Cannabis treatment outcomes among legally coerced and non-coerced adults

Exploring correlates of involuntary treatment in substance use disorders: a global systematic review and meta-analysis

Given the legislative heterogeneity about involuntary treatment and psychoactive substance users, we opted to perform a systematic review and meta-analysis of the correlates of involuntary substance use disorders (SUD) treatment across different countries. We conducted research on the Pubmed database, searching for involuntary SUD treatment data worldwide. The systematic review analysed a total of 36 articles and included a sample of 47,739 patients. Our review highlights the elevated risk of involuntary treatment among male, unmarried individuals with alcohol and/or opioid use disorders. Targeted preventive and therapeutic interventions should focus on addressing the underlying factors contributing to involuntary treatment, such as psychosis, aggressiveness, suicidal ideation, legal problems, and severe social exposure. By targeting these factors and providing comprehensive care, we can strive to improve outcomes and reduce the burden of substance use disorders in this vulnerable population. It is essential to critically examine and understand the factors contributing to the selection of patients for compulsory treatment. By doing so, we can identify potential gaps or inconsistencies in the current processes and work towards ensuring that decisions regarding compulsory treatment are based on sound clinical and ethical principles.

Cigarette, electronic cigarette, and marijuana use among young adults under policy changes in California

Introduction

Since 2016, California has implemented a series of policies, including prohibiting the sale of tobacco products and electronic cigarettes (e-cigarettes) to persons under 21, cigarette tax increase, and recreational marijuana legalization. The study aims to examine the use of cigarettes, e-cigarettes, and marijuana among young adults (ages 18-25) and their associations with other factors in the context of these policy changes.

Methods

We used the data from the California Health Interview Survey (CHIS) 2017-2018 to compare the rates of using cigarettes, e-cigarettes, and marijuana separately or any use of the three. Using CHIS 2018 data, weighted logistic regression models were used to examine associations of using cigarettes, e-cigarettes, and marijuana separately or any use of these products/substance with demo-socioeconomic factors, psychological distress, and use of each product/substances.

Results

Cigarette smoking remained flat while the use of e-cigarettes and marijuana escalated among young adults from 2017 to 2018. Using tobacco products increased the use of marijuana or vice versa among young adults. Severe psychological distress was significantly associated with cigarette use (adjusted odds ratio [AOR] = 4.06; 95% CI = 1.32, 12.55), marijuana use (AOR = 2.32; 95% CI = 1.10, 4.48), and any use (AOR = 4.11; 95% CI = 1.93, 8.77). Moderate psychological distress was also significantly associated with the use of these products/substance. Underage (ages 18-20) young adults had lower odds of using cigarettes than other young adults (ages 21-25).

Conclusions

Our findings highlight the importance of addressing the use of cigarettes, e-cigarettes, and marijuana simultaneously through policies to curtail tobacco and marijuana use among young adults.

Correlates of treatment engagement and client outcomes: results of a randomised controlled trial of nabiximols for the treatment of cannabis use disorder

INTRODUCTION AND AIMS

There is increasing interest and evidence for the use of cannabinoid medications in the treatment of cannabis use disorder, but little examination of the correlates of successful treatment. This paper is a secondary analysis of a randomised placebo-controlled trial of nabiximols for the treatment of cannabis use disorder (CUD), aiming to identify which client and treatment characteristics impact treatment engagement and outcomes.

METHOD

Bayesian multiple regression models were used to examine the impact of age, gender, duration of regular cannabis use, daily quantity of cannabis, cannabis use problems, self-efficacy for quitting, sleep, mental health, pain measures, and treatment group upon treatment engagement (retention, medication dose, and counselling participation) and treatment outcomes (achieving end-of-study abstinence, and a 50% or greater reduction in cannabis use days) among the 128 clients participating in the 12-week trial.

