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Background and aims: There are concerns that availability of recreational cannabis dispensaries (RCDs) and point‐of‐sale marketing may lead to increased cannabis use in jurisdictions where cannabis retail sale is legal. This paper examined whether the availability RCDs and the presence of storefront signage indicative of cannabis and signs promoting health benefits in RCDs were associated with cannabis use and risk perceptions. Design: Cross‐sectional, secondary data analysis. Setting: California, USA. Participants: A representative sample of 3385 adults in California who participated in the 2020 probability‐based Marijuana Use and Environment Survey. Measurements Binary outcomes included past‐month overall cannabis use, perceiving cannabis smoking as harmful and past‐month cannabis use by purpose (medical only, recreational only and dual). The objectively assessed predictors included proximity and density of RCDs and presence of storefront signage indicative of cannabis and signs promoting health benefits in RCDs. Findings In terms of proximity, thepresence of storefront signage in the nearest RCD was associated with smaller odds of perceiving cannabis smoking as harmful [odds ratio (OR) = 0.63, 95% confidence interval (CI) = 0.39, 0.99] if the RCD was located within 2 miles of home. Presence of health benefit signs in the nearest RCD was associated with greater odds of overall cannabis use (OR = 2.45, 95% CI = 1.17, 5.16) and recreational use (OR = 3.50, 95% CI = 1.027, 11.91) if the RCD was located within 2–4 miles of home. In terms of density, count of RCDs, count of RCDs with storefront signage and count of RCDs with health benefit signs within 2 miles of home were each separately associated with greater odds of overall cannabis use and cannabis use for dual purposes. Conclusions: The availability of recreational cannabis dispensaries within 2 miles of one's home and the presence of storefront signage indicating the availability of cannabis and signs promoting health benefits of cannabis appear to be associated with increased cannabis use and reduced risk perceptions among adults in California, USA. [ABSTRACT FROM AUTHOR]

Background and aims Addictive behaviours are among the greatest scourges on humankind. It is important to estimate the extent of the problem globally and in different geographical regions. Such estimates are available, but there is a need to collate and evaluate these to arrive at the best available synthetic figures. Addiction has commissioned this paper as the first of a series attempting to do this. Methods Online sources of global, regional and national information on prevalence and major harms relating to alcohol use, tobacco use, unsanctioned psychoactive drug use and gambling were identified through expert review and assessed. The primary data sources located were the websites of the World Health Organization (WHO), the United Nations Office on Drugs and Crime (UNODC) and the Alberta Gambling Research Institute. Summary statistics were compared with recent publications on the global epidemiology of addictive behaviours. Results An estimated 4.9% of the world's adult population (240 million people) suffer from alcohol use disorder (7.8% of men and 1.5% of women), with alcohol causing an estimated 257 disability-adjusted life years lost per 100 000 population. An estimated 22.5% of adults in the world (1 billion people) smoke tobacco products (32.0% of men and 7.0% of women). It is estimated that 11% of deaths in males and 6% of deaths in females each year are due to tobacco. Of 'unsanctioned psychoactive drugs', cannabis is the most prevalent at 3.5% globally, with each of the others at < 1%; 0.3% of the world's adult population (15 million people) inject drugs. Use of unsanctioned psychoactive drugs accounts for an estimated 83 disability-adjusted life years lost per 100 000 population. Global estimates of problem gambling are not possible, but in countries where it has been assessed the prevalence is estimated at 1.5%. Conclusions Tobacco and alcohol use are by far the most prevalent addictive behaviours and cause the large majority of the harm. However, the quality of data on prevalence and addiction-related harms is mostly low, and comparisons between countries and regions must be viewed with caution. There is an urgent need to review the quality of data on which global estimates are made and coordinate efforts to arrive at a more consistent approach. [ABSTRACT FROM AUTHOR]

Background and Aims: Treatments for cannabis use disorder (CUD) have limited efficacy and little is known about who responds to existing treatments. Accurately predicting who will respond to treatment can improve clinical decision‐making by allowing clinicians to offer the most appropriate level and type of care. This study aimed to determine whether multivariable/machine learning models can be used to classify CUD treatment responders versus non‐responders. Methods: This secondary analysis used data from a National Drug Abuse Treatment Clinical Trials Network multi‐site outpatient clinical trial in the United States. Adults with CUD (n = 302) received 12 weeks of contingency management, brief cessation counseling and were randomized to receive additionally either (1) N‐Acetylcysteine or (2) placebo. Multivariable/machine learning models were used to classify treatment responders (i.e. two consecutive negative urine cannabinoid tests or a 50% reduction in days of use) versus non‐responders using baseline demographic, medical, psychiatric and substance use information. Results: Prediction performance for various machine learning and regression prediction models yielded area under the curves (AUCs) >0.70 for four models (0.72–0.77), with support vector machine models having the highest overall accuracy (73%; 95% CI = 68–78%) and AUC (0.77; 95% CI = 0.72, 0.83). Fourteen variables were retained in at least three of four top models, including demographic (ethnicity, education), medical (diastolic/systolic blood pressure, overall health, neurological diagnosis), psychiatric (depressive symptoms, generalized anxiety disorder, antisocial personality disorder) and substance use (tobacco smoker, baseline cannabinoid level, amphetamine use, age of experimentation with other substances, cannabis withdrawal intensity) characteristics. Conclusions: Multivariable/machine learning models can improve on chance prediction of treatment response to outpatient cannabis use disorder treatment, although further improvements in prediction performance are likely necessary for decisions about clinical care. [ABSTRACT FROM AUTHOR]

Aims: To test the effectiveness of a digital intervention to reduce cannabis use (ICan) with adherence‐focused guidance compared with educational cannabis information. Design: This was a single‐blind randomized controlled trial. Follow‐up clinical outcome measurements took place 3 and 6 months after randomization. Setting: The trial was conducted in the Netherlands. The intervention and guidance took place on‐line, with recruitment via Facebook/Instagram advertisement campaigns. Participants: Inclusion criteria were ≥ 18 years, cannabis use on ≥ 3 days/week, the desire to reduce/quit cannabis and using a smartphone. Participants were allocated to either ICan (n = 188) or control (n = 190) (69% male, mean age = 27.5 years). Intervention and comparator: ICan is a mobile (web‐)application based on motivational interviewing and cognitive behavioural therapy and includes three main components: screening, brief intervention (six modules) and referral to treatment. The control condition consisted of non‐interactive educational cannabis information. Measurements Primary outcome was the number of cannabis use days in the 7 days prior to the 6‐month follow‐up measurement. Secondary outcome measures at 3‐ and 6‐month follow‐up were the number of grams of cannabis used and attitudes towards seeking professional help for cannabis use related problems. Findings Intention‐to‐treat analysis showed that 6 months after randomization the mean number of cannabis use days in the past 7 days was reduced in both conditions (time P < 0.001), with no significant group × time interaction effect [ICan = 4.17 days, control = 4.31 days, Cohen's dbetween = 0.06, 95% confidence interval (CI) = −0.15, 0.26, P = 0.93]. Three months after randomization the mean number of grams used in the past 7 days was reduced in both conditions, with a significantly larger reduction in the ICan condition (P = 0.009, Cohen's dbetween = 0.15). At 6‐month follow‐up the significant group × time interaction effect was no longer present (P = 0.30). In both conditions, attitudes towards seeking professional help remained virtually unchanged over time. Conclusions: A digital intervention to reduce cannabis use (ICan) was more effective than non‐interactive educational cannabis information in reducing grams of cannabis used over 3 months, but not more effective at reducing cannabis use days at 6‐month follow‐up. Cannabis use reductions were maintained in both conditions between 3 and 6 months' follow‐up. [ABSTRACT FROM AUTHOR]

