Individualized treatment effects of a digital alcohol intervention and their associations with participant characteristics and engagement

AIMS

Conditional average treatment effects are often reported in intervention studies, in which assumptions are made regarding how effects are similar across a heterogeneous sample. Nonetheless, differing factors, such as genetics, age, and sex, can impact an intervention's effect on outcomes. The study aimed to estimate the individualized effects of a digital alcohol intervention among individuals looking online to reduce their drinking.

METHODS

We used data from a randomized controlled trial (RCT), including 2129 adults from the Swedish general population. The RCT concerned a text message-based alcohol intervention that sought to engender change through increasing knowledge on how to change and instilling confidence in changing behaviour. Outcomes were total weekly alcohol consumption and monthly heavy episodic drinking. Individualized treatment effects were modelled using baseline characteristics (age, gender, alcohol consumption, and psychosocial variables) and engagement with the intervention content.

RESULTS

We found evidence that the effects of the digital alcohol intervention were heterogeneous concerning participants' age, baseline alcohol consumption, confidence, and importance. For heavy episodic drinking, there was evidence that effects were heterogeneous concerning age, sex, and baseline alcohol consumption. Overall, women, older individuals, and heavier drinkers benefitted more from the intervention in terms of effect size. In addition, participants who engaged more with the goal-setting and screening content reported better outcomes.

CONCLUSIONS

The results highlight how different individuals respond differently to a digital alcohol intervention. This allows insight into who benefits the most and least from the intervention and highlights the potential merit of designing interventions adapted to different individuals' needs.

Measuring Cannabis Reinforcement among Young Adults: A Mixed Methods Examination

Introduction

Increasing reinforcement received from cannabis-free activities, relative to reinforcement from cannabis-related activities, is one way to reduce harmful cannabis use. Thus, accurate measurement of cannabis reinforcement is important. Using convergent mixed methods, we developed the Adolescent Reinforcement Survey Schedule-Cannabis Use Version (ARSS-CUV). ARSS-CUV, adapted from the alcohol use version, measures cannabis reinforcement by asking individuals how frequently they engaged in, and how much they enjoyed, different activities when using and not using cannabis.

Method

Young adults (N = 65; M age = 20.4 years [SD = 1.8]) completed measures of cannabis use, the ARSS-CUV, and provided feedback on included activities, via focus groups. Following Standards for Educational and Psychological Testing framework, this study examined evidence of measurement validity based on item content.

Results

Quantitative findings revealed that peer interactions were the most reinforcing activities, whereas activities related to family were least reinforcing. Qualitative findings indicated some confusion with question wording. Participants also indicated the importance of environmental context when using cannabis and noted who they use cannabis with may be more important than the activity they are doing. Changes were made to survey flow and response choices after participant feedback.

Conclusions

ARSS-CUV includes revisions in activities solicited and response format. The revised ARSS-CUV provides opportunities to advance measurement of an important construct (i.e., reinforcement) in the study of cannabis use. Psychometric properties of the ARSS-CUV across different populations and contexts of use (e.g., polysubstance use) should be examined.

Longitudinal examination of alcohol demand and alcohol-related reinforcement as predictors of heavy drinking and adverse alcohol consequences in emerging adults

BACKGROUND AND AIMS

Behavioral economic theory predicts that high alcohol demand and high proportionate alcohol-related reinforcement are important determinants of risky alcohol use in emerging adults, but the majority of research to date has been cross-sectional in nature. The present study investigated prospective and dynamic relationships between alcohol demand and proportionate alcohol-related reinforcement in relation to heavy drinking days and alcohol problems.

DESIGN

Longitudinal cohort with assessments every 4 months for 20 months.

SETTING

Ontario, Canada.

PARTICIPANTS

Emerging adults reporting regular heavy episodic drinking (n = 636, Mage = 21.44; 55.8% female).

MEASUREMENTS

Heavy drinking days (HDD; Daily Drinking Questionnaire), alcohol problems (Brief Young Adult Alcohol Consequences Questionnaire), alcohol demand (Alcohol Purchase Task) and proportionate alcohol-related reinforcement (Activity Level Questionnaire).

FINDINGS

Linear mixed effects models revealed that behavioral economic indicators and alcohol-related outcomes significantly decreased over the study, consistent with 'aging out' of risky alcohol use. Random intercept cross-lagged panel models revealed significant between-person relationships, such that higher alcohol demand and alcohol-related reinforcement were positively associated with HDD and alcohol problems (random intercepts = 0.187-0.534, Ps < 0.01). Moreover, alcohol demand indicators (particularly the rate of change in elasticity of the demand curve, as measured by α, and the maximum expenditure, Omax) and proportionate alcohol-related reinforcement significantly forecasted changes in HDD at all time points (|βs| = 0.063-0.103, Ps < 0.05) in cross-lagged relationships, with bidirectional associations noted for the rate of change in elasticity (βs = -0.085 to -0.104, Ps < 0.01). Proportionate alcohol-related reinforcement also significantly forecasted changes in alcohol problems at all time points (βs = 0.072-0.112, Ps < 0.01).

CONCLUSIONS

Multiple behavioral economic indicators (demand elasticity, maximum expenditure and reinforcement ratio) forecast changes in heavy episodic drinking and alcohol problems over the course of emerging adulthood. These results further implicate alcohol demand and proportionate alcohol-related reinforcement as etiologically and developmentally important mechanisms in alcohol use trajectories.