RESULTS

Among the treatment factors, greater counselling attendance was associated with greater odds of abstinence and ≥ 50% reduction in cannabis use; nabiximols with greater odds of ≥ 50% reduction and attending counselling, and reduced hazard of treatment dropout; and higher dose with lower odds of ≥ 50% reduction. Among the client factors, longer duration of regular use was associated with higher odds of abstinence and 50% reduction, and lower hazard of treatment dropout; greater quantity of cannabis use with reduced hazard of dropout, greater odds of attending counselling, and higher average dose; greater pain at baseline with greater odds of ≥ 50% reduction and higher average dose; and more severe sleep issues with lower odds of ≥ 50% reduction. Males had lower odds of attending counselling.

DISCUSSIONS AND CONCLUSIONS

These findings suggest that counselling combined with agonist pharmacotherapy may provide the optimal treatment for cannabis use disorder. Younger clients, male clients, and clients with sleep issues could benefit from extra support from treatment services to improve engagement and outcomes.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ACTRN12616000103460) https://www.anzctr.org.au.

Trends in Cannabis Treatment Admissions in Adolescents/Young Adults: Analysis of TEDS-A 1992 to 2016

OBJECTIVES

This study aims to evaluate changes in cannabis use patterns, referral sources, and admissions in adolescents and young adults (YAs). As the United States increasingly moves toward liberalization of cannabis laws, it is critical to have baseline information of use patterns in this population.

METHODS

Data were drawn from Treatment Episode Data Set-Admissions (TEDS-A) for adolescents (12-17 years) and young adults (18-24 years) entering treatment from 1992 to 2016 for primary cannabis use (N = 3,794,213). Rao-Scott chi-square tests were used to test for significant changes in proportions of individuals admitted to treatment for primary cannabis use and between 4-year increments from 1992 to 2016 (N = 1,052,724). Logistic regression assessed odds of admissions for primary cannabis use versus other substances.

RESULTS

Treatment admissions for cannabis among adolescents/YAs rose 3-fold from 1992 (49,996) to 1996 (125,858). The majority of referrals came from the criminal justice system (56%). Cannabis is increasingly the sole substance of use, with polysubstance use decreasing from 89% in 1992 to 59% in 2016. While alcohol-related treatment admissions were most common in 1992, admissions for treatment of cannabis use (followed by heroin and alcohol) were highest (38%) by 2016. Being an adolescent (odds ratio [OR] 3.1, 95% confidence interval [CI] 3.1-3.2), non-Hispanic black (OR 6.2, 95% CI 6.2-6.3), male (female OR 0.6, 95% CI 0.6-0.6) with co-occurring alcohol use (OR 25.9, 95% CI 25.7-26.1) was associated with admission for treatment of primary cannabis use as compared with other substances.

CONCLUSIONS

Public health efforts will be needed to ensure ongoing access and referral to treatment as the legal status of cannabis continues to change. Prevention and treatment efforts should target co-occurring alcohol and cannabis use.

Predictors of treatment response in a web-based intervention for cannabis users

BACKGROUND

Trials demonstrate the effectiveness of web-based interventions for cannabis-related disorders. For further development of these interventions, it is of vital interest to identify user characteristics which predict treatment response.

METHODS

Data from a randomized factorial trial on a web-based intervention for cannabis-users (n = 534) was reanalyzed. As potential predictors for later treatment response, 31 variables from the following categories were tested: socio-demographics, substance use and cognitive processing. The association of predictors and treatment outcome was analyzed using unbiased recursive partitioning and represented as classification tree. Predictive performance of the tree was assessed by comparing its cross-validated results to models derived with all-subsets logistic regression and random forest.

RESULTS

Goal commitment (p < .001), the extent of self-reflection (p < .001), the preferred effect of cannabis (p = .005) and initial cannabis use (p = .015) significantly differentiate between successful and non-successful participants in all three analysis methods. The predictive accuracy of all three models is comparable and modest.