Background and Aims: The prevalence of cannabis use based on self‐reports is likely to be underestimated in population surveys, especially in contexts where its use is a criminal offence. Indirect survey methods ask sensitive questions ensuring that answers cannot be identified with an individual respondent, therefore potentially resulting in more reliable estimates. We aimed to measure whether the indirect survey method 'randomized response technique' (RRT) increased response rate and/or increased disclosure of cannabis use among young adults compared with a traditional survey. Design: We conducted two parallel nation‐wide surveys during the spring and the summer of 2021. The first survey was a traditional questionnaire‐based one (focusing on substance use and gambling). The second survey applied an indirect survey method known as 'the cross‐wise model' to questions related to cannabis use. The two surveys employed identical procedures (e.g. invitations, reminders and wording of the questions) Setting and Participants: The participants were young adults (aged 18–29 years) living in Sweden. The traditional survey had 1200 respondents (56.9% women) and the indirect survey had 2951 respondents (53.6% women). Measurements In both surveys, cannabis use was assessed according to three time‐frames: life‐time use; use during the past year; and use during the past 30 days. Findings The estimated prevalence of cannabis use was two‐ to threefold higher on all measures when estimated using the indirect survey method compared with the traditional survey: use during life‐time (43.2 versus 27.3%); during the past year (19.2 versus 10.4%); and during the past 30 days (13.2 versus 3.7%). The discrepancy was larger among males and individuals with an education shorter than 10 years, who were unemployed, and who were born in non‐European countries. Conclusions: Indirect survey methods may provide more accurate estimates than traditional surveys on prevalence of self‐reported cannabis use. [ABSTRACT FROM AUTHOR]

Background and aims: The Marijuana Purchase Task (MPT) is increasingly used to measure cannabis reinforcing value and has potential use for cannabis etiological and regulatory research. This meta‐analysis sought to evaluate for the first time the MPT's concurrent validity in relation to cannabis involvement. Methods: Electronic databases and pre‐print repositories were searched for MPT studies that examined the cross‐sectional relationship between frequency and quantity of cannabis use, problems, dependence, and five MPT indicators: intensity (i.e. unrestricted consumption), Omax (i.e. maximum consumption), Pmax (i.e. price at which demand becomes elastic), breakpoint (i.e. first price at which consumption ceases), and elasticity (i.e. sensitivity to rising costs). Random effects meta‐analyses of cross‐sectional effect sizes were conducted, with Q tests for examining differences by cannabis variables, meta‐regression to test quantitative moderators, and publication bias assessment. Moderators included sex, number of MPT prices, variable transformations, and year of publication. Populations included community and clinical samples. Results: The searches yielded 14 studies (n = 4077, median % females: 44.8%: weighted average age = 29.08 [SD = 6.82]), published between 2015 and 2022. Intensity, Omax, and elasticity showed the most robust concurrent validity (|r's| = 0.147–325, ps < 0.014) with the largest significant effect sizes for quantity (|r| intensity = 0.325) and cannabis dependence (|r| Omax = 0.320, |r| intensity = 0.305, |r| elasticity = 0.303). Higher proportion of males was associated with increased estimates for elasticity‐quantity and Pmax‐problems. Higher number of MPT prices significantly altered magnitude of effects sizes for Pmax and problems, suggesting biased estimations if excessively low prices are considered. Methodological quality was generally good, and minimal evidence of publication bias was observed. Conclusions: The marijuana purchase task presents adequate concurrent validity to measure cannabis demand, most robustly for intensity, Omax, and elasticity. Moderating effects by sex suggest potentially meaningful sex differences in the reinforcing value of cannabis. [ABSTRACT FROM AUTHOR]

Aims We investigate the extent of and factors associated with denial of previously reported cannabis and other illicit drug use, and assess the potential of hair testing for measuring substance use in general population samples. Design Birth cohort study. Setting United Kingdom, 1991-present. Participants A total of 3643 participants who provided hair and self-report measures of cannabis and other illicit drug use in the Avon Longitudinal Study of Parents and Children (ALSPAC) at age 18 years. Measurements Denial of ever use of cannabis and other illicit drugs at age 18 following previously reported use. Positive hair drug tests for cannabis and other illicit drugs, and expected numbers of false positives and false negatives based on expected sensitivity and specificity. Findings Cannabis and other illicit drug use was reported by 1223 and 393 individuals, respectively, before age 18 years. Of these 176 (14.4%) and 99 (25.2%), respectively, denied use at age 18. Denial of cannabis use decreased with the reporting of other substances and antisocial behaviour. Cannabis and other illicit drug use at age 18 was reported by 547 (22.5%) and 203 (8.4%) individuals, respectively. Of these, 111 (20.3%) and 13 (6.4%) were hair-positive for cannabis and other illicit drugs, respectively. Based on hair testing for cannabis use we expect 0 [95% confidence interval (CI) = 0-169] false positives and 394 (95% CI = 323-449) false negatives compared to observed 362 potential false positives and 436 potential false negatives based on self-report. In hair-positive individuals, reporting the use of other substances and antisocial behaviour decreased the odds of a negative self-report. Conclusions Hair analysis provides an unreliable marker of substance use in general population samples. People who report more frequent substance use before age 18 are less likely to later deny previous substance use at age 18 than people who report occasional use. [ABSTRACT FROM AUTHOR]

Aims To estimate cannabis use disorder (CUD) trajectory classes from ages 14 to 30 years and compare classes on clinical characteristics, risk factors and psychosocial outcomes. Design Four waves (T1-T4) of data from an epidemiological study of psychopathology among a regionally representative sample. Trajectory classes described risk for CUD as a function of age. The number of classes was determined by model fit. Setting Participants were selected randomly from nine high schools in western Oregon, USA. Participants The sample included 816 participants [age at T1 mean = 16.6, standard deviation (SD) = 1.2; 44% male; 8% non-white]. Measurements Participants completed diagnostic interviews, Child Trauma Questionnaire, Social Adjustment Scale and items adapted from the Wisconsin Manual for Assessing Psychotic-Like Experiences. Findings There were three CUD trajectory classes (Lo-Mendell-Rubin likelihood ratio test < 0.001): (1) persistent increasing risk; (2) maturing out, with increasing risk then decreasing risk; and (3) stable low risk. The persistent increasing class had later initial CUD onsets ( η2 = 0.16, P < 0.001) and greater cumulative CUD durations ( η2 = 0.26, P < 0.001). Male sex [odds ratio (OR) = 2.57, P = 0.018], externalizing disorders between ages 24 and 30 years (OR = 2.64, P < 0.001) and psychotic experiences during early adulthood (Cohen's d = 0.44, P = 0.016) discriminated between the persistent increasing and the maturing-out classes. Conclusions Evidence suggests three distinguishable types of trajectory for development of cannabis use disorder starting in early teens: (1) persistent increasing risk; (2) maturing out, with increasing risk then decreasing risk; and (3) stable low risk. [ABSTRACT FROM AUTHOR]

