adult twins (born 1972–1979) and their siblings. Cannabis use was common with 75.2% of males and 64.7% of females reporting some lifetime use of cannabis while 24.5% of males and 11.8% of females reported meeting criteria for DSM-IV cannabis abuse or dependence. Rates of other drug use disorders and common psychiatric conditions were highly correlated with extent of cannabis involvement and there was consistent evidence of heritable influences across a range of cannabis phenotypes including early (≤15 years) opportunity to use (h 2 = 72%), early (≤16 years) onset use (h 2 = 80%), using cannabis 11+ times lifetime (h 2 = 76%), and DSM abuse/dependence (h 2 = 72%). Early age of onset of cannabis use was strongly associated with increased rates of subsequent use of other illicit drugs and with illicit drug abuse/dependence; further analyses indicating that some component of this association may have been mediated by increasing exposure to and opportunity to use other illicit drugs.
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Aims. To examine the reliability of self-reported age of first substance use experiences among national samples of adult and child respondents. Design. Survey responses from seven waves of the National Longitudinal Survey of Youth (NLSY) were examined. Participants. Adult and child NLSY respondents reporting age of first tobacco, alcohol, marijuana, cocaine and/or crack use during two or more survey interviews. Measurements. Four indicators of reliability: intraclass correlation coefficients (ICC), mean and absolute mean differences in reported age and reports consistent within 1 year. Findings. The adjusted mean ICC for all comparisons was 0.69. The adjusted mean difference in self-reported age of first substance use was - 0.52 years and the adjusted absolute mean difference was 2.00 years. The adjusted percentage of all comparisons reporting ages consistent within 1 year was 55.28%. More consistent reports were provided by adults, and in response to questions posed over 2 years as opposed to longer time intervals. Respondent answers to questions concerned with first use of marijuana were generally found to be most reliable; questions concerned with first use of crack were least reliable and reports of tobacco, alcohol and cocaine were intermediate. Logistic regression analyses also identified age, race, gender, education and poverty status as predictors of consistent reporting. Conclusions. Self-reports of age of first substance use experiences, as currently collected via survey questionnaires, are of sufficient reliability for most current epidemiological applications. For inquiries where age of substance use onset is itself a research focus, however, researchers should invest additional effort in improving the reliability of measurement.
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Marijuana is the most prevalent illicit drug used by adolescents and young adults, yet marijuana initiation is rarely studied past adolescence. The present study sought to advance our understanding of parent and peer influences on marijuana exposure opportunity and incident use during college. A sample of 1,253 students was assessed annually for 4 years starting with the summer prior to college entry. More than one-third (38%(wt)) of students had already used marijuana at least once prior to college entry; another 25%(wt) initiated use after starting college. Of the 360 students who did not use marijuana prior to college, 74% were offered marijuana during college; of these individuals, 54% initiated marijuana use. Both low levels of parental monitoring during the last year of high school and a high percentage of marijuana-using peers independently predicted marijuana exposure opportunity during college, holding constant demographics and other factors (AOR = 0.92, 95% CI = 0.88-0.96, p < .001 and AOR = 1.11, 95% CI = 1.08-1.14, p < .001, respectively). Among individuals with exposure opportunity, peer marijuana use (AOR = 1.04, 95% CI = 1.03-1.05, p < .001), but not parental monitoring, was associated with marijuana initiation. Results underscore that peer influences operate well into late adolescence and young adulthood and thus suggest the need for innovative peer-focused prevention strategies. Parental monitoring during high school appears to influence exposure opportunity in college; thus, parents should be encouraged to sustain rule-setting and communication about adolescent activities and friend selection throughout high school.
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Sex differences in opportunities to use alcohol or drugs, and transition to use, were investigated in 15 surveys, in 2001-2004 (Europe 6; Americas 3; Africa 2, Asia 3; Oceania 1). The paper focuses on 18-29 year olds (N = 9,873). The World Mental Health Survey Initiative oversaw the surveys; each country obtained its own funding. A complex picture emerged with different results for alcohol and for drugs and for opportunity to use and the transition to use. Sex differences in opportunity to use alcohol were small except in Lebanon and Nigeria, whereas for drugs, the largest differences were in Mexico and Colombia.
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Among adolescents and young adults with DSM-IV alcohol use disorders (AUDs), there are inter-individual differences in the speed of transition from initial alcohol use (AU) to AUD. AUDs are highly co-morbid with other mental disorders. The factors associated with rapid transition from first AU to AUD remain unknown and the role of mental disorders in rapid transitions is unclear. Given this background we examined (1) whether prior anxiety, mood, externalizing and non-alcohol substance use disorders are related to the risk and speed of transition from first AU to DSM-IV alcohol abuse (AA) and alcohol dependence (AD) and (2) whether early age of onset of prior mental disorders (PMDs) is a promoter of rapid transition. A total of 3021 community subjects (97.7% lifetime AU) aged 14-24 years at baseline were followed up prospectively for up to 10 years. AU and mental disorders were assessed with the DSM-IV/M-CIDI. Among subjects with lifetime AU, several PMDs, such as specific phobia, bipolar disorder and nicotine dependence, were associated with an increased risk of AUD independent of externalizing disorders. Associations of PMDs with the speed of transition to AUDs were mostly weak and inconsistent. Only social phobia and externalizing disorders were associated with faster transitions to AD even after adjustment for other PMDs. Earlier age of onset of PMD was not associated with rapid transition. Mental disorders are associated with the risk of AUD. With the possible exception of social phobia and externalizing disorders, they do not promote rapid transition, even if they occur particularly early. Future research needs to identify factors relevant to rapid transition to AUD.
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The Cox model relies on the proportional hazards (PH) assumption, implying that the factors investigated have a constant impact on the hazard - or risk - over time. We emphasize the importance of this assumption and the misleading conclusions that can be inferred if it is violated; this is particularly essential in the presence of long follow-ups. We illustrate our discussion by analyzing prognostic factors of metastases in 979 women treated for breast cancer with surgery. Age, tumour size and grade, lymph node involvement, peritumoral vascular invasion (PVI), status of hormone receptors (HRec), Her2, and Mib1 were considered. Median follow-up was 14 years; 264 women developed metastases. The conventional Cox model suggested that all factors but HRec, Her2, and Mib1 status were strong prognostic factors of metastases. Additional tests indicated that the PH assumption was not satisfied for some variables of the model. Tumour grade had a significant time-varying effect, but although its effect diminished over time, it remained strong. Interestingly, while the conventional Cox model did not show any significant effect of the HRec status, tests provided strong evidence that this variable had a non-constant effect over time. Negative HRec status increased the risk of metastases early but became protective thereafter. This reversal of effect may explain non-significant hazard ratios provided by previous conventional Cox analyses in studies with long follow-ups. Investigating time-varying effects should be an integral part of Cox survival analyses. Detecting and accounting for time-varying effects provide insights on some specific time patterns, and on valuable biological information that could be missed otherwise.