The Use of Nonmonetary Outcomes in Health-Related Delay Discounting Research: Review and Recommendations

Delay discounting (DD) refers to the tendency to devalue an outcome as a function of its delay. Most contemporary human DD research uses hypothetical money to assess individual rates of DD. However, nonmonetary outcomes such as food, substances of misuse, and sexual outcomes have been used as well, and have advantages because of their connections to health. This article reviews the literature on the use of nonmonetary outcomes of food, drugs, and sexual outcomes in relation to health and reinforcer pathologies such as substance use disorders, obesity, and sexual risk behaviors, respectively, and makes a case for their use in discounting research. First, food, substances, and sex may be more ecologically valid outcomes than money in terms of their connections to health problems and reinforcer pathologies. Second, consistent trends in commodity-specific (i.e., domain) effects, in which nonmonetary outcomes are discounted more steeply than money, enhance variation in discounting values. Third, commodity-specific changes in discounting with treatments designed to change health choices are described. Finally, methodological trends such as test-retest reliability, magnitude effects, the use of hypothetical versus real outcomes, and age-related effects are discussed in relation to the three outcome types and compared to trends with monetary discounting. Limitations that center around individual preferences, nonsystematic data, and deprivation are discussed. We argue that researchers can enhance their DD research, especially those related to health problems and reinforcer pathologies, with the use of nonmonetary outcomes. Recommendations for future directions of research are delineated.

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.

Neuroscience-informed classification of prevention interventions in substance use disorders: An RDoC-based approach

Neuroscience has contributed to uncover the mechanisms underpinning substance use disorders (SUD). The next frontier is to leverage these mechanisms as active targets to create more effective interventions for SUD treatment and prevention. Recent large-scale cohort studies from early childhood are generating multiple levels of neuroscience-based information with the potential to inform the development and refinement of future preventive strategies. However, there are still no available well-recognized frameworks to guide the integration of these multi-level datasets into prevention interventions. The Research Domain Criteria (RDoC) provides a neuroscience-based multi-system framework that is well suited to facilitate translation of neurobiological mechanisms into behavioral domains amenable to preventative interventions. We propose a novel RDoC-based framework for prevention science and adapted the framework for the existing preventive interventions. From a systematic review of randomized controlled trials using a person-centered drug/alcohol preventive approach for adolescents, we identified 22 unique preventive interventions. By teasing apart these 22 interventions into the RDoC domains, we proposed distinct neurocognitive trajectories which have been recognized as precursors or risk factors for SUDs, to be targeted, engaged and modified for effective addiction prevention.

A new statistical model for binge drinking pattern classification in college-student populations

Background

Binge drinking (BD) among students is a frequent alcohol consumption pattern that produces adverse consequences. A widely discussed difficulty in the scientific community is defining and characterizing BD patterns. This study aimed to find homogenous drinking groups and then provide a new tool, based on a model that includes several key factors of BD, to assess the severity of BD regardless of the individual's gender.

Methods

Using the learning sample (N1 = 1,271), a K-means clustering algorithm and a partial proportional odds model (PPOM) were used to isolate drinking and behavioral key factors, create homogenous groups of drinkers, and estimate the probability of belonging to these groups. Robustness of our findings were evaluated with Two validations samples (N2 = 2,310, N3 = 120) of French university students (aged 18-25 years) were anonymously investigated via demographic and alcohol consumption questionnaires (AUDIT, AUQ, Alcohol Purchase Task for behavioral economic indices).

Results

The K-means revealed four homogeneous groups, based on drinking profiles: low-risk, hazardous, binge, and high-intensity BD. The PPOM generated the probability of each participant, self-identified as either male or female, to belong to one of these groups. Our results were confirmed in two validation samples, and we observed differences between the 4 drinking groups in terms of consumption consequences and behavioral economic demand indices.

Conclusion

Our model reveals a progressive severity in the drinking pattern and its consequences and may better characterize binge drinking among university student samples. This model provides a new tool for assessing the severity of binge drinking and illustrates that frequency of drinking behavior and particularly drunkenness are central features of a binge drinking model.

Pilot trial of a telehealth-delivered behavioral economic intervention promoting cannabis-free activities among adults with cannabis use disorder

BACKGROUND

Cannabis is increasingly consumed and increasingly perceived as harmless. Among those whose use develops into a cannabis use disorder (CUD), <5% initiate and engage in treatment. Thus, novel options for low-barrier, appealing treatments are needed to foster engagement in care.

METHODS

We conducted an open trial of a telehealth-delivered multicomponent behavioral economic intervention for non-treatment-engaged adults with CUD. Participants with CUD were recruited from a health system and screened for eligibility. Participants completed behavioral economic indices (cannabis demand, proportionate cannabis-free reinforcement), measures of cannabis use and mental health symptoms, and provided open-ended feedback on the intervention experience.

RESULTS

Of the 20 participants who enrolled and engaged in the initial intervention session, 70% (14 out of 20) completed all intervention components. All participants were satisfied/very satisfied with the intervention and 85.7% reported the telehealth delivery made it at least slightly easier/more likely for them to receive substance use care. Baseline to immediate post-treatment, behavioral economic cannabis demand decreased (intensity: Hedges' g = 0.14, maximum total expenditure: Hedges' g = 0.53, maximum expenditure for a single hit: Hedges' g = 0.10) and proportionate cannabis-free reinforcement (Hedges' g = 0.12) increased. Past-month total cannabis use decreased by 8.9% from baseline to post-treatment (Hedges' g = 0.39), along with decreases in recent depression (Hedges' g = 0.50) and anxiety symptoms (Hedges' g = 0.29).

DISCUSSION

These preliminary findings suggest that this behavioral economic intervention was highly acceptable and feasible for adults with untreated CUD. Changes in potential mechanisms of behavior change (cannabis demand, proportionate cannabis-free reinforcement) were consistent with reduced frequency of cannabis use and improved mental health outcomes.

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.

Use of a sequential multiple assignment randomized trial to test contingency management and an integrated behavioral economic and mindfulness intervention for buprenorphine-naloxone medication adherence for opioid use disorder

BACKGROUND

Buprenorphine-naloxone is a medication shown to improve outcomes for individuals seeking treatment for opioid use disorder (OUD); however, outcomes are limited by low medication adherence rates. This is especially true during the early stages of treatment.