Aims To test, among US students: (1) whether perceived harmfulness of marijuana has changed over time, (2) whether perceived harmfulness of marijuana changed post-passage of state medical marijuana laws (MML) compared with pre-passage; and (3) whether perceived harmfulness of marijuana statistically mediates and/or modifies the relation between MML and marijuana use as a function of grade level. Design Cross-sectional nationally representative surveys of US students, conducted annually, 1991-2014, in the Monitoring the Future study. Setting Surveys conducted in schools in all coterminous states; 21 states passed MML between 1996 and 2014. Participants The sample included 1 134 734 adolescents in 8th, 10th and 12th grades. Measurements State passage of MML; perceived harmfulness of marijuana use (perceiving great or moderate risk to health from smoking marijuana occasionally versus slight or no risk); and marijuana use (prior 30 days). Data were analyzed using time-varying multi-level regression modeling. Findings The perceived harmfulness of marijuana has decreased significantly since 1991 (from an estimated 84.0% in 1991 to 53.8% in 2014, P < 0.01) and, across time, perceived harmfulness was lower in states that passed MML [odds ratio (OR) = 0.86, 95% confidence interval (CI) = 0.75-0.97]. In states with MML, perceived harmfulness of marijuana increased among 8th graders after MML passage (OR = 1.21, 95% CI = 1.08-1.36), while marijuana use decreased (OR = 0.81, 95% CI = 0.72-0.92). Results were null for other grades, and for all grades combined. Increases in perceived harmfulness among 8th graders after MML passage was associated with ~33% of the decrease in use. When adolescents were stratified by perceived harmfulness, use in 8th graders decreased to a greater extent among those who perceived marijuana as harmful. Conclusions While perceived harmfulness of marijuana use appears to be decreasing nationally among adolescents in the United States, the passage of medical marijuana laws (MML) is associated with increases in perceived harmfulness among young adolescents and marijuana use has decreased among those who perceive marijuana to be harmful after passage of MML. [ABSTRACT FROM AUTHOR]

Background and Aims Young adults with attention deficit/hyperactivity disorder (ADHD) show higher substance use disorder (SUD) prevalence relative to non-ADHD controls; few longitudinal studies have examined the course of substance use with reference to conduct disorder (CD). We compared initiation and escalation of substance use at 15-month follow-up in men screened positive or negative for ADHD (ADHD+ versus ADHD-), controlling for CD presence in early adolescence. Design Participants were recruited during August 2010 and November 2011 from the census of all young men who have to pass mandatory army conscription from three of six Swiss Army recruitment centres. A two-wave data collection was performed via questionnaires at baseline and 15-month follow-up as a part of the longitudinal Cohort Study on Substance Use Risk Factors. Setting Recruitment centres in Lausanne, Windisch and Mels, responsible for 21 cantons in German- and French-speaking areas of Switzerland. Participants Consecutive sample of 5103 male Swiss Army conscripts who provided informed consent and responded to questionnaires at baseline and 15-month follow-up. Their mean age was 20.0 (standard deviation = 1.21) years at baseline. Measurements ADHD and CD were assessed using the adult ADHD Self-Report Scale and the MINI International Neuropsychiatric Interview Plus, respectively, at baseline, and substance use was measured via self-administered substance use questionnaires at baseline and follow-up. Findings Compared with the ADHD- group, the ADHD+ group ( n = 215, 4.2%) showed heavier baseline substance use and increased likelihood of alcohol (χ2 = 53.96; P < 0.001), tobacco (χ2 = 21.73; P < 0.001) and cannabis use disorders (χ2 = 48.43; P < 0.001). The extent of alcohol, tobacco and cannabis use in the two groups remained stable from baseline to follow-up (no escalation). The ADHD+ group was more likely to initiate substance use compared with the ADHD- group (higher initiation rates), particularly with amphetamines [odds ratio (OR) = 3.81; 95% confidence interval (CI) = 2.20-6.60; P < 0.001] and non-medical use of ADHD medication (OR = 4.45; 95% CI = 2.06-9.60; P < 0.001). CD was associated with initiation of substance use but did not mediate the associations between ADHD and substance use, revealing that the impact of ADHD on substance use was independent of CD. Conclusions For men in their early 20s, attention deficit/hyperactivity disorder is a risk factor for continued heavier but not escalating use of alcohol, tobacco and cannabis when already consuming these substances, compared with young men with no ADHD. It is also a risk factor for initiating the use of cannabis, stimulants, hallucinogens and sedatives, independent of conduct disorder in early adolescence. [ABSTRACT FROM AUTHOR]

Aims We tested race/ethnic differences in alcohol and marijuana (AM) trajectories (comprising an intercept term, reflecting overall probability of use, and a slope term, reflecting change in probability of use) during adolescence, whether AM use trajectories predicted high school outcomes, and whether outcomes differed by race/ethnicity after controlling for trajectory of AM use. Design This longitudinal study involved 6509 youth from 16 middle schools in Southern California surveyed from age 11.5 (2008) to age 17 (2015) years; all surveys assessed AM use, and the final survey also examined high school outcomes. Setting Youth completed five surveys in middle school and two on-line surveys in high school. Participants The sample was 50% male and 80% non-white. Measurements Intercept (at 2.75 years post-baseline) and slope of AM use were examined as outcomes for race/ethnic differences. AM use trajectories were examined as predictors of academic performance and unpreparedness, social functioning, mental and physical health and delinquency. Findings We found differences in trajectories of use by race/ethnicity, with white youth reporting a higher overall intercept of alcohol use compared to all other groups (versus Asian P < 0.001, black P = 0.001, multi-ethnic P = 0.008). Overall, examination of trajectories of use showed that adolescents with a higher alcohol use intercept term reported greater academic unpreparedness ( P < 0.001) and delinquency ( P < 0.001) at wave 7 in high school. In addition, youth with a higher intercept for marijuana use reported greater academic unpreparedness ( P < 0.001) and delinquency ( P < 0.001), and poorer academic performance ( P = 0.032) and mental health ( P = 0.002) in high school. At wave 7, compared to white youth, Hispanic and multi-ethnic youth reported poorer academic performance ( P < 0.001 and P = 0.034, respectively); Asian, black and Hispanic youth reported higher academic unpreparedness ( P < 0.001, P = 0.019, and P = 0.001); and Asian youth and multi-ethnic youth reported poorer physical health ( P = 0.012 and P = 0.018) controlling for AM use. Conclusions Greater AM use was associated with worse functioning in high school for all youth. After controlling for AM use, non-white youth reported worse outcomes in high school for academics and health. [ABSTRACT FROM AUTHOR]

Aims To describe patterns of cannabis use, the degree of overlap between medicinal and recreational users, and their differential use patterns, modes of consumption and sources of cannabis. Design An ongoing probability-based internet panel maintained by the market research firm GfK Group. Setting Households in Colorado, Washington, Oregon and New Mexico, USA. Participants A total of 2009 individuals from Washington ( n = 787), Oregon ( n = 506), Colorado ( n = 503) and New Mexico ( n = 213). Post stratification sampling weights were provided so that estimates could be made representative of the household population in each of these states. Respondents were aged between 18 and 91 years, with a mean age of 53 years. Methods We compare patterns of cannabis consumption for medicinal and recreational users as well as simultaneous use of alcohol and cannabis. We also examine the extent to which patterns of use differ across states that chose to legalize ( Washington and Colorado) and those that did not ( New Mexico and Oregon). Findings Rates of life-time medical cannabis use are similar in Colorado and Washington (8.8% and 8.2%) but lower in Oregon and New Mexico (6.5% and 1%). Recreational use is considerably higher than medical use across all states (41%), but highest in Oregon and Washington. Approximately 86% of people who report ever using cannabis for medicinal purposes also use it recreationally. Medical users are more likely to vaporize and consume edibles and report a higher amount (in grams) consumed, and spend more money per month than recreational users. Individuals who use cannabis do not commonly use it with alcohol, irrespective of whether they are consuming cannabis recreationally or medically. Fewer than one in five recreational users report simultaneous use of alcohol and cannabis most or all of the time and fewer than 3% of medicinal users report frequent simultaneous use of alcohol and cannabis. Conclusions In the United States, the degree of overlap between medicinal and recreational cannabis users is 86%. Medicinal and recreational cannabis users favor different modes and amounts of consumption. Only a small proportion (12%) of cannabis users usually consume cannabis and alcohol simultaneously, while concurrent use is common among recreational users. [ABSTRACT FROM AUTHOR]

