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1.  Initiation of Abstinence in Adolescents Treated for Marijuana Use Disorders 
This study assessed the time to initiation of marijuana abstinence in an adolescent treatment-seeking sample, and identified variables that were predictive of abstinence. Adolescents (n= 69), ages 14 to 18 were randomly assigned to one of two 14-week behavioral treatments. Abstinence was measured with twice-weekly urine toxicology plus teen and parent reports. Discrete-time survival and hazard functions were conducted. The majority of adolescents achieved at least one week of abstinence, and 51% achieved six weeks of abstinence. Initiation of abstinence occurred by the sixth treatment week for 94% of teens with any abstinence suggesting that alternative, clinical approaches should be considered for those not responding by Week 6. Teens with a drug negative urinalysis at intake, and teens that had 2 parents participating in treatment were more likely to achieve at least 6 weeks of abstinence. These findings, if replicated, can be used to inform clinical and research strategies that might lead to enhanced treatment efficacy and cost effectiveness for substance abuse treatment programming.
PMCID: PMC3556197  PMID: 23085041
2.  Delay Discounting Predicts Adolescent Substance Abuse Treatment Outcome 
The purpose of the current study was to identify predictors of delay discounting among adolescents receiving treatment for marijuana abuse or dependence, and to test delay discounting as a predictor of treatment outcome. Participants for this study were 165 adolescents (88% male) between the ages of 12 and 18 (M =15.8; SD = 1.3) who enrolled in a clinical trial comparing three behavioral treatments for adolescent marijuana abuse or dependence. Participants completed a delay discounting task at treatment onset for $100 and $1,000 of hypothetical money and marijuana. Overall, smaller magnitude rewards were discounted more than larger magnitude rewards. Delay discounting rates were concurrently related to demographic variables (SES, race). Delay discounting of $1,000 of money predicted during treatment abstinence outcomes among adolescent marijuana abusers, over and above the effects of type of treatment received. Teens who show higher levels of discounting of the future may be an important subgroup to identify at treatment onset. Youth with a greater tendency to discount the future may require different intervention strategies that address their impulsivity (e.g., targeting executive function or inhibitory control) and/or different schedules of reinforcement to address their degree of preference for immediate rewards.
PMCID: PMC3906638  PMID: 22182419
delay discounting; adolescent substance abuse; marijuana
3.  Pharmacological and psychosocial interventions for cannabis use disorders 
Cannabis remains the most widely used illicit substance in most developed countries. Its addictive potential has been established and the need for interventions for cannabis-related problems has become apparent. This article provides a review of the research evaluating potential treatments for cannabis use disorders.
A search of publication databases identified research studies and reviews of the scientific literature on psychosocial and pharmacological interventions for cannabis use disorders.
For adults, behaviorally-based interventions engender significant positive effects on abstinence and reductions in cannabis use. With adolescents, similar treatments and family-based interventions have demonstrated efficacy. Across studies, response rates appear modest even with the most potent psychosocial treatments. Evaluations of pharmacological approaches to cannabis use disorders have yet to provide clinical efficacy data for any specific medication. Agonist and antagonist approaches appear to offer the most promise. Advances in understanding of the neurobiology of the cannabinoid system provide optimism that the synthesis of compounds that alter CB1 receptor site functioning may produce promising medications.
Clinical research has identified effective psychosocial treatments, but has yet to yield effective pharmacotherapies. Much work remains to enhance the potency of and access to interventions for those seeking treatment for cannabis use disorders.
PMCID: PMC3690346  PMID: 20512270
Cannabis; Marijuana; Pharmacological process; Family relations; Treatment outcome
4.  Clinical Correlates of Co-Occurring Cannabis and Tobacco Use: A Systematic Review 
Addiction (Abingdon, England)  2012;107(8):1404-1417.
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.
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 vs. 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.
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 consistently associated with a greater likelihood of tobacco use disorders, more psychosocial problems, nor poorer tobacco cessation outcomes.
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.
PMCID: PMC3377777  PMID: 22340422
cannabis; marijuana; tobacco; smoking; co-occurring; outcomes; interventions
5.  The Co-occurring Use and Misuse of Cannabis and Tobacco: A Review 
Addiction (Abingdon, England)  2012;107(7):1221-1233.