METHODS

The present study proposes to utilize a sequential multiple assignment randomized trial design to compare two psychological interventions targeting buprenorphine-naloxone adherence: (1) contingency management (CM) and (2) brief motivational interviewing plus substance-free activities session plus mindfulness (BSM). Participants will be N = 280 adults who present to a university-based addictions clinic seeking treatment for OUD. Participants will be randomized to condition to receive 4 sessions of their assigned intervention (CM or BSM). Participants who are adherent, defined as attending physician appointments and having buprenorphine present in urine toxicology, will enter maintenance intervention for an additional 6 months. Those who are not adherent will be re-randomized to receive either the other intervention or both interventions. Follow-up will occur at 8 months post-randomization.

CONCLUSIONS

This novel design will examine the benefit of sequential treatment decisions following non-adherence. The primary outcome of this study is buprenorphine-naloxone medication adherence, as assessed by physician visit attendance and presence of buprenorphine in urine. Results will elicit the relative efficacy of CM and BSM compared to one another and whether keeping the initial treatment approach when adding the alternative approach for initially non-adherent individuals is beneficial.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04080180.

Poorer decision making among college students during the COVID-19 pandemic: Evidence for "pandemic-brain"

OBJECTIVE

Did living through the COVID-19 pandemic cause healthy college students to experience "pandemic-brain," a phenomenon characterized by difficulties with various cognitive abilities? Did students shift from deliberative to more impulsive decision making?

PARTICIPANTS

We compared a pre-pandemic sample of 722 undergraduate students to 161 undergraduate students recruited in Fall 2020, during the COVID-19 pandemic.

METHOD

We compared scores on the Adult Decision Making Competence scale among participants who completed the task pre-pandemic or across two time points in Fall 2020, during the pandemic.

RESULTS

Decision making was less consistent and more reliant on gain/loss framing during the pandemic compared to pre-pandemic, but college students were no less confident in their decisions. No significant changes in decision making occurred during the pandemic.

CONCLUSIONS

These decision making changes could increase the risk of making an impulsive choice with negative health consequences affecting demands on student health centers and imperiling learning environments.

A contextualized reinforcer pathology approach to addiction

Behavioural economic accounts of addiction conceptualize harmful drug use as an operant reinforcer pathology, emphasizing that a drug is consumed because of overvaluation of smaller immediate rewards relative to larger delayed rewards (delay discounting) and high drug reinforcing value (drug demand). These motivational processes are within-individual determinants of behaviour. A third element of learning theory posits that harmful drug use depends on the relative constraints on access to other available activities and commodities in the choice context (alternative reinforcers), reflecting the substantial influence of environmental factors. In this Perspective, we integrate alternative reinforcers into the contemporary behavioural economic account of harmful drug use - the contextualized reinforcer pathology model - and review empirical literature across the translational spectrum in support of this model. Furthermore, we consider how increases in drug-related mortality and health disparities in addiction can be understood and potentially ameliorated via a contextualized reinforcer pathology model in which lack of alternative reinforcement is a major risk factor for addiction.

Behavioral economics indices predict alcohol use and consequences in young men at 4-year follow-up

BACKGROUND AND AIMS

The alcohol purchase task (APT), which presents a scenario and asks participants how many drinks they would purchase and consume at different prices, generates indices of alcohol reward value that have shown robust associations with alcohol-related outcomes in numerous studies. The aim was to test its prospective validity at 4-year follow-up.

DESIGN

Prospective cohort study.

SETTING

General population sample of young Swiss men.

PARTICIPANTS

A total of 4594 Swiss young men (median age = 21, 25th - 75th quartiles = 20.5 - 21.5) completed baseline questionnaires; among those, 4214 (91.7%) were successfully followed-up 4 years later.

MEASUREMENTS

Alcohol reward value parameters (i.e. intensity, the planned consumption when drinks are free; breakpoint, the price at which consumption would be suppressed; O_max , the maximum alcohol expenditure; P_max , the price associated with O_max ; and elasticity, the relative change in alcohol consumption as a function of the relative change in price) were derived from the APT at baseline and used to predict self-reported weekly drinking amount, monthly binge drinking, alcohol-related consequences and DSM-5 alcohol use disorder criteria.

FINDINGS

Regression analyses, adjusting for the baseline alcohol measure, age, linguistic region and socio-economic indicators showed that intensity, breakpoint, O_max and elasticity significantly predicted all tested outcomes in the expected direction (e.g. standardized incidence rate ratio [95% confidence interval] = 1.11 [1.07-1.15], 1.07 [1.03-1.10], 1.08 [1.04-1.11], and 0.92 [0.89-0.95], respectively, for weekly drinking amount, all P < 0.001). P_max did not significantly predict any outcomes. Non-adjusted correlations, baseline adjusted regression and ancillary analyses using (1) latent alcohol variables, (2) multiple imputation for missing data and (3) replications in training and testing subsamples to evaluate predictive accuracy provided consistent findings.

CONCLUSIONS

The alcohol purchase task demand curve measures of alcohol reward value are useful in characterizing alcohol-related risk in young men and have long-term predictive utility.

Change in alcohol demand following a brief intervention predicts change in alcohol use: A latent growth curve analysis

BACKGROUND

The association between behavioral economic demand and various alcohol use outcomes is well established. However, few studies have examined whether changes in demand occur following a brief alcohol intervention (BAI), and whether this change predicts alcohol outcomes over the long term.

METHODS

Parallel process piecewise latent growth curve models were examined in a sample of 393 heavy drinking emerging adults (60.8% women; 85.2% white; M_age  = 18.77). In these models, two linear slopes represented rates of change in alcohol use, heavy drinking episodes, alcohol-related problems, and demand (intensity and highest expenditure across all price points or O_max ) from baseline to 1 month (slope 1) and 1 month to 16 months (slope 2). Mediation analyses were conducted to estimate the effect of a BAI on 16-month alcohol outcomes through slope 1 demand.

