Delay discounting in adults receiving treatment for marijuana dependence

Gender disparities in neuropsychological assessment research in drug abuse populations: A systematic review

Objective: To systematically review the literature on the neurocognitive effects of drug use to determine if there are significant gender differences. Methods: In April 2023, we conducted a broad search in MEDLINE (via PubMed), PsycINFO, and Embase for original research studies that used objective neuropsychological assessment to evaluate neurocognition in persons with drug use. Data extraction was performed in a masked, duplicate fashion. Results: Our initial search returned 22,430 records, of which 273 articles were included in our analysis. We found significant underrepresentation of women as participants in the studies. Twenty-one percent of studies had exclusively male participants; when women were included, they averaged only 23% of the sample. Only 49 studies sufficiently documented an analysis of their results by gender; due to the heterogeneity in study characteristics, no conclusions about cognitive differences between women and men could be made. Conclusions: Women are significantly underrepresented in the research on cognition in drug use. Increased efforts to include more women participants and consistent analysis and reporting of data for potential gender differences will be required to close this gap in knowledge, which may lead to improved substance abuse treatment approaches for women.

Effects of delay sequence in a delay discounting task

Delay discounting refers to the decrease in subjective value of a reward as the delay until its receipt increases. In the present study we assessed the effects of the sequence of delay blocks (increasing or decreasing) on discounting and the data systematicity using a titrating procedure with human participants. All participants completed the delay discounting task in both an increasing and decreasing sequence of delays. Delays ranged from one day to ten years. We found steeper discounting when the delays were presented in an increasing sequence compared with when they were presented in a decreasing sequence. We also found steeper discounting when participants completed the increasing sequence condition first. Our results agree with other findings reported in the literature and suggest that delay discounting may be affected by prior and subsequent experience.

The Impact of Monetary Incentives on Delay Discounting Within a Year-Long Physical Activity Intervention

BACKGROUND

Delay discounting is the depreciation in a reward's perceived value as a function of the time until receipt. Monetary incentive programs that provide rewards contingent on meeting daily physical activity (PA) goals may change participants' delay discounting preferences.

PURPOSE

Determine if monetary incentives provided in close temporal proximity to meeting PA goals changed delay discounting, and if such changes mediated intervention effects.

METHODS

Inactive adults (n = 512) wore accelerometers during a 12-month intervention where they received proximal monetary incentives for meeting daily moderate-to-vigorous PA (MVPA) goals or delayed incentives for study participation. Delay discount rate and average MVPA were assessed at baseline, end of intervention, and a 24-month follow-up. Using structural equation modeling, we tested effects of proximal versus delayed rewards on delay discounting and whether any changes mediated intervention effects on MVPA. PA self-efficacy was also evaluated as a potential mediator, and both self-efficacy and delay discounting were assessed as potential moderators of intervention effects.

RESULTS

Proximal rewards significantly increased participants' delay discounting (β = 0.238, confidence interval [CI]: -0.078, 0.380), indicating greater sensitivity to reinforcement timing. This change did not mediate incentive-associated increases in MVPA at the end of the 12-month intervention (β = -0.016, CI: -0.053, 0.019) or at a 24-month follow-up (β = -0.020, CI: -0.059, 0.018). Moderation effects were not found.

CONCLUSIONS

Incentive-induced increases in delay discounting did not deleteriously impact MVPA. This finding may help assuage concerns about using monetary incentives for PA promotion, but further research regarding the consequences of changes in delay discounting is warranted.

The Effect of Cognitive Behavioral Therapy on Impulsivity in Addictive Disorders: a Narrative Review

Purpose of Review

Impulsivity is considered an important construct in the cycle of addiction, yet the effect of evidence-based treatments on impulsivity is unclear. The goal of this paper was to review the evidence regarding the effect of cognitive behavioral therapy (CBT), one of the most studied psychotherapies for addiction, on measures of impulsivity in addictive disorders.

Recent Findings

There is a robust literature implicating impulsivity as risk factor for development of a range of addictions and poorer treatment outcomes. However, this review identified only four randomized controlled trials evaluating CBT for an addictive behavior that included repeated assessment of impulsivity. All four were studies targeting substance use.

Summary

There is limited evidence that CBT has a direct effect on change in measures of impulsivity among individuals being treated for substance use. Future clinical trials should include repeated measurement of impulsivity to examine CBT's effect on the underlying characteristics of addiction.

The hidden-zero effect in male individuals with opioid use disorder

Background: Explicitly expressing the hidden opportunity cost in intertemporal choice significantly reduces healthy participants' delay discounting - a phenomenon named the "hidden-zero effect," which is undetermined in individuals with substance use disorder (SUD).Objectives: This study aimed to determine whether the hidden-zero effect occurs among individuals with opioid use disorder (OUD) and the degree to which this effect differs between the OUD group and healthy controls.Methods: In two different experiments, Exp#1) 29 male individuals with OUD (13.5 ± 6.0 months abstinence) and 29 male controls performed an intertemporal choice task (ICT); Exp#2) 28 male individuals with OUD (17.5 ± 5.6 months abstinence) and 27 male controls performed a delay discounting task (DDT). The OUD group was recruited from a mandatory treatment, and controls from WeChat. There were two choice conditions in both two tasks: the hidden-zero (H0) condition (standard), and the explicit-zero (E0) condition (explicitly expressing opportunity cost).Results: Compared with the H0 condition, all participants' delay discounting was significantly decreased in the E0 condition (ps < .05, ηp2 = 0.254, 0.110). There was no significant difference in the changed degree between these two groups in either experiment (ps > .05). The delay discounting of the OUD group was significantly higher than that of controls only in Experiment 2 (p < .001, ηp2 = 0.376).Conclusion: This study extended the population in which the hidden-zero effect occurs to individuals with OUD. With respect to delay discounting, the hidden-zero effect benefit did not differ in OUD and control participants.