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Although previous twin studies have modeled the association between drug initiation and abuse, none has included the obvious risk factor of drug availability. Our aim is to determine whether the genetic and environmental risk factors for cannabis availability also generate variation in cannabis initiation and/or progression to DSM-IV symptoms of abuse. We used multi-stage modeling, also known as causal-common-contingent (CCC) analysis, to partition the genetic and environmental factors into common and stage-specific components. This report is based on data collected from 1772 adult males from the Mid Atlantic Twin Registry. The twins participated in two structured interviews which included clinical and non-clinical measures of cannabis abuse as well as retrospective assessments of perceived cannabis availability between ages 8 and 25 years. Cannabis availability explained almost all the shared environmental risks in cannabis initiation and abuse. The influence of availability on the symptoms of abuse was indirect and mediated entirely by cannabis initiation. These findings have begun to elucidate the causal processes underlying the liability to drug use and abuse in terms of putative risk factors. Specifically, our results show that the latent shared environmental factors in cannabis initiation and abuse can be explained by measured aspects of the shared environment--those responsible for variation in cannabis availability.
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Within- and cross-center test-retest studies were conducted to study the reliability of a new, semistructured, comprehensive, polydiagnostic psychiatric interview being used in a multisite genetic linkage study of alcoholism. Findings from both studies indicated that reliability for the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) was high for DSM-III-R substance dependence disorders, but less so for substance abuse disorders. Reliability of depression was good in both studies, but mixed for antisocial personality disorder (ASP). Findings are presented in terms of specific substance dependence and abuse diagnoses, as well as for depression and ASP. Criterion-specific reliabilities are examined by type of substance used. Although SSAGA was designed to provide for broad phenotyping of alcoholism, review of its new features suggests its suitability for a variety of family studies, not just those focusing on substance abuse.
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Genetic influences on alcoholism risk are well-documented in men, but uncertain in women. We tested for gender differences in genetic influences on, and risk-factors for, DSM-III-R alcohol dependence (AD). Diagnostic follow-up interviews were conducted in 1992-3 by telephone with twins from an Australian twin panel first surveyed in 1980-82 (N = 5889 respondents). Data were analysed using logistic regression models. Significantly higher twin pair concordances were observed in MZ compared to DZ same-sex twin pairs in women and men, even when data were weighted to adjust for over-representation of well-educated respondents, and for selective attrition. AD risk was increased in younger birth cohorts, in Catholic males or women reporting no religious affiliation, in those reporting a history of conduct disorder or major depression and in those with high Neuroticism, Social Non-conformity, Toughmindedness, Novelty-Seeking or (in women only) Extraversion scores; and decreased in 'Other Protestants', weekly church attenders, and university-educated males. Controlling for these variables, however, did not remove the significant association with having an alcoholic MZ co-twin, implying that much of the genetic influence on AD risk remained unexplained. No significant gender difference in the genetic variance in AD was found (64% heritability, 95% confidence interval 32-73%). Genetic risk-factors play as important a role in determining AD risk in women as in men. With the exception of certain sociocultural variables such as religious affiliation, the same personality, sociodemographic and axis I correlates of alcoholism risk are observed in women and men.
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To determine whether cannabis use in adolescence predisposes to higher rates of depression and anxiety in young adulthood. Seven wave cohort study over six years. 44 schools in the Australian state of Victoria. A statewide secondary school sample of 1601 students aged 14-15 followed for seven years. Interview measure of depression and anxiety (revised clinical interview schedule) at wave 7. Some 60% of participants had used cannabis by the age of 20; 7% were daily users at that point. Daily use in young women was associated with an over fivefold increase in the odds of reporting a state of depression and anxiety after adjustment for intercurrent use of other substances (odds ratio 5.6, 95% confidence interval 2.6 to 12). Weekly or more frequent cannabis use in teenagers predicted an approximately twofold increase in risk for later depression and anxiety (1.9, 1.1 to 3.3) after adjustment for potential baseline confounders. In contrast, depression and anxiety in teenagers predicted neither later weekly nor daily cannabis use. Frequent cannabis use in teenage girls predicts later depression and anxiety, with daily users carrying the highest risk. Given recent increasing levels of cannabis use, measures to reduce frequent and heavy recreational use seem warranted.
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Parenting practices have been linked with an array of adolescent health-compromising behaviors, but little is known about their possible long-lasting effects. In this study, we estimate the extent to which parental monitoring, parental involvement and reinforcement, and coercive parental discipline during primary school might exert a durable influence on the risk of transitioning into an early stage of youthful cannabis involvement, ie, the first chance to try cannabis. Data were from a prospective study of first-graders who entered an urban public school system in the middle 1980s. Parenting was assessed in fourth grade, and cannabis experiences were evaluated during periodic assessments from middle childhood through young adulthood. The estimated risk of the first chance to try cannabis peaked around 16 to 18 years of age. Lower parental involvement and reinforcement and higher coercive parental discipline were associated modestly with a greater risk of cannabis exposure opportunity through the years of adolescence and into early adulthood (parental involvement and reinforcement: adjusted relative risk: 1.4; 95% confidence interval: 1.1-1.7; parental discipline: adjusted relative risk: 1.3; 95% confidence interval: 1.1-1.5); the estimated impact of parental monitoring was less durable. Early-onset cannabis involvement can be hazardous. Certain parenting practices in the mid-primary school years may have a durable impact, perhaps helping to shield youths from having a chance to try cannabis throughout adolescence and into young adulthood.
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Alcohol, tobacco, and illegal drug use cause considerable morbidity and mortality, but good cross-national epidemiological data are limited. This paper describes such data from the first 17 countries participating in the World Health Organization's (WHO's) World Mental Health (WMH) Survey Initiative. Household surveys with a combined sample size of 85,052 were carried out in the Americas (Colombia, Mexico, United States), Europe (Belgium, France, Germany, Italy, Netherlands, Spain, Ukraine), Middle East and Africa (Israel, Lebanon, Nigeria, South Africa), Asia (Japan, People's Republic of China), and Oceania (New Zealand). The WHO Composite International Diagnostic Interview (CIDI) was used to assess the prevalence and correlates of a wide variety of mental and substance disorders. This paper focuses on lifetime use and age of initiation of tobacco, alcohol, cannabis, and cocaine. Alcohol had been used by most in the Americas, Europe, Japan, and New Zealand, with smaller proportions in the Middle East, Africa, and China. Cannabis use in the US and New Zealand (both 42%) was far higher than in any other country. The US was also an outlier in cocaine use (16%). Males were more likely than females to have used drugs; and a sex-cohort interaction was observed, whereby not only were younger cohorts more likely to use all drugs, but the male-female gap was closing in more recent cohorts. The period of risk for drug initiation also appears to be lengthening longer into adulthood among more recent cohorts. Associations with sociodemographic variables were consistent across countries, as were the curves of incidence of lifetime use. Globally, drug use is not distributed evenly and is not simply related to drug policy, since countries with stringent user-level illegal drug policies did not have lower levels of use than countries with liberal ones. Sex differences were consistently documented, but are decreasing in more recent cohorts, who also have higher levels of illegal drug use and extensions in the period of risk for initiation.