RESULTS

A two-session BAI predicted significant reductions in all five outcomes from baseline to 1-month follow-up. Although no further reduction was observed from the 1-month to the 16-month follow-up, there was no regression to baseline levels. Slope 1 demand intensity, but not O_max , significantly mediated the association between BAI and both outcomes-heavy drinking episodes (Est. = -0.23, SE = 0.08, p < 0.01) and alcohol-related problems (Est. = -0.15, SE = 0.07, p < 0.05)-at the 16-month follow-up.

CONCLUSIONS

Reducing high valuation of alcohol among heavy drinking emerging adults within the first month following BAI is critical for the long-term efficacy of the intervention. A two-session BAI was associated with enduring reductions in alcohol demand, and the change in demand intensity, but not O_max , was associated with sustained reductions in heavy drinking and alcohol-related problems.

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.

The social contagion of temporal discounting in small social networks

Decisions often require a tradeoff between immediate and long-term gratification. How individuals resolve such tradeoffs reflects constructs such as temporal discounting, the degree that individuals devalue delayed rewards. Recent research has started to focus on temporal decisions made in collaborative contexts (e.g., dyads, small groups). Results suggest that directly interacting with others leads to revisions in preferences, such that decision makers become more similar to their collaborative partners over time (e.g., more patient following collaboration with a patient other). What remains to be seen is whether this social influence extends to indirect social effects, such as when an individual influences another’s preferences through a shared collaborative partner. In the current study, the focus was on decisions regarding hypothetical monetary rewards. Groups of three participated in a collaborative decision-making chain, in which network member X collaborated with member Y, who then subsequently collaborated with member Z. Though network members X and Z never directly interacted, a significant indirect link was observed between member X’s pre-collaborative decision preferences and member Z’s post-collaborative decision preferences. These results demonstrate that temporal decision preferences can be transmitted through intervening connections in a small social network (i.e., social contagion), showing that indirect social influence can be empirically observed and measured in controlled environments.

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).

Concurrent validity of the Alcohol Purchase Task for measuring the reinforcing efficacy of alcohol: an updated systematic review and meta-analysis

BACKGROUND AND AIMS

An early meta-analysis testing the concurrent validity of the Alcohol Purchase Task (APT), a measure of alcohol's relative reinforcing value, reported mixed associations, but predated a large number of studies. This systematic review and meta-analysis sought to: (1) estimate the relationships between trait-based alcohol demand indices from the APT and multiple alcohol indicators, (2) test several moderators and (3) analyze small study effects.

METHODS

A meta-analysis of 50 cross-sectional studies in four databases (n = 18 466, females = 43.32%). Sex, year of publication, number of APT prices and index transformations (logarithmic, square root or none) were considered as moderators. Small study effects were examined by using the Begg-Mazumdar, Egger's and Duval & Tweedie's trim-and-fill tests. Alcohol indicators were quantity of alcohol use, number of heavy drinking episodes, alcohol-related problems and hazardous drinking. APT indices were intensity (i.e. consumption at zero cost), elasticity (i.e. sensitivity to increases in costs), O_max (i.e. maximum expenditure), P_max (i.e. price associated to O_max ) and breakpoint (i.e. price at which consumption ceases).

RESULTS

All alcohol demand indices were significantly associated with all alcohol-related outcomes (r = 0.132-0.494), except P_max , which was significantly associated with alcohol-related problems only (r = 0.064)_. The greatest associations were evinced between intensity in relation to alcohol use, hazardous drinking and heavy drinking and between O_max and alcohol use. All the tested moderators emerged as significant moderators. Evidence of small-study effects was limited.

CONCLUSIONS

The Alcohol Purchase Task appears to have concurrent validity in alcohol research. Intensity and O_max are the most relevant indices to account for alcohol involvement.

Statistically derived patterns of behavioral economic risk among heavy-drinking college students: A latent profile analysis

High levels of 3 behavioral economic indices (delay discounting, alcohol demand, and proportionate substance-related reinforcement) are consistently associated with greater alcohol misuse and alcohol-related problems. However, it is unclear whether and how these variables jointly increase the risk for alcohol-related outcomes among college students who engage in heavy episodic drinking (HED; 4/5+ drinks for women/men, respectively). The current study used a person-centered approach to identify similar patterns of behavioral economic domains among heavy-drinking college students and investigate the relationship between these empirically derived classes and alcohol-related outcomes. A sample of 393 college students (60.8% female, 78.9% White/Caucasian) reporting at least 2 heavy drinking episodes in the previous month completed measures of alcohol use and problems, demographics, delay discounting, and alcohol reward value (alcohol demand and proportionate substance-related reinforcement). Latent profile analyses revealed that a 3-class solution provided the best fit to the data: a low reward value, high discounting (LRHD) class (n = 53), a moderate reward value, low discounting (MRLD) class (n = 214), and a high reward value, high discounting (HRHD) class (n = 126). Members of the HRHD class reported significantly greater alcohol consumption, past-month HED episodes, alcohol-related problems, and symptoms of alcohol use disorder than those in the MRLD and LRHD classes. The results suggest that there are 3 constellations of behavioral economic processes and that, consistent with the reinforcer pathology model, students who overvalue alcohol-related reward and discount the future more steeply are at the greatest risk for alcohol misuse and alcohol-related problems. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Behavioral economic demand in opioid treatment: Predictive validity of hypothetical purchase tasks for heroin, cocaine, and benzodiazepines

BACKGROUND

Behavioral economics provides a framework in which to understand choice and motivation in the field of substance use disorders. Hypothetical purchase tasks (HPT), which indicate the amount or probability of purchasing substances at different prices, have been suggested as a clinical tool that can help predict future substance use and identify targets for intervention.

METHODS

Hypothetical demand for heroin, cocaine, and benzodiazepines was assessed at baseline and after six-months in 52 opioid-agonist treatment patients. The results were analyzed using a novel exponential demand equation (normalized zero-bounded exponential model [ZBEn]) that uses a log-like transform that accommodates zero consumption values.