Cannabis and tobacco use and misuse frequently co-occur. This review examines the epidemiological evidence supporting the lifetime co-occurrence of cannabis and tobacco use and outlines the mechanisms that link these drugs to each other. Mechanisms include (a) shared genetic factors; (b) shared environmental influences, including (c) route of administration (via smoking), (d) co-administration and (e) models of co-use. We also discuss respiratory harms associated with co-use of cannabis and tobacco, overlapping withdrawal syndromes and outline treatment implications for cooccurring use.
Selective review of published studies.
Both cannabis and tobacco use and misuse are influenced by genetic factors and a proportion of these genetic factors influence both cannabis and tobacco use and misuse. Environmental factors such as availability play an important role, with economic models suggesting a complementary relationship where increases in price of one drug decrease the use of the other. Route of administration and smoking cues may contribute to their sustained use. Similar withdrawal syndromes, with many symptoms in common, may have important treatment implications. Emerging evidence suggests that dual abstinence may predict better cessation outcomes, yet empirically researched treatments tailored for co-occurring use are lacking.
There is accumulating evidence that some mechanisms linking cannabis and tobacco use are distinct from those contributing to co-occurring use of drugs in general. There is an urgent need for research to identify the underlying mechanisms and harness their potential etiological implications to tailor treatment options for this serious public health challenge.
PMCID: PMC3397803  PMID: 22300456
Cannabis; Tobacco; Nicotine; Marijuana; Genetics; Treatment; Policy; Co-administration
6.  Parent training plus contingency management for substance abusing families: A Complier Average Causal Effects (CACE) analysis* 
Drug and alcohol dependence  2011;118(2-3):119-126.
Children of substance abusers are at risk for behavioral/emotional problems. To improve outcomes for these children, we developed and tested an intervention that integrated a novel contingency management (CM) program designed to enhance compliance with an empirically-validated parent training curriculum. CM provided incentives for daily monitoring of parenting and child behavior, completion of home practice assignments, and session attendance.
Forty-seven mothers with substance abuse or dependence were randomly assigned to parent training + incentives (PTI) or parent training without incentives (PT). Children were 55% male, ages 2-7 years.
Homework completion and session attendance did not differ between PTI and PT mothers, but PTI mothers had higher rates of daily monitoring. PTI children had larger reductions in child externalizing problems in all models. Complier Average Causal Effects (CACE) analyses showed additional significant effects of PTI on child internalizing problems, parent problems and parenting. These effects were not significant in standard Intent-to-Treat analyses.
Results suggest our incentive program may offer a method for boosting outcomes.
PMCID: PMC3162088  PMID: 21466925
contingency management; preschool; children of substance abusers; parent training; Complier Average Causal Effects
7.  Marijuana Dependence and Its Treatment 
The prevalence of marijuana abuse and dependence disorders has been increasing among adults and adolescents in the United States. This paper reviews the problems associated with marijuana use, including unique characteristics of marijuana dependence, and the results of laboratory research and treatment trials to date. It also discusses limitations of current knowledge and potential areas for advancing research and clinical intervention.
PMCID: PMC2797098  PMID: 18292704
8.  Sleep disturbance and the effects of extended-release zolpidem during cannabis withdrawal 
Drug and alcohol dependence  2011;117(1):38-44.
Sleep difficulty is a common symptom of cannabis withdrawal, but little research has objectively measured sleep or explored the effects of hypnotic medication on sleep during cannabis withdrawal.
Twenty daily cannabis users completed a within-subject crossover study. Participants alternated between periods of ad-libitum cannabis use and short-term cannabis abstinence (3 days). Placebo was administered at bedtime during one abstinence period (withdrawal test) and extended-release zolpidem, a non-benzodiazepine GABAA receptor agonist, was administered during the other. Polysomnographic (PSG) sleep architecture measures, subjective ratings, and cognitive performance effects were assessed each day.
During the placebo-abstinence period, participants had decreased sleep efficiency, total sleep time, percent time spent in Stage 1 and Stage 2 sleep, REM latency and subjective sleep quality, as well as increased sleep latency and time spent in REM sleep compared with when they were using cannabis. Zolpidem attenuated the effects of abstinence on sleep architecture and normalized sleep efficiency scores, but had no effect on sleep latency. Zolpidem was not associated with any significant side effects or next-day cognitive performance impairments.
These data extend prior research that indicates abrupt abstinence from cannabis can lead to clinically significant sleep disruption in daily users. The findings also indicate that sleep disruption associated with cannabis withdrawal can be attenuated by zolpidem, suggesting that hypnotic medications might be useful adjunct pharmacotherapies in the treatment of cannabis use disorders.