Delay discounting and substance use treatment outcomes: A systematic review focused on treatment outcomes and discounting methodology

INTRODUCTION

Delay discounting-the tendency to choose small, immediate rewards over larger, delayed rewards-is robustly associated with substance use. Delay discounting may present challenges in treatment for substance use disorders, as individuals with elevated discounting may struggle to wait for the long-term rewards that come from abstinence, which may yield poorer treatment outcomes. However, evidence on the role of discounting in treatment outcomes has been inconsistent. The study conducted a systematic review of the literature to characterize the prospective effects of delay discounting measured pre-treatment on substance use treatment outcomes, with a focus on characterizing findings across: 1) type of treatment outcome and 2) methodology used to assess and characterize discounting.

METHOD

A systematic literature search identified N = 17 studies that examined the association between delay discounting at treatment entry (pre-treatment) and substance use treatment outcomes. Findings were reported across the following substance use treatment outcomes: abstinence, relapse, use frequency and related problems, and treatment adherence. Findings regarding discounting methodology were reported by type of discounting measure (adjusting choice task, fixed choice task, or experiential task) and parameter used to characterize discounting (k, log transformed k (lnk), and area under the curve).

RESULTS

Delay discounting at treatment entry was not consistently associated with substance use treatment outcomes when examined across all studies overall (47 %) or by treatment outcome (0-40 % for most outcomes). The majority of studies (64 %) that used an adjusting choice, computer-based task reported a significant association between discounting and treatment outcomes, whereas few studies that used a fixed choice or experiential task reported significant associations with treatment outcomes (0-25 %). Most studies (71 %) that used the lnk parameter to characterize discounting reported significant associations between discounting and a range of treatment outcomes. In contrast, few studies that used k or AUC (25-33 %) reported significant associations between discounting and treatment outcomes.

CONCLUSION

When examined overall and by treatment outcome, evidence did not consistently indicate that delay discounting was prospectively associated with substance use treatment outcomes. However, delay discounting at treatment entry was more commonly associated with a variety of poorer treatment outcomes when researchers used more fine-grained methods to characterize discounting.

Rate-dependent effects of narrative interventions in a longitudinal study of individuals who use alcohol

BACKGROUND

Delay discounting (DD), the decrease in reward valuation as a function of delay to receipt, is a key process undergirding alcohol use. Narrative interventions, including episodic future thinking (EFT), have decreased delay discounting and demand for alcohol. Rate dependence, the relationship between a baseline rate and change in that rate after an intervention, has been evidenced as a marker of efficacious substance use treatment, but whether narrative interventions have rate-dependent effects needs to be better understood. We investigated the effects of narrative interventions on delay discounting and hypothetical demand for alcohol in this longitudinal, online study.

METHODS

Individuals (n = 696) reporting high- or low-risk alcohol use were recruited for a longitudinal 3-week survey via Amazon Mechanical Turk. Delay discounting and alcohol demand breakpoint were assessed at baseline. Individuals returned at weeks 2 and 3 and were randomized into the EFT or scarcity narrative interventions and again completed the delay discounting tasks and alcohol breakpoint task. Oldham's correlation was used to explore the rate-dependent effects of narrative interventions. Study attrition as a function of delay discounting was assessed.

RESULTS

Episodic future thinking significantly decreased, while scarcity significantly increased delay discounting relative to baseline. No effects of EFT or scarcity on the alcohol demand breakpoint were observed. Significant rate-dependent effects were observed for both narrative intervention types. Higher delay discounting rates were associated with a greater likelihood of attrition from the study.

CONCLUSION

The evidence of a rate-dependent effect of EFT on delay discounting rates offers a more nuanced, mechanistic understanding of this novel therapeutic intervention and can allow more precise treatment targeting by demonstrating who is likely to receive the most benefit from it.

Initial evaluation of domain-specific episodic future thinking on delay discounting and cannabis use

Episodic Future Thinking (EFT), mental simulation of personally relevant and positive future events, may modulate delay discounting (DD) in cannabis users. Whether EFT impacts cannabis use, whether DD mediates this effect, and whether EFT can be enhanced by prompting future events across specific life domains is unknown. Active, adult cannabis users (n = 90) recruited from Amazon mTurk and Qualtrics Panels were administered an Episodic Specificity Induction (ESI) to enhance quality of imagined events before being randomized to EFT, domain-specific-EFT (DS-EFT), or Episodic Recent Thinking (ERT). All participants created four, positive life events; DS-EFT participants imagined social, leisure, health, and financial events. Event-quality ratings were assessed (e.g., enjoyment). DD was assessed at baseline (Day 1), post-intervention (Days 2-4), and follow-up (Days 9-12). Cannabis use was assessed at baseline and follow-up. Differences in change in days and grams of cannabis use between conditions and mediation of changes in use by DD were examined. No differences in DD were observed between conditions. DS-EFT, but not EFT, showed significantly greater reductions in grams (d = .54) and days of cannabis use (d = .50) than ERT. DS-EFT and EFT demonstrated significantly greater event-quality ratings than ERT (ds > .55). EFT-based interventions showed potential for reducing cannabis use. Unexpectedly, effects on DD did not mediate this effect. Further testing with larger samples of cannabis users is needed to better understand EFT's mechanisms of action and determine optimal implementation strategies. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Additive roles of tobacco and cannabis co-use in relation to delay discounting in a sample of heavy drinkers

RATIONALE

Alcohol use disorder (AUD) is associated with steeper delay discounting rates; however, it is unknown whether substance co-use, particularly cannabis use, has an additive effect on discounting rates among heavy drinkers. Furthermore, it is unclear whether substance co-use and delay discounting are independently associated with AUD severity.

OBJECTIVES

The purpose of this study was to determine whether alcohol, tobacco, and cannabis co-use impacts delay discounting rates. We also sought to determine whether substance co-use and delay discounting were associated with AUD symptom counts.

METHODS

The study sample was culled from several human laboratory studies and consisted of 483 heavy drinking individuals who completed a baseline visit (prior to experimental procedures). Participants were divided into groups based on self-reported alcohol, tobacco, and cannabis use during the past 30 days: alcohol only (n = 184), alcohol + cigarettes (n = 89), alcohol + cannabis (n = 82), and tri-use (n = 128). We examined discounting rates across the 4 groups and used multiple linear regression to test whether co-use and delay discounting were associated with AUD symptoms.