RESULTS

Demand for these drugs was well described by the ZBEn model. After six months, demand intensity for heroin was decreased and demand metrics for cocaine and benzodiazepines increased. Multiple demand curve indices at baseline predicted the percentage of drug-positive urinalysis results at follow-up, even after controlling for covariates. Additionally, participants were divided into High and Low baseline demand groups for each drug based on demand indices. Participants with High demand at baseline for 8 out of 9 groups had significantly more drug-positive urine samples in the subsequent 6-month period.

CONCLUSIONS

This report provides evidence that demand assessment is predictive of future substance use and could help guide treatment planning at intake. These results also demonstrated that the ZBEn model provides good fits to consumption data and allows for sensitive statistical analyses.

Purchase task sensitivity to drug and nondrug reinforcers in opioid-agonist treatment patients

The behavioral economics of substance abuse has been increasingly recognized as a method of determining the value of abused substances for individuals who use those substances. It has been hypothesized that such analyses could serve as a clinical tool and that demand functions can be targeted predictors for the level of intervention necessary. This study evaluated the sensitivity of a demand task in 2 patient groups in a medication assisted treatment program (methadone maintenance), those who had used opioids in the last 2 months and those who had not used opioids in at least 18 months. Demand for 7 drugs and a control was assessed using hypothetical purchase tasks. Participants maintaining long-term abstinence had significantly higher α (sensitivity to price) and lower Q₀ (intensity of demand) for heroin than participants who had recently used opioids. Further research is necessary to illustrate if treatment is responsible for this reduction in demand. If so, demand analyses may provide clinical utility as an aid for treatment planning or as a target for treatment.

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.

Reinforcer pathology II: Reward magnitude, reward delay, and demand for alcohol collectively relate to college students' alcohol related problems

The reinforcer pathologies model of addiction posits that two characteristic patterns of operant behavior characterize addiction. Specifically, individuals suffering from addiction have elevated levels of behavioral economic demand for their substances of abuse and have an elevated tendency to devalue delayed rewards (reflected in high delay discounting rates). Prior research has demonstrated that these behavioral economic markers are significant predictors of many of college students' alcohol-related problems. Delay discounting, however, is a complex behavioral performance likely undergirded by multiple behavioral processes. Emerging analytical approaches have isolated the role of participants' sensitivity to changes in reinforcer magnitude and changes in reinforcer delay. The current study uses these analytic approaches to compare participants' discounting of money versus alcohol, and to build regression models that leverage these new insights to predict a wider range of college students' alcohol related problems. Using these techniques, we were able to 1) demonstrate that individuals differed in their sensitivity to magnitudes of alcohol versus money, but not sensitivity to delays to those commodities and 2) that we could use our behavioral economic measures to predict a range of students' alcohol related problems.

Partial MHC/neuroantigen peptide constructs attenuate methamphetamine-seeking and brain chemokine (C-C motif) ligand 2 levels in rats

There are no medications that target the neurotoxic effects or reduce the use of methamphetamine. Recombinant T-cell receptor ligand (RTL) 1000 [a partial major histocompatibility complex (pMHC) class II construct with a tethered myelin peptide], addresses the neuroimmune effects of methamphetamine addiction by competitively inhibiting the disease-promoting activity of macrophage migration inhibitory factor to CD74, a key pathway involved in several chronic inflammatory conditions, including substance use disorders. We previously reported that RTL constructs improve learning and memory impairments and central nervous system (CNS) inflammation induced by methamphetamine in mouse models. The present study in Lewis rats evaluated the effects of RTL1000 on maintenance of self-administration and cue-induced reinstatement using operant behavioral methods. Post-mortem brain and serum samples were evaluated for the levels of inflammatory factors. Rats treated with RTL1000 displayed significantly fewer presses on the active lever as compared to rats treated with vehicle during the initial extinction session, indicating more rapid extinction in the presence of RTL1000. Immunoblotting of rat brain sections revealed reduced levels of the pro-inflammatory chemokine (C-C motif) ligand 2 (CCL2) in the frontal cortex of rats treated with RTL1000, as compared to vehicle. Post hoc analysis identified a positive association between the levels of CCL2 detected in the frontal cortex and the number of lever presses during the first extinction session. Taken together, results suggest that RTL1000 may block downstream inflammatory effects of methamphetamine exposure and facilitate reduced drug seeking-potentially offering a new strategy for the treatment of methamphetamine-induced CNS injury and neuropsychiatric impairments.

Relative expected value of drugs versus competing rewards underpins vulnerability to and recovery from addiction

Behavioural economic theories of addiction contend that greater expected value of drug relative to alternative non-drug rewards is the core mechanism underpinning vulnerability to and recovery from addiction. To evaluate this claim, we exhaustively review studies with human drug users that have measured concurrent choice between drugs vs. alternative rewards, and explored individual differences. These studies show that drug choice can be modulated by drug cues, drug devaluation, imposition of costs/punishment and negative mood induction. Regarding individual differences, dependence severity was reliably associated with overall drug preference, and self-reported drug use to cope with negative affect was reliably associated with greater sensitivity to mood induced increases in drug choice. By contrast, there were no reliable individual differences in sensitivity to the effect of drug cues, drug devaluation or punishment on drug choice. These findings provide insight into the mechanisms that underpin vulnerability to dependence: vulnerability is conferred by greater relative value ascribed to drugs, and relative drug value is further augmented by negative affective states in those who report drug use coping motives. However, dependence does not appear to be characterised by abnormal cue-reactivity, habit learning or compulsion. We then briefly review emerging literature which demonstrates that therapeutic interventions and recovery from addiction might be attributed to changes in the expected relative value of drug versus alternative rewards. Finally, we outline a speculative computational account of the distortions in decision-making that precede action selection in addiction, and we explain how this account provides a blueprint for future research on the determinants of drug choice, and mechanisms of treatment and recovery from addiction. We conclude that a unified economic decision-making account of addiction has great promise in reconciling diverse addiction theories, and neuropsychological evaluation of the underlying decision mechanisms is a fruitful area for future research and treatment.