CONCLUSIONS

Participants who commit to quit using cannabis, who at least have moderate levels of self-reflection and who prefer mild intoxicating effects were most likely to respond to treatment. To predict treatment response on an individual level, the classification tree should only be used as one of several sources of information.Trial registration: http://www.isrctn.com/ISRCTN99818059.

The service-seeking profiles of youth reporting a legal mandate or perceived coercion for substance use treatment

INTRODUCTION

There is paucity of research on treatment-related coercion in youth: most research focuses on adult populations and legally mandated treatment. This study aims to examine the service-seeking profiles of youth with substance misuse issues who report a legal mandate or perceived coercion to enter treatment.

METHODS

Differences between youth who were legally mandated and not legally mandated, and differences between youth reporting high and low perceived coercion, were examined for demographic characteristics, mental health and substance use profiles, motivation, and readiness to change.

RESULTS

Compared to participants reporting low perceived coercion, those experiencing high perceived coercion reported more substance use problems, greater mental health needs, and greater external and introjected motivation. Legally mandated youth reported fewer mental health issues, lower identified motivation, and greater readiness to change than those reporting no legal mandate.

DISCUSSION

Many youth who present for substance use services report experiencing a sense of coercion, which suggests the potential importance of considering youth-centered strategies for involving youth in treatment planning and the development of treatment goals. Youth seeking treatment also have multiple intersecting needs which may benefit from a collaborative and integrative approach.

Levels and predictors of participation in integrated treatment programs for pregnant and parenting women with problematic substance use

Background

Women who are seeking services for problematic substance use are often also balancing responsibilities of motherhood. Integrated treatment programs were developed to address the diverse needs of women, by offering a holistic and comprehensive mix of services that are trauma- and violence-informed, and focus on maternal and child health promotion and the development of healthy relationships.

Methods

Using system-level administrative data from a suite of outpatient integrated programs in Ontario, Canada, we described the clients and rates and predictors of treatment participation over a 7-year period (2008–2014; N = 5162).

Results

All participants were either pregnant or parenting children under 6 years old at admission to treatment. Retention (length of time between the first and last visit) averaged 124.9 days (SD = 185.6), with episodes consisting of 14.6 visits (SD = 28.6). The vast majority of women attended more than one visit (87.2%), typically returning within 2 weeks (mean 12.3 days, SD = 11.1). In addition to being pregnant or new mothers experiencing problematic substance use, most were unemployed, on social assistance, and single.

Conclusions

Programs appeared to be able to successfully engage most women in treatment once they accessed the programs. Although rates of treatment participation did vary across subgroups defined by sociodemographic and admission characteristics, effect sizes tended to be small on average, providing little evidence in general of sociodemographic inequities in participation. Further work is needed to study the influence of program-level factors on participation, and how these link to maternal and child outcomes.

A system-level study of initiation, engagement, and equity in outpatient substance use treatment

Understanding the nature of variations in the quality of substance use treatment is critical to ensuring equity in service delivery and maximizing treatment effectiveness. We used adapted versions of the US Healthcare Effectiveness Data and Information Set (HEDIS) treatment initiation and engagement measures to assess care quality in specialized outpatient services for substance use in Ontario, Canada. Using administrative data, we calculated rates of outpatient treatment initiation and engagement (N = 120,394 episodes) and investigated variation by client characteristics and treatment mandates. About half of clients who entered outpatient treatment met the criteria for initiation (i.e., had a second visit within 14 days) and 30% met the criteria for engagement (i.e., had another two visits within 30 days of initiation). The likelihood of treatment initiation and engagement was greater among older people, those with more education, those who were not mandated to enter treatment, and those with greater substance use at admission. People who entered treatment for cannabis were less likely to engage. Engagement was less likely among men than women, but gender differences were slight overall. This study demonstrates the feasibility of using adapted versions of two common measures to characterise care quality in substance use treatment services in the Canadian context. Overall, the magnitude of associations with client characteristics were quite small, suggesting that initiation and engagement were not overly localized to specific client subgroups. Findings suggest that the Ontario system has difficulty retaining clients who enter treatment and that most outpatient treatment involves care episodes of limited duration.