Aim To estimate associations between recent licit and illicit substance use and subsequent suicide attempt among people who inject drugs (PWID). Design Secondary analysis of longitudinal data from a prospective cohort study of PWID followed bi-annually between 2004 and 2011. Setting Montréal, Canada. Participants Seven hundred and ninety-seven PWID who reported injection drug use in the previous 6 months, contributing to a total of 4460 study visits. The median number of visits per participant was five (interquartile range: 3-8). Measurements An interviewer-administered questionnaire eliciting information on socio-demographic factors, detailed information on substance use patterns and related behaviours, mental health markers and suicide attempt. The primary exposure variables examined were past-month use of alcohol [heavy (≥ 60 drinks); moderate (one to 59 drinks); none], sedative-hypnotics, cannabis, cocaine, amphetamine and opioids [regular (≥ 4 days); occasional (1-3 days); none]. The outcome was a binary measure of suicide attempt assessed in reference to the previous 6 months. Findings In multivariate analyses, a positive association was found among licit substances between heavy alcohol consumption [adjusted odds ratio (AOR) = 2.05; 95% confidence interval (CI) = 1.12-3.75], regular use of sedative-hypnotics (AOR = 1.89; 95% CI = 1.21-2.95) and subsequent attempted suicide. Among illicit substances, occasional use of cannabis (AOR = 1.84; 95% CI = 1.09-3.13) had a positive association with subsequent suicide attempt. No statistically significant association was found for the remaining substances. Conclusion Among people who inject drugs, use of alcohol, sedative-hypnotics and cannabis, but not cocaine, amphetamine or opioids, appears to be associated with an increased likelihood of later attempted suicide. [ABSTRACT FROM AUTHOR]

Aims To examine the effectiveness of a personality-targeted intervention program (Adventure trial) delivered by trained teachers to high-risk (HR) high-school students on reducing marijuana use and frequency of use. Design A cluster-randomized controlled trial. Setting Secondary schools in London, UK. Participants Twenty-one secondary schools were randomized to intervention ( n = 12) or control ( n = 9) conditions, encompassing a total of 1038 HR students in the ninth grade [mean (standard deviation) age = 13.7 (0.33) years]. Interventions Brief personality-targeted interventions to students with one of four HR profiles: anxiety sensitivity, hopelessness, impulsivity and sensation-seeking. Measurements Primary outcome: marijuana use. Secondary outcome: frequency of use. Assessed using the Reckless Behaviour Questionnaire at intervals of 6 months for 2 years. Personality risk was measured with the Substance Use Risk Profile Scale. Findings Logistic regression analysis revealed significant intervention effects on cannabis use rates at the 6-month follow-up in the intent-to-treat sample [odds ratio (OR) = 0.67, P = 0.05, 95% confidence interval (CI) = 0.45-1.0] and significant reductions in frequency of use at 12- and 18-month follow-up (β = -0.14, P ≤ 0.05, 95% CI = -0.6 to -0.01; β = -0.12, P ≤ 0.05, 95% CI = -0.54 to 0.0), but this was not supported in two-part latent growth models. Subgroup analyses (both logistic and two-part models) reveal that the sensation-seeking intervention delayed the onset of cannabis use among sensation seekers (OR = 0.25, β = -0.833, standard error = 0.342, P = 0.015). Conclusions Personality-targeted interventions can be delivered effectively by trained school staff to delay marijuana use onset among a subset of high-risk teenagers: sensation-seekers. [ABSTRACT FROM AUTHOR]

Background and aims It is well established that craving increases following exposure to substance-related 'cues', but the role of life-styles or substance use habits that are unique to each person remains poorly understood. This study examines the association of substance-specific and personal cues with craving and substance use in daily life. Design Ecological momentary assessment was used during a 2-week period. Setting Data were collected in a French out-patient addiction treatment centre. Participants A total of 132 out-patients beginning treatment for alcohol, tobacco, cannabis or opiate addiction were included. Measurements Using mobile technologies, participants were questioned four times per day relative to craving, substance use and exposure to either substance-specific cues (e.g. seeing a syringe) or personal cues unique to that individual (e.g. seeing the specific person with whom the substance is used). Findings Craving intensity was associated with the number of concurrently assessed substance-specific cues ( t = 4.418, P < 0.001) and person-specific cues ( t = 4.006, P < 0.001) when analysed jointly within the same model. However, only person-specific cues were associated with increases in craving over subsequent hours of the day ( t = 2.598, P < 0.05). Craving intensity, in turn, predicted increases in later substance use ( t = 4.076, P < 0.001). Causal mediation analyses demonstrated that the association of cues with later substance use was mediated by craving intensity (mediated effect = 0.007, 95% confidence interval = 0.004-0.011). Conclusions Unique person-specific cues appear to have a robust effect on craving addictive substances, and the duration of this association may persist longer than for more general substance-specific cues. Mobile technologies provide new opportunities for understanding these person-specific risk factors and for providing individually tailored interventions. [ABSTRACT FROM AUTHOR]

Aims To investigate the relationship between cannabis and tobacco use by age 15 and subsequent educational outcomes. Design Birth cohort study. Setting England. Participants The sample was drawn from the Avon Longitudinal Study of Parents and Children; a core sample of 1155 individuals had complete information on all the variables. Measurements The main exposures were cannabis and tobacco use at age 15 assessed in clinic by computer-assisted questionnaire and serum cotinine. The main outcomes were performance in standardized assessments at 16 [Key Stage 4, General Certificate of Secondary Education (GCSE)] in English and mathematics (mean scores), completion of five or more assessments at grade C level or higher and leaving school having achieved no qualifications. Analyses were sequentially adjusted for multiple covariates using a hierarchical approach. Covariates considered were: maternal substance use (ever tobacco or cannabis use, alcohol use above recommended limits); life course socio-economic position (family occupational class, maternal education, family income); child sex; month and year of birth; child educational attainment prior to age 11 (Key Stage 2); child substance use (tobacco, alcohol and cannabis) prior to age 15 and child conduct disorder. Findings In fully adjusted models both cannabis and tobacco use at age 15 were associated with subsequent adverse educational outcomes. In general, the dose-response effect seen was consistent across all educational outcomes assessed. Weekly cannabis use was associated negatively with English GCSE results [grade point difference (GPD), -5.93, 95% confidence interval (CI) = -8.34, -3.53] and with mathematics GCSE results (GPD, -6.91, 95% CI = -9.92, -3.89). Daily tobacco smoking was associated negatively with English GCSE (GPD, -11.90, 95% CI = -13.47, -10.33) and with mathematics GCSE (GPD, -16.72, 95% CI = -18.57, -14.86). The greatest attenuation of these effects was seen on adjustment for other substance use and conduct disorder. Following adjustment, tobacco appeared to have a consistently stronger effect than cannabis. Conclusions Both cannabis and tobacco use in adolescence are associated strongly with subsequent adverse educational outcomes. Given the non-specific patterns of association seen and the attenuation of estimates on adjustment, it is possible that these effects arise through non-causal mechanisms, although a causal explanation cannot be discounted. © 2015 Society for the Study of Addiction [ABSTRACT FROM AUTHOR]

