Adolescent precursors of cannabis dependence: findings from the Victorian Adolescent Health Cohort Study

Predicting cannabis abuse screening test (CAST) scores: a recursive partitioning analysis using survey data from Czech Republic, Italy, the Netherlands and Sweden

Introduction

Cannabis is Europe's most commonly used illicit drug. Some users do not develop dependence or other problems, whereas others do. Many factors are associated with the occurrence of cannabis-related disorders. This makes it difficult to identify key risk factors and markers to profile at-risk cannabis users using traditional hypothesis-driven approaches. Therefore, the use of a data-mining technique called binary recursive partitioning is demonstrated in this study by creating a classification tree to profile at-risk users.

Methods

59 variables on cannabis use and drug market experiences were extracted from an internet-based survey dataset collected in four European countries (Czech Republic, Italy, Netherlands and Sweden), n = 2617. These 59 potential predictors of problematic cannabis use were used to partition individual respondents into subgroups with low and high risk of having a cannabis use disorder, based on their responses on the Cannabis Abuse Screening Test. Both a generic model for the four countries combined and four country-specific models were constructed.

Results

Of the 59 variables included in the first analysis step, only three variables were required to construct a generic partitioning model to classify high risk cannabis users with 65–73% accuracy. Based on the generic model for the four countries combined, the highest risk for cannabis use disorder is seen in participants reporting a cannabis use on more than 200 days in the last 12 months. In comparison to the generic model, the country-specific models led to modest, non-significant improvements in classification accuracy, with an exception for Italy (p = 0.01).

Conclusion

Using recursive partitioning, it is feasible to construct classification trees based on only a few variables with acceptable performance to classify cannabis users into groups with low or high risk of meeting criteria for cannabis use disorder. The number of cannabis use days in the last 12 months is the most relevant variable. The identified variables may be considered for use in future screeners for cannabis use disorders.

Effectiveness of training family physicians to deliver a brief intervention to address excessive substance use among young patients: a cluster randomized controlled trial

BACKGROUND

Brief interventions delivered by family physicians to address excessive alcohol use among adult patients are effective. We conducted a study to determine whether such an intervention would be similarly effective in reducing binge drinking and excessive cannabis use among young people.

METHODS

We conducted a cluster randomized controlled trial involving 33 family physicians in Switzerland. Physicians in the intervention group received training in delivering a brief intervention to young people during the consultation in addition to usual care. Physicians in the control group delivered usual care only. Consecutive patients aged 15-24 years were recruited from each practice and, before the consultation, completed a confidential questionnaire about their general health and substance use. Patients were followed up at 3, 6 and 12 months after the consultation. The primary outcome measure was self-reported excessive substance use (≥ 1 episode of binge drinking, or ≥ 1 joint of cannabis per week, or both) in the past 30 days.

RESULTS

Of the 33 participating physicians, 17 were randomly allocated to the intervention group and 16 to the control group. Of the 594 participating patients, 279 (47.0%) identified themselves as binge drinkers or excessive cannabis users, or both, at baseline. Excessive substance use did not differ significantly between patients whose physicians were in the intervention group and those whose physicians were in the control group at any of the follow-up points (odds ratio [OR] and 95% confidence interval [CI] at 3 months: 0.9 [0.6-1.4]; at 6 mo: 1.0 [0.6-1.6]; and at 12 mo: 1.1 [0.7-1.8]). The differences between groups were also nonsignificant after we restricted the analysis to patients who reported excessive substance use at baseline (OR 1.6, 95% CI 0.9-2.8, at 3 mo; OR 1.7, 95% CI 0.9-3.2, at 6 mo; and OR 1.9, 95% CI 0.9-4.0, at 12 mo).

INTERPRETATION

Training family physicians to use a brief intervention to address excessive substance use among young people was not effective in reducing binge drinking and excessive cannabis use in this patient population.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry, no. ACTRN12608000432314.

Stress modulates illness-course of substance use disorders: a translational review

Childhood trauma and post-childhood chronic/repeated stress could increase the risk of a substance use disorder by affecting five stages of addiction illness-course: (a) initial experimentation with substances; (b) shifting from experimental to regular use; (c) escalation from regular use to abuse or dependence; (d) motivation to quit; and (e) risk of (re-)lapse. We reviewed the human literature on relationships between stress and addiction illness-course. We explored per illness-course stage: (i) whether childhood trauma and post-childhood chronic/repeated stress have comparable effects and (ii) whether effects cut across classes of substances of abuse. We further discuss potential underlying mechanisms by which stressors may affect illness-course stages for which we relied on evidence from studies in animals and humans. Stress and substances of abuse both activate stress and dopaminergic motivation systems, and childhood trauma and post-childhood stressful events are more chronic and occur more frequently in people who use substances. Stressors increase risk to initiate early use potentially by affecting trait-like factors of risk-taking, decision making, and behavioral control. Stressors also accelerate transition to regular use potentially due to prior effects of stress on sensitization of dopaminergic motivation systems, cross-sensitizing with substances of abuse, especially in people with high trait impulsivity who are more prone to sensitization. Finally, stressors increase risk for abuse and dependence, attenuate motivation to quit, and increase relapse risk potentially by intensified sensitization of motivational systems, by a shift from positive to negative reinforcement due to sensitization of the amygdala by corticotropin releasing factor, and by increased sensitization of noradrenergic systems. Stress generally affects addiction illness-course across stressor types and across classes of substances of abuse.

Psychiatric, psychosocial, and physical health correlates of co-occurring cannabis use disorders and nicotine dependence

BACKGROUND

Several gaps in the literature on individuals with co-occurring cannabis and tobacco use exist, including the extent of psychiatric, psychosocial, and physical health problems. We examine these gaps in an epidemiological study, the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), of a large, nationally representative sample.

METHODS

The sample was drawn from Wave 2 NESARC respondents (N=34,653). Adults with current cannabis use disorders and nicotine dependence (CUD+ND) (n=74), CUD only (n=100), and ND only (n=3424) were compared on psychiatric disorders, psychosocial correlates (e.g., binge drinking; partner violence), and physical health correlates (e.g., medical conditions).

RESULTS

Relative to those with CUD only, respondents with CUD+ND were significantly more likely to meet criteria for bipolar disorder, Clusters A and B personality disorders, and narcissistic personality disorder, and reported engaging in a significantly higher number of antisocial behaviors. Relative to those with ND only, respondents with CUD+ND were significantly more likely to meet criteria for bipolar disorder, anxiety disorders, and paranoid, schizotypal, narcissistic, and borderline personality disorders; were significantly more likely to report driving under the influence of alcohol and being involved in partner violence; and reported engaging in a significantly higher number of antisocial behaviors. CUD+ND was not associated with physical health correlates.

CONCLUSIONS

Poor treatment outcomes for adults with co-occurring cannabis use disorders and nicotine dependence may be explained in part by differences in psychiatric and psychosocial problems.

Predicting the transition from frequent cannabis use to cannabis dependence: a three-year prospective study

BACKGROUND

Frequent cannabis users are at high risk of dependence, still most (near) daily users are not dependent. It is unknown why some frequent users develop dependence, whereas others do not. This study aims to identify predictors of first-incidence DSM-IV cannabis dependence in frequent cannabis users.