RESULTS

After adjusting for covariates, individuals in the alcohol + cannabis group and the tri-use group had steeper discounting rates relative to the alcohol-only group. In addition, tri-use and delay discounting rates were independently correlated with a greater number of AUD symptoms.

CONCLUSIONS

Delay discounting rates were significantly greater among subgroups reporting cannabis use providing partial support for an additive effect, while also highlighting the importance of co-use substance type. Both tri-use and delay discounting were associated with greater AUD severity, which may provide relevant intervention targets.

Is irregular time estimation a common factor in smoking behavior and delay discounting?

INTRODUCTION

Smoking is known to be associated with steeper delay discounting which is a widely used measure of externalizing behavior. This study investigates individual aspects of time estimation and the extent to which these are associated with differences in delay discounting and smoking behavior.

METHODS

The study was conducted as an online experiment in a sample of undergraduate students (N = 495), including 51 smokers. Participants completed a serial time estimation, delay discounting task (MCQ), BIS/BAS questionnaire, Fagerstrom test for nicotine dependence and an alcohol use assessment (QFV).

RESULTS

Smoking, heavy drinking and delay discounting were associated with faster estimation of time. Furthermore, smoking and delay discounting were associated with differences in autocorrelation. Fun seeking was associated with smoking and alcohol use, but not with time estimation or delay discounting.

CONCLUSIONS

This study provides evidence for the hypothesis that an acceleration of the internal clock might lead to time over-estimation which could lead towards delayed consequence sensitivity and addiction. The study also found further evidence for the hypothesis that distortions in time estimation (i.e., autocorrelation) may be related to delay discounting and smoking. Smoking and delay discounting were associated with faster estimations of time and differences in autocorrelation.

A systematic review and meta-analysis of delay discounting and cannabis use

Delay discounting reflects the systematic reduction in the value of a consequence by delay to delivery. Theoretical and empirical work suggests that delay discounting is a key behavioral mechanism underlying substance use disorder. Existing work on cannabis use, however, is mixed with many studies reporting null results. The purpose of this review was to provide an in-depth assessment of the association between delay discounting and cannabis use. We conducted metaregression analyses to determine the omnibus correlation between delay discounting and cannabis use, and to evaluate task-based and sample-based moderators. Studies included evaluated an association between delay discounting and cannabis quantity-frequency or severity measures in human participants (27 studies, 61 effect sizes, 24,782 participants). A robust variance estimation method was used to account for dependence among effect sizes. A significant, but small, omnibus effect was observed (r = .082) in which greater cannabis use frequency or severity was associated with greater discounting. Incentive structure and outcome type were each significant moderators in a multiple moderator model such that incentivized tasks correlated with severity measures showed stronger associations (r = .234) than hypothetical tasks correlated with quantity-frequency measures (r = .029). Comparisons to historic effect size data supported the hypothesis that, at present, the relationship between cannabis use and delay discounting appears empirically smaller than for other substances. Future work should explore theoretical rationales explaining this modest relationship involving cannabis use and delay discounting, such as reflecting the smaller magnitude of perceived long-term clinical outcomes associated with cannabis compared to other substances. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Decision Making and Impulsivity in Young Adult Cannabis Users

Aims: Chronic cannabis users show impairments on laboratory measures of decision making which reflect risk factors for initiation and continued use of cannabis. However, the differential sensitivity of these tasks to cannabis use has not been established. Moreover, studies to date have often lacked assessment of psychiatric histories and use of other illicit substances, both of which may influence decision making outcomes. The current study aimed to address these limitations by (1) including multiple types of decision making tasks, (2) implementing the Probabilistic Reversal Learning Task, a measure of decision making under uncertainty, for the first time in cannabis users, (3) including young adult cannabis users with no other psychiatric disorders, and (4) conducting urinalysis to exclude users of other illicit drugs.

Methods: Thirty-three current cannabis users without comorbid psychiatric disorders and 35 cannabis non-users completed behavioral measures of decision-making (Iowa Gambling Task), reward discounting (Delay Discounting Task), choice-outcome learning (the Probabilistic Reversal Learning Task) and a questionnaire assessment of impulsivity (Barratt Impulsiveness Scale).

Results: Relative to non-users, cannabis users demonstrated greater preference for immediate vs. delayed rewards on the Delay Discounting Task, made fewer advantageous decisions on the Iowa Gambling Task, and endorsed greater impulsivity on the Barratt Impulsiveness Scale scales. Cannabis users and non-users showed comparable performance on the Probabilistic Reversal Learning Task. Frequency of past-month cannabis use and total years of use did not predict decision making or impulsivity.

Conclusions: Young adult cannabis users demonstrated higher discounting rates and impairments in learning cost-benefit contingencies, while reversal learning was unaffected. Self-reported impulsivity was elevated as well. None of these measures correlated with current or lifetime estimates of cannabis use, arguing against a dose-relationship. Interventions that target improvement in affected components of decision making may be helpful in reducing cannabis use and relapse.

Sifting through the weeds: Relationships between cannabis use frequency measures and delay discounting

BACKGROUND

Delay Discounting (DD) relates to more frequent cannabis use, but results are variable, potentially because of variations in whether integrated or single-item measures are used, and whether the timeframe of measures is narrow or broad. Explicating the relationship between DD and cannabis use may result from comparing use indices that vary on these characteristics.

METHODS

This online study of current cannabis users (n = 1,800) assessed DD and three cannabis use frequency items: number of days of use in the past month, times used per day, and weekly-monthly use. A fourth index derived with Latent Class Analysis (LCA) integrated days per month and times per day to try to better characterize frequency patterns. Effect sizes reflecting relations between cannabis use frequency indices and DD were compared.

