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1.  Caffeine Withdrawal and Dependence: A Convenience Survey Among Addiction Professionals 
Journal of Caffeine Research  2013;3(2):67-71.
Aims
Caffeine withdrawal was included in the research appendix of the DSM-IV to encourage additional research to assist with determining its status for the next version of the manual. Caffeine dependence was not included because of a lack of empirical research at the time of publication. This study assessed the beliefs of addiction professionals about the clinical importance of caffeine withdrawal and dependence.
Methods
A 6-item survey was developed and delivered electronically to the members of six professional organizations that focus on addiction. Open-ended comments were also solicited. Five hundred members responded.
Results
The majority (95%) thought that cessation of caffeine could produce a withdrawal syndrome, and that caffeine withdrawal can have clinical importance (73%); however, only half (48%) thought that caffeine withdrawal should be included in the Diagnostic and Statistical Manual of Mental Disorders (DSM). A majority (58%) believed that some people develop caffeine dependence; however, only 44% indicated that it should be in the DSM. Comments suggested that trepidation about inclusion of caffeine diagnoses was due to the concerns about the field of psychiatry being criticized for including common disorders with a relatively low clinical severity. Others, however, expressed an urgent need to take caffeine-related problems more seriously.
Conclusions
The majority of addiction professionals believe that caffeine withdrawal and dependence disorders exist and are clinically important; however, these professionals are divided in whether caffeine withdrawal and dependence should be included in DSM. Wider dissemination of the extant literature on caffeine withdrawal and additional research on caffeine dependence will be needed to provide additional guidance to policymakers and healthcare workers.
doi:10.1089/jcr.2013.0005
PMCID: PMC3680976  PMID: 24761276
2.  Pharmacological and psychosocial interventions for cannabis use disorders 
Objective
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.
Method
A search of publication databases identified research studies and reviews of the scientific literature on psychosocial and pharmacological interventions for cannabis use disorders.
Results
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.
Conclusion
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
3.  A Multicomponent Motivational Intervention to Improve Adherence Among Adolescents With Poorly Controlled Type 1 Diabetes: A Pilot Study 
Journal of Pediatric Psychology  2013;38(6):629-637.
Objective To adapt and pilot test a multicomponent motivational intervention that includes family-based contingency management (CM) for adolescents with poorly controlled type 1 diabetes. Methods A total of 17 adolescents, age 12–17 years (M = 14.8, SD = 1.5), with type 1 diabetes (duration M = 6.2 years, SD = 4.5) and mean HbA1c of 11.6% (SD = 2.5%) were enrolled. Adolescents and their parents received 14 weeks of motivational interviewing, clinic-based CM, and parent-directed CM that targeted increased blood glucose monitoring (BGM). Results Adolescents significantly increased their BGM (p < .001) and showed significantly improved HbA1c levels (glycemic control) from pre-to posttreatment (p < .0001). Conclusions The magnitude of improvements in the frequency of BGM and glycemic control in adolescents with type 1 diabetes is encouraging and will be tested in a randomized controlled trial.
doi:10.1093/jpepsy/jst032
PMCID: PMC3701130  PMID: 23699750
cognitive behavior therapy; contingency management; motivational interviewing; type 1 diabetes
4.  Neuroeconomics and Adolescent Substance Abuse: Individual Differences in Neural Networks and Delay Discounting 
Objective
Many adolescents with substance use problems show poor response to evidence based treatments. Treatment outcome has been associated with individual differences in impulsive decision making as reflected by delay discounting (DD) rates (preference for immediate rewards). Adolescents with higher rates of DD were expected to show greater neural activation in brain regions mediating impulsive/habitual behavioral choices and less activation in regions that mediate reflective/executive behavioral choices.
Method
Thirty adolescents being treated for substance abuse completed a DD task optimized to balance choices of immediate versus delayed rewards and a control condition accounted for activation during magnitude valuation. A group independent component analysis on functional magnetic resonance imaging (fMRI) time courses identified neural networks engaged during DD. Network activity was correlated with individual differences in discounting rate.
Results
Higher discounting rates were associated with diminished engagement of an executive attention control network involving the dorsolateral prefrontal cortex, dorsomedial prefrontal cortex, inferior parietal cortex, cingulate cortex, and precuneus. Higher discounting rates were also associated with less deactivation in a “bottom up” reward valuation network involving the amygdala, hippocampus, insula, and ventromedial prefrontal cortex. These 2 networks were significantly negatively correlated.