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.

Concurrent validity of the alcohol purchase task in relation to alcohol involvement: protocol for a systematic review and meta-analysis

INTRODUCTION

Alcohol demand, as measured by an alcohol purchase task (APT), provides a multidimensional assessment of the relative reinforcing efficacy of alcohol. The objective of this meta-analysis is to critically appraise the existing literature on the concurrent validity of the APT by meta-analysing the cross-sectional relationships between indices of the APT (ie, breakpoint, O_max, P_max, elasticity and intensity) and alcohol-related measures. It also aims to examine methodological procedures used to obtain APT indices and individual variables as potential moderators on the assessed estimations.

METHODS AND ANALYSIS

A comprehensive literature search conducted from inception to April 2020 will be conducted in the PubMed, PsycINFO, Web of Science and Scopus databases. Two authors will independently screen and extract data from articles using a predefined protocol search and extraction forms. Disagreements will be resolved through discussion with two additional reviewers. All results will be tabulated, and a random-effect meta-analysis will be conducted. Participants' sex, number of prices and APT methodological procedures will be examined as potential moderators on the observed effect sizes.

ETHICS AND DISSEMINATION

Results of this meta-analysis will characterise the concurrent validity of the APT in the existing literature. Further, the results are anticipated to provide evidence on which index (or indices) is most robustly associated with alcohol use and severity. Ethics approval was not required for this study and the results will be published in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42019137512.

Integrating Behavioral Economic and Social Network Influences in Understanding Alcohol Misuse in a Diverse Sample of Emerging Adults

BACKGROUND

Behavioral economic alcohol demand is a measure of motivation to consume alcohol and a robust risk factor for alcohol misuse. Social networks that are dense with alcohol are also associated with heavy drinking, but the intersection of these risk factors has not been investigated to date. This study examined these interrelationships with structural equation modeling using cross-sectional data from a diverse community sample of heavy-drinking emerging adults (N = 602).

METHODS

Latent variables for alcohol social network, alcohol demand, and alcohol misuse were constructed. Next, relations between the latent variables were examined, including the indirect effect of alcohol demand in the relation between alcohol social network and alcohol misuse. An alternative modeling testing the indirect effect of alcohol social network on the relation between alcohol demand and misuse was also tested.

RESULTS

When alone in the model, social network alcohol density significantly predicted alcohol misuse. When alcohol demand was included in the model, social network alcohol density predicted alcohol demand, alcohol demand predicted alcohol misuse, and an indirect effect on alcohol misuse through alcohol demand was present. In the alternative model, an indirect effect was not present between alcohol demand and alcohol misuse by social network alcohol density. Exploratory analyses revealed significant sex, race, and college status differences.

CONCLUSIONS

These results suggest that the influence of social network alcohol density on alcohol misuse may be, in part, through variance accounted for by alcohol reinforcing value. Longitudinal testing of this mechanistic pathway is warranted.

Experimental manipulations of behavioral economic demand for addictive commodities: a meta-analysis

BACKGROUND AND AIMS

Reinforcing value, an index of motivation for a drug, is commonly measured using behavioral economic purchase tasks. State-oriented purchase tasks are sensitive to phasic manipulations, but with heterogeneous methods and findings. The aim of this meta-analysis was to characterize the literature examining manipulations of reinforcing value, as measured by purchase tasks and multiple-choice procedures, to inform etiological models and treatment approaches METHODS: A random-effects meta-analysis of published findings in peer-reviewed articles. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol, studies were gathered through searches in PsycINFO and PubMed/MEDLINE (published 22 May 2018). Searches returned 34 unique studies (aggregate sample n = 2402; average sample size = 68.94) yielding 126 effect sizes. Measurements included change (i.e. Cohen's d) in six behavioral economic indices (intensity, breakpoint, O_max , P_max , elasticity, cross-over point) in relation to six experimental manipulations (cue exposure, stress/negative affect, reinforcer magnitude, pharmacotherapy, behavioral interventions, opportunity cost).

RESULTS

Cue exposure (d range = 0.25-0.44, all Ps < 0.05) and reinforcer magnitude [d = 0.60; 95% confidence interval (CI) = 0.18, 1.01; P < 0.005] manipulations resulted in significant increases in behavioral economic demand across studies. Stress/negative affect manipulations also resulted in a small, significant increase in O_max (d = 0.18; 95% CI = 0.01, 0.34; P = 0.03); all other effect sizes for negative affect/stress were non-significant, albeit similar in size (d range = 0.14-0.18). In contrast, pharmacotherapy (d range = -0.37 to -0.49; Ps < 0.04), behavioral intervention (d = -0.36 to -1.13) and external contingency (d = -1.42; CI = -2.30, -0.54; P = 0.002) manipulations resulted in a significant decrease in intensity. Moderators (substance type) explained some of the heterogeneity in findings across meta-analyses.

CONCLUSIONS

In behavioral economic studies, purchase tasks and multiple-choice procedures appear to provide indices that are sensitive to manipulations found to influence motivation to consume addictive substances in field experiments.

Pilot trial investigating a brief behavioral economic intervention as an adjunctive treatment for alcohol use disorder

OBJECTIVE

Behavioral economic research suggests that increasing the salience of a delayed reward may improve capacity for delaying gratification and increase behavior allocated toward obtaining larger, delayed substance-free reward rather than smaller, more immediate reward such as alcohol use. This study aimed to improve the efficacy of outpatient alcohol use disorder (AUD) treatment by adding elements that target behavioral economic mechanisms of change.