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This chapter describes selected features of cannabis epidemiology, with a focus upon recent evidence from field studies of cannabis dependence. An epidemiologist's interest in cannabis can be motivated by an appreciation that cannabis smoking represents the most common illegal drug use behavior in the world, with a roughly estimated 140–150 million cannabis users, as compared to rough estimates of 14–15 million for cocaine and 13–14 million for opium, heroin, and other opioid drugs (United Nations, 2002). Based upon recent estimates, projections, and averages for the USA, an estimated 7000–8000 individuals start using cannabis every day and there are 95 million US community residents who have tried cannabis on at least one occasion (Substance Abuse and Mental Health Services Administration, Office of Applied Studies (SAMHSA), 2002c, d). As will be documented later in this chapter, our rough averaged estimate is that some 50–80 recent-onset cannabis users develop a cannabis dependence syndrome each day during the year; some substantial fraction of these cases appear to require clinical intervention services. It is generally possible to dissect epidemiological research in relation to five general rubrics or sub-headings. The first rubric concerns quantification of disease burden, including the burdens associated with mental and behavioral disturbances that do not qualify as formal diseases, as well as the population-averaged “incidence” and individual-level risk of becoming a cannabis user, and the separately estimated population-averaged “prevalence” and individual-level likelihood of being an active or former cannabis user (e.g., see Anthony & Van Etten, 1998, Wu, et al ., 2003, for detailed discussions of the distinctions between incidence and prevalence).
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To test whether speed of transition from first use to subsequent use of cannabis is associated with likelihood of later cannabis dependence and other outcomes, and whether transition speed is attributable to genetic or environmental factors. Cross-sectional interview study SETTING: Australia PARTICIPANTS: 2239 twins and siblings who reported using cannabis at least twice (mean age at time of survey = 32.0, 95% CI 31.9 - 32.1, range 22-45). Time between first and subsequent cannabis use (within 1 week; within 3 months; between 3 months - 12 months; more than 1 year later), later use of cannabis and symptoms of DSM-IV cannabis abuse/dependence. Multinomial regression analyses (comparison group: more than 1 year later) adjusted the association between speed of transition and the outcomes of cannabis daily use, abuse/dependence, and treatment-seeking after controlling for socio-demographic, childhood, mental health, peer and licit drug factors. Twin modelling estimated the proportion of variance in transition speed attributable to genetic (A), common environment (C) and unique environmental (E) factors. Subsequent use of cannabis within one week of first use was associated with daily use (OR 2.64, 95% CI 1.75 - 3.99), abuse and/or dependence (OR 3.25, 95%CI 2.31 - 4.56) and treatment-seeking for cannabis problems (OR 1.89, 95%CI 1.03 - 3.46). Subsequent use within 3 months was associated with abuse and/or dependence (OR 1.61, 95%CI 1.18 - 2.19). The majority of the variation of the speed of transition was accounted for by unique environment factors (0.75). Rapid transition from initiation to subsequent use of cannabis is associated with increased likelihood of subsequent daily cannabis use and abuse/dependence. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
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Background: The association between cannabis use and mood disorders is well documented, yet evidence regarding causality is conflicting. This study explored the association between cannabis use, major depressive disorder (MDD) and bipolar disorder (BPD) in a 3-year prospective study. Methods: Data was drawn from waves 1 and 2 of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). MDD and BPD were controlled at baseline and defined as meeting full criteria in the 12 months prior to the follow-up. Initiation of cannabis use was defined as any cannabis used by former lifetime abstainers in the time period between baseline and follow-up. Results: Cannabis use was not significantly associated with increased incidence of MDD (Adjusted Odds Ratio (AOR) for daily use=0.58(0.22-1.51)). Weekly to almost daily cannabis use was associated with increased incidence of BPD ((AOR for weekly to daily use=2.47(1.03-5.92)); daily use was not (AOR=0.52(0.17-1.55)). Baseline MDD was associated with initiation of cannabis use (AOR=1.72(1.1-2.69)). A crude association between baseline BPD and incidence of cannabis use was not maintained in adjusted models (AOR=0.61(0.36-1.04)). Limitations: Lack of information regarding frequency of cannabis use at follow-up and limitations regarding generalization of the results. Conclusions: Our findings do not support a longitudinal association between cannabis use and incidence of MDD. Results regarding the association between cannabis use and incidence of BPD are conflicting and require further investigation. Baseline MDD, but not BPD, may be associated with future initiation of cannabis use. This may have implications for clinical, social and legislative aspects of cannabis use.
Article
Background: The aim of this study was to examine how patterns of academic and behavior problems in the first grade relate to longitudinal transitions in marijuana use from middle school through entry into high school among African-Americans. Methods: Latent class and latent transition analyses were conducted on a community sample of 458 low-income, urban-dwelling African-Americans. Results: Two behavior problem classes emerged at school entry; externalizing and attention/concentration. Academic problems co-occurred with both problem behavior classes although more strongly with attention/concentration. Youth in the attention/ concentration problem class were more likely to transition from no marijuana involvement to use and problems beginning in the 7th grade and to use and problems given the opportunity to use marijuana early in high school compared to youth with no problems. Youth in the externalizing behavior problem class were significantly more likely to transition from no involvement to having a marijuana opportunity during the transition to high school compared to youth in the attention/concentration problems class. Conclusions: These findings highlight the importance of developing prevention programs and providing school services that address the co-occurrence of academic and behavior problems, as well as their subtype specific risks for marijuana involvement, particularly for low-income minority youth who may be entering school less ready than their non-minority peers. These findings also provide evidence for a need to continue to deliver interventions in middle school and high school focused on factors that may protect youth during these critical transition periods when they may be especially vulnerable to opportunities to use marijuana based on their academic and behavioral risk profiles.