Background and Aims Twin and family studies suggest that genetic influences are shared across substances of abuse. However, despite evidence of heritability, genome-wide association and candidate gene studies have indicated numerous markers of limited effects, suggesting that much of the heritability remains missing. We estimated (1) the aggregate effect of common single nucleotide polymorphisms (SNPs) on multiple indicators of comorbid drug problems that are typically employed across community and population-based samples, and (2) the genetic covariance across these measures. Participants A total of 2596 unrelated subjects from the Study of Addiction: Genetics and Environment provided information on alcohol, tobacco, cocaine, cannabis and other illicit substance dependence. Phenotypic measures included: (1) a factor score based on DSM-IV drug dependence diagnoses (DD), (2) a factor score based on problem use (PU; i.e. 1+ DSM-IV symptoms) and (3) dependence vulnerability (DV; a ratio of DSM-IV symptoms to the number of substances used). Findings Univariate and bivariate genome-wide complex trait analyses of this selected sample indicated that common SNPs explained 25-36% of the variance across measures, with DD and DV having the largest effects [h2SNP (standard error) = 0.36 (0.13) and 0.33 (0.13), respectively; PU = 0.25 (0.13)]. Genetic effects were shared across the three phenotypic measures of comorbid drug problems [rDD-PU = 0.92 (0.08), rDD-DV = 0.97 (0.08) and rPU-DV = 0.96 (0.07)]. Conclusion At least 20% of the variance in the generalized vulnerability to substance dependence is attributable to common single nucleotide polymorphisms. The additive effect of common single nucleotide polymorphisms is shared across important indicators of comorbid drug problems. [ABSTRACT FROM AUTHOR]

Background and Aims The World Health Organization's Alcohol, Smoking and Substance Involvement Screening Test ( ASSIST) has strong support as a clinical screening tool and research instrument, but has only been validated with adults. This study evaluated the ASSIST and ASSIST- Lite in an adolescent population. Design Internal consistency, concurrent validity, discriminant validity and diagnostic accuracy were examined for tobacco, alcohol and cannabis ASSIST scores. An abbreviated version (the ASSIST- Lite) was evaluated for cannabis. Setting Three community health centers in Baltimore, MD, USA. Participants A total of 525 primary care patients, ages 12-17 years. Measurements Measures included the ASSIST, the CRAFFT screening tool and items from the Composite International Diagnostic Interview ( CIDI) corresponding to substance use disorder criteria in the Diagnostic and Statistical Manual of Mental Disorders, 5th edition. Findings The ASSIST had good internal consistency (α = 0.68-0.88), good concurrent validity with the CRAFFT ( r = 0.41-0.76; P < 0.001), and was able to discriminate between gradations of cannabis problem severity. In receiver operating characteristics analysis of optimal clinical cut-points, the ASSIST accurately identified tobacco, alcohol and cannabis use disorders (sensitivities = 95-100%; specificities = 79-93%; area under the curve [ AUC] = 0.90-0.94), but did so at minimally low cut-points (indicative of any use in the past 3 months). The ASSIST- Lite performed similarly to the ASSIST in identifying cannabis use disorders (sensitivity = 96%; specificity = 88%; AUC = 0.92), also at a minimally low cut-point. However, confirmatory factor analysis of the ASSIST indicated poor model fit. Conclusions The Alcohol, Smoking and Substance Involvement Screening Test ( ASSIST) is promising as a research and screening/brief assessment tool with adolescents, but revisions to clinical risk thresholds are warranted. The ASSIST- Lite is sufficiently informative for rapid clinical screening of adolescents for cannabis use disorders. [ABSTRACT FROM AUTHOR]

Background and Aims Increased delta-9-tetrahydrocannabinol ( THC) concentrations in cannabis may lead to higher THC exposure, cannabis dependence and treatment need, but users may also adapt the actual intake of THC through reduced inhalation of THC containing smoke (titration). We investigated whether consumers of stronger cannabis use less cannabis per joint or inhale less smoke than those using less potent cannabis and whether these factors predict cannabis dependence severity. Methods Heavy cannabis users ( n = 98) brought their own cannabis, rolled a joint and smoked it ad libitum in a naturalistic setting. We analysed the content of the joint, its association with smoking behaviour and the cross-sectional and prospective (1.5-year follow-up) relations between smoking behaviour and cannabis dependence severity (total number of DSM- IV dependence symptoms). Results THC concentration in cannabis (range 1.10-24.70%) was correlated positively with cannabis dose per joint ( b = 0.008, P = 0.01), but the resulting THC concentration per joint (range 0.24-15.72%) was associated negatively with inhalation volume ( b = −0.05, P = 0.03). Smoking behaviour measures (number of puffs, inhaled volume, reduction of puff volume and puff duration while smoking) predicted follow-up dependence severity, independently of baseline dependence severity and monthly THC dose (number of joints × cannabis dose × cannabis THC concentration). Monthly THC dose only predicted follow-up dependence severity when unadjusted for baseline severity. Conclusions Cannabis users titrate their delta-9-tetrahydrocannabinol intake by inhaling lower volumes of smoke when smoking strong joints, but this does not fully compensate for the higher cannabis doses per joint when using strong cannabis. Thus, users of more potent cannabis are generally exposed to more delta-9-tetrahydrocannabinol. Smoking behaviour appears to be a stronger predictor for cannabis dependence severity than monthly delta-9-tetrahydrocannabinol dose. [ABSTRACT FROM AUTHOR]

Background and Aims To test prospective associations between cannabis disorder symptoms/frequency of cannabis use and health issues and to investigate stability versus transience in cannabis use trajectories. Design Two waves of data collection from the longitudinal Cohort Study on Substance Use Risk Factors ( C- SURF). Setting A representative sample of young Swiss men in their early 20s from the general population. Participants A total of 5084 young men (mean age 19.98 ± 1.19 years at time 1). Measurements Cannabis use (life-time use, frequency of use, cannabis disorder symptoms) and self-reported measures of health issues (depression, mental/physical health, health consequences) were assessed. Significant changes in cannabis use were tested using t-test/ Wilcoxon's rank test for paired data. Cross-lagged panel models provided evidence regarding longitudinal associations between cannabis use and health issues. Findings Most of the participants (84.5%) remained in the same use category and cannabis use kept to similar levels at times 1 and 2 ( P = 0.114 and P = 0.755; average of 15 ± 2.8 months between times 1 and 2). Cross-lagged panel models showed that cannabis disorder symptoms predicted later health issues (e.g. depression, β = 0.087, P < 0.001; health consequences, β = 0.045, P < 0.05). The reverse paths from health issues to cannabis disorder symptoms and the cross-lagged panel model between frequency of cannabis use and health issues were non-significant. Conclusions Patterns of cannabis use showed substantial continuity among young Swiss men in their early 20s. The number of symptoms of cannabis use disorder, rather than the frequency of cannabis use, is a clinically important measure of cannabis use among young Swiss men. [ABSTRACT FROM AUTHOR]