PMCID: PMC3119729  PMID: 21296508
Cannabis; Marijuana; Sleep; Withdrawal; Zolpidem; Pharmacotherapy
9.  An Initial Trial of a Computerized Behavioral Intervention for Cannabis Use Disorder 
Drug and alcohol dependence  2010;115(1-2):74-79.
The most potent outcomes for cannabis use disorders have been observed with a combination of three evidence-based interventions, motivational enhancement therapy (MET), cognitive-behavioral therapy (CBT), and abstinence-based contingency-management (CM). Access to this intervention remains limited because of cost and service availability issues. This report describes the initial stages of a project designed to develop and test a computer-assisted version of MET/CBT/CM that could address many of the current barriers to its dissemination. A nonrandomized, 12-week comparison study assigned 38 adults seeking treatment for a cannabis use disorder to either therapist-delivered (n=22) or computer-delivered (n=16) MET/CBT/CM. Attendance, retention, and cannabis use outcomes did not differ significantly between groups, and there were no indications of superior outcomes favoring therapist delivery. Participants provided positive ratings of the computer-delivered sessions. These preliminary findings suggest that computer-assisted delivery of MET/CBT/CM is acceptable to outpatients and does not adversely impact compliance or outcomes achieved during treatment with MET/CBT/CM for cannabis use disorders. Assessment of post-treatment outcomes and replication in randomized trials are needed to determine reliability and longer-term effects. As observed in a growing number of studies, computerized therapies have the potential to increase access to, reduce costs, and enhance fidelity of providing evidence-based treatments without sacrificing and possibly enhancing effectiveness.
PMCID: PMC3071451  PMID: 21131143
cannabis; marijuana; treatment; computer delivered; contingency management; internet
10.  General Anxiety Disorder Symptoms, Tension Reduction, and Marijuana Use Among Young Adult Females 
Journal of Women's Health  2010;19(9):1635-1642.
The current study tested the hypothesis that tension reduction expectancies mediate the relationship between anxiety symptoms and marijuana use.
Interview data for 332 young adult females from Southern New England were collected from 2004 to 2009.
In structural equation modeling, anxiety symptoms had a significant direct effect (byx = 0.227, 95% confidence interval [CI] 0.086-0.369, p < 0.05) on tension reduction expectancies and a significant indirect effect (byx = 0.026, 95% CI 0.010-0.046, p < 0.05) on marijuana use.
The effect of anxiety symptoms on marijuana use was fully mediated by tension reduction expectancies. Implications for tension reduction as a possible component of treatment interventions are discussed.
PMCID: PMC2965700  PMID: 20718677
11.  Contingency Management Approaches for Adolescent Substance Use Disorders 
The addition of contingency management (CM) to the menu of effective treatments for adolescent substance abuse has generated excitement in the research and treatment communities. CM interventions are based on extensive basic science and clinical research evidence demonstrating that drug use is sensitive to systematically applied consequences. This article provides (a) a review of basic CM principles, (b) implementation guidelines, (c) a review of the clinical CM research targeting adolescent substance abuse, and (d) a discussion of implementation successes and challenges. Although the research base for CM with adolescents is in its infancy, there are multiple reasons for high expectations.
PMCID: PMC2916869  PMID: 20682220
contingency management; adolescent substance abuse; marijuana; parenting
12.  Marijuana use subtypes in a community sample of young adult females 
This study sought to empirically derive marijuana user subtypes based on DSM abuse and dependence criteria and examine demographic and substance abuse distinctions of derived classes.
A community sample of 308 female marijuana users between the ages of 18-24 were recruited in the Southern New England region. Latent class analysis was used to derive subgroups based on DSM criteria. The use and demographic characteristics of classes were further analyzed using ANOVA and chi-square tests.
Based on fit criteria, a three class solution was selected. Class I (37%), an “unaffected/mild” group was characterized by very low endorsement rates of abuse and dependence criteria. This class was also found to have significantly lower rates of other substance use problems. Class II (41.6%) “moderate problem users” showed moderate endorsement rates of abuse and dependence criteria. Class III (21.4%) - “severe problem users” showed the greatest levels of abuse and dependence with 90% meeting DSM criteria for abuse and 100% meeting diagnostic criteria for marijuana dependence. Class III also showed the greatest levels of other substance use problems.
Three distinct marijuana abuse and dependence subtypes were derived using LCA. Findings may have implications for the development of more targeted treatment and prevention interventions for young women struggling with varying degrees of marijuana abuse and dependence.