Article
The Global Burden of Disease (GBD) 2010 study updated the findings of earlier exercises. It provided regional and global estimates of the burden of disease attributable to diseases, injuries and risk factors. Here we provide a brief summary of the work for illicit drug use. Systematic reviews were undertaken to estimate the major epidemiological parameters (incidence, prevalence, duration/remission and mortality) for each drug. Reviews evaluated the nature and quality of evidence for illicit drug use as a risk factor for many health outcomes, for the comparative risk assessment (CRA) exercise. Substantial gaps existed in basic epidemiological parameters. Following modelling and imputation of missing data, it was estimated that opioid and amphetamine dependence were the most common forms of illicit drug dependence in 2010; opioid dependence was responsible for the greatest burden. Few putative consequences of illicit drug use had the quality or quantity of data required to be included in the CRA. Estimates of the extent and distribution of disease burden are likely to shape global and regional health policy development. The GBD exercise will be repeated on an annual basis; GBD 2010 clearly demonstrated that although the illicit drug field is generating more and better epidemiological data on the health risks of drug use, there is still much work to be done to generate defensible estimates of the magnitude of risk, particularly for impactful and prevalent outcomes, such as injuries, violence and mental health complications. Until then, burden of disease attributable to illicit drugs will be underestimated. [Degenhardt L, Whiteford H, Hall WD. The Global Burden of Disease projects: What have we learned about illicit drug use and dependence and their contribution to the global burden of disease? Drug Alcohol Rev 2013].
Article
Twin studies are well known for their value in quantifying the contribution of genes to population variation in behaviors and personality traits. Twin studies also provide a unique opportunity to untangle the contribution of environmental experiences to emotional and behavioral development. This is particularly true when examining monozygotic (MZ) twins since they represent a pair of individuals naturally matched on both their genetic background and their shared environment, thus allowing the identification of environmental experiences unique to each twin which may impact developmental outcome. This article presents two analytical strategies based on the discordant MZ-twin method. It stresses the power of this method to establish plausible causal pathways between environmental factors and developmental outcomes, and provides examples from the socio-developmental literature to illustrate its application. It also describes the limitations of this method and its requirements for optimal utilization.
Article
D.R. Cox has suggested a simple method for the regression analysis of censored data. We carry out an information calculation which shows that Cox's method has full asymptotic efficiency under conditions which are likely to be satisfied in many realistic situations. The connection of Cox's method with the Kaplan-Meier estimator of a survival curve is made explicit.
Article
Background: Studies have shown that those who experience chronic childhood adversity have a greater likelihood of substance abuse and dependence. However, substance use disorders are first preceded by substance use, and substance use is preceded by substance use opportunities. This study aims to estimate the association of chronic adversity with different stages of substance involvement: opportunities, use given the opportunity and abuse or dependence given use. Methods: 3005 adolescents aged 12-17 were interviewed in a stratified multistage general population probability survey of Mexico City, Mexico. Substance involvement and chronic childhood adversities were assessed with the World Mental Health Composite International Diagnostic Interview Adolescent Version (WMH-CIDI-A). Discrete-time survival models were performed; their survival coefficients and standard errors were exponentiated, and reported as odds-ratios (ORs). Results: Childhood adversities were associated with alcohol opportunity, alcohol use and alcohol abuse/dependence with significant ORs for individual adversities ranging from 1.4 to 4.1. Childhood adversities were also associated with illicit drug opportunity, drug use and drug abuse/dependence with significant ORs for individual adversities ranging from 1.6 to 17.3. Having more adversities was associated with greater incremental odds of substance involvement, particularly drug use given the opportunity. Conclusions: While adversities are mostly related to transitioning into use and disorder, a few are related to substance opportunities, particularly those which were likely to make substances available through parents. Attending to the needs of youth living in adversity, particularly adversities related to parental dysfunction and child abuse should be integral to addiction prevention efforts.
Article
INTRODUCTION: Alcohol use disorders (AUD) and cannabis use disorders (CUD) are common in the United States (US), and are associated with major depressive disorder (MDD). Co-occurring alcohol and cannabis use/use disorders (AUD+CUD), though understudied, have been found to be associated with greater adverse outcomes than alcohol or cannabis use/use disorders alone. There is a paucity of research on the co-occurring relationships of the two disorders with depression. METHODS: Data came from Waves 1 and 2 of the National Epidemiologic Survey of Alcohol and Related Conditions (NESARC), a population-based longitudinal survey of the adult non-institutionalized, civilian population in the US. Logistic regression analyses were used to assess the associations between: 1) baseline AUD, CUD, and co-occurring AUD+CUD with incident MDD at follow-up and 2) baseline MDD with incident AUD, CUD, and co-occurring AUD+CUD at follow-up, adjusted for potential confounding variables. RESULTS: For Aim 1, most of the AUD and CUD were positively associated with MDD. The strongest associations with incident MDD were observed for cannabis dependence (OR=6.61, CI=1.67-26.21) and co-occurring alcohol and cannabis dependence (OR=2.34, CI=1.23-4.48). For Aim 2, baseline MDD was significantly associated with comparatively fewer cases of incident AUD and CUD but the strongest association was observed for new onset co-occurring alcohol and cannabis dependence (OR=4.51, CI=1.31-15.60). LIMITATIONS: The present study is limited by the potential for social desirability and recall biases. DISCUSSION: Positive associations between AUD, CUD and MDD were observed bidirectionally. Findings have implications for preventive and treatment programs and initiatives.
Article
Introduction: We examine whether regular cigarette smokers were more likely to be exposed to and use cannabis at an earlier age, and further, upon initiation, whether their initial experiences with cannabis varied from those reported by never/non-regular cigarette smokers. Method: A sample of 3797 Australian twins and siblings aged 21-46 years was used. Survival analyses examined whether cigarette smokers were at increased likelihood of early opportunity to use cannabis and early onset of cannabis use. Logistic regression examined whether cigarette smokers reported greater enjoyment of their cannabis experience, inhaling on the first try, differing positive and negative initial subjective reactions, smoked cigarettes with cannabis the first time and were more likely to try cannabis again within a week. Results: Regular cigarette smokers were more likely to report an earlier opportunity to use cannabis and early onset of cannabis use. Regular cigarette smokers were also considerably more likely to have enjoyed their first experience with cannabis and reported higher rates of positive initial reactions. They were more likely to report inhaling on the first try and smoking cigarettes with cannabis. Potentially negative subjective reactions were also elevated in regular cigarette smokers. Importantly, cigarette smokers were at 1.87 increased odds of smoking cannabis within a week of their initial use. Conclusion: These findings indicate that the well-known overlap in cannabis and cigarette smoking behaviors may evolve as early as opportunity to use and extend through the course of the substance use trajectory.