METHOD

Forty-one (N = 41) adults in outpatient AUD treatment were recruited and 37 participants were retained at follow-up. Following baseline assessment, participants received either the Substance Free Activity Session (SFAS), a single-session behavioral economic-informed intervention focused on increasing future orientation and engagement in values-based substance-free activities or a health education control intervention. Participants in both conditions received weekly prompts (via text or email) relevant to their respective intervention for four weeks. Participants (68.3% male; 70.7% Caucasian, M age = 38.24, SD = 12.69) reported an average of 3.95 (SD = 4.72) binge drinking episodes (4/5 drinks per occasion for a woman/man) and 5.05 (SD = 5.32) drinks per drinking day 30-days prior to treatment entry.

RESULTS

The study provided initial support for the feasibility and acceptability of implementing the SFAS within a treatment setting. Participants reported high levels of satisfaction with the SFAS (M = 9.08 (SD = 0.94), on a scale of 1-10). At 3-month follow-up, the SFAS was associated with reductions in the proportion of activity participation and enjoyment (reinforcement) related to substance-use relative to substance-free activities and in alcohol demand compared to control.

CONCLUSION

These preliminary results provide initial support for targeting behavioral economic mechanisms of change in an outpatient AUD treatment with a single-session intervention plus remote delivery of booster prompts.

Utilizing the commodity purchase task to evaluate behavioral economic demand for illicit substances: a review and meta-analysis

BACKGROUND ANDAIMS

The commodity purchase task is a simulated demand procedure that is easy and quick to complete (< 5 minutes) as well as adaptable for remote delivery and use with varied study populations. The purpose of this meta-analysis was to synthesize research using the commodity purchase task with illicit substances to evaluate the magnitude of omnibus effects sizes and moderators of the correlation of demand indices with quantity-frequency (QF) and severity measures.

DESIGN

Random-effects meta-analyses and meta-regressions involving studies with cross-sectional correlational designs.

SETTING AND PARTICIPANTS

Eleven studies, 10 outcomes and 2146 participants from two countries (USA and UK) published up to 1 October 2018.

MEASUREMENTS

Omnibus effect sizes (correlation coefficients) of five demand indices from the commodity purchase task [intensity (unconstrained consumption), elasticity (price sensitivity), O_max (maximum expenditure), P_max (price at maximum expenditure) and breakpoint (first price of zero consumption)] with QF and severity measures. Meta-regression models tested moderators of effect sizes (i.e. sample age and sex composition, commodity type and number of prices used in the commodity purchase task).

FINDINGS

Significant omnibus effect sizes were observed with QF and severity measures for intensity (r = 0.32/0.28, QF/severity, respectively), elasticity (r = -0.14/-0.18), O_max (r = 0.30/0.29) and breakpoint (r = 0.17/0.22) values. P_max was only significantly associated with severity measures (r = 0.15). The percentage of female participants and number of prices used in the purchase task significantly moderated P_max and breakpoint effect-size estimates in that stronger associations were observed in samples with a greater percentage of women and in studies using tasks with more price points. Commodity type (cannabis versus cocaine) did not significantly moderate associations involving any demand index.

CONCLUSIONS

Behavioral economic demand as measured by the commodity purchase task is consistently correlated with measures of illicit substance use quantity-frequency and severity.

The condom purchase task: A hypothetical demand method for evaluating sexual health decision-making

Behavioral economic theory has proved useful for understanding the influence of delay and probability on sexual health decision-making. Demand is another principle at the intersection of microeconomics and psychology that has helped advance research relevant to health behaviors. The purpose of the present study was to develop and test a demand measure related to sexual health decision-making and the influence of sexually transmitted infection (STI) risk. Participants (N = 438) recruited using Amazon Mechanical Turk completed a commodity purchase task assessing hypothetical condom demand. Condom demand was evaluated at varied prices for use with hypothetical sexual partners that varied in STI risk. Demand was characterized by prototypic decreases in consumption with increases in cost. Higher partner STI risk was associated with greater intentions for condom-protected sex at no cost and smaller decreases in condom demand with increases in cost. Price sensitivity was also related to individual difference factors relevant to sexual health (e.g., alcohol use severity, lower STI knowledge). This study supports the utility of a condom purchase task for indexing condom valuation and capturing individual difference and contextual risk factors relevant to STI transmission. Future studies may leverage this methodology as a means to study sexual health decision-making.

The influence of sex and estrous cyclicity on cocaine and remifentanil demand in rats

The application of behavioral economic demand theory in addiction science has proved useful for evaluating individual characteristics underlying abuse liability. Two factors that have received comparably little attention within this literature are sex and gonadal hormones. We determined cocaine and remifentanil demand in male and female rats using a within‐session procedure. Cocaine and remifentanil demand were evaluated for 15 consecutive days using a balanced, crossover design that randomized drug order. This design allowed for the evaluation of temporal and exposure effects on two independent dimensions of demand, unconstrained demand (Q₀) and demand elasticity (α). Estrous cyclicity was tracked to determine the contribution of phase to demand. No overall sex differences were observed. Increased unconstrained demand for cocaine and remifentanil was observed in females during periods in which estrogen was high (eg, estrus phase). Unconstrained remifentanil demand escalated over the 15‐day testing period, but escalation was not observed for cocaine or for demand elasticity. A significant exposure effect was also observed in which greater prior remifentanil intake increased unconstrained cocaine demand and reduced cocaine demand elasticity. These effects were directionally specific as no significant effects of prior cocaine exposure were observed on remifentanil demand measures. These data suggest that unconstrained demand and demand elasticity do not differ between male and female subjects; however, that unconstrained demand is associated with estrous cyclicity. These findings also suggest that opioid exposure enhances subsequent demand for psychomotor stimulants, which may be important when considering recent increases in nonmedical prescription opioid use in the United States.

Neurocognitive Dysfunctions and Their Therapeutic Modulation in Patients With Methamphetamine Dependence: A Pilot Study

AIM

Methamphetamine (MA) abuse and dependence are increasing worldwide and are commonly associated with cognitive deficits. Some studies indicate that such impairments can improve if users become abstinent, but overall results remain inconclusive. Hence, we have performed a longitudinal case-control study investigating key surrogates for attention and impulsive decision-making before and after treatment.