PMCID: PMC2992809  PMID: 20457408
Marijuana; Cannabis; Latent Class Analysis; Females; Young Adults; Substance Use
13.  A Randomized Trial of Contingency Management for Adolescent Marijuana Abuse and Dependence 
Drug and alcohol dependence  2009;105(3):240-247.
An initial efficacy test of an innovative behavioral outpatient treatment model for adolescents with problematic use of marijuana enrolled 69 adolescents, aged 14–18, and randomly assigned them to one of two treatment conditions. Both conditions received individualized Motivational Enhancement and Cognitive Behavioral Therapy (MET/CBT) and a twice-weekly drug-testing program. The experimental contingency management condition involved a clinic delivered, abstinence-based incentive program, and weekly behavioral parent training sessions that included a parent-delivered, abstinence-based, substance monitoring contract. The comparison condition included an attendance-based incentive program, and weekly psychoeducational parent sessions. Follow-up assessments were performed at 3, 6, 9 months post-treatment. The experimental condition showed greater marijuana abstinence during treatment, e.g., 7.6 vs. 5.1 continuous weeks and 50% vs. 18% achieved ≥ 10 weeks of abstinence. Improvements were found in parenting and youth psychopathology across treatment conditions, and improvements in negative parenting uniquely predicted post treatment abstinence. The outcomes observed in the experimental condition are consistent with adult substance dependence treatment literature, and suggest that integrating CM abstinence-based approaches with other empirically-based outpatient interventions provides an alternative and efficacious treatment model for adolescent substance abuse/dependence. Replication and continued development of more potent interventions remain needed to further advance the development of effective substance abuse treatments for adolescents.
PMCID: PMC2763939  PMID: 19717250
contingency management; adolescent; marijuana; cannabis; treatment
14.  Attempts to Stop or Reduce Marijuana Use in Non-Treatment Seekers 
Drug and alcohol dependence  2008;97(1-2):180-184.
Daily marijuana smokers (n=19) who intended to quit or reduce in the next month on their own called a phone each night for 28 nights to report marijuana use and reported intentions to change at the end of each week. Outcomes did not differ between those who initially planned to reduce vs. quit in the next month. Participants averaged three attempts to reduce and one attempt to quit during the 28 days. Participants reduced on 11% and abstained on 14% of days. Most participants were successful in reducing or abstaining on half or more of the days they attempted; however, only four participants (21%) reduced ≥ 50% for ≥ 7 consecutive days and only two (10%) abstained for that long. Abstinence or reduction did not appear to change alcohol or caffeine use. We conclude a) initial intentions are poor predictors of outcomes, b) most users make multiple, short-lived attempts to change, c) reduction was as common as abstinence, d) many attempts to change are initially successful but few persist, and e) other drug use does not appear to worsen with marijuana reduction or abstinence.
PMCID: PMC2556038  PMID: 18485619
cannabis; marijuana; cessation; natural history; substance use disorder
15.  Cannabis withdrawal in adolescent treatment seekers 
Drug and alcohol dependence  2004;78(2):205-210.
A valid cannabis withdrawal syndrome has been demonstrated in controlled studies with adult marijuana abusers, yet few published reports have examined cannabis withdrawal among adolescents. Adolescents presenting for outpatient substance abuse treatment, whose primary substance of abuse was cannabis, completed a questionnaire reporting the presence and severity of withdrawal symptoms during past periods of cannabis abstinence. Nearly two-thirds of the sample indicated that they had experienced four or more symptoms, and over one-third reported four or more symptoms that occurred at a moderate or greater severity. The magnitude of withdrawal severity was positively correlated with current emotional and behavioral symptoms and self-reported problems with cannabis use. These findings are consistent with previous studies, though the prevalence and magnitude of withdrawal symptoms were lower than that observed in a similar study with adult treatment seekers [Budney, A.J., Novy, P., Hughes, J.R., 1999. Marijuana withdrawal among adults seeking treatment for marijuana dependence. Addiction 94, 1311–1322]. Further research is needed to elucidate associations between cannabis withdrawal effects, the initiation of cessation attempts, and relapse.
PMCID: PMC1626354  PMID: 15845324
Cannabis; Marijuana; Withdrawal; Adolescent
16.  Respiratory Effects of Marijuana and Tobacco Use in a U.S. Sample 
Although a number of studies have examined the respiratory impact of marijuana smoking, such studies have generally used convenience samples of marijuana and tobacco users. The current study examined respiratory effects of marijuana and tobacco use in a nationally representative sample while controlling for age, gender, and current asthma.