RESULTS

Three frequency classes emerged from the LCA (Low-Moderate-High). DD was significantly associated with times per day (r = 0.11, d = 0.21), days of use (r = 0.09, d = 0.18), and the LCA index (r = 0.06, d = 0.13), but not weekly-monthly use (r = 0.04, d = 0.09). Times per day was more strongly related to DD than LCA classes (p < 0.01) and weekly-monthly use (p < 0.05), but not days of use (p = 0.66). Days of use exhibited a stronger relationship with DD than weekly-monthly use (p < 0.001), but not LCA classes (p = 0.06).

CONCLUSIONS

Cannabis use frequency measures with narrower timeframes may demonstrate stronger positive relationships to DD. The LCA index did not improve the relationship between frequency and DD, potentially because of shared variance between use days and times per day. Specific characteristics of cannabis use frequency may be particularly indicative of excessive DD.

Interventions for cannabis use disorder

How to treat adults and adolescents with a Cannabis Use Disorder is a burgeoning research area. This article reviews the empirical literature pertaining to several psychosocial approaches (cognitive-behavior therapy, motivational enhancement, and contingency management), all of which are associated with favorable outcomes. We also review the emerging research on the use of pharmacotherapy, brief interventions and technology-delivered interventions, and conclude with an overview of future research needs.

A systematic review and Bayesian meta-analysis of interventions which target or assess co-use of tobacco and cannabis in single- or multi-substance interventions

BACKGROUND AND AIMS

Tobacco and cannabis are commonly co-used, and evidence for the influence of co-use on quit outcomes for either substance is mixed. We sought to determine the efficacy of tobacco and/or cannabis use interventions delivered to co-users on cannabis and tobacco use outcomes.

METHOD

Systematic review with meta-analysis and narrative review, using five databases and author requests for co-use data. Controlled and uncontrolled intervention studies focusing on treatment of tobacco and/or cannabis use assessing use of both pre- and post-intervention were included. Prevention interventions were excluded. Bayesian meta-analysis was used across four outcome measures: risk ratio for tobacco and cannabis cessation post-intervention separately; standardized mean change for tobacco and cannabis reduction post-intervention separately. Narrative reporting of the same outcome measures in non-randomized clinical trials (non-RCTs) and quality assessment of all included studies were conducted.

RESULTS

Twenty studies (12 RCTs and eight uncontrolled) were included. Bayesian meta-analysis with informative priors based on existing data of 11 RCTs (six single-substance, five multi-substance interventions) delivered to co-users (n = up to 1117) showed weak evidence for an effect on cannabis cessation [risk ratio (RR) = 1.48, credibility interval (CrI) = 0.92, 2.49, eight studies] and no clear effect on tobacco cessation (RR = 1.10, CrI = 0.68, 1.87, nine studies). Subgroup analysis suggested that multi-substance interventions might be more effective than cannabis-targeted interventions on cannabis cessation (RR = 2.19, CrI = 1.10, 4.36 versus RR = 1.39, CrI = 0.75, 2.74). A significant intervention effect was observed on cannabis reduction (RR = 0.25, CrI = 0.03, 0.45, nine studies) but not on tobacco reduction (RR = 0.06, CrI = -0.11, 0.23, nine studies). Quality of evidence was moderate, although measurement of co-use and cannabis use requires standardization. Uncontrolled studies targeting both cannabis and tobacco use indicated feasibility and acceptability.

CONCLUSIONS

Single and multi-substance interventions addressing tobacco and/or cannabis have not shown a clear effect on either tobacco or cannabis cessation and reduction among co-users. However, dual substance interventions targeting tobacco and cannabis appear feasible.

Cognitive-motivational, interpersonal, and behavioral functioning in relationship to treatment and research engagement in forensic patients with ADHD

Objectives

To provide more insight into treatment and research responsivity in offenders with attention‐deficit hyperactivity disorder (ADHD).

Method

Via self‐reports and patients' scores on cognitive computer tasks, it was examined whether poorer cognitive‐motivational, interpersonal, and behavioral functioning were related to treatment no‐shows, longer treatment time duration intervals, and no‐show at the research appointment in 52 forensic outpatients with ADHD (M_age = 35.3, SD = 9.38). Treatment adherence was tracked for 10 appointments after research participation.

Results

Regression analyses showed that higher self‐reported impulsivity was associated with research no‐show, and more alcohol use with longer treatment time intervals. Yet, self‐reported delay aversion was associated with fewer treatment no‐shows, and, uncontrolled for alcohol use, impulsivity was associated with shorter treatment time intervals in a subsample of patients.

Conclusions

These preliminary results indicate that externalizing behaviors increase the risk for nonadherence in forensic ADHD patients, but that cognitive‐motivational problems also motivate patients to be more engaged.

Long-term changes in delay discounting following a smoking cessation treatment for patients with depression

BACKGROUND

Delay discounting (DD) has been identified as a trans-disorder process underlying addictive behaviors, including smoking. Previous studies have evaluated how different treatments for drug dependence have affected DD, showing mixed results. Furthermore, no study has examined the effects of changes in depression on DD rates. The aim of this study was to evaluate the impact of treatment type: cognitive behavioral treatment (CBT), CBT + behavioral activation (BA), or CBT + BA + contingency management (CM), and changes in smoking status and depression on DD rates in long-term follow-up among a sample of treatment-seeking smokers with depression.

METHODS

Participants were 180 treatment-seeking smokers with depression who were randomly assigned to one of the following treatment conditions: CBT (n = 60), CBT + BA (n = 60), and CBT + BA + CM (n = 60). Depressive symptomatology and major depression diagnosis were evaluated through the BDI-II and the SCID-I of the DSM-IV-TR. DD rates were assessed using the DD task with hypothetical monetary rewards. Smoking status, DD, and depressive symptomatology were collected at baseline, at end-of-treatment and at one-, two-, three-, and six-month follow-ups.

RESULTS

CM for smoking cessation reduces DD rates (p = .0094). Smoking abstinence (p = .0024) and reduction in depressive symptoms (p = .0437) were associated with decreases in DD rates in long-term follow-up.

CONCLUSIONS

CM interventions for smoking cessation, smoking abstinence, and the improvement of depression contribute to reductions in DD over time.