METHODS

A prospective cohort of frequent cannabis users (aged 18-30, n=600) with baseline and two follow-up assessments (18 and 36 months) was used. Only participants without lifetime diagnosis of DSM-IV cannabis dependence at baseline (n=269) were selected. Incidence of DSM-IV cannabis dependence was established using the Composite International Diagnostic Interview version 3.0. Variables assessed as potential predictors of the development of cannabis dependence included sociodemographic factors, cannabis use variables (e.g., motives, consumption habits, cannabis exposure), vulnerability factors (e.g., childhood adversity, family history of mental disorders or substance use problems, personality, mental disorders), and stress factors (e.g., life events, social support).

RESULTS

Three-year cumulative incidence of cannabis dependence was 37.2% (95% CI=30.7-43.8%). Independent predictors of the first incidence of cannabis dependence included: living alone, coping motives for cannabis use, number and type of recent negative life events (major financial problems), and number and type of cannabis use disorder symptoms (impaired control over use). Cannabis exposure variables and stable vulnerability factors did not independently predict first incidence of cannabis dependence.

CONCLUSIONS

In a high risk population of young adult frequent cannabis users, current problems are more important predictors of first incidence cannabis dependence than the level and type of cannabis exposure and stable vulnerability factors.

Factors associated with variability and stability of cannabis use in young adulthood

BACKGROUND

This study investigated the factors associated with initiating cannabis use, reverting to cannabis use and remaining a cannabis user in young adulthood. This is an important area of research as the risk for cannabis initiation is extending beyond adolescence and opportunities to influence cannabis use pathways can emerge throughout the life-course.

METHODS

A large, community-based sample was followed prospectively. Data from two successive waves (mean age 23 years and 27 years respectively) of the Path Through Life Study (PATH) were analysed (n=2045). The longitudinal design enabled change in cannabis use in young adulthood to be predicted based on factors assessed approximately four years prior.

RESULTS

An environment of licit drug use was strongly associated with initiating cannabis use (tobacco: OR=4.98, 95%CI: 2.31-10.76) and reverting to cannabis use in young adulthood (alcohol: OR=2.13, 95%CI: 1.42-3.19). Greater fun seeking was found to orientate people towards initiating cannabis use in young adulthood (OR=1.17, 95%CI: 1.04-1.30). Higher psychoticism increased the odds of remaining a cannabis user (OR=1.19, 95%CI: 1.07-1.33). Religious involvement was protective of cannabis initiation (OR=0.89, 95%CI: 0.83-0.95). Early childhood factors did not influence the pattern of cannabis use in young adulthood.

CONCLUSIONS

The findings make an important contribution to the development of prevention and intervention strategies for young adults by drawing attention to specific areas of risk and protection.

Relationships between marijuana dependence and condom use intentions and behavior among justice-involved adolescents

The current study examined the relationships among marijuana dependence, a theoretical model of condom use intentions, and subsequent condom use behavior in justice-involved adolescents. Participants completed baseline measures of prior sexual and substance use behavior. Of the original 720 participants, 649 (90.13 %) completed follow-up measures 6 months later. There were high levels of marijuana use (58.7 % met criteria for dependence) and risky sexual behavior among participants. Baseline model constructs were associated with condom use intentions, and intentions were a significant predictor of condom use at follow-up. Marijuana dependence did not significantly influence the relationships between model constructs, nor did it moderate the relationship of model constructs with subsequent condom use. Findings suggest that the theoretical model of condom use intentions is equally valid regardless of marijuana dependence status, suggesting that interventions to reduce sexual risk behavior among both marijuana dependent and non-dependent justice-involved adolescents can be appropriately based on the model.

Relationship between tobacco and cannabis use status in outpatients with schizophrenia

BACKGROUND AND OBJECTIVE

While high prevalence of tobacco and cannabis use are well established in schizophrenia, reports on their co-morbid use is limited. We explored the links between tobacco and cannabis use in an outpatient population meeting DSM-IV criteria for schizophrenia.

METHODS

Cigarette smoking behaviors were assessed in an outpaitent population with schizophrenia (N=54) with current (n=18), former (n=24), and no lifetime cannabis dependence (n=12).

RESULTS

We found significant differences in cigarettes per day (CPD) across groups: current dependent patients smoked less CPD than patients with former dependence and those with no history of dependence; former dependent patients smoked significantly less than patients with no history of cannabis dependence.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

Preliminary results support an effect of cannabis use status on tobacco consumption. In the absence of cannabis, patients may increase cigarette smoking, suggesting state-dependent effects of cannabis on tobacco. Prospective designs should further examine this relationship between cannabis and tobacco in schizophrenia versus non-psychiatric controls.

A validation of the Cannabis Abuse Screening Test (CAST) using a latent class analysis of the DSM-IV among adolescents

This paper explored the latent class structure of the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) (assessed with the Munich Composite International Diagnostic Interview). Secondly, the screening properties of the Cannabis Abuse Screening Test (CAST) in adolescents were assessed with classical test theory using the latent class structure as empirical gold standard. The sample comprised 3266 French cannabis users aged 17 to 19 from the general population. Three latent classes of cannabis users were identified reflecting a continuum of problem severity: non-symptomatic, moderate and severe. Gender-specific analyses showed the best model fit, although results were almost identical in the total sample. The latent classes were good predictors of daily cannabis use, number of joints per day and age of first experimentation. The CAST showed good screening properties for the moderate/severe class (area under receiver operating characteristic curve > 0.85) and very good for the severe class (0.90). It was more sensitive for boys, more specific for girls. Although structural equivalence across gender was rejected, results suggest small gender differences in the latent structure of the DSM-IV. The performance of the CAST in screening for the latent class structure was good and superior to those obtained with the classical DSM-IV diagnoses.

Motivation for change and barriers to treatment among young cannabis users

BACKGROUND/AIMS

Despite cannabis use among adolescents has shown to be related to psychosocial and mental health problems, the demand from adolescents for professional help is very low, and determinants of motivation for change among nonclinical populations remain unknown. The purpose of this study was to assess motivation for change among young cannabis users and to identify determinants of intention to change and self-change, as well as perceived barriers to seeking professional help.

METHODS

261 cannabis users aged 16-21 participated in a computerized survey in Spain.

RESULTS

Data from this cross-sectional study indicated that few users intend to stop taking the drug. Determining factors of intention to change were the following: having more drug-related problems, paranoid symptomatology and greater concern about the consequences of use. Self-change was facilitated by lower use of cannabis, and could be hindered by tobacco smoking and cannabis dependence. Lack of awareness of the problems and the desire to solve one's problems alone constitute the main barriers to seeking professional help.

CONCLUSIONS

Adolescent cannabis users show low motivation for change though experiencing more problems associated with its use emerges as a determinant of increased motivation. Several barriers impede this motivation from turning into treatment demand.