Conclusions
Results support relations between competing executive and reward valuation neural networks and temporal decision making, an important potentially modifiable risk factor relevant for prevention and treatment of adolescent substance abuse.
Clinical trial registration information—The Neuroeconomics of Behavioral Therapies for Adolescent Substance Abuse; http://clinicaltrials.gov/; NCT01093898.
doi:10.1016/j.jaac.2013.04.013
PMCID: PMC3712894  PMID: 23800488
adolescent substance abuse; delay discounting; functional magnetic resonance imaging (fMRI); neuroeconomics
5.  A Developmental Perspective on Neuroeconomic Mechanisms of Contingency Management 
This paper provides a developmental overview of relevant theory and research on delay discounting and neuroeconomics, and their implications for CM approaches to treatment. Recent advances in neuroscience, and in particular the neuroscience of decision making, have the potential to inform treatment development for adolescent substance use in general, and contingency management (CM) treatments in particular. CM utilizes abstinence-based reinforcement to enhance motivation to engage in treatment and engender abstinence. CM interventions may be informed by research on delay discounting, a type of decision making that reflects how individuals value immediate vs. delayed rewards. Delay discounting reliably distinguishes substance abusers from non abusers and is a significant predictor of individual differences in response to substance use treatments. Delay discounting is also of high potential importance in the development of substance use problems in adolescence. Discounting may also be important in predicting response to CM, as CM attempts to directly influence this decision making process, shifting the preference from the immediate rewards of use to delayed rewards for choosing not to use. Multiple neural processes underlie decision making, and those processes have implications for adolescent substance abuse. There are significant neurodevelopmental processes that differentiate adolescents from adults. These processes are implicated in delay discounting, suggesting that adolescence may reflect a period of plasticity in temporal decision making. Understanding the neural mechanisms of delay discounting has led to promising working memory interventions directly targeting the executive functions that underlie individual choices. These interventions may be particularly helpful in combination with CM interventions that offer immediate rewards for brief periods of abstinence, and may show particular benefit in adolescence due to the heightened neural plasticity of systems that underlie temporal discounting in adolescence.
doi:10.1037/a0028748
PMCID: PMC3443497  PMID: 22663343
adolescent substance abuse; contingency management; neuroeconomics
6.  The Impact of Disruptive Behavior Disorder on Substance Use Treatment Outcome in Adolescents 
Journal of substance abuse treatment  2012;44(5):10.1016/j.jsat.2012.11.003.
The current study examined the impact of disruptive behavior disorder (DBD) on substance use outcomes in an adolescent sample. Sixty-eight adolescents and their caregivers were randomized to one of two fourteen-week, outpatient treatments: Motivational Enhancement Therapy/Cognitive Behavior Therapy (MET/CBT) + Parent Management Training + Contingency Management (CM; experimental) and MET/CBT + Parent Drug Education (attention control). This study assessed abstinence, substance use, externalizing behavior, and parenting outcomes over five assessment periods for youth with DBD (DBD+) and without DBD (DBD−). Results showed DBD+/experimental adolescents reported fewer days of marijuana use than DBD+/control adolescents. Results also showed that parents of DBD− adolescents in the experimental condition reported significantly better parenting outcomes compared to DBD−/control. Substance abuse treatment for adolescents with DBD which includes a component such as contingency management and parent training has the potential to contribute to substance use outcomes. Such treatment strategies, however, should include additional support for parents.
doi:10.1016/j.jsat.2012.11.003
PMCID: PMC3882152  PMID: 23228436
contingency management; adolescents; substance abuse; disruptive behavior disorder; marijuana
7.  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.
doi:10.1016/j.jsat.2012.08.223
PMCID: PMC3556197  PMID: 23085041
8.  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.
doi:10.1016/j.drugalcdep.2010.10.014
PMCID: PMC3071451  PMID: 21131143
cannabis; marijuana; treatment; computer delivered; contingency management; internet
9.  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.
doi:10.1037/a0026543
PMCID: PMC3906638  PMID: 22182419
delay discounting; adolescent substance abuse; marijuana
10.  Clinical Correlates of Co-Occurring Cannabis and Tobacco Use: A Systematic Review 
Addiction (Abingdon, England)  2012;107(8):1404-1417.