Effects of opioid/cannabinoid mixtures on impulsivity and memory in rhesus monkeys

The opioid epidemic underscores the need for safer and more effective treatments for pain. Combining opioid receptor agonists with drugs that relieve pain through nonopioid mechanisms could be a useful strategy for reducing the dose of opioid needed to treat pain, thereby reducing risks associated with opioids alone. Opioid/cannabinoid mixtures might be useful in this context; individually, opioids and cannabinoids have modest effects on cognition, and it is important to determine whether those effects occur with mixtures. Delay discounting and delayed matching-to-sample tasks were used to examine effects of the mu-opioid receptor agonist morphine (0.32-5.6 mg/kg), the cannabinoid CB1/CB2 receptor agonist CP55940 (0.0032-0.1 mg/kg), and morphine/CP55940 mixtures on impulsivity (n = 3) and memory (n = 4) in rhesus monkeys. Alone, each drug decreased rate of responding without modifying choice in the delay-discounting task, and morphine/CP55940 mixtures reduced choice of one pellet in a delay dependent manner, with monkeys instead choosing delayed delivery of the larger number of pellets. With the exception of one dose in one monkey, accuracy in the delayed matching-to-sample task was not altered by either drug alone. Morphine/CP55940 mixtures decreased accuracy in two monkeys, but the doses in the mixture were equal to or greater than doses that decreased accuracy or response rate with either drug alone. Rate-decreasing effects of morphine/CP55940 mixtures were additive. These data support the notion that opioid/cannabinoid mixtures that might be effective for treating pain do not have greater, and might have less, adverse effects compared with larger doses of each drug alone.

A web-based episodic specificity and future thinking session modulates delay discounting in cannabis users

Episodic future thinking (EFT), a brief intervention involving mental simulation of positive future events, improves delay discounting (DD) in nicotine and alcohol dependent individuals. This study is the first to assess effects of a single-session, online episodic training (ET) on constructs that might impact cannabis use and cannabis use disorder. A sample of 200 active cannabis users recruited via Amazon Mechanical Turk were randomized to an EFT group (n = 102) or an episodic recent thinking control group (ERT; n = 98). A novel episodic specificity induction (ES) was included to enhance quality of episodic thinking for the ET group, and an ES attention control was provided to the ERT group (control training group; CT). Quality and manipulation ratings of event excitement, vividness, importance, and enjoyment of trainings were collected in addition to DD tasks (gains and losses) and readiness to change cannabis use. The ET group reported higher overall quality and manipulation ratings than did the CT group (p < .001, d = 0.79). DD of gains was lower in the ET relative to those of the CT group after controlling for relevant variables (p = .003, d = 0.48), unlike DD of losses (p = .50, d = 0.11). The ET group showed larger pre/post increases in readiness to change, but they were not statistically significant (p = .069, d = 0.26). These effects, following a session of online ET, suggests that ET may positively impact factors related to reduction in cannabis use. Differential effects of EFT and ES components on DD and the development of ET as an adjunctive mHealth intervention targeting reduction in cannabis use appears warranted. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Behavioral trainings and manipulations to reduce delay discounting: A systematic review

In everyday decision-making, individuals make trade-offs between short-term and long-term benefits or costs. Depending on many factors, individuals may choose to wait for larger delayed reward, yet in other situations they may prefer the smaller, immediate reward. In addition to within-subject variation in the short-term versus long-term reward trade-off, there are also interindividual differences in delay discounting (DD), which have been shown to be quite stable. The extent to which individuals discount the value of delayed rewards turns out to be associated with important health and disorder-related outcomes: the more discounting, the more unhealthy or problematic choices. This has led to the hypothesis that DD can be conceptualized as trans-disease process. The current systematic review presents an overview of behavioral trainings and manipulations that have been developed to reduce DD in human participants aged 12 years or older. Manipulation studies mostly contain one session and measure DD directly after the manipulation. Training studies add a multiple session training component that is not per se related to DD, in between two DD task measurements. Ninety-eight studies (151 experiments) were identified that tested behavioral trainings and manipulations to decrease DD. Overall, results indicated that DD can be decreased, showing that DD is profoundly context dependent and changeable. Most promising avenues to pursue in future research seem to be acceptance-based/mindfulness-based trainings, and even more so manipulations involving a future orientation. Limitations and recommendations are discussed to identify the mechanistic processes that allow for changes in discount rate and behavior accordingly.

The neurobiology of impulsivity and substance use disorders: implications for treatment

Impulsivity is strongly associated with substance use disorders (SUDs). Our review discusses impulsivity as an underlying vulnerability marker for SUDs, and treatment of co-occurring impulsivity in SUDs. Three factors should be considered for the complex relationship between impulsivity and a SUD: (1) the trait effect of impulsivity, centering on decreased cognitive and response inhibition, (2) the state effect resulting from either acute or chronic substance use on brain structure and function, and (3) the genetic and environmental factors (e.g., age and sex) may influence impulsive behavior associated with SUDs. Both subjective and objective measures are used to assess impulsivity. Together, treatment developments (pharmacological, behavioral, and neurophysiological) should consider these clinically relevant dimensions assessed by a variety of measures, which have implications for treatment matching in individuals with SUD. Despite its heterogeneity, impulsivity is a marker associated with SUDs and may be understood as an imbalance of bottom-up and top-down neural systems. Further investigation of these relationships may lead to more effective SUD treatments.

The relationship between the UPPS-P impulsive personality traits and substance use psychotherapy outcomes: A meta-analysis

BACKGROUND

Although impulsive personality traits have been well implicated in substance use disorder (SUD) risk, little work has established how specific impulsive personality traits influence and are influenced by SUD psychotherapy outcomes. The purpose of this meta-analysis was to quantitatively review existing work to examine 1) how impulsive personality traits affect SUD psychotherapy outcomes and 2) reductions in impulsive personality traits during SUD psychotherapy.

METHODS

Studies were identified by conducting a comprehensive review of the literature.