Article
There is substantial evidence that alcohol, tobacco, and cannabis dependence problems surface more quickly when use of these drugs starts before adulthood, but the evidence based on other internationally regulated drugs (e.g., cocaine) is meager. With focus on an interval of up to 24 months following first drug use, we examine drug-specific and age-specific variation in profiles of early-emerging clinical features associated with drug dependence. Based upon the United States National Surveys on Drug Use and Health (NSDUH) conducted in 2000–2002, the risk of experiencing drug dependence problems was robustly greater for adolescent recent-onset users of cocaine, psychostimulant drugs other than cocaine, analgesics, anxiolytic medicines, inhalants drugs, and cannabis, as compared to adult recent-onset users (odds ratio = 1.5–4.3, p < 0.05). This was not the case for the NSDUH hallucinogens group (e.g., LSD). The adolescent onset associated excess risk was not constant across all clinical features. Our evidence suggests promoting earlier detection and interventions, as well as greater parent and peer awareness of drug dependence clinical features that may develop early among young people who have just started using drugs.
Article
  Cannabis and tobacco use and misuse frequently co-occur. This review examines the epidemiological evidence supporting the life-time co-occurrence of cannabis and tobacco use and outlines the mechanisms that link these drugs to each other. Mechanisms include (i) shared genetic factors; (ii) shared environmental influences, including (iii) route of administration (via smoking), (iv) co-administration and (v) models of co-use. We also discuss respiratory harms associated with co-use of cannabis and tobacco, overlapping withdrawal syndromes and outline treatment implications for co-occurring use.   Selective review of published studies.   Both cannabis and tobacco use and misuse are influenced by genetic factors, and a proportion of these genetic factors influence both cannabis and tobacco use and misuse. Environmental factors such as availability play an important role, with economic models suggesting a complementary relationship where increases in price of one drug decrease the use of the other. Route of administration and smoking cues may contribute to their sustained use. Similar withdrawal syndromes, with many symptoms in common, may have important treatment implications. Emerging evidence suggests that dual abstinence may predict better cessation outcomes, yet empirically researched treatments tailored for co-occurring use are lacking.   There is accumulating evidence that some mechanisms linking cannabis and tobacco use are distinct from those contributing to co-occurring use of drugs in general. There is an urgent need for research to identify the underlying mechanisms and harness their potential etiological implications to tailor treatment options for this serious public health challenge.
Article
A younger age at onset of use of a specific substance is a well-documented risk-factor for a substance use disorder (SUD) related to that specific substance. However, the cross-substance relationship between a younger age at onset of alcohol use (AU) and nicotine use (NU) and the risk of cannabis use disorders (CUD) in adolescence and early adulthood remains unclear. To identify the sequence of and latency between initial AU/NU and initial cannabis use (CU). To investigate whether younger age at AU- and NU-onset is associated with any and earlier CU-onset and a higher risk of transition from first CU to CUD, taking into account externalizing disorders (ED) and parental substance use disorders as putative influential factors. Prospective-longitudinal community study with N=3021 subjects (baseline age 14-24) and up to four assessment waves over up to ten years with additional direct parental and family history information. Substance use and CUD were assessed with the DSM-IV/M-CIDI. Most subjects with CU reported AU (99%) and NU (94%). Among users of both substances, 93% reported AU prior to CU (87% for NU). After adjustment for ED and parental substance use disorders younger age at AU-onset was associated with any CU. Younger age at NU-onset was associated with earlier CU initiation. Younger age at AU- and NU-onset was not associated with a higher risk of CUD. The cross-substance relevance of younger age at first AU and NU for the risk of CUD is limited to early CU involvement.
Article
As drugs become more ubiquitous and fewer resources are available for drug prevention and treatment, understanding the early stages of drug use involvement becomes increasingly important for prevention efforts. This study aims to explore the concept of drug use opportunity, and to disentangle, from a socio-ecological perspective, the factors associated with experiencing a drug use opportunity. Data from 2279 standardized questionnaires administered in 23 schools in Bogotá was analyzed. Schools were selected in a multistage probability cluster sample. Multilevel logistic regression modeling estimated the effects of multiple level factors on the likelihood of having experienced an opportunity to use illicit drugs or inhalants. One-third of respondents (32.1%) reported having had an opportunity to use drugs. Even among those who perceived drugs to be readily available and/or expressed intentions to use drugs in the near future, most reported never having experienced an opportunity to use drugs. For most of the drugs assessed, peer drug use, cigarette smoking, alcohol drinking, problematic behavior, and degree of school safety were the strongest correlates of having had a drug use opportunity. Despite living in an environment of high drug availability, most adolescents do not experience opportunities to use drugs. The likelihood of experiencing an opportunity is influenced by multiple interacting individual and macro-social factors, just as drug use is. Drug use opportunities were mainly promoted by friends, suggesting the need to consider their role within close social networks, alongside that of drug suppliers, in the design of intervention activities and drug policy development.
Article
To examine whether male-female differences in rates of drug use could be traced back to differences in rates of exposure to initial opportunities to try drugs, rather than to sex differences in the probability of making a transition to use, once opportunity has occurred. Cross-sectional sample survey research with nationally representative samples and retrospective assessments. United States, 1979-94. Respondents were 131,226 residents aged 12 years and older, recruited for the National Household Surveys on Drug Abuse by multi-stage probability sampling at nine time points. Estimated proportion of males and females with an opportunity to use marijuana, cocaine, hallucinogens and heroin; proportions reporting use among those having an opportunity to use each drug; proportion making a "rapid transition" from initial opportunity to initial use. For each survey year, males were more likely than females to have an initial opportunity to use drugs. However, few male-female differences were observed in the probability of making a transition into drug use, once an opportunity had occurred. Previously documented male excess in rates of drug use may be due to greater male exposure to opportunities to try drugs, rather than to greater chance of progressing from initial opportunity to actual use. This suggests that sex differences in drug involvement emerge early in the process. Implications of these findings are discussed in relation to the epidemiology and prevention of drug use, and future research on sex differences in drug involvement.
Article
Given the weight placed on retrospective reports of age at first drink in studies of later drinking-related outcomes, it is critical that its reliability be established and possible sources of systematic bias be identified. The overall aim of the current study is to explore the possibility that the estimated magnitude of association between early age at first drink and problem alcohol use may be inflated in studies using retrospectively reported age at alcohol use onset. The sample was comprised of 1,716 participants in the Missouri Adolescent Female Twin Study who reported an age at first drink in at least 2 waves of data collection (an average of 4 years apart). Difference in reported age at first drink at Time 2 versus Time 1 was categorized as 2 or more years younger, within 1 year (consistent), or 2 or more years older. The strength of the association between age at first drink and peak frequency of heavy episodic drinking (HED) at Time 1 was compared with that at Time 2. The association between reporting pattern and peak frequency of HED was also examined. A strong association between age at first drink and HED was found for both reports, but it was significantly greater at Time 2. Just over one-third of participants had a 2 year or greater difference in reported age at first drink. The majority of inconsistent reporters gave an older age at Time 2 and individuals with this pattern of reporting engaged in HED less frequently than consistent reporters. The low rate of HED in individuals reporting an older age at first drink at Time 2 suggests that the upward shift in reported age at first drink among early initiates is most pronounced for light drinkers. Heavy drinkers may therefore be overrepresented among early onset users in retrospective studies, leading to inflated estimates of the association between early age at initiation and alcohol misuse.