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 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.
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 consistently associated with a greater likelihood of tobacco use disorders, more psychosocial problems, nor 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.
doi:10.1111/j.1360-0443.2012.03843.x
PMCID: PMC3377777  PMID: 22340422
cannabis; marijuana; tobacco; smoking; co-occurring; outcomes; interventions
11.  The Co-occurring Use and Misuse of Cannabis and Tobacco: A Review 
Addiction (Abingdon, England)  2012;107(7):1221-1233.
Aims
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.
Methods
Selective review of published studies.
Results
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.
Conclusion
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.
doi:10.1111/j.1360-0443.2012.03837.x
PMCID: PMC3397803  PMID: 22300456
Cannabis; Tobacco; Nicotine; Marijuana; Genetics; Treatment; Policy; Co-administration
12.  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
13.  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.
Background
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.
Methods
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.
Results
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.
Conclusion
Results suggest our incentive program may offer a method for boosting outcomes.
doi:10.1016/j.drugalcdep.2011.03.007
PMCID: PMC3162088  PMID: 21466925
contingency management; preschool; children of substance abusers; parent training; Complier Average Causal Effects
14.  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).
Conclusions
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.
doi:10.1371/journal.pone.0044864
PMCID: PMC3458862  PMID: 23049760
15.  Sleep disturbance and the effects of extended-release zolpidem during cannabis withdrawal 
Drug and alcohol dependence  2011;117(1):38-44.
Background
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.
Methods
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.
Results
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.
Conclusions
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.
doi:10.1016/j.drugalcdep.2011.01.003
PMCID: PMC3119729  PMID: 21296508
Cannabis; Marijuana; Sleep; Withdrawal; Zolpidem; Pharmacotherapy
16.  General Anxiety Disorder Symptoms, Tension Reduction, and Marijuana Use Among Young Adult Females 
Journal of Women's Health  2010;19(9):1635-1642.
Abstract
Background
The current study tested the hypothesis that tension reduction expectancies mediate the relationship between anxiety symptoms and marijuana use.
Methods
Interview data for 332 young adult females from Southern New England were collected from 2004 to 2009.
Results
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.
Conclusions
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.
doi:10.1089/jwh.2010.1973
PMCID: PMC2965700  PMID: 20718677
17.  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.
doi:10.1016/j.chc.2010.03.007
PMCID: PMC2916869  PMID: 20682220
contingency management; adolescent substance abuse; marijuana; parenting
18.  Marijuana use subtypes in a community sample of young adult females 
Objective
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.
Method
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.
Results
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.
Conclusion
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.
doi:10.1016/j.whi.2010.02.001
PMCID: PMC2992809  PMID: 20457408
Marijuana; Cannabis; Latent Class Analysis; Females; Young Adults; Substance Use
19.  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.
doi:10.1037/a0018333
PMCID: PMC2874198  PMID: 20158299
marijuana; cannabis; delay discounting; temporal discounting; drug dependence
20.  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.
doi:10.1016/j.drugalcdep.2009.07.009
PMCID: PMC2763939  PMID: 19717250
contingency management; adolescent; marijuana; cannabis; treatment
21.  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.
doi:10.1016/j.drugalcdep.2008.03.031
PMCID: PMC2556038  PMID: 18485619
cannabis; marijuana; cessation; natural history; substance use disorder
22.  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.
doi:10.1016/j.drugalcdep.2004.11.001
PMCID: PMC1626354  PMID: 15845324
Cannabis; Marijuana; Withdrawal; Adolescent
23.  Respiratory Effects of Marijuana and Tobacco Use in a U.S. Sample 
OBJECTIVE
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.
DESIGN
Analysis of the nationally representative third National Health and Nutrition Examination Survey (NHANES III).
SETTING
U.S. households.
PARTICIPANTS
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.
MEASUREMENTS AND MAIN RESULTS
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).
CONCLUSION
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.
doi:10.1111/j.1525-1497.2004.40081.x
PMCID: PMC1490047  PMID: 15693925
marijuana; tobacco; smoking; respiratory symptoms; epidemiology

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