Mental distress following inpatient substance use treatment, modified by substance use; comparing voluntary and compulsory admissions

Background

Treatment services to patients with substance use disorders (SUDs), including those mandated to treatment, needs to be evaluated and evidence based. The Norwegian Municipal Health Care Act (NMHCA) calls for compulsory treatment for persons with “severe and life-threatening substance use disorder” if these individuals are not otherwise willing to be voluntarily treated and consequently risk their lives over drug use. Mental distress is known to be high among SUD patients admitted to inpatient treatment. The purpose of this study is to describe changes in mental distress from admission to a 6-month follow-up in patients with SUDs, which underwent either voluntary or compulsory treatment.

Method

This prospective study followed 202 hospitalized patients with SUDs who were admitted voluntarily (VA; n = 137) or compulsorily (CA; n = 65). Levels of mental distress were assessed with SCL-90-R. Of 123 patients followed-up at 6 months, 97 (62 VA and 35 CA) had rated their mental distress at admission, discharge and follow-up. Sociodemographics and substance use severity were recorded with the use of The European Addiction Severity Index (EuropASI). We performed a regression analysis to examine factors associated with changes in psychiatric distress at the 6-month follow-up.

Results

The VA group exhibited higher mental distress than the CA group at admission, but both groups improved significantly during treatment. At the 6-month follow-up, the VA group continued to show reduced distress, but the CA group showed increases in mental distress to the levels observed before treatment. The deterioration appeared to be associated with higher scores that reflected paranoid ideas, somatization, obsessive-compulsive symptoms, interpersonal sensitivity, and depression. Active substance use during follow-up was significantly associated with increased mental distress.

Conclusion

In-patient treatment reduces mental distress for both CA and VA patients. The time after discharge seems critical especially for CA patients regarding active substance use and severe mental distress. A greater focus on continuing care initiatives to assist the CA patients after discharge is needed to maintain the reduction in mental distress during treatment. Continuing-care initiatives after discharge should be intensified to assist patients in maintaining the reduced mental distress achieved with treatment.

Trial registration

ClinicalTrials.gov NCT 00970372 December 02, 2016.

Improved drug-use patterns at 6 months post-discharge from inpatient substance use disorder treatment: results from compulsorily and voluntarily admitted patients

Background

Treatment services to patients with substance use disorders (SUDs), including those mandated to treatment, needs to be evaluated and evidence based. The Norwegian Municipal Health Care Act calls for mandated treatment for persons with “severe and life-threatening substance use disorder” if these individuals are not otherwise willing to be voluntarily treated and consequently risk their lives over drug use. This study aims to examine substance use–related outcomes at 6 months following inpatient treatment and to analyse factors associated with improved outcomes and abstinence.

Method

This prospective study followed 202 hospitalized patients with SUD who were admitted voluntarily (VA; n = 137) or compulsorily (CA; n = 65). The European Addiction Severity Index was used at baseline and at follow-up to assess socio-demographic and substance use variables. Regression analysis was conducted to investigate factors associated with abstinence at 6 months of follow-up.

Results

The frequency of use of a preferred substance showed marked improvement for both VA and CA patients (61 and 37 %, respectively) at follow-up. Seventy-five percent of VA patients using amphetamine reported improvement compared to 53 % of CA patients. At follow-up, the CA group continued to have a higher rate of injection use. The CA group had experienced higher rates of overdose in the past 6 months and lower abstinence rates (24 % versus 50 %) at follow-up. A lower severity of drug use at intake (non–injection drug use), voluntary treatment modality, and higher treatment involvement during follow-up all were significant factors associated with abstinence at 6 months after treatment.