Article
To prospectively examine the linkage between childhood antecedents and progression to early cannabis involvement as manifest in first chance to try it and then first onset of cannabis use. Two consecutive cohorts of children entering first grade of a public school system of a large mid-Atlantic city in the mid 1980s (n=2311) were assessed (mean age 6.5 years) and then followed into young adulthood (15 years later, mean age 21) when first chance to try and first use were assessed for 75% (n=1698) of the original sample. Assessments obtained at school included standardized readiness scores (reading; math) and teacher ratings of behavioral problems. Regression and time to event models included covariates for sex, race, and family disadvantage. Early classroom misconduct, better reading readiness, and better math readiness predicted either occurrence or timing of first chance to try cannabis, first use, or both. Higher levels of childhood concentration problems and lower social connectedness were not predictive. Childhood school readiness and behavioral problems may influence the risk for cannabis smoking indirectly via an increased likelihood of first chance to use. Prevention efforts that seek to shield youths from having a chance to try cannabis might benefit from attention to early predictive behavioral and school readiness characteristics. When a youth's chance to try cannabis is discovered, there are new windows of opportunity for prevention and intervention.
Article
Using twins assessed during adolescence (Virginia Twin Study of Adolescent Behavioral Development: 8-17 years) and followed up in early adulthood (Young Adult Follow-Up, 18-27 years), we tested 13 genetically informative models of co-occurrence, adapted for the inclusion of covariates. Models were fit, in Mx, to data at both assessments allowing for a comparison of the mechanisms that underlie the lifetime co-occurrence of cannabis and tobacco use in adolescence and early adulthood. Both cannabis and tobacco use were influenced by additive genetic (38-81%) and non-shared environmental factors with the possible role of non-shared environment in the adolescent assessment only. Causation models, where liability to use cannabis exerted a causal influence on the liability to use tobacco fit the adolescent data best, while the reverse causation model (tobacco causes cannabis) fit the early adult data best. Both causation models (cannabis to tobacco and tobacco to cannabis) and the correlated liabilities model fit data from the adolescent and young adult assessments well. Genetic correlations (0.59-0.74) were moderate. Therefore, the relationship between cannabis and tobacco use is fairly similar during adolescence and early adulthood with reciprocal influences across the two psychoactive substances. However, our study could not exclude the possibility that 'gateways' and 'reverse gateways', particularly within a genetic context, exist, such that predisposition to using one substance (cannabis or tobacco) modifies predisposition to using the other. Given the high addictive potential of nicotine and the ubiquitous nature of cannabis use, this is a public health concern worthy of considerable attention.
Article
Studying youthful drug involvement in the Republic of Chile, we sought to replicate North American research findings about the earliest stages of drug involvement (e.g., initial opportunities to use tobacco and alcohol, and transitions leading toward illegal drug use). A nationally representative multistage probability sample of middle and high school students was drawn; 30,490 youths completed surveys that assessed age at first drug exposure opportunities and first actual drug use. Cox discrete-time survival models accommodate the complex sample design and provide transition probability estimates. An estimated 39% of the students had an opportunity to use cannabis, and 70% of these transitioned to actual cannabis use. The probability of cannabis use and the conditional probability of cannabis use (given opportunity) are greater for users of alcohol only, tobacco only, and alcohol plus tobacco, as compared to non-users of alcohol and tobacco. Male-female differences in cannabis use were traced back to male-female differences in drug exposure opportunities. In Chile as in North America, when cannabis use follows alcohol and tobacco use, the mechanism may be understood in two parts: users of alcohol and tobacco are more likely to have opportunities to try cannabis, and once the opportunity occurs, they are more likely to use cannabis. Male-female differences do not seem to be operative within the mechanism that governs transition to use, once the chance to use cannabis has occurred.
Article
The risks associated with early age at initiation for alcohol, cigarette, and cannabis use are well documented, yet the timing of first use has rarely been studied in genetically informative frameworks, leaving the relative contributions of genetic and environmental factors to age at initiation largely unknown. The current study assessed overlap in heritable and environmental influences on the timing of initiation across these three substances in African-American women, using a sample of 462 female twins (100 monozygotic and 131 dizygotic pairs) from the Missouri Adolescent Female Twin Study. Mean age at the time of interview was 25.1 years. Ages at first use of alcohol, cigarettes, and cannabis were gathered in diagnostic interviews administered over the telephone. Standard genetic analyses were conducted with substance use initiation variables categorized as never, late, and early onset. Variance in the timing of first use was attributable in large part to genetic sources: 44% for alcohol, 62% for cigarettes, and 77% for cannabis. Genetic correlations across substances ranged from 0.25 to 0.70. Shared environmental influences were modest for alcohol (10%) and absent for cigarettes and cannabis. Findings contrast with reports from earlier studies based on primarily Caucasian samples, which have suggested a substantial role for shared environment on substance use initiation when measured as lifetime use. By characterizing onset as timing of first use, we may be tapping a separate construct. Differences in findings may also reflect a distinct etiological pathway for substance use initiation in African-American women that could not be detected in previous studies.
Article
Early substance use (SU) in adolescence is known to be associated with an elevated risk of developing substance use disorders (SUD); it remains unclear though whether early SU is associated with more rapid transitions to SUD. To examine the risk and speed of transition from first SU (alcohol, nicotine, cannabis) to SUD as a function of age of first use. N=3021 community subjects aged 14-24 years at baseline were followed-up prospectively over 10-years. SU and SUD were assessed using the DSM-IV/M-CIDI. (1) The conditional probability of substance-specific SU-SUD transition was the greatest for nicotine (36.0%) and the least for cannabis (18.3% for abuse, 6.2% for dependence) with alcohol in between (25.3% for abuse; 11.2% for dependence). (2) In addition to confirming early SU as a risk factor for SUD we find: (3) higher age of onset of any SU to be associated with faster transitions to SUD, except for cannabis dependence. (4) Transitions from first cannabis use (CU) to cannabis use disorders (CUD) occurred faster than for alcohol and nicotine. (5) Use of other substances co-occurred with risk and speed of transitions to specific SUDs. Type of substance and concurrent use of other drugs are of importance for the association between age of first use and the speed of transitions to substance use disorders. Given that further research will identify moderators and mediators affecting these differential associations, these findings may have important implications for designing early and targeted interventions to prevent disorder progression.