Aims To examine the efficacy of a brief intervention delivered by a therapist ( TBI) or a computer ( CBI) in preventing cannabis use among adolescents in urban primary care clinics. Design A randomized controlled trial comparing: CBI and TBI versus control. Setting Urban primary care clinics in the United States. Participants Research staff recruited 714 adolescents (aged 12-18 years) who reported no life-time cannabis use on a screening survey for this study, which included a baseline survey, randomization (stratified by gender and grade) to conditions (control; CBI; TBI) and 3-, 6- and 12-month assessments. Measurements Using an intent-to-treat approach, primary outcomes were cannabis use (any, frequency); secondary outcomes included frequency of other drug use, severity of alcohol use and frequency of delinquency (among 85% completing follow-ups). Findings Compared with controls, CBI participants had significantly lower rates of any cannabis use over 12 months (24.16%, 16.82%, respectively, P < 0.05), frequency of cannabis use at 3 and 6 months ( P < 0.05) and other drug use at 3 months ( P < 0.01). Compared with controls, TBI participants did not differ in cannabis use or frequency, but had significantly less other drug use at 3 months ( P < 0.05), alcohol use at 6 months ( P < 0.01) and delinquency at 3 months ( P < 0.01). Conclusions Among adolescents in urban primary care in the United States, a computer brief intervention appeared to prevent and reduce cannabis use. Both computer and therapist delivered brief interventions appeared to have small effects in reducing other risk behaviors, but these dissipated over time. [ABSTRACT FROM AUTHOR]

Aims To investigate the prevalence of cannabis use and problem use in boys and girls at age 16 years, and to investigate the role of adversity in early life and of conduct disorder between the ages of 4 and 13 years as risk factors for these outcomes. Design Birth cohort study. Setting England. Participants A total of 4159 (2393 girls) participants in the Avon Longitudinal Study of Parents and Children ( ALSPAC) birth cohort providing information on cannabis use at age 16. Measurements Cannabis use and problem cannabis use at age 16 were assessed by postal questionnaire. Material adversity, maternal substance use, maternal mental health and child conduct disorder were all assessed by maternal report. Findings Cannabis use was more common among girls than boys (21.4% versus 18.3%, P = 0.005). Problem cannabis use was more common in boys than girls (3.6% versus 2.8%, P = 0.007). Early-onset persistent conduct problems were associated strongly with problem cannabis use [odds ratio ( OR) = 6.46, 95% confidence interval ( CI) = 4.06-10.28]. Residence in subsidized housing ( OR = 3.10, 95% CI = 1.95, 4.92); maternal cannabis use ( OR 8.84, 95% CI 5.64-13.9) and any maternal smoking in the postnatal period ( OR = 2.69, 95% CI = 1.90-3.81) all predicted problem cannabis use. Attributable risks for adolescent problem cannabis use associated with the above factors were 25, 13, 17 and 24%, respectively. Conclusions Maternal smoking and cannabis use, early material disadvantage and early-onset persistent conduct problems are important risk factors for adolescent problem cannabis use. This may have implications for prevention. [ABSTRACT FROM AUTHOR]

Aims To assess the reliability and validity of self-reported cannabis dose and potency measures. Design Cross-sectional study comparing self-reports with objective measures of amount of cannabis and delta-9-tetrahydrocannabinol ( THC) concentration. Setting Ecological study with assessments at participants' homes or in a coffee shop. Participants Young adult frequent cannabis users ( n = 106) from the Dutch Cannabis Dependence ( Can Dep) study. Measurements The objectively measured amount of cannabis per joint (dose in grams) was compared with self-reported estimates using a prompt card and average number of joints made from 1 g of cannabis. In addition, objectively assessed THC concentration in the participant's cannabis was compared with self-reported level of intoxication, subjective estimate of cannabis potency and price per gram of cannabis. Findings Objective estimates of doses per joint (0.07-0.88 g/joint) and cannabis potency (1.1-24.7%) varied widely. Self-reported measures of dose were imprecise, but at group level, average dose per joint was estimated accurately with the number of joints made from 1 g [limit of agreement (LOA) = −0.02 g, 95% confidence interval ( CI) = −0.29; 0.26], whereas the prompt card resulted in serious underestimation (LOA = 0.14 g, 95% CI = −0.10; 0.37). THC concentration in cannabis was associated with subjective potency ['average' 3.77% ( P = 0.002) and '(very) strong' 5.13% more THC ( P < 0.001) than '(very) mild' cannabis] and with cannabis price (about 1% increase in THC concentration per euro spent on 1 g of cannabis, P < 0.001), but not with level of intoxication. Conclusions Self-report measures relating to cannabis use appear at best to be associated weakly with objective measures. Of the self-report measures, number of joints per gram, cannabis price and subjective potency have at least some validity. [ABSTRACT FROM AUTHOR]

Aims To determine the longitudinal associations between perceived pubertal timing and recent substance use between the ages of 11 and 17 years. Design, setting and participants A school-based cohort sequential study of adolescents in rural North Carolina, USA ( n = 6892, 50% female) in the 6-8th grades at baseline and interviewed across five consecutive semesters. Measurements Self-administered questionnaires in a group setting measured perceived pubertal development using the Pubertal Development Scale and adolescents reported past 3-month use of cigarettes, alcohol and marijuana. Latent class growth analysis determined the longitudinal relationships between perceived pubertal timing (early, on-time and late) and use of the three substances. Findings A negative quadratic model was the best-fitting model for all three substances. Higher proportions of early developers had used cigarettes and marijuana within the past 3 months at age 11 compared with on-time ( P < 0.001 and P = 0.013) and late developers ( P = 0.010 and P = 0.014) and a higher proportion of early developers had recently used alcohol at age 11 compared with on-time adolescents ( P < 0.001). However, the proportion of recent cigarette and marijuana users increased more across adolescence for on-time adolescents compared with early developers ( P = 0.020 and P = 0.037). Desistance in the proportion of substance users was similar for all adolescents (all P > 0.050). Conclusions Adolescents who believe they are more advanced in puberty than their peers are more likely to have used cigarettes, alcohol and marijuana recently compared with adolescents who believe they are on-time or late developing; these findings are mainly due to differences in use at age 11. [ABSTRACT FROM AUTHOR]

Aims To examine whether DSM- IV symptoms of substance dependence are psychometrically equivalent between existing community-sampled and clinically overselected studies. Participants A total of 2476 adult twins born in Minnesota and 4121 unrelated adult participants from a case-control study of alcohol dependence. Measurements Life-time DSM- IV alcohol, marijuana and cocaine dependence symptoms and ever use of each substance. Design We fitted a hierarchical model to the data, in which ever use and dependence symptoms for each substance were indicators of alcohol, marijuana or cocaine dependence which were, in turn, indicators of a multi-substance dependence factor. We then tested the model for measurement invariance across participant groups, defined by study source and participant sex. Findings The hierarchical model fitted well among males and females within each sample [comparative fit index ( CFI) > 0.96, Tucker- Lewis index ( TLI) > 0.95 and root mean square error of approximation ( RMSEA) < 0.04 for all], and a multi-group model demonstrated that model parameters were equivalent across sample- and sex-defined groups (Δ CFI = 0.002 between constrained and unconstrained models). Differences between groups in symptom endorsement rates could be expressed solely as mean differences in the multi-substance dependence factor. Conclusions Life-time substance dependence symptoms fitted a dimensional model well. Although clinically overselected participants endorsed more dependence symptoms, on average, than community-sampled participants, the pattern of symptom endorsement was similar across groups. From a measurement perspective, DSM- IV criteria are equally appropriate for describing substance dependence across different sampling methods. [ABSTRACT FROM AUTHOR]