Clinical correlates of co-occurring cannabis and tobacco use: a systematic review

AIMS

  A growing literature has documented the substantial prevalence of and putative mechanisms underlying co-occurring (i.e. concurrent or simultaneous) cannabis and tobacco use. Greater understanding of the clinical correlates of co-occurring cannabis and tobacco use may suggest how intervention strategies may be refined to improve cessation outcomes and decrease the public health burden associated with cannabis and tobacco use.

METHODS

  A systematic review of the literature on clinical diagnoses, psychosocial problems and outcomes associated with co-occurring cannabis and tobacco use. Twenty-eight studies compared clinical correlates in co-occurring cannabis and tobacco users versus cannabis- or tobacco-only users. These included studies of treatment-seekers in clinical trials and non-treatment-seekers in cross-sectional or longitudinal epidemiological or non-population-based surveys.

RESULTS

  Sixteen studies examined clinical diagnoses, four studies examined psychosocial problems and 11 studies examined cessation outcomes in co-occurring cannabis and tobacco users (several studies examined multiple clinical correlates). Relative to cannabis use only, co-occurring cannabis and tobacco use was associated with a greater likelihood of cannabis use disorders, more psychosocial problems and poorer cannabis cessation outcomes. Relative to tobacco use only, co-occurring use did not appear to be associated consistently with a greater likelihood of tobacco use disorders, more psychosocial problems or poorer tobacco cessation outcomes.

CONCLUSIONS

  Cannabis users who also smoke tobacco are more dependent on cannabis, have more psychosocial problems and have poorer cessation outcomes than those who use cannabis but not tobacco. The converse does not appear to be the case.

Daily marijuana use and suicidality: the unique impact of social anxiety

Despite a clear relationship between marijuana use and suicidality, little is known about psychological vulnerability factors that may interact with marijuana use to increase suicidality among this high-risk group. The present study examined the moderational impact of social anxiety on the relationship between marijuana use status (current users vs abstainers) and suicidality among 343 community adults. We also examined whether social anxiety moderated the relation between more frequent use (daily vs less frequent) among the 134 current marijuana users. Although social anxiety did not moderate the relation between use status and suicidality, it did moderate the relation between daily use status and suicidality after controlling for a wide range of relevant variables (e.g., demographics, depression, negative affect, and other types of anxiety). The overall model accounted for 59% of the variance in suicidality such that daily marijuana users with elevated social anxiety reported the highest suicidality. Findings highlight the importance of considering social anxiety in efforts to understand and prevent suicidality among this high-risk population.

Evidence of increasing age of onset of cannabis use among younger Australians

AIM

To determine whether declines in the prevalence of cannabis use in Australia have been accompanied by changes in age of onset of cannabis use.

DESIGN

A retrospective cohort study. To account for right censoring error we contrasted the mean age of onset for comparable age groups across the four surveys conducted from 1998 to 2007. Kaplan-Meier failure graphs were used to describe how the cumulative risk of first use of cannabis varied across birth cohorts born from 1947 to 1993.

SETTING

Australian data collected in the nationally representative, triennial, National Drug Strategy Household Surveys (NDSHS) PARTICIPANTS: A total of 88,268 Australian household residents aged 14 years and older.

MEASUREMENTS

Life-time use of cannabis and age of first use.

FINDINGS

For respondents under the age of 20 years, mean age of first use of cannabis has increased from 14.6 years in 1998 to 15.2 years in 2007.

CONCLUSIONS

The decline in cannabis use prevalence that has occurred since 1998 in Australia has been accompanied by an increase in age of first use among those aged under 20 years.

Risk of marijuana use in male and female college student athletes and nonathletes

OBJECTIVE

A large minority of collegiate athletes report past-year marijuana use even though there is a significant possibility of experiencing negative athlete-specific consequences related to performance, eligibility, and scholarship. The present study examined risk factors that can drive or curb marijuana use in college athletes and nonathletes.

METHOD

Logistic regressions, performed separately for men and for women, assessed the relationship of past-year marijuana use to sensation seeking, negative mood, perceptions of peer marijuana use, motivations for marijuana use, and stress related to body image and academics in athletes (233 men, 156 women) and nonathletes (184 men, 313 women). Risk factors also were compared for male past-year marijuana users who reported using (n = 26) or not using (n = 61) the substance during their competitive season.

RESULTS

For athletes and nonathletes of both genders, being White, being past-year cigarette smokers, having higher sensation-seeking scores, and having exaggerated perceptions of student use norms were associated with past-year marijuana use. Enhancement motivations for use were higher among athletes compared with their same-gender nonathlete peers. In women, but not in men, greater body image stress and lower academic stress were associated with past-year marijuana use. Male athletes who continued using marijuana into their competitive season demonstrated a qualitatively different risk profile compared with athlete past-year users who reported no in-season use, including greater coping motivations for marijuana use.

CONCLUSIONS

This preliminary study suggests that although the overall risk profile of college athletes and nonathletes is similar, athletes appear to be particularly motivated to use marijuana because of its enhancement or pleasurable properties.

Tobacco and marijuana use among adolescents and young adults: a systematic review of their co-use

Tobacco (TOB) and marijuana (MJ) are the most widely used drugs among adolescents and young adults. The literature on their co-use, however, has not been systematically reviewed. We identified 163 English language articles published from 1999 to 2009 examining TOB and MJ co-use, correlates or consequences of co-use, or interventions for prevention or cessation of co-use with participants aging 13-25 years. Most studies (n=114, 70%) examined TOB and MJ co-use, and 85% of relationships studied indicated a significant association. Fifty-nine studies (36%) examined correlates or consequences of co-use. Factors consistently associated with increased likelihood of co-use, defined as significant associations in at least four studies, were African-American ethnicity, mental and physical health characteristics (e.g., high-intensity pleasure temperament), and school characteristics (e.g., good grades). The only consistent consequence of co-use was exacerbation of mental health symptoms. Few studies examined prevention (n=3) or cessation (n=2) interventions for TOB and MJ co-use, and the findings were stronger for prevention efforts. A sufficient literature base has documented that TOB and MJ use are strongly related in young people, yet few consistent correlates and consequences of co-use have been identified to inform intervention targets.

The Dutch Cannabis Dependence (CanDep) study on the course of frequent cannabis use and dependence: objectives, methods and sample characteristics

This paper presents an overview of the prospective cohort design of the Dutch Cannabis Dependence (CanDep) study, which investigates (i) the three-year natural course of frequent cannabis use (≥ three days per week in the past 12 months) and cannabis dependence; and (ii) the factors involved in the transition from frequent non-dependent cannabis use to cannabis dependence, and remission from dependence. Besides its scientific relevance, this knowledge may contribute to improve selective and indicated prevention, early detection, treatment and cannabis policies. The secondary objectives are the identification of factors related to treatment seeking and the validation of self report measures of cannabis use. Between September 2008 and April 2009, baseline data were collected from 600 frequent cannabis users with an average age of 22.1 years, predominantly male (79.3%) and an average cannabis use history of 7.1 years; 42.0% fulfilled a (12-month DSM-IV) diagnosis of cannabis dependence. The response rate was 83.7% after the first follow up at 18 months. The second and last follow-up is planned at 36 months. Computer assisted personal interviews (CAPI) were conducted which covered: cannabis use (including detailed assessments of exposure, motives for use and potency preference); use of other substances; DSM-IV internalizing and externalizing mental disorders; treatment seeking; personality; life events; social support and social functioning.