Conclusion

Voluntary treatment for SUD generally yielded better outcomes; nevertheless, we also found improved outcomes for CA patients. It is important to keep in mind that in reality, the alternative to CA treatment is no treatment at all and instead a continuation of life-threatening drug use behaviours. Our observed outcomes for CA patients support the continuation of CA treatment.

Psychosocial interventions for cannabis use disorder

BACKGROUND

Cannabis use disorder is the most commonly reported illegal substance use disorder in the general population; although demand for assistance from health services is increasing internationally, only a minority of those with the disorder seek professional assistance. Treatment studies have been published, but pressure to establish public policy requires an updated systematic review of cannabis-specific treatments for adults.

OBJECTIVES

To evaluate the efficacy of psychosocial interventions for cannabis use disorder (compared with inactive control and/or alternative treatment) delivered to adults in an out-patient or community setting.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 6), MEDLINE, EMBASE, PsycINFO, the Cumulaive Index to Nursing and Allied Health Literature (CINAHL) and reference lists of articles. Searched literature included all articles published before July 2015.

SELECTION CRITERIA

All randomised controlled studies examining a psychosocial intervention for cannabis use disorder (without pharmacological intervention) in comparison with a minimal or inactive treatment control or alternative combinations of psychosocial interventions.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures as expected by The Cochrane Collaboration.

MAIN RESULTS

We included 23 randomised controlled trials involving 4045 participants. A total of 15 studies took place in the United States, two in Australia, two in Germany and one each in Switzerland, Canada, Brazil and Ireland. Investigators delivered treatments over approximately seven sessions (range, one to 14) for approximately 12 weeks (range, one to 56).Overall, risk of bias across studies was moderate, that is, no trial was at high risk of selection bias, attrition bias or reporting bias. Further, trials included a large total number of participants, and each trial ensured the fidelity of treatments provided. In contrast, because of the nature of the interventions provided, participant blinding was not possible, and reports of researcher blinding often were unclear or were not provided. Half of the reviewed studies included collateral verification or urinalysis to confirm self report data, leading to concern about performance and detection bias. Finally, concerns of other bias were based on relatively consistent lack of assessment of non-cannabis substance use or use of additional treatments before or during the trial period.A subset of studies provided sufficient detail for comparison of effects of any intervention versus inactive control on primary outcomes of interest at early follow-up (median, four months). Results showed moderate-quality evidence that approximately seven out of 10 intervention participants completed treatment as intended (effect size (ES) 0.71, 95% confidence interval (CI) 0.63 to 0.78, 11 studies, 1424 participants), and that those receiving psychosocial intervention used cannabis on fewer days compared with those given inactive control (mean difference (MD) 5.67, 95% CI 3.08 to 8.26, six studies, 1144 participants). In addition, low-quality evidence revealed that those receiving intervention were more likely to report point-prevalence abstinence (risk ratio (RR) 2.55, 95% CI 1.34 to 4.83, six studies, 1166 participants) and reported fewer symptoms of dependence (standardised mean difference (SMD) 4.15, 95% CI 1.67 to 6.63, four studies, 889 participants) and cannabis-related problems compared with those given inactive control (SMD 3.34, 95% CI 1.26 to 5.42, six studies, 2202 participants). Finally, very low-quality evidence indicated that those receiving intervention reported using fewer joints per day compared with those given inactive control (SMD 3.55, 95% CI 2.51 to 4.59, eight studies, 1600 participants). Notably, subgroup analyses found that interventions of more than four sessions delivered over longer than one month (high intensity) produced consistently improved outcomes (particularly in terms of cannabis use frequency and severity of dependence) in the short term as compared with low-intensity interventions.The most consistent evidence supports the use of cognitive-behavioural therapy (CBT), motivational enhancement therapy (MET) and particularly their combination for assisting with reduction of cannabis use frequency at early follow-up (MET: MD 4.45, 95% CI 1.90 to 7.00, four studies, 612 participants; CBT: MD 10.94, 95% CI 7.44 to 14.44, one study, 134 participants; MET + CBT: MD 7.38, 95% CI 3.18 to 11.57, three studies, 398 participants) and severity of dependence (MET: SMD 4.07, 95% CI 1.97 to 6.17, two studies, 316 participants; MET + CBT: SMD 7.89, 95% CI 0.93 to 14.85, three studies, 573 participants), although no particular intervention was consistently effective at nine-month follow-up or later. In addition, data from five out of six studies supported the utility of adding voucher-based incentives for cannabis-negative urines to enhance treatment effect on cannabis use frequency. A single study found contrasting results throughout a 12-month follow-up period, as post-treatment outcomes related to overall reduction in cannabis use frequency favoured CBT alone without the addition of abstinence-based or treatment adherence-based contingency management. In contrast, evidence of drug counselling, social support, relapse prevention and mindfulness meditation was weak because identified studies were few, information on treatment outcomes insufficient and rates of treatment adherence low. In line with treatments for other substance use, abstinence rates were relatively low overall, with approximately one-quarter of participants abstinent at final follow-up. Finally, three studies found that intervention was comparable with treatment as usual among participants in psychiatric clinics and reported no between-group differences in any of the included outcomes.