RESULTS

For aim one (k=6), significant effects were found for lack of premeditation (g=0.60, SE=0.30, 95% CI 0.01-1.20; z=1.99, p=0.05) and negative urgency (g=0.55, SE=0.17, 95% CI 0.22-0.88, z=3.30, p=0.001), with trait scores related to poorer SUD psychotherapy outcomes. For aim two (k=10), decreases in sensation seeking (g=-0.10, SE=0.05, 95% CI -0.20 to 0.004; z=-1.88, p=0.02) and negative urgency (g=-0.25, SE=0.14, 95% CI -0.53 to 0.03; z=-1.75, p=0.03) during SUD psychotherapy were significant.

CONCLUSIONS

Overall, our quantitative synthesis suggests that lack of premeditation and negative urgency are related to poorer SUD psychotherapy outcomes. Although negative urgency and sensation seeking are decreasing during SUD psychotherapy, the magnitude of the change is quite small. Overall, we suggest that the measurement and targeting of impulsive personality traits in psychotherapy has strong potential to improve clinical outcomes across SUDs and a wide range of clinical problems and disorders.

Withdrawal-Related Changes in Delay Discounting Predict Short-Term Smoking Abstinence

INTRODUCTION

Impulsive decision making is associated with smoking behavior and reflects preferences for smaller, immediate rewards and intolerance of temporal delays. Nicotine withdrawal may alter impulsive decision making and time perception. However, little is known about whether withdrawal-related changes in decision making and time perception predict smoking relapse.

METHODS

Forty-five smokers (14 female) completed two laboratory sessions, one following 24-hour abstinence and one smoking-as-usual (order counterbalanced; biochemically verified abstinence). During each visit, participants completed measures of time perception, decision making (ie, discount rates), craving, and withdrawal. Following the second laboratory session, subjects underwent a well-validated model of short-term abstinence (quit week) with small monetary incentives for each day of biochemically confirmed abstinence.

RESULTS

Smokers significantly overestimated time during abstinence, compared to smoking-as-usual (p = .021), but there were no abstinence effects on discount rates (p = .6). During the quit week, subjects were abstinent for 3.5 days (SD = 2.15) and smoked a total of 12.9 cigarettes (SD = 15.8). Importantly, higher discount rates (ie, preferences for immediate rewards) during abstinence (abstinence minus smoking difference score) predicted greater number of days abstinent (p = .01) and fewer cigarettes smoked during the quit week (p = .02). Withdrawal-related change in time reproduction did not predict relapse (p = .2).

CONCLUSIONS

These data suggest that individuals who have a greater preference for immediate rewards during abstinence (vs. smoking-as-usual) may be more successful at maintaining short-term abstinence when provided with frequent (eg, daily) versus less frequent incentive schedules (eg, 1 month). Abstinence-induced changes in decision making may be important for identifying smokers who may benefit from interventions that incentivize abstinence such as contingency management (CM).

IMPLICATIONS

The present results suggest that smokers who place greater subjective value on immediate rewards during withdrawal (compared to smoking-as-usual) may be less likely to relapse if offered small, frequent monetary incentives to maintain abstinence. Thus, the current findings may have important implications for identifying smokers most likely to benefit from particular interventions such as CM. Future research might evaluate whether withdrawal-related changes in delay discounting moderate treatment response to different incentive schedules with the goal of optimizing CM effectiveness to improve abstinence rates.

Unique prediction of cannabis use severity and behaviors by delay discounting and behavioral economic demand

Few studies have simultaneously evaluated delay discounting and behavioral economic demand to determine their unique contribution to drug use. A recent study in cannabis users found that monetary delay discounting uniquely predicted cannabis dependence symptoms, whereas cannabis demand uniquely predicted use frequency. This study sought to replicate and extend this research by evaluating delay discounting and behavioral economic demand measures for multiple commodities and including a use quantity measure. Amazon.com's Mechanical Turk was used to sample individuals reporting recent cannabis use (n=64) and controls (n=72). Participants completed measures of monetary delay discounting as well as alcohol and cannabis delay discounting and demand. Cannabis users and controls did not differ on monetary delay discounting or alcohol delay discounting and demand. Among cannabis users, regression analyses indicated that cannabis delay discounting uniquely predicted use severity, whereas cannabis demand uniquely predicted use frequency and quantity. These effects remained significant after controlling for other delay discounting and demand measures. This research replicates previous outcomes relating delay discounting and demand with cannabis use and extends them by accounting for the contribution of multiple commodities. This research also demonstrates the ability of online crowdsourcing methods to complement traditional human laboratory techniques.

Impact of general cognition and executive function deficits on addiction treatment outcomes: Systematic review and discussion of neurocognitive pathways

This systematic review aims to examine growing evidence linking cognitive-executive functions with addiction treatment outcomes, and to discuss significant cognitive predictors drawing upon addiction neuroscience theory. We conducted a systematic search to identify studies using measures of general cognition and executive functions in patients with substance use disorders for the purpose of predicting two treatment outcomes: therapeutic adherence and relapse. Forty-six studies were selected, and sample characteristics, timing of assessments, and cognitive measures were analyzed. We observed significant methodological differences across studies, resulting in substantial variability in the relationships between cognitive-executive domains and treatment outcomes. Notwithstanding this variability, we found evidence of associations, of medium effect size, between general cognition and treatment adherence, and between reward-based decision-making and relapse. The link between general cognition and treatment adherence is consistent with emerging evidence linking limited cognitive-executive resources with less ability to benefit from talk therapies. The link between reward-based decision-making and relapse accords with decision neuroscience models of addiction. Findings may inform preclinical and clinical research concerning addiction treatment mechanisms.

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.

Delay Discounting and Preference Reversals by Cigarette Smokers

Quit attempts made by smokers that result in relapse to smoking are conceptualized in behavioral economics as preference reversals, in which preference for a larger-later outcome switches to preference for a smaller-sooner outcome. Though preference reversals are predicted by models of delay discounting, we are aware of no human research that has explicitly established that rate of delay discounting is associated with preference reversals. The present study attempted to establish this connection. Assessments of delay discounting of hypothetical money rewards at two magnitudes ($50, $1000) were examined from forty-five smokers, as well as a novel preference reversal task designed to determine when a preference reversal would occur for the same amounts of hypothetical money. Results from the preference reversal task were used to classify participants as predicted high, moderate, and low discounters, and rates of delay discounting were compared between these classifications at each magnitude. Statistically significant differences were observed between predicted high and low discounters in both magnitude conditions, and between predicted high and moderate discounters in the $1000 magnitude condition. Correlations between delay discounting and preference reversal amongst moderate discounters, though in the predicted direction, did not reach statistical significance. The overall pattern of results are consistent with the indication that rate of delay discounting is associated with the timing of preference reversals.