Aims To compile and analyze critically the literature published on street children and substance use in resource-constrained settings. Methods We searched the literature systematically and used meta-analytical procedures to synthesize literature that met the review's inclusion criteria. Pooled-prevalence estimates and 95% confidence intervals (CI) were calculated using the random-effects model for life-time substance use by geographical region as well as by type of substance used. Results Fifty studies from 22 countries were included into the review. Meta-analysis of combined life-time substance use from 27 studies yielded an overall drug use pooled-prevalence estimate of 60% (95% CI = 51-69%). Studies from 14 countries contributed to an overall pooled prevalence for street children's reported inhalant use of 47% (95% CI = 36-58%). This review reveals significant gaps in the literature, including a dearth of data on physical and mental health outcomes, HIV and mortality in association with street children's substance use. Conclusions Street children from resource-constrained settings reported high life-time substance use. Inhalants are the predominant substances used, followed by tobacco, alcohol and marijuana. [ABSTRACT FROM AUTHOR]

Aims Debate continues about whether the association between cannabis use in adolescence and common mental disorders is causal. Most reports have focused on associations in adolescence, with few studies extending into adulthood. We examine the association from adolescence until the age of 29 years in a representative prospective cohort of young Australians. Design Nine-wave, 15-year representative longitudinal cohort study, with six waves of data collection in adolescence (mean age 14.9-17.4 years) and three in young adulthood (mean age 20.7, 24.1 and 29.1 years). Participants Participants were a cohort of 1943 recruited in secondary school and surveyed at each wave when possible from mid-teen age to their late 20s. Setting Victoria, Australia. Measurements Psychiatric morbidity was assessed with the Revised Clinical Interview Schedule ( CIS-R) at each adolescent wave, and as Composite International Diagnostic Interview ( CIDI)-defined ICD-10 major depressive episode and anxiety disorder at 29 years. Frequency of cannabis use was measured in the past 6 months in adolescence. Cannabis use frequency in the last year and DSM- IV cannabis dependence were assessed at 29 years. Cross-sectional and prospective associations of these outcomes with cannabis use and dependence were estimated as odds ratios (OR), using multivariable logistic regression models, with the outcomes of interest, major depressive episode ( MDE) and anxiety disorder ( AD) at 29 years. Findings There were no consistent associations between adolescent cannabis use and depression at age 29 years. Daily cannabis use was associated with anxiety disorder at 29 years [adjusted OR 2.5, 95% confidence interval ( CI):< 1.2-5.2], as was cannabis dependence (adjusted OR 2.2, 95% CI: 1.1-4.4). Among weekly+ adolescent cannabis users, those who continued to use cannabis use daily at 29 years remained at significantly increased odds of anxiety disorder (adjusted OR 3.2, 95% CI: 1.1-9.2). Conclusions Regular (particularly daily) adolescent cannabis use is associated consistently with anxiety, but not depressive disorder, in adolescence and late young adulthood, even among regular users who then cease using the drug. It is possible that early cannabis exposure causes enduring mental health risks in the general cannabis-using adolescent population. [ABSTRACT FROM AUTHOR]

ABSTRACT Aims This study aims to estimate the prevalence of drug use by pregnant women living in Ibiza, using structured interviews and biomarkers in maternal hair. In addition, the potentially detrimental effects of maternal drug abuse on their newborns were investigated. Ibiza has a large international night-life resort associated with clubs, music and use of recreational drugs. Design, setting and participants Hair samples were collected prospectively from January to March 2010 from a cohort of consecutive mothers after giving birth in the Hospital Can Misses in Ibiza. Measurements Opiates, cocaine, cannabis, methadone, amphetamines, 3,4-methylenedioxymethamphetamine (MDMA) and their metabolites were detected in a 3-cm-long proximal segment of maternal hair corresponding to the last trimester of pregnancy by gas chromatography coupled to mass spectrometry ( n = 107). Data on socio-demographic characteristics and on tobacco, alcohol, drugs of prescription and drugs of abuse consumption during pregnancy were collected using a structured questionnaire. Findings Hair analysis showed an overall 16% positivity for drugs of abuse in the third trimester of pregnancy, with a specific prevalence of cannabis, cocaine, MDMA and opiates use of 10.3, 6.4, 0.9 and 0%, respectively. In the questionnaires, only 1.9% of mothers declared using drugs of abuse during pregnancy. Gestational drug of abuse consumption was associated with active tobacco smoking, a higher number of smoked cigarettes and the mother being Spanish. Conclusions Illicit drug use is substantially under-reported among pregnant women living in Ibiza, particularly among Spanish nationals. Voluntary, routine objective biological toxicology screening should be considered as part of routine examinations in antenatal clinics on this Mediterranean island. [ABSTRACT FROM AUTHOR]

ABSTRACT 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. [ABSTRACT FROM AUTHOR]

ABSTRACT Aims To assess correlations and agreement between timeline follow-back (TLFB)-assisted self-report and blood samples for cannabis use. Design Secondary analysis of a randomized trial. Setting Copenhagen, Denmark. Participants One hundred and three patients from the CapOpus trial with cannabis use disorder and psychosis, providing 239 self-reports of cannabis use and 88 valid blood samples. Measurements Delta-9-tetrahydrocannabinol (THC), 11-hydroxy-delta-9-tetrahydrocannabinol (11-OH-THC) and 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) detected in plasma using high-performance liquid chromatography with tandem mass spectrometry detection. Self-report of cannabis-use last month by TLFB. Pearson's r, sensitivity and specificity calculated as measures of correlation or agreement. Findings Correlations were strong; r = 0.75 for number of days and r = 0.83 for number of standard joints in the preceding month when excluding outliers. Including outliers, coefficients were moderate to strong ( r = 0.49). There were differences in subgroups, mainly inconsistent, depending on inclusion or exclusion of outliers. Sensitivity and specificity for TLFB detecting the presence or absence of cannabis use were 95.7% [95% confidence interval (CI) 88.0-99.1%) and 72.2% (95% CI 46.5-90.3%), respectively. Using 19 days as cut-off on TLFB, they were 94.3% (95% CI 86.0-98.4%) and 94.4% (95% CI 72.2-99.9%), respectively. Area under the receiver operating characteristic (ROC) curve was 0.96. Conclusions Timeline follow-back (TLFB)-assisted self-report of cannabis use correlates highly with plasma-delta-9-tetrahydrocannabinol in patients with comorbid cannabis use disorder and psychosis. Sensitivity and specificity of timeline follow-back appear to be optimized with 19 days as the cut-off point. As such, timeline follow-back may be superior to analysis of blood when going beyond 19 days of recall. [ABSTRACT FROM AUTHOR]