AUTHORS' CONCLUSIONS

Included studies were heterogeneous in many aspects, and important questions regarding the most effective duration, intensity and type of intervention were raised and partially resolved. Generalisability of findings was unclear, most notably because of the limited number of localities and homogeneous samples of treatment seekers. The rate of abstinence was low and unstable although comparable with treatments for other substance use. Psychosocial intervention was shown, in comparison with minimal treatment controls, to reduce frequency of use and severity of dependence in a fairly durable manner, at least in the short term. Among the included intervention types, an intensive intervention provided over more than four sessions based on the combination of MET and CBT with abstinence-based incentives was most consistently supported for treatment of cannabis use disorder.

Assessing self-determined motivation for addiction treatment: validity of the Treatment Entry Questionnaire

Although legal, formal, and informal social controls are frequently used to pressure individuals to enter treatment, motivational consequences of using these tactics have been neglected. Self-determination theory (SDT) provides a useful perspective for understanding client experiences of social controls and highlights the importance of self-determined motivation for long-term behavior change. This study assessed the construct validity of the Treatment Entry Questionnaire (TEQ), a brief scale derived from SDT to measure identified, introjected, and external treatment motivation. Two independent samples of clients entering Canadian residential and outpatient treatment completed TEQ items (ns = 529 and 623). Exploratory and confirmatory factor analyses supported a 9-item version of the scale, with 3 factors aligning with SDT motivational subtypes. Subscales showed high internal consistency and correlated as expected with social controls and perceived coercion at treatment entry. The TEQ-9 is a valid option for assessing self-determined motivation in clinical practice and evaluating coerced addiction treatment.

Brief Motivational Intervention and telemedicine: a new perspective of treatment to marijuana users

The main purpose of this study was to evaluate the telephone Brief Motivational Intervention (BMI) efficacy in marijuana consumption cessation. A clinical trial was performed on Brazilian citizens, who were randomly divided into experimental (BMI) and minimal intervention (reference material) treatment groups; the study involved 524 participants who were monitored for 6 months. In addition, the data was collected by a free-service call center; both marijuana consumption and level of motivation for behavior change were evaluated, based on the telephone service offered. The proportion of abstainers in the BMI group was significantly greater than in the control group: 73% of the individuals in the BMI group were abstainers. In the control group, 59% of them ceased on using marijuana. The ratio of probability for marijuana cessation was 1.6 times higher in the BMI group. There was no significant difference on the motivation for behavior change in both groups. The collected data demonstrated the telephone BMI's positive efficacy in marijuana consumption cessation.