The validity of DSM-IV cannabis abuse and dependence criteria in adolescents and the value of additional cannabis use indicators

AIMS

This study assessed the validity of DSM-IV cannabis abuse and dependence criteria in an adolescent general population sample and evaluated the usefulness of additional cannabis use indicators.

DESIGN AND SETTING

Data came from the 2008 Survey on Health and Consumption during the Day of Defense Preparation (ESCAPAD), a cross-sectional self-administered survey conducted in France.

PARTICIPANTS

The analytical sample comprised 3641 adolescents aged 17-19 years who reported cannabis use in the past 12 months.

MEASUREMENTS

To assess DSM-IV criteria of cannabis abuse and dependence, the Munich Composite International Diagnostic Interview (M-CIDI) was used. As additional cannabis use indicators, daily use, use when alone and use before midday were assessed. Confirmatory factor analyses and two-parameter logistic item response theory (IRT) models were run. Differential item functioning was assessed using the IRT log-likelihood ratio approach.

RESULTS

A one-factor model comprising both abuse and dependence criteria showed the best fit to the data. Abuse item legal problems showed the greatest severity, whereas dependence items larger/longer and tolerance were found least severe. Discriminatory power was lowest for impaired control and legal problems. Additional cannabis use indicators increased the precision of the overall DSM-IV criterion set. Gender-based differential item functioning was observed for items tolerance, withdrawal and use before midday.

CONCLUSION

The current DSM conceptualization with two distinct and graded diagnostic classes has limited validity among adolescents. In forthcoming revisions of the classification system, several existing criteria should be revised or dropped, new indicators of substance use disorders should be included and gender should be considered.

The 'grass ceiling': limitations in the literature hinder our understanding of cannabis use and its consequences

AIM

To illustrate how limitations in the cannabis literature undermine our ability to understand cannabis-related harms and problems experienced by users and identify users at increased risk of experiencing adverse outcomes of use.

METHOD AND RESULTS

Limitations have been organized into three overarching themes. The first relates to the classification systems employed by researchers to categorize cannabis users, their cannabis use and the assumptions on which these systems are based. The second theme encompasses methodological and reporting issues, including differences between studies, inadequate statistical control of potential confounders, the under-reporting of effect sizes and the lack of consideration of clinical significance. The final theme covers differing approaches to studying cannabis use, including recruitment methods. Limitations related to the nature of the data collected by researchers are discussed throughout, with a focus on how they affect our understanding of cannabis use and users.

CONCLUSIONS

These limitations must be addressed to facilitate the development of effective and appropriately targeted evidence-based public health campaigns, treatment programmes and preventative, early intervention and harm minimization strategies, and to inform cannabis-related policy and legislation.

Cannabis use patterns and their association with DSM-IV cannabis dependence and gender

AIMS

To investigate the gender differences in the patterns of cannabis use (CU), namely frequency, times of day, social context and methods and in their association with DSM-IV cannabis dependence.

METHODS

A sample of 3,904 students from German universities was recruited via an internet survey. Logistic regressions and associated areas under the ROC curve (AUC) were calculated among current cannabis users (at least once a month, n = 843).

RESULTS

CU using a water pipe was more often reported by males (50 vs. 34.6%). Usual CU 'before going to sleep at night' was more often reported by females (47.3 vs. 35.7%). Most CU patterns showed a similar association with DSM-IV cannabis dependence in both genders. The association of CU 'with strangers' was stronger in females (AUC 0.68 vs. AUC 0.56). Slightly different multiple models were found (females AUC 0.86, males AUC 0.77).

CONCLUSIONS

There are considerable gender differences in the CU patterns and, thus, in the way CU functions. In the association of CU patterns with cannabis dependence, the similarities are rather great. Examining the CU patterns might make a considerable contribution to the better detection of high-risk population segments for prevention and early intervention in both genders.

Cannabis Dependence in Swiss Adolescents

This naturalistic cross-sectional study explores how and to what extent cannabis dependence was associated with intrapersonal aspects (anxiety, coping styles) and interpersonal aspects of adolescent functioning (school status, family relationships, peer relationships, social life). A convenience sample of 110 adolescents (aged 12 to 19) was recruited and subdivided into two groups (38 with a cannabis dependence and 72 nondependent) according to DSM-IV-TR criteria for cannabis dependence. Participants completed the State-Trait Anxiety Inventory (STAI-Y), the Coping Across Situations Questionnaire (CASQ), and the Adolescent Drug Abuse Diagnosis (ADAD) interview investigating psychosocial and interpersonal problems in an adolescent’s life. Factors associated with cannabis dependence were explored with logistic regression analyses. The results indicated that severity of problems in social life and peer relationships (OR = 1.68, 95% CI = 1.21 – 2.33) and avoidant coping (OR = 4.22, 95% CI = 1.01 – 17.73) were the only discriminatory factors for cannabis dependence. This model correctly classified 84.5% of the adolescents. These findings are partially consistent with the “self-medication hypothesis” and underlined the importance of peer relationships and dysfunctional coping strategies in cannabis dependence in adolescence. Limitations of the study and implications for clinical work with adolescents are discussed.

Outcomes of occasional cannabis use in adolescence: 10-year follow-up study in Victoria, Australia

BACKGROUND

Regular adolescent cannabis use predicts a range of later drug use and psychosocial problems. Little is known about whether occasional cannabis use carries similar risks.

AIMS

To examine associations between occasional cannabis use during adolescence and psychosocial and drug use outcomes in young adulthood; and modification of these associations according to the trajectory of cannabis use between adolescence and age 20 years, and other potential risk factors.

METHOD

A 10-year eight-wave cohort study of a representative sample of 1943 secondary school students followed from 14.9 years to 24 years.

RESULTS

Occasional adolescent cannabis users who continued occasional use into early adulthood had higher risks of later alcohol and tobacco dependence and illicit drug use, as well as being less likely to complete a post-secondary qualification than non-users. Those using cannabis at least weekly either during adolescence or at age 20 were at highest risk of drug use problems in young adulthood. Adjustment for smoking in adolescence reduced the association with later educational achievement, but associations with drug use problems remained.

CONCLUSIONS

Occasional adolescent cannabis use predicts later drug use and educational problems. Partial mediation by tobacco use raises a possibility that differential peer affiliation may play a role.

Brief intervention addressing excessive cannabis use in young people consulting their GP: a pilot study

BACKGROUND

When excessive cannabis consumption occurs in adolescence, the adverse consequences extend into adulthood. Interventions by GPs are effective in preventing harm associated with alcohol use. Similar interventions have potential in addressing cannabis use.

AIM

To develop and pilot test a brief intervention targeting excessive cannabis use (defined as > or = 1x/week) in young people in primary care.

DESIGN OF THE STUDY

Pilot intervention trial.