Heroin delay discounting: Modulation by pharmacological state, drug-use impulsivity, and intelligence

Delay discounting (DD) refers to how rapidly an individual devalues goods based on delays to receipt. DD usually is considered a trait variable but can be state dependent, yet few studies have assessed commodity valuation at short, naturalistically relevant time intervals that might enable state-dependent analysis. This study aimed to determine whether drug-use impulsivity and intelligence influence heroin DD at short (ecologically relevant) delays during two pharmacological states (heroin satiation and withdrawal). Out-of-treatment, intensive heroin users (n = 170; 53.5% African American; 66.7% male) provided complete DD data during imagined heroin satiation and withdrawal. Delays were 3, 6, 12, 24, 48, 72, and 96 hours; maximum delayed heroin amount was thirty $10 bags. Indifference points were used to calculate area under the curve (AUC). We also assessed drug-use impulsivity (subscales from the Impulsive Relapse Questionnaire [IRQ]) and estimated intelligence (Shipley IQ) as predictors of DD. Heroin discounting was greater (smaller AUC) during withdrawal than satiation. In regression analyses, lower intelligence and IRQ Capacity for Delay as well as higher IRQ Speed (to return to drug use) predicted greater heroin discounting in the satiation condition. Lower intelligence and higher IRQ Speed predicted greater discounting in the withdrawal condition. Sex, race, substance use variables, and other IRQ subscales were not significantly related to the withdrawal or satiation DD behavior. In summary, heroin discounting was temporally rapid, pharmacologically state dependent, and predicted by drug-use impulsivity and estimated intelligence. These findings highlight a novel and sensitive measure of acute DD that is easy to administer.

A comparison of delay discounting in adolescents and adults in treatment for cannabis use disorders

Delay discounting is associated with problematic substance use and poorer treatment outcomes in adolescents and adults with substance use disorders. Although some research has addressed delay discounting among individuals with cannabis use disorders (CUDs), results have been equivocal, and no study has examined whether discounting rates differ between adolescent and adult cannabis users. The aim of this study was to compare discounting rates between adolescents and adults in treatment for CUD to determine whether discounting at intake or changes in discounting across treatment differed between age groups. Participants were 165 adolescents and 104 adults enrolled in treatment for CUD. Participants completed a delay discounting task at intake and end of treatment for 2 commodities (money and cannabis) at 2 different magnitudes ($100 and $1,000). Repeated measures mixed models examined differences in discounting rates by commodity and magnitude across age groups at intake and changes in discounting across treatment. At intake, adolescents discounted money more than adults whereas adults showed greater discounting at $100 magnitude than $1,000. In addition, adults had greater decreases in discounting of cannabis over the course of treatment. Overall, adolescents appeared less sensitive to changes in magnitude of rewards, discounted money at higher rates, and showed less improvement in discounting over the course of treatment compared to adults. Comparing delay discounting in adolescents and adults with CUD can contribute to a better understanding of how development influences the effect of discounting on substance use to better inform treatment for substance use disorders.

Opportunity costs of reward delays and the discounting of hypothetical money and cigarettes

Humans are reported to discount delayed rewards at lower rates than nonhumans. However, nonhumans are studied in tasks that restrict reinforcement during delays, whereas humans are typically studied in tasks that do not restrict reinforcement during delays. In nonhuman tasks, the opportunity cost of restricted reinforcement during delays may increase delay discounting rates. The present within-subjects study used online crowdsourcing (Amazon Mechanical Turk, or MTurk) to assess the discounting of hypothetical delayed money (and cigarettes in smokers) under four hypothetical framing conditions differing in the availability of reinforcement during delays. At one extreme, participants were free to leave their computer without returning, and engage in any behavior during reward delays (modeling typical human tasks). At the opposite extreme, participants were required to stay at their computer and engage in little other behavior during reward delays (modeling typical nonhuman tasks). Discounting rates increased as an orderly function of opportunity cost. Results also indicated predominantly hyperbolic discounting, the "magnitude effect," steeper discounting of cigarettes than money, and positive correlations between discounting rates of these commodities. This is the first study to test the effects of opportunity costs on discounting, and suggests that procedural differences may partially account for observed species differences in discounting.

Decreased delay discounting in former cigarette smokers at one year after treatment

Current cigarette smokers exhibit greater delay discounting relative to ex-smokers. However, few studies have assessed longitudinal changes in delay discounting and cigarette smoking. The purpose of this study was to assess changes in delay discounting of hypothetical monetary rewards and smoking among treatment-seeking smokers (N=80) at baseline, after 6 weeks of behavioral treatment, and at 12-month follow-up. Results showed no changes in delay discounting in either smokers or abstainers at the end-of-treatment. In contrast, at 12-month follow-up, significant decreases in delay discounting were observed in abstainers while delay discounting remained the same for smokers. To our knowledge, this is the first study to observe significant decreases in delay discounting following prolonged smoking abstinence. Such findings provide evidence that delay discounting may have more state-like characteristics than previously believed.