Coerced addiction treatment: Client perspectives and the implications of their neglect

Recent work has criticized the evidence base for the effectiveness of addiction treatment under social controls and coercion, suggesting that the development of sound policies and treatment practices has been hampered by numerous limitations of the research conducted to date. Implicit assumptions of the effectiveness of coerced treatment are evident in the organization and evolution of treatment, legal, and social service systems, as well as in related legislative practices. This review builds upon previous work by focusing in greater detail on the potential value of incorporating client perspectives on coercion and the implications for interpreting and applying existing research findings. Reviewing the existing empirical and theoretical literature, a case is made for greater accuracy in representing coercive experiences and events in research, so as to better align the measured concepts with actual processes of treatment entry and admission. Attention is given to studies of the effectiveness of treatment under social controls or pressures, the connections to coercion and decision-making, and theoretical perspectives on motivation and behaviour change, including Self-Determination Theory in particular. This synthesis of the available research on coerced addiction treatment suggests that it remains largely unclear to what extent many of the commonly employed methods for getting people into treatment may be detrimental to the treatment process and longer-term outcomes. The impact of coercion upon individual clients, treatment systems, and population health has not been adequately dealt with by addiction researchers to date.

Candidate genes for cannabis use disorders: findings, challenges and directions

AIM

Twin studies have shown that cannabis use disorders (abuse/dependence) are highly heritable. This review aims to: (i) review existing linkage studies of cannabis use disorders and (ii) review gene association studies, to identify potential candidate genes, including those that have been tested for composite substance use disorders and (iii) to highlight challenges in the genomic study of cannabis use disorders.

METHODS

Peer-reviewed linkage and candidate gene association studies are reviewed.

RESULTS

Four linkage studies are reviewed: results from these have homed in on regions on chromosomes 1, 3, 4, 9, 14, 17 and 18, which harbor candidates of predicted biological relevance, such as monoglyceride lipase (MGLL) on chromosome 3, but also novel genes, including ELTD1[epidermal growth factor (EGF), latrophilin and seven transmembrane domain containing 1] on chromosome 1. Gene association studies are presented for (a) genes posited to have specific influences on cannabis use disorders: CNR1, CB2, FAAH, MGLL, TRPV1 and GPR55 and (b) genes from various neurotransmitter systems that are likely to exert a non-specific influence on risk of cannabis use disorders, e.g. GABRA2, DRD2 and OPRM1.

CONCLUSIONS

There are challenges associated with (i) understanding biological complexity underlying cannabis use disorders (including the need to study gene-gene and gene-environment interactions), (ii) using diagnostic versus quantitative phenotypes, (iii) delineating which stage of cannabis involvement (e.g. use versus misuse) genes influence and (iv) problems of sample ascertainment.

Pharmacotherapy and psychotherapy in cannabis withdrawal and dependence

Cannabis has long been perceived as a drug causing questionable dependence. Only recently has a clinically recognized withdrawal syndrome been described, thus laying the foundations for specific treatment evaluations. Six different pharmacotherapies have been studied in cannabis withdrawal. Of these, only oral tetrahydrocannabinol, and perhaps mirtazapine, have shown some promise in the specific treatment of withdrawal symptoms. In cannabis dependence, rimonabant, and perhaps buspiron, have shown promising results. Clinical trials of oral tetrahydrocannabinol were less convincing. Cognitive and behavioral therapies and motivational enhancement therapies have proven their efficacy in several randomized controlled trials. Brief therapies have also been associated with good compliance and efficacy. Combinations with voucher incentives in certain populations have been associated with improved treatment compliance and reduced cannabis use. Only two studies have analyzed the cost-efficacy of psychotherapies. It would seem that brief combined cognitive and behavioral therapies, and motivational enhancement therapies are the most cost effective. For the moment, it is uncertain whether the additional treatment costs associated with voucher incentives are proportional to the accrued abstinence duration.