SETTING

Seven family practices in Switzerland.

METHOD

The team collaborated with GPs and young people to develop the intervention. Seven GPs piloted its use in their consultations. Patients aged 15 to 24 years consulting for any health problem were recruited before the consultation. Cannabis use, other substance use, and their psychosocial correlates were assessed with a short confidential questionnaire administered before the consultation and 1 month later. GPs, staff, and patients were asked to comment on the study and its feasibility.

RESULTS

Of 81 young people invited to participate, 78 (70% female) agreed (participation rate: 96%). One in seven (13.2%, 95% confidence interval = 7.5% to 18.9%) used cannabis at least once a week. Data at 1 month were available for 42% who had provided email contact details and 91% of those who had provided their mobile phone number (63% overall). In most cases, the intervention lasted no more than 5 minutes. Comments from participants added favourable data towards the feasibility of the study.

CONCLUSION

This pilot study provides a solid base on which to build a randomised trial of a brief intervention addressing cannabis use in young people consulting in family practice.

The adverse health effects of cannabis use: what are they, and what are their implications for policy?

BACKGROUND

The adverse health effects of cannabis are a source of contention in debates about policies towards the drug.

METHODS

This paper provides a review of epidemiological evidence on the major adverse health effects of cannabis use and considers its implications for policy.

RESULTS

The evidence strongly suggests that cannabis can adversely affect some users, especially adolescents who initiate use early and young adults who become regular users. These adverse effects probably include increased risks of: motor vehicle crashes, the development of cannabis dependence, impaired respiratory function, cardiovascular disease, psychotic symptoms, and adverse outcomes of adolescent development, namely, poorer educational outcomes and an increased likelihood of using other illicit drugs.

CONCLUSIONS

Politically, evidence of adverse health effects favours the status quo in developed countries like Australia where cannabis policy has been framed by the media as a choice between two views: (1) either cannabis use is largely harmless to most users and so we should legalize, or at the very least decriminalize its use; or (2) it harms some of its users so we should continue to prohibit its use.

Tobacco and cannabis co-occurrence: does route of administration matter?

BACKGROUND

Qualitative research suggests that a shared route of administration (i.e. via inhalation) for the common forms of both tobacco (i.e. cigarettes) and cannabis (i.e. joints) may contribute to their co-occurring use.

METHODS

We used data on 43,093 U.S. adults who participated in the 2001-2002 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) to examine whether cannabis use and abuse/dependence were associated with smoked (cigarettes, cigars, pipes) versus smokeless (snuff, chewed tobacco) forms of tobacco use, even after controlling for socio-demographic, psychiatric and substance-related covariates.

RESULTS

Tobacco smoking was associated with a 3.3-4.5 times increased risk for cannabis use and abuse/dependence respectively. After covariate adjustment, importantly for nicotine dependence, smoking tobacco (but not smokeless tobacco) was still significantly associated with both cannabis use (multinomial odds-ratio (MOR) 1.99) and cannabis dependence (MOR 1.55). In contrast, use of smokeless tobacco was not significantly correlated with elevated rates of cannabis use (MOR 0.96) or abuse/dependence (MOR 1.04).

CONCLUSIONS

Route of administration may play an important role in the observed association between tobacco and cannabis use. This may represent a physiological adaptation of the aero-respiratory system and/or index social and cultural influences surrounding the use of smoked versus smokeless forms of tobacco.

Sessions, Cyphers, and Parties

The importance of settings for marijuana use has been widely noted, but the way that informal social controls are organized to moderate the amounts consumed have not been well documented. A major ethnographic study of blunts/marijuana use in New York City observed several hundred marijuana users in group locations and conducted intensive interviews with 92 focal subjects. The vast majority of blunt smokers preferred to consume in a group setting. Participants identified three group settings in which blunt smoking often occurred-sessions, cyphers, and parties. The analysis identifies various conduct norms, rituals, and behavior patterns associated with each of these settings. Regardless of the setting, group processes encouraged equal sharing of blunts, moderation in consumption, intermission and breaks between smoking episodes, and involvement in non-smoking activities. Blunt smoking groups rarely encouraged high consumption and intoxication from marijuana.

Links between ethnic identification, cannabis use and dependence, and life outcomes in a New Zealand birth cohort

OBJECTIVE

To examine the role of ethnic identity in cannabis use, and links between ethnic identity, cannabis use and life outcomes, in a birth cohort of >1000 young people studied to age 25.

METHODS

Data were gathered on cultural identification, cannabis use, socioeconomic factors, childhood adversity, and a range of life outcomes as part of a longitudinal study of a New Zealand birth cohort (Christchurch Health and Development Study).

RESULTS

Those reporting Maori identity had rates of cannabis use and dependence that were significantly higher (p<0.05) than rates for non-Maori. Regression analysis suggested that the elevated rates of cannabis use among Maori were largely explained by their higher exposure to socioeconomic disadvantage and childhood adversity. Further analyses examined the role of cannabis use in the links between ethnicity and a range of life outcomes, including education, income and employment, mental health, criminal offending, and intimate partner violence. These analyses showed that cannabis use made a small but detectable contribution to rates of Maori disadvantage in life outcomes, with this contribution being most evident in the areas of crime, education, and unemployment.

CONCLUSIONS

Maori ethnic identification was associated with increased risks of cannabis use and dependence. The higher rate of cannabis use by Maori could be largely attributed to a combination of socioeconomic factors and greater exposure to environmental factors known to influence risk of cannabis use. The higher rates of cannabis use by Maori made a small contribution to higher rates of early school leaving, crime, and unemployment among Maori.

Early childhood predictors of early substance use and substance use disorders: prospective study

OBJECTIVES

The purpose of the present study was to examine the longitudinal association between early childhood factors and early initiation of use of substances and substance use disorders in a large prospective study.

METHOD

Data were from the Mater Hospital University of Queensland Study of Pregnancy, a prospective birth cohort study in Brisbane, Australia. Use of nicotine, alcohol and cannabis and age of initiation of such use were reported at the 21 year follow up. DSM-IV diagnosis of nicotine, alcohol and cannabis use disorders was assessed at 21 years using a computerized version of the Composite International Diagnostic Interview (CIDI-Auto). Early childhood factors were measured between mother's pregnancy and child age 5 years.

RESULTS

Of the 3647 respondents with complete data, 15.4% had started to smoke cigarettes before 15 years. Another 17.4% and 12.2% reported having started to consume alcohol or use cannabis in early adolescence, respectively. Some 16.2%, 27.8% and 21.9% had ever had nicotine, alcohol or cannabis abuse or dependence (disorder) by 21 years, respectively. In multivariate models early initiation of use of substances, and substance use disorders were associated with disrupted families or drug-using parents, childhood problem behaviours, and poor parental monitoring and supervision in childhood.

CONCLUSIONS

There are four independent factors in early or middle childhood that predict early initiation of use of substances and subsequent substance use disorders by early adulthood. There is a need to consider whether what is known about the risk factors that predict young age of substance use, and substance use disorders, may be incorporated into treatment and/or prevention initiatives.