ABSTRACT Aims To determine whether collaborative behavioral management (CBM) reduces substance use, crime and re-arrest among drug-involved parolees. Design Step'n Out was a randomized behavioral trial of CBM versus standard parole (SP) during 2004-08. CBM adapted evidence-based role induction, behavioral contracting and contingent reinforcement to provide parole officer/treatment counselor dyads with positive tools in addition to sanctions to manage parolees' behavior over 12 weeks. Setting Six parole offices in five states in the USA. Participants Parolee volunteers with a mandate for addiction treatment and a minimum of 3 months of parole ( n = 476). Follow-up was 94% at 3 months and 86% at 9 months. Measurements Drug use and crime in a given month from calendar interviews 3 and 9 months after parole initiation, and re-arrests from criminal justice administrative data. Findings The CBM group had fewer months in which they used their primary drug [adjusted risk ratio (ARR) 0.20, 95% confidence interval (CI): 0.05, 0.78, P = 0.02] and alcohol (ARR 0.38, 95% CI: 0.22, 0.66, P = 0.006) over follow-up. CBM had its greatest effects among parolees who reported marijuana or another 'non-hard' drug as their primary drug; parolees who preferred stimulants or opiates did not benefit. No differences were seen in total crime, re-arrests or parole revocations. Conclusions Collaborative behavioral management may reduce substance use among primary marijuana or other 'non-hard' drug-using parolees without increasing revocations. Because the majority of drug violation arrests in the United States are for marijuana, these findings have important implications for the management of a substantial proportion of the US community correctional population. [ABSTRACT FROM AUTHOR]

ABSTRACT Aims This study evaluated the effectiveness of a brief intervention (BI) for illicit drugs (cannabis, cocaine, amphetamine-type stimulants and opioids) linked to the World Health Organization (WHO) Alcohol, Smoking and Substance Involvement Screening Test (ASSIST). The ASSIST screens for problem or risky use of 10 psychoactive substances, producing a score for each substance that falls into either a low-, moderate- or high-risk category. Design Prospective, randomized controlled trial in which participants were either assigned to a 3-month waiting-list control condition or received brief motivational counselling lasting an average of 13.8 minutes for the drug receiving the highest ASSIST score. Setting Primary health-care settings in four countries: Australia, Brazil, India and the United States. Participants A total of 731 males and females scoring within the moderate-risk range of the ASSIST for cannabis, cocaine, amphetamine-type stimulants or opioids. Measurements ASSIST-specific substance involvement scores for cannabis, stimulants or opioids and ASSIST total illicit substance involvement score at baseline and 3 months post-randomization. Findings Omnibus analyses indicated that those receiving the BI had significantly reduced scores for all measures, compared with control participants. Country-specific analyses showed that, with the exception of the site in the United States, BI participants had significantly lower ASSIST total illicit substance involvement scores at follow-up compared with the control participants. The sites in India and Brazil demonstrated a very strong brief intervention effect for cannabis scores ( P < 0.005 for both sites), as did the sites in Australia ( P < 0.005) and Brazil ( P < 0.01) for stimulant scores and the Indian site for opioid scores ( P < 0.01). Conclusions The Alcohol, Smoking and Substance Involvement Screening Test-linked brief intervention aimed at reducing illicit substance use and related risks is effective, at least in the short term, and the effect generalizes across countries. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim To evaluate the relationship between change in cannabis use and changed cognitive performance over 8 years. Design We used survey methodology with a cohort design. Setting and participants An Australian community sample aged 20-24 years at baseline. Measures We assessed cognitive performance with the California Verbal Learning Test (CVLT) (immediate and delayed), Spot-the-Word test (STW), Symbol Digit Modality test (SDMT) and Digit Backwards (DB). Groups of cannabis users were defined from self-reports across three waves as: 'never' ( n= 420) 'remain light' ( n= 71), 'former light' ( n= 231), 'remain heavy' ( n= 60), 'former heavy' ( n= 60) and 'always former' (since start of study) ( n= 657). Planned contrasts within mixed model repeated-measures analysis of variance was used for longitudinal analysis with an adjusted alpha of 0.01. Findings Data were obtained from 2404 participants with 1978 (82.3%) completing wave 3. At baseline there were significant differences between cannabis groups on CVLT (immediate and delayed) and SDMT. However, after controlling for education, gender, gender × group and gender × wave, there were no significant between-group differences and only CVLT immediate recall reached adjusted statistically significant longitudinal change associated with changed cannabis use (group × wave P= 0.007). Specifically, former heavy users improved their performance relative to remaining heavy users (estimated marginal means: former heavy 6.1-7.5: remain heavy 6.4-6.6). Conclusions Cessation of cannabis use appears to be associated with an improvement in capacity for recall of information that has just been learned. No other measures of cognitive performance were related to cannabis after controlling for confounds. [ABSTRACT FROM AUTHOR]

ABSTRACT Aims Studies of the relationship between social norms and marijuana use have generally focused on individual attitudes, leaving the influence of larger societal-level attitudes unknown. The present study investigated societal-level disapproval of marijuana use defined by birth cohort or by time-period. Design Combined analysis of nationally representative annual surveys of secondary school students in the United States conducted from 1976 to 2007 as part of the Monitoring the Future study. Setting In-school surveys completed by adolescents in the United States. Participants A total of 986 003 adolescents in grades 8, 10 and 12. Measurements Main predictors included the percentage of students who disapproved of marijuana in each birth cohort and time-period. Multi-level models with individuals clustered in time-periods of observation and birth cohorts were modeled, with past-year marijuana use as the outcome. Findings Results indicated a significant and strong effect of birth cohort disapproval of marijuana use in predicting individual risk of marijuana use, after controlling for individual-level disapproval, perceived norms towards marijuana and other characteristics. Compared to birth cohorts in which most (87-90.9%) adolescents disapproved of marijuana use, odds of marijuana use were 3.53 times higher in cohorts where fewer than half (42-46.9%) disapproved (99% confidence interval: 2.75, 4.53). Conclusions Individuals in birth cohorts that are more disapproving of marijuana use are less likely to use, independent of their personal attitudes towards marijuana use. Social norms and attitudes regarding marijuana use cluster in birth cohorts, and this clustering has a direct effect on marijuana use even after controlling for individual attitudes and perceptions of norms. [ABSTRACT FROM AUTHOR]

ABSTRACT Aims Repeated drug exposure can lead to an approach-bias, i.e. the relatively automatically triggered tendencies to approach rather that avoid drug-related stimuli. Our main aim was to study this approach-bias in heavy cannabis users with the newly developed cannabis Approach Avoidance Task (cannabis-AAT) and to investigate the predictive relationship between an approach-bias for cannabis-related materials and levels of cannabis use, craving, and the course of cannabis use. Design, settings and participants Cross-sectional assessment and six-month follow-up in 32 heavy cannabis users and 39 non-using controls. Measurements Approach and avoidance action-tendencies towards cannabis and neutral images were assessed with the cannabis AAT. During the AAT, participants pulled or pushed a joystick in response to image orientation. To generate additional sense of approach or avoidance, pulling the joystick increased picture size while pushing decreased it. Craving was measured pre- and post-test with the multi-factorial Marijuana Craving Questionnaire (MCQ). Cannabis use frequencies and levels of dependence were measured at baseline and after a six-month follow-up. Findings Heavy cannabis users demonstrated an approach-bias for cannabis images, as compared to controls. The approach-bias predicted changes in cannabis use at six-month follow-up. The pre-test MCQ emotionality and expectancy factor were associated negatively with the approach-bias. No effects were found on levels of cannabis dependence. Conclusions Heavy cannabis users with a strong approach-bias for cannabis are more likely to increase their cannabis use. This approach-bias could be used as a predictor of the course of cannabis use to identify individuals at risk from increasing cannabis use. [ABSTRACT FROM AUTHOR]