Article
The use of behavioural self-reports of drug users is widespread among studies of illicit drug use. Despite widespread use, concerns about the accuracy of these reports continue to be raised. The current paper critically reviews the literature on the reliability and validity of self-reported drug use, criminality and HIV risk-taking among injecting drug users. The literature shows respectable reliability and validity of self-reported behaviours when compared to biomarkers, criminal records and collateral interviews. It concludes that the self-reports of drug users are sufficiently reliable and valid to provide descriptions of drug use, drug-related problems and the natural history of drug use.
Article
The earliest stages of involvement with illicit drugs have been understudied. In a recent report, we examined initial opportunities to try marijuana and transitions from first opportunity to first use of that drug. This report extends that work by investigating early involvement with cocaine, heroin, and hallucinogens as well. We examine sex and race ethnicity differences in estimates of having a drug opportunity, and in the probability of progressing from having an opportunity to try a drug to actually using the drug. Self-report interview data collected for the National Household Surveys on Drug Abuse (NHSDA) from 1979 to 1994 were analyzed. Results showed that an estimated 51% of US residents have had an opportunity to try marijuana; comparative estimates for cocaine, hallucinogens, and heroin are 23, 14, and 5%, respectively. Among those who eventually used each drug, the vast majority made the transition from first opportunity to first use within 1 year. Males were more likely than females to have opportunities to try these drugs, but were not more likely than females to progress to actual use once an opportunity occurred. Time trends indicate recent increases from 1990 to 1994 in the estimated probability of using an illicit drug once an opportunity occurs, particularly for hallucinogens. Exploratory analyses on race ethnicity yielded some interesting leads for future research. This study sheds light on the epidemiology of the earliest stages of drug involvement in the USA. Implications for prevention efforts and for our understanding of sex differences in drug involvement are discussed.
Article
To replicate previous findings among adults of an inverse association between religiosity and substance use among a nationally representative sample of adolescents. Subjects were 676 (328 female and 348 male) adolescents in the National Comorbidity Survey who were assessed for substance use and abuse with the Composite International Diagnostic Interview. Religiosity was assessed through affiliation with religious denomination and through response to 7 questions concerning belief and practice. Confirmatory factor analyses replicated in adolescents the 2 religiosity factors of personal devotion and personal conservatism previously identified by Kendler among adults, although the 2 factors were more highly correlated in adolescents than in adults. Personal devotion (a personal relationship with the Divine) and affiliation with more fundamentalist religious denominations were inversely associated with substance use and substance dependence or abuse across a range of substances (alcohol, marijuana, cocaine, or any contraband drug). Personal conservatism (a personal commitment to teaching and living according to creed) was inversely associated with use of alcohol only. Low levels of religiosity may be associated with adolescent onset of substance use and abuse.
Article
To examine predictors of cannabis use initiation, continuity and progression to daily use in adolescents. Population-based cohort study over 3 years with 6 waves of data collection. 2032 students, initially aged 14-15 years, from 44 secondary schools in the state of Victoria, Australia. Self-report cannabis use was categorized on four levels (none, any, weekly, daily) and summarized as mid-school (waves 2/3) and late-school (waves 4/5/6) use. Background, school environment, mid-school peer use and individual characteristics were assessed. Peer cannabis use, daily smoking, alcohol use, antisocial behaviour and high rates of school-level cannabis use were associated with mid-school cannabis use and independently predicted late-school uptake. Cannabis use persisted into late-school use in 80% of all mid-school users. Persisting cannabis use from mid- to late-school was more likely in regular users (odds ratio (OR) 3.4), cigarette smokers (OR any smoking: 2.0, daily smoking: 3.3) and those reporting peer use (OR 2.1). Mid-school peer use independently predicted incident late-school daily use in males (OR 6.5) while high-dose alcohol use (OR 6.1) and antisocial behaviour (OR 6.6) predicted incident late-school daily use in females. Most cannabis use remained occasional during adolescence but escalation to potentially harmful daily use in the late-school period occurred in 12% of early users. Transition was more likely in males, for whom availability and peer use were determinants. In contrast, females with multiple extreme behaviours were more likely to become daily users. Cigarette smoking was an important predictor of both initiation and persisting cannabis use.
Article
To examine the reliability of self-reported age of first substance use experiences among national samples of adult and child respondents. Survey responses from seven waves of the National Longitudinal Survey of Youth (NLSY) were examined. Adult and child NLSY respondents reporting age of first tobacco, alcohol, marijuana, cocaine and/or crack use during two or more survey interviews. Four indicators of reliability: intraclass correlation coefficients (ICC), mean and absolute mean differences in reported age and reports consistent within 1 year. The adjusted mean ICC for all comparisons was 0.69. The adjusted mean difference in self-reported age of first substance use was -0.52 years and the adjusted absolute mean difference was 2.00 years. The adjusted percentage of all comparisons reporting ages consistent within 1 year was 55.28%. More consistent reports were provided by adults, and in response to questions posed over 2 years as opposed to longer time intervals. Respondent answers to questions concerned with first use of marijuana were generally found to be most reliable; questions concerned with first use of crack were least reliable and reports of tobacco, alcohol and cocaine were intermediate. Logistic regression analyses also identified age, race, gender, education and poverty status as predictors of consistent reporting. Self-reports of age of first substance use experiences, as currently collected via survey questionnaires, are of sufficient reliability for most current epidemiological applications. For inquiries where age of substance use onset is itself a research focus, however, researchers should invest additional effort in improving the reliability of measurement.
Article
Drawing upon an "exposure opportunity" concept described by Wade Hampton Frost, the authors studied two mechanisms to help account for prior observations about the "stepping-stone" or "gateway" sequences that link the use of alcohol, tobacco, marijuana, and cocaine. Data were obtained from four nationally representative and independent cross-sectional samples of US household residents (n = 44,624 persons aged 12-25 years). Data were gathered using standardized self-report methods and were analyzed via survival methods. Results indicated that users of tobacco and alcohol were more likely than nonusers to have an opportunity to try marijuana and were more likely to actually use marijuana once a marijuana opportunity had occurred. Opportunity to use cocaine was associated with prior marijuana smoking. Among young people with a cocaine opportunity, those who had used marijuana were more likely to use cocaine than were those with no history of marijuana use. The observed associations did not seem to arise solely as a result of young drug users' seeking out opportunities to use drugs. Applying Frost's epidemiologic concept of exposure opportunity, the authors offer new epidemiologic evidence on the sequences that link earlier use of alcohol and tobacco to later illegal drug involvement.