Adolescent cannabis users at 24 years: trajectories to regular weekly use and dependence in young adulthood

AIMS

To examine the association between cannabis use by 18 years and problematic cannabis use at 24 years, considering possible mediating and confounding factors.

DESIGN

Ten-year representative prospective study with data from six time-points in adolescence (mean age 14.9-17.4 years) and two in young adulthood (mean age 20.7 and 24.1 years)

SETTING

Victoria, Australia.

PARTICIPANTS

Inception cohort of 1943 secondary school students (95.6% response rate), with 1520 (78% of adolescent participants) interviewed in the final wave.

MEASUREMENTS

Participants reported frequency of cannabis use for the past 6 months at each time-point in adolescence (age 14-17 years). Cannabis exposure was defined as: maximum frequency of use (occasional, weekly, daily), number of waves of use (1 or 2; 3-6) and first wave of use (early use: first waves 1-3). Young adult (24 years) outcomes were: weekly+ cannabis use and DSM-IV cannabis dependence, referred to collectively as problematic use.

FINDINGS

Of those interviewed at age 24 (wave 8), 34% had reported cannabis use in adolescence (waves 1-6), 12% at a level of weekly or more frequent use; 37% of these adolescent cannabis users were using at least weekly at wave 8, with 20% exhibiting dependence. Persistent adolescent cannabis and tobacco use as well as persistent mental health problems were associated strongly with problematic cannabis use at 24 years, after adjustment for potential confounding factors.

CONCLUSIONS

Heavy, persistent and early-onset cannabis use were all strongly predictive of later cannabis problems. Even so, occasional use was not free of later problems. Where there was co-occurring tobacco use or persistent mental health problems, risks for later problem cannabis use was higher.

Puberty as a highly vulnerable developmental period for the consequences of cannabis exposure

During puberty, neuronal maturation of the brain, which began during perinatal development, is completed such that the behavioral potential of the adult organism can be fully achieved. These maturational events and processes of reorganization are needed for the occurrence of adult behavioral performance but simultaneously render the organism highly susceptible to perturbations, such as exposure to psychoactive drugs, during this critical developmental time span. Considering the variety of maturational processes occurring in the endocannabinoid system during this critical period, it is not surprising that the still-developing brain might by highly susceptible to cannabis exposure. Emerging evidence from human studies and animal research demonstrates that an early onset of cannabis consumption might have lasting consequences on cognition, might increase the risk for neuropsychiatric disorders, promote further illegal drug intake and increase the likelihood of cannabis dependence. These findings suggest that young people represent a highly vulnerable cannabis consumer group and that they run a higher risk than adult consumers of suffering from adverse consequences from cannabinoid exposure. The aim of the present review is to provide an overview over the possible deleterious residual cannabinoid effects during critical periods of postnatal maturation and to offer a more precise delineation of the vulnerable time window for cannabinoid exposure.

How high: quantity as a predictor of cannabis-related problems

Background

Research on cannabis use has emphasized frequency as a predictor of problems. Studies of other drugs reveal that frequency relates to psychological and physiological outcomes, but quantity also plays an important role. In the study of cannabis, quantity has been difficult to assess due to the wide range of products and means of consumption.

Methods

The present study introduces three new measures of quantity, and examines their contribution to cannabis-related problems. Over 5,900 adults using cannabis once or more per month completed an internet survey that inquired about use, dependence, social problems and respiratory health. In addition to detailing their frequency of cannabis use, participants also reported three measures of quantity: number of quarter ounces consumed per month, usual intensity of intoxication, and maximum intensity of intoxication.

Results

Frequency of use, monthly consumption, and levels of intoxication predicted respiratory symptoms, social problems and dependence. What is more, each measure of quantity accounted for significant variance in outcomes after controlling for the effects of frequency.

Conclusion

These findings indicate that quantity is an important predictor of cannabis-related outcomes, and that the three quantity measures convey useful information about use.

Likelihood of developing an alcohol and cannabis use disorder during youth: association with recent use and age

AIM

We extend the literature on the association of early onset of drug use and estimated risk for developing a substance use disorder (SUD) by investigating the risk that recent onset of alcohol and cannabis use confers for developing a substance use disorder at each chronological age of adolescence and young adulthood (12-21-years-old).

DESIGN

Using 2003 data from the National Survey on Drug Use and Health [Substance Abuse Mental Health Service Administration (SAMHSA), 2004. Overview of Findings from the 2003 National Survey on Drug Use and Health. Office of Applied Studies, NSDUH Series H-24, DHHS Publication No. SMA-04-3963, Rockville, MD], we computed separate risk indices for developing an alcohol and cannabis use disorder for recent (prior 2 years) alcohol and cannabis users, respectively, at each age from 12 to 21 years of age, and compared estimated risk to recent onsets users among respondents aged 22-26.

FINDINGS

The results indicated that the teenage years were strongly linked to an elevated risk status. The odds ratio (OR) of having a prior year alcohol use disorder (AUD) among recent onset alcohol users was significantly elevated for youth at ages 14, 16, 17 and 18 (range of ORs=2.0-2.1) compared to the estimated risk for AUD among recent onset users aged 22-26. For cannabis, we obtained significantly elevated ORs for a cannabis use disorder (CUD) at each of teenage years (ages 12-18; range of ORs=3.9-7.2), when compared to older recent onset users (aged 22-26).

CONCLUSIONS

These data provide further epidemiological support that adolescence is a particularly vulnerable period for developing a SUD.

Who are the new amphetamine users? A 10-year prospective study of young Australians

AIMS

Despite good evidence of increased availability and use of amphetamines world-wide, relatively little is known about the epidemiology of young adult amphetamine use; relationships with social functioning, other drug use and mental health at this age; nor of the adolescent predictors of such use. We examined these issues using a representative cohort of young people followed-up in Victoria, Australia.

METHODS

A stratified, random sample of 1943 adolescents was recruited from secondary schools across Victoria at age 14-15 years. This cohort was interviewed on eight occasions until the age of 24-25 years (78% follow-up at that age). Cross-sectional and predictive associations were assessed using logistic regression.

RESULTS

At age 24 years, 12% of the sample had used amphetamines in the past year, with 1-2% using at least weekly. Young adult amphetamine use was predicted strongly by adolescent drug use and was associated robustly with other drug use and dependence in young adulthood. Associations were stronger for more frequent users. Among young adults who had not been using amphetamines at age 20 years, the strongest predictor of use at age 24 years was the use of other drugs, particularly cannabis, at 20 years. Psychological distress did not predict independently an increased likelihood of amphetamine use in this cohort.

CONCLUSION

Young people in Australia using amphetamine at age 24 years are highly likely to be significant polydrug users. The risks for both initiation of young adult amphetamine use, and maintenance of such use, pertain to the heavy use of other drugs. Interventions for heavy amphetamine users at this age are likely to require attention to multiple drug problems.

Prevalence and correlates of cannabis use in developed and developing countries

PURPOSE OF REVIEW

The aim of this article is to review recent research on the prevalence, antecedents and correlates of cannabis use in young adults in developed and developing countries.