Does temporal discounting explain unhealthy behavior? A systematic review and reinforcement learning perspective

The tendency to make unhealthy choices is hypothesized to be related to an individual's temporal discount rate, the theoretical rate at which they devalue delayed rewards. Furthermore, a particular form of temporal discounting, hyperbolic discounting, has been proposed to explain why unhealthy behavior can occur despite healthy intentions. We examine these two hypotheses in turn. We first systematically review studies which investigate whether discount rates can predict unhealthy behavior. These studies reveal that high discount rates for money (and in some instances food or drug rewards) are associated with several unhealthy behaviors and markers of health status, establishing discounting as a promising predictive measure. We secondly examine whether intention-incongruent unhealthy actions are consistent with hyperbolic discounting. We conclude that intention-incongruent actions are often triggered by environmental cues or changes in motivational state, whose effects are not parameterized by hyperbolic discounting. We propose a framework for understanding these state-based effects in terms of the interplay of two distinct reinforcement learning mechanisms: a “model-based” (or goal-directed) system and a “model-free” (or habitual) system. Under this framework, while discounting of delayed health may contribute to the initiation of unhealthy behavior, with repetition, many unhealthy behaviors become habitual; if health goals then change, habitual behavior can still arise in response to environmental cues. We propose that the burgeoning development of computational models of these processes will permit further identification of health decision-making phenotypes.

Impulsivity as a vulnerability factor for poor addiction treatment outcomes: a review of neurocognitive findings among individuals with substance use disorders

With the current review, we explore the hypothesis that individual differences in neurocognitive aspects of impulsivity (i.e., cognitive and motor disinhibition, delay discounting and impulsive decision-making) among individuals with a substance use disorder are linked to unfavorable addiction treatment outcomes, including high drop-out rates and difficulties in achieving and maintaining abstinence. A systematic review of the literature was carried out using PubMed, PsycINFO and Web of Knowledge searches. Twenty-five unique empirical papers were identified and findings were considered in relation to the different impulsivity dimensions. Although conceptual/methodological heterogeneity and lack of replication are key limitations of studies in this area, findings speak for a prominent role of cognitive disinhibition, delay discounting and impulsive decision-making in the ability to successfully achieve and maintain abstinence during and following addiction treatment. In contrast, indices of motor disinhibition appear to be unrelated to abstinence levels. Whereas the relationship between impulsivity and treatment retention needs to be examined more extensively, preliminary evidence suggests that impulsive/risky decision-making is unrelated to premature treatment drop-out among individuals with a substance use disorder. The reviewed findings are discussed in terms of their clinical implications.

Endocannabinoid-dependent modulation of phasic dopamine signaling encodes external and internal reward-predictive cues

The mesolimbic dopamine (DA) system plays an integral role in incentive motivation and reward seeking and a growing body of evidence identifies signal transduction at cannabinoid receptors as a critical modulator of this system. Indeed, administration of exogenous cannabinoids results in burst firing of DA neurons of the ventral tegmental area and increases extracellular DA in the nucleus accumbens (NAcc). Implementation of fast-scan cyclic voltammetry (FSCV) confirms the ability of cannabinoids to augment DA within the NAcc on a subsecond timescale. The use of FSCV along with newly developed highly selective pharmacological compounds advances our understanding of how cannabinoids influence DA transmission and highlights a role for endocannabinoid-modulated subsecond DAergic activation in the incentive motivational properties of not only external, but also internal reward-predictive cues. For example, our laboratory has recently demonstrated that in mice responding under a fixed-interval (FI) schedule for food reinforcement, fluctuations in NAcc DA signal the principal cue predictive of reinforcer availability - time. That is, as the interval progresses, NAcc DA levels decline leading to accelerated food seeking and the resulting characteristic FI scallop pattern of responding. Importantly, administration of WIN 55,212-2, a synthetic cannabinoid agonist, or JZL184, an indirect cannabinoid agonist, increases DA levels during the interval and disrupts this pattern of responding. Along with a wealth of other reports, these results illustrate the role of cannabinoid receptor activation in the regulation of DA transmission and the control of temporally guided reward seeking. The current review will explore the striatal beat frequency model of interval timing as it pertains to cannabinoid signaling and propose a neurocircuitry through which this system modulates interoceptive time cues.

Test-retest reliability and construct validity of the Experiential Discounting Task

Delay discounting (the devaluation of delayed rewards) has been studied extensively using animal models with psychophysical adjustment procedures. Similar procedures have been developed to assess delay discounting in humans and these procedures most often use hypothetical rewards and delays. The Experiential Discounting Task (EDT) was developed to assess human delay discounting using real rewards and delays. In the present study we examined the test-retest reliability and construct validity of the EDT. Construct validity was evaluated by comparing it with a standard delay discounting task. The EDT had poor test-retest reliability and discounting rates obtained with this task were uncorrelated with those obtained in the standard delay discounting task. Area under the EDT discounting curve was negatively correlated with scores on a measure of boredom proneness (i.e., individuals prone to boredom more steeply discounted delayed money in the EDT). This correlation may underlie previous reports that discounting in the EDT is correlated with addictions, as some evidence suggests boredom proneness is correlated with gambling, cigarette smoking, alcohol consumption, and sensation seeking. Boredom proneness scores were correlated with no other measure of discounting. These findings suggest the EDT measures a different construct than that measured by traditional delay discounting tasks.

Disadvantageous Decision-Making as a Predictor of Drop-Out among Cocaine-Dependent Individuals in Long-Term Residential Treatment

BACKGROUND

The treatment of cocaine-dependent individuals (CDI) is substantially challenged by high drop-out rates, raising questions regarding contributing factors. Recently, a number of studies have highlighted the potential of greater focus on the clinical significance of neurocognitive impairments in treatment-seeking cocaine users. In the present study, we hypothesized that disadvantageous decision-making would be one such factor placing CDI at greater risk for treatment drop-out.

METHODS

In order to explore this hypothesis, the present study contrasted baseline performance (at treatment onset) on two validated tasks of decision-making, the Iowa Gambling Task (IGT) and the Cambridge Gamble Task (CGT) in CDI who completed treatment in a residential Therapeutic Community (TC) (N = 66) and those who dropped out of TC prematurely (N = 84).

RESULTS

Compared to treatment completers, CDI who dropped out of TC prematurely did not establish a consistent and advantageous response pattern as the IGT progressed and exhibited a poorer ability to choose the most likely outcome on the CGT. There were no group differences in betting behavior.

CONCLUSION

Our findings suggest that neurocognitive rehabilitation of disadvantageous decision-making may have clinical benefits in CDI admitted to long-term residential treatment programs.