Article
To investigate the role of religiosity in the earliest stages of drug involvement, the authors studied recent-onset occurrence of first chances to try a drug and first actual drug use, expressed as a function of religious practice behaviors, levels of religious devotion, and religious affiliation. Based upon standardized questionnaire assessments of nationally representative samples of school-attending youths drawn in Panama, the five Spanish heritage countries of Central America, and the Dominican Republic (n = 12,797), the 1999–2000 study estimates indicate that higher levels of religious practice are inversely associated with the earliest stages of tobacco and cannabis experiences (i.e., the first chance to try and the first actual use) but not so for alcohol. To illustrate, for each unit increase in levels of religious practice behaviors, there was an associated reduced occurrence of the first chance to try tobacco (odds ratio = 0.76, 95% confidence interval: 0.62, 0.94). Occurrence of first actual use of tobacco and cannabis was not associated with levels of religious practice behaviors among youths exposed to the opportunity to try these drugs. As such, these behaviors apparently have not strengthened resistance. Rather, autarcesis may be at work, functioning to shield youths from drug exposure opportunities.
Article
The present study examined Lengths Of Times for important transitions in substance involvement from Initiation to Regular use (LOTIR), first Problem from drug use (LOTIP), and first experience of Dependence (LOTID) for alcohol, tobacco, cannabis, cocaine, and opiates. Data were from a longitudinal study of 590 children (22.2% female) at different levels of risk for substance use disorders based on their fathers' substance use-related diagnoses. Participants' substance involvement was assessed at four ages: 10-12, and follow-ups at two, five, and eight years later. Results suggested that faster transitions were more due to drug-related constructs (including possible social milieus of different drug classes and interactions between drug class and neurophysiology) than intrapersonal constructs. The shortest transition times (and greatest addictive liabilities) were for opiates followed respectively by cocaine, cannabis, tobacco, and alcohol. Females had shorter transition times, though gender differences were small. Some evidence was found for a familial influence on transition times above what was accounted for by differences between substances.
Article
The modifying effects of psychiatric and familial risk factors on age at smoking initiation, rate of progression from first cigarette to regular smoking, and transition time from regular smoking to nicotine dependence (ND) were examined in 1269 offspring of male twins from the Vietnam Era Twin Registry. Mean age of the sample was 20.1 years. Cox proportional hazard regression analyses adjusting for paternal alcohol dependence and ND status and maternal ND were conducted. Both early age at first cigarette and rapid transition from initiation to regular smoking were associated with externalizing disorders, alcohol consumption, and cannabis use. Rapid escalation from regular smoking to ND was also predicted by externalizing disorders, but in contrast to earlier transitions, revealed a strong association with internalizing disorders and no significant relationship with use of other substances. Findings characterize a rarely examined aspect of the course of ND development and highlight critical distinctions in risk profiles across stages of tobacco involvement.
Article
This study examines the association between childhood physical abuse (CPA) and sexual abuse (CSA) and the development of cannabis abuse and dependence among adolescents and young adults while controlling for genetic and environmental risk factors. To control for familial risk differences related to paternal drug dependence that might confound the relationship between CSA and CPA and cannabis abuse/dependence, we created four groups based on father's and uncle's substance use dependence (SUD) status reflecting different degrees of genetic and environmental risks to offspring: (i) high genetic, high environmental risk; (ii) high genetic, low environmental risk; (iii) medium genetic, low environmental risk; and (iv) low genetic, low environmental risk. Adolescent and young adult offspring of monozygotic and dizygotic US military veteran twin fathers (n = 819). Data on CPA and CSA, DSM-IV offspring cannabis abuse/dependence, other SUD and psychopathology and maternal and paternal SUD and psychopathology were collected via semi-structured telephone interview. Twenty-three per cent of the offspring sample met life-time criteria for cannabis abuse/dependence and 8.55% and 12.82% reported CSA and CPA, respectively. Offspring exposed to CSA, but not CPA, were at significantly greater risk of developing cannabis abuse/dependence compared to those who had not experienced CSA (hazard ratio = 2.16; 95% confidence interval = 1.48-3.16) after controlling for genetic and familial environmental risk and offspring gender, alcohol abuse and dependence and conduct disorder. These results indicate that there are effects of CSA on development of cannabis abuse/dependence in addition to the genetic and familial environmental risk imparted by having a drug-dependent father.
Article
For a better understanding of the evolution of addictive disorders and the timely initiation of early intervention and prevention, we have to learn when and how quickly the critical transitions from first substance use (SU) to regular use and from first SU and regular SU to abuse and dependence occur. Little data are currently available on the transitions to substance use disorders (SUDs) across the spectrum of legal and illegal drugs taking into account gender differences. It is the aim of this paper to describe the high density incidence and transition periods of SU and SUD for alcohol, nicotine, cannabis and other illicit drugs for young males and females. A sample of (N = 3021) community subjects aged 14-24 at baseline were followed-up prospectively over 10-years. SU and SUD were assessed using the DSM-IV/M-CIDI. Ages 10-16 are the high risk period for first alcohol and nicotine use (up to 38% of subjects start before age 14). Onset of illegal SU occurs later. Substantial proportions of transitions to regular SU and SUD occur in the first three years after SU onset. Only few gender differences were found for time patterns of SU/SUD incidence and transition. Except for alcohol the time windows for targeted intervention to prevent progression to malignant patterns in adolescence are critically small, leaving little time for targeted intervention to prevent transition. The fast transitions to abuse and dependence in adolescence may be indicative for the increased vulnerability to substance effects in this time period. Basic research on the determinants of transitions should thus target this period in adolescence.
Associations between cigarette smoking Please cite this article in press as Onset of opportunity to use cannabis and progression from opportunity to dependence: Are influences consistent across transitions? Drug Alcohol Depend
  • C Hindocha
  • N D Shaban
  • T P Freeman
  • R K Das
  • G Gale
  • G Schafer
  • C J Falconer
  • C J A Morgan
  • H V Curran
  • L A Hines
Hindocha, C., Shaban, N.D.C., Freeman, T.P., Das, R.K., Gale, G., Schafer, G., Falconer, C.J., Morgan, C.J.A., Curran, H.V., 2015. Associations between cigarette smoking Please cite this article in press as: Hines, L.A., et al., Onset of opportunity to use cannabis and progression from opportunity to dependence: Are influences consistent across transitions? Drug Alcohol Depend. (2016), http://dx.doi.org/10.1016/j.drugalcdep.2015.12.032 ARTICLE IN PRESS G Model DAD-5875; No. of Pages 8