RECENT FINDINGS

Cannabis is the most widely used illicit drug globally and its use appears to be increasing in developed and developing countries. In developed countries rebelliousness, antisocial behaviour, poor school performance, and affiliation with drug-using peers are risk factors for early and regular cannabis use. Similar antecedents are now being reported in developing countries. Dependence is an underappreciated risk of cannabis that affects one in six to seven adolescents who use cannabis in developed countries. Adolescent cannabis dependence is correlated with an increased risk of using other illicit drugs, symptoms of depression, and symptoms of psychosis. The plausibility of cannabis playing a contributory causal role has increased for symptoms of psychosis in longitudinal studies but remains contentious. In the case of other illicit drug use and mood disorders common causal explanations remain difficult to exclude.

SUMMARY

Early and regular cannabis use in adolescence predicts an increased risk of cannabis dependence which in turn predicts an increased risk of using other illicit drugs, and reporting symptoms of mood and psychotic disorders.

The predictors and consequences of adolescent amphetamine use: findings from the Victoria Adolescent Health Cohort Study

OBJECTIVES

Previous work has highlighted the adverse consequences of early-onset cannabis use. However, little is known about the predictors and effects of early-onset amphetamine use. We set out to examine these issues using a representative cohort of young people followed-up over 11 years in Victoria, Australia.

METHODS

A stratified, random sample of 1943 adolescents was recruited from secondary schools across Victoria at age 14-15 years. This cohort was interviewed on eight occasions until the age of 24-25 years (78% follow-up at that age). Cross-sectional associations were assessed using logistic regression with allowance for repeated measures. Both proportional hazards models and logistic regression models were used to assess prospective associations.

RESULTS

Approximately 7% of the sample had used amphetamines by the age of 17 years. Amphetamine use by this age was associated with poorer mental health and other drug use. The incidence of amphetamine use during the teenage years was predicted by heavier drug use and by mental health problems. By young adulthood (age 24-25 years), adolescent amphetamine users were more likely to meet criteria for dependence upon a range of drugs, to have greater psychological morbidity and to have some limitations in educational attainment. Most of these associations were not sustained after adjustment for early-onset cannabis use.

CONCLUSION

Young people in Australia who begin amphetamine use by age 17 years are at increased risk for a range of mental health, substance use and psychosocial problems in young adulthood. However, these problems are largely accounted for by their even earlier-onset cannabis use.

Age and sex differences in factors associated with the onset of cannabis use: a cohort study

OBJECTIVE

To investigate age and sex differences in factors associated with the onset of cannabis use among adolescents.

METHODS

A representative sample of schoolchildren from secondary schools in Barcelona (n=1056) was selected and followed-up from the first to the fourth year of secondary education (7-10th grades). The participants completed a self-administered lifestyle questionnaire each year. Multilevel logistic regression models were used for each year and sex to analyse predictors of cannabis use; the second level was adjusted by school.

RESULTS

Onset of cannabis use during follow-up was associated with a prior history of tobacco smoking [odds ratio (OR)=7.7 in boys; OR=3.8 in girls], alcohol consumption (OR=6.4 in boys; OR=3.2 in girls), antisocial behavior (OR=2.8 in boys; OR=2.2 in girls), intention to use drugs (OR=3.5 in boys; OR=4.2 in girls), drug use among friends (OR=2.5 in boys; OR=3.7 in girls) and spending leisure time in bars or discos (OR=2.1 in boys; OR=3.8 in girls). Moreover, among girls, attending state schools (OR=2.9), low academic performance (OR=5.7) and living in a single-parent family (OR=2.0) also independently predicted cannabis use.

CONCLUSIONS

This study reveals a wide array of predictive factors in cannabis use onset that largely differed by age and sex. The results support the role of tobacco and alcohol, as well as the influence of drug use among friends, and the importance of leisure time patterns as facilitators of cannabis use.

Does gender contribute to heterogeneity in criteria for cannabis abuse and dependence? Results from the national epidemiological survey on alcohol and related conditions

Previous research has noted that a unidimensional latent construct underlies criteria for cannabis abuse and dependence. However, no study to date has explored whether gender contributes to heterogeneity in the latent abuse and dependence construct and furthermore, whether after accounting for differences in the mean scores of abuse and dependence across genders, there is any evidence for heterogeneity in the individual abuse and dependence criteria. The present study utilizes data on criteria for cannabis abuse and dependence from a large, nationally representative sample (National Epidemiological Survey on Alcohol and Related Conditions) of 8172 lifetime cannabis users to investigate whether gender contributes to heterogeneity in the underlying construct of cannabis abuse and dependence, and in each individual criterion as well. Analyses, all of which were conducted in MPlus, included factor analysis, as well as MIMIC and multiple-group models for an examination of dimensionality and gender heterogeneity, respectively. Results favor a unidimensional construct for cannabis abuse/dependence, as seen in prior research. We also identify two abuse (legal and hazard) and two dependence (quit and problems) criteria, which show significant gender heterogeneity with the abuse criteria exhibiting higher thresholds in women and the dependence criteria in men. We conclude that the criteria that serve as indicators of DSM-IV cannabis abuse and dependence do not function identically in men and women and that certain criteria (e.g. hazardous use) require further refinement.

Frequent cannabis use among 14/15 years old in Northern Ireland

The relatively high levels of cannabis use among young people is a cause of concern because of the positive relationship between its early onset use, antisocial behaviours and associated lifestyle. Amongst a survey of 3919 young people at school year 11 in Northern Ireland (aged 14/15 years) 142 reported daily cannabis use. These young people also reported particularly high levels of legal and illegal drug use and accounted for a high proportion of use of hard drugs such as cocaine and heroin for the full school cohort. Daily cannabis users also reported high levels of antisocial behaviour and disaffection with school. The findings perhaps raise questions about the existence of a potentially 'hidden' high risk school based group of young people during adolescence who require specific targeted prevention strategies.

Trajectories of adolescent alcohol and cannabis use into young adulthood

BACKGROUND

Both alcohol and cannabis use carry health risks. Both are commonly initiated in adolescence. To date little research has described trajectories of adolescent cannabis or alcohol use or compared their respective consequences in young adulthood.

METHODS

The design was a 10-year eight-wave cohort study of a state-wide community sample of 1943 Victorians initially aged 14-15 years. Moderate- and high-risk alcohol use was defined according to total weekly alcohol consumption. Moderate- and high-risk cannabis use were defined as weekly and daily use, respectively.

RESULTS

Around 90% of young adults used either alcohol or cannabis. Although an association existed between alcohol and cannabis use, there was a tendency for heavy users to use one substance predominantly at any one time. Weekly or more frequent cannabis use in the absence of moderate-risk alcohol use in teenagers predicted a sevenfold higher rate of daily cannabis use in young adults but only a twofold increase in high-risk alcohol use. Conversely, moderate-risk adolescent alcohol use in the absence of weekly cannabis predicted an approximately threefold increased rate of both high-risk drinking and daily cannabis use in young adulthood. Selective heavy cannabis use in both adolescence and young adulthood was associated with greater illicit substance use and poorer social outcomes in young adulthood than selective alcohol use.