Analysis of the nationally representative third National Health and Nutrition Examination Survey (NHANES III).
U.S. households.
A total of 6,728 adults age 20 to 59 who completed the drug, tobacco, and health sections of the NHANES III questionnaire in 1988 and 1994. Current marijuana use was defined as self-reported 100+ lifetime use and at least 1 day of use in the past month.
Self-reported respiratory symptoms included chronic bronchitis, frequent phlegm, shortness of breath, frequent wheezing, chest sounds without a cold, and pneumonia. A medical exam also provided an overall chest finding and a measure of reduced pulmonary functioning. Marijuana use was associated with respiratory symptoms of chronic bronchitis (P =.02), coughing on most days (P =.001), phlegm production (P =.0005), wheezing (P <.0001), and chest sounds without a cold (P =.02).
The impact of marijuana smoking on respiratory health has some significant similarities to that of tobacco smoking. Efforts to prevent and reduce marijuana use, such as advising patients to quit and providing referrals for support and assistance, may have substantial public health benefits associated with decreased respiratory health problems.
PMCID: PMC1490047  PMID: 15693925
marijuana; tobacco; smoking; respiratory symptoms; epidemiology
17.  Quantifying the Clinical Significance of Cannabis Withdrawal 
PLoS ONE  2012;7(9):e44864.
Background and Aims
Questions over the clinical significance of cannabis withdrawal have hindered its inclusion as a discrete cannabis induced psychiatric condition in the Diagnostic and Statistical Manual of Mental Disorders (DSM IV). This study aims to quantify functional impairment to normal daily activities from cannabis withdrawal, and looks at the factors predicting functional impairment. In addition the study tests the influence of functional impairment from cannabis withdrawal on cannabis use during and after an abstinence attempt.
Methods and Results
A volunteer sample of 49 non-treatment seeking cannabis users who met DSM-IV criteria for dependence provided daily withdrawal-related functional impairment scores during a one-week baseline phase and two weeks of monitored abstinence from cannabis with a one month follow up. Functional impairment from withdrawal symptoms was strongly associated with symptom severity (p = 0.0001). Participants with more severe cannabis dependence before the abstinence attempt reported greater functional impairment from cannabis withdrawal (p = 0.03). Relapse to cannabis use during the abstinence period was associated with greater functional impairment from a subset of withdrawal symptoms in high dependence users. Higher levels of functional impairment during the abstinence attempt predicted higher levels of cannabis use at one month follow up (p = 0.001).
Cannabis withdrawal is clinically significant because it is associated with functional impairment to normal daily activities, as well as relapse to cannabis use. Sample size in the relapse group was small and the use of a non-treatment seeking population requires findings to be replicated in clinical samples. Tailoring treatments to target withdrawal symptoms contributing to functional impairment during a quit attempt may improve treatment outcomes.
PMCID: PMC3458862  PMID: 23049760
18.  Delay Discounting in Current and Former Marijuana-Dependent Individuals 
Studies have found that a variety of drug dependent groups discount delayed rewards more than matched-controls. This study compared delay discounting for a hypothetical $1000 reward among dependent marijuana users, former dependent marijuana users, and matched-controls. Discounting of marijuana was also assessed in the currently marijuana-dependent group. No significant difference in discounting was detected among the groups, however currently dependent users showed a trend to discount money more than the other two groups. Within the dependent marijuana group, marijuana was discounted more than money, and discounting for money and marijuana were significantly and positively correlated. Regression analyses indicated that delay discounting was more closely associated with tobacco use than marijuana use. A variety of questionnaires were also administered, including impulsivity questionnaires. Dependent marijuana users scored as significantly more impulsive on the Impulsiveness subscale of the Eysenck Impulsiveness-Venturesomeness-Empathy questionnaire than controls. However, the three groups did not significantly differ on several other personality questionnaires including the Barratt Impulsivity Scale-11. The Stanford Time Perception Inventory Present-Fatalistic subscale was positively correlated with money and marijuana discounting, indicating that a greater sense of powerlessness over the future is related to greater delay discounting. Results suggest that current marijuana dependence may be associated with a trend toward increased delay discounting, but this effect size appears to be smaller for marijuana than for previously examined drugs.
PMCID: PMC2874198  PMID: 20158299
marijuana; cannabis; delay discounting; temporal discounting; drug dependence

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