CONCLUSIONS

Heavier teenage cannabis users tend to continue selectively with cannabis use. Considering their poor young adult outcomes, regular adolescent cannabis users appear to be on a problematic trajectory.

Marijuana and tobacco use among young adults in Canada: are they smoking what we think they are smoking?

The authors characterized marijuana smoking among young adult Canadians, examined the co-morbidity of tobacco and marijuana use, and identified correlates associated with different marijuana use consumption patterns. Data were collected from 20,275 individuals as part of the 2004 Canadian Tobacco Use Monitoring Survey. Logistic regression models were conducted to examine characteristics associated with marijuana use behaviors among young adults (aged 15-24). Rates of marijuana use were highest among current smokers and lowest among never smokers. Marijuana use was more prevalent among males, young adults living in rural areas, and increased with age. Young adults who were still in school were more likely to have tried marijuana, although among those who had tried, young adults outside of school were more like to be heavy users. Males and those who first tried marijuana at an earlier age also reported more frequent marijuana use. These findings illustrate remarkably high rates of marijuana use and high co-morbidity of tobacco use among young adult Canadians. These findings suggest that future research should consider whether the increasing popularity of marijuana use among young adults represents a threat to the continuing decline in tobacco use among this population.

Negative consequences associated with dependence in daily cannabis users

BACKGROUND

Cannabis is the most widely consumed illicit substance in America, with increasing rates of use. Some theorists tend to link frequency of use with cannabis dependence. Nevertheless, fewer than half of daily cannabis users meet DSM-IV-TR criteria for cannabis dependence. This study seeks to determine whether the negative aspects associated with cannabis use can be explained by a proxy measure of dependence instead of by frequency of use.

RESULTS

Over 2500 adult daily cannabis users completed an Internet survey consisting of measures of cannabis and other drug use, in addition to measures of commonly reported negative problems resulting from cannabis use. We compared those who met a proxy measure of DSM-IV-TR criteria for cannabis dependence (N = 1111) to those who did not meet the criteria (N = 1770). Cannabis dependent subjects consumed greater amounts of cannabis, alcohol, and a variety of other drugs. They also had lower levels of motivation, happiness, and satisfaction with life, with higher levels of depression and respiratory symptoms.

CONCLUSION

Although all of our subjects reported daily use, only those meeting proxy criteria for cannabis dependence reported significant associated problems. Our data suggest that dependence need not arise from daily use, but consuming larger amounts of cannabis and other drugs undoubtedly increases problems.

Cannabis receptor haplotype associated with fewer cannabis dependence symptoms in adolescents

Cannabis is a major substance of abuse, and the gene encoding for the central cannabinoid receptor (CNR1) is a logical candidate gene for vulnerability toward developing symptoms of cannabis dependence. We studied four single-nucleotide polymorphisms (SNPs) in the CNR1 gene for association with having one or more symptoms of cannabis dependence in 541 adolescent subjects who had all tried cannabis five or more times. Cases (327) were defined as those who had tried marijuana and developed one or more symptoms, and controls (214) as those who had tried marijuana but developed no dependence symptoms. Cannabis dependence symptoms were assessed in these youth when they were 17 or older with the Composite International Diagnostic Interview--Substance Abuse Module. Univariate (single-marker) association tests demonstrated that SNP rs806380, located in intron 2 of the CNR1 gene, was significantly associated with developing one or more cannabis dependence symptoms, with the G allele having a protective effect (P < 0.02). This was consistent with the results of the global haplotype test (P < 0.01). One of the common haplotypes examined (present in 21% of the subjects) was significantly associated with a lower rate of having one or more cannabis dependence symptoms. Our findings provide evidence suggesting that a common CNR1 haplotype is associated with developing fewer cannabis dependence symptoms among adolescents who have experimented with cannabis.

The mental health risks of adolescent cannabis use

Wayne Hall summarizes the research evidence on whether cannabis use is associated with psychiatric problems.

Intercity differences in drug use by pre-teenage school children

BACKGROUND

Regional variations in rates of drug use have been described previously in relation to adolescents. However, reasons for these differences are not clear. Previous publications pointed to higher rates of drug use by Glasgow children compared to children living in Newcastle upon Tyne. This paper explores the hypothesis that a higher rate of drug use in Glasgow is due to higher availability there.

METHOD

School surveys were conducted in Glasgow and Newcastle upon Tyne on a total of 2,318 children aged 10-12. These concerned aspects of behaviour, lifestyle, family life and drug use.

FINDINGS

The data indicate that the higher rate of drug use by Glasgow children was attributable to greater opportunities for children to gather at leisure centres and other venues and activities facilitating exposure to more drug-experienced young people.

Screening for Internet Addiction: An Empirical Study on Cut-off Points for the Chen Internet Addiction Scale

The aim of this study was to establish the optimal cut-off points of the Chen Internet Addiction Scale (CIAS), to screen for and diagnose Internet addiction among adolescents in the community by using the well-established diagnostic criteria of Internet addiction. This survey of 454 adolescents used screening (57/58) and diagnostic (63/64) cut-off points of the CIAS, a self-reported instrument, based on the results of systematic diagnostic interviews by psychiatrists. The area under the curve of the receiver operating characteristic curve revealed that CIAS has good diagnostic accuracy (89.6%). The screening cut-off point had high sensitivity (85.6%) and the diagnostic cut-off point had the highest diagnostic accuracy, classifying 87.6% of participants correctly. Accordingly, the screening point of the CIAS could provide a screening function in two-stage diagnosis, and the diagnostic point could serve as a diagnostic criterion in one-stage massive epidemiologic research.

Cannabis‐related problems and their management

Despite being the most common illicit drug in the Western world, treatment for cannabis use is not readily available. Primary health care and even specialist drug treatment services have often under‐recognised, and undertreated, cannabis‐related problems. Australian researcher Jan Copeland is one of the few people to test cannabis treatment models. Here she outlines the most effective models for treating cannabis and how they can be applied to other services.

Who becomes cannabis dependent soon after onset of use? Epidemiological evidence from the United States: 2000-2001

In this paper we estimate the risk of becoming cannabis dependent within 24 months after first use of cannabis and examine subgroup variation in this risk. The study estimates are based on the National Household Survey on Drug Abuse conducted during 2000-2001, with a representative sample of U.S. residents ages 12 and older (n=114,241). A total of 3352 respondents were found to have used cannabis for the first time within a span of up to 24 months prior to assessment. An estimated 3.9% of these recent-onset users developed a cannabis dependence syndrome during the interval since first use (median interval duration approximately 12 months). Excess risk of cannabis dependence was found for those with cannabis onset before late-adolescence, those with family income less than US dollars 20,000, and those who had used three or more drugs before the first use of cannabis (i.e., tobacco, alcohol, and other drugs). While these findings generally support previous study results, this study's focus on recent-onset users more closely approximates prospective and longitudinal research on the incidence (risk) of becoming cannabis dependent soon after onset of cannabis use, removing the influence of users with long-sustained or persistent cannabis dependence developed years ago.