METHODS

Thirty patients with MA dependence and 24 non-substance-abusing control participants were recruited. Groups were matched on age, sex and education. All subjects performed a baseline assessment to obtain neurocognitive measures of sustained attention and delay discounting. Patients subsequently participated in an MA-specific relapse prevention program including repeated monitoring of relapse status. After 3 months, participants of both groups were reevaluated for neurocognitive performance.

RESULTS

At baseline, MA patients showed a significantly higher number of omissions compared to controls, indicative of lower sustained attention. Interestingly, we observed a steep decrease of omissions in MA patients to control-group level post treatment. On the other hand, MA patients discounted delayed rewards significantly stronger than controls, indicating a more impulsive choice behavior both before and after treatment.

LIMITATION

The results should be interpreted with care because of the small sample and short follow-up period.

CONCLUSION

Our data support earlier findings on partial recovery of cognitive deficits in MA patients. They also strengthen the indication for recently recommended psychotherapeutic interventions and may provide a behavioral monitoring tool to inform treatment progress.

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.

High Opportunity Cost Demand as an Indicator of Weekday Drinking and Distinctly Severe Alcohol Problems: A Behavioral Economic Analysis

INTRODUCTION

Behavioral economic theory views addiction as a reinforcer pathology characterized by excessive demand for drugs relative to alternatives. Complementary to this theory, Lamb and Ginsburg (Pharmacology Biochemistry and Behavior, 164, 2018, 62) describe addiction as a behavioral allocation disorder and predict that decisions to drink under increasingly stringent constraints are a central indicator of addiction. This study used a modified demand-curve paradigm to examine alcohol demand in the context of a next-day contingency (high opportunity cost demand) as a specific indicator of a severe pattern of alcohol problems.

METHODS

Participants were 370 undergraduates (61.1% female, 86.5% white, Mage  = 18.8) reporting multiple past-month heavy drinking episodes (5/4 drinks per occasion for men/women) who completed 2 versions of an alcohol purchase task (APT), along with measures of past-month alcohol use and problems. In 1 APT (low opportunity cost), students imagined they had no next-day responsibilities, and in the other APT (high opportunity cost), they imagined having a 10:00 am test the next day. Item-response theory analyses were used to determine mild and severe alcohol problems from the Young Adult Alcohol Consequences Questionnaire (Journal of Studies on Alcohol, 67, 2006, 169), and the most and least severe binge drinking days throughout the week.

RESULTS

Low opportunity cost demand (β = 0.15, p = 0.02) significantly predicted beyond high opportunity cost demand for the least severe problems, and high opportunity cost demand (β = 0.17, p = 0.009) significantly predicted beyond low opportunity cost demand for the most severe problems. Similarly, low opportunity cost demand (β = 0.26, p < 0.001) was more highly associated with weekend drinking, whereas high opportunity cost demand (β = 0.21, p = 0.001) was more highly associated with weekday drinking.

CONCLUSIONS

The current results suggest high opportunity cost alcohol demand is a distinct marker of severe alcohol problems among college student heavy drinkers.

Alcohol demand moderates brief motivational intervention outcomes in underage young adult drinkers

INTRODUCTION

The Alcohol Purchase Task (APT), a behavioral economic measure of alcohol's reinforcing value (demand), has been used to predict the effects of Brief Motivational Intervention (BMI) on alcohol use outcomes. However, it is not known whether BMI may be more or less efficacious, relative to control, among those with different levels of alcohol demand prior to treatment.

METHODS

Non college-attending young adults (N = 150) reporting past-month heavy drinking were randomized to a single in-person session of BMI or a relaxation training control (REL). The BMI included delivery of personalized feedback and focused on developing discrepancy between the young adults' goals and their current pattern of alcohol use. At baseline, participants completed assessments of alcohol use and the APT. Drinking levels were re-assessed at 6 weeks and 3 months post-intervention. Demand indices derived from the APT were examined as moderators of treatment effects on follow-up drinking after covarying for baseline alcohol use.

RESULTS

Two of four APT demand indices - intensity and Omax - moderated treatment outcomes. Relative to REL, BMI led to greater reductions in total number of drinks consumed and drinks per drinking day among participants with higher baseline alcohol demand. This association was not observed among participants with lower levels of alcohol demand.

CONCLUSIONS

These results demonstrate that BMI may be particularly beneficial for those with a high reinforcing value of alcohol. The mechanism for this effect is unclear, and determining the process by which BMI confers increased benefit for these individuals is a fruitful area for future work.

Sensitivity of hypothetical purchase task indices when studying substance use: A systematic literature review

Hypothetical Purchase Tasks (HPTs) simulate demand for a substance as a function of escalating price. HPTs are increasingly used to examine relationships between substance-related correlates and outcomes and demand typically characterized using a common battery of indices (Intensity, Omax, Pmax, Breakpoint, Elasticity). This review examines the relative sensitivity of the HPT indices. Reports were identified using the search term "purchase task" in PubMed and Web of Science. For inclusion, reports had to be original studies in English, examine relationships between HPT indices and substance-related correlates or outcomes, and appear in a peer-reviewed journal through December 2017. Indices were compared using effect sizes (Cohen's d) and the proportion of studies in which statistically significant relationships were observed. The search identified 1274 reports with 114 (9%) receiving full-text review and 82 (6%) meeting inclusion criteria. 41 reports examined alcohol, 34 examined cigarettes/nicotine products, and 10 examined other substances. Overall, statistically significant relationships between HPT indices and substance-related correlates and outcomes were most often reported for Intensity (88.61%, 70/79), followed by Omax (81.16%, 56/69), Elasticity (72.15%, 57/59), Breakpoint (62.12%, 41/66), and Pmax (48.08%; 25/52). The largest effect sizes were observed for Intensity (0.75 ± 0.04, CI 0.67-0.84) and Omax (0.64 ± 0.04, CI 0.56-0.71), followed by Elasticity (0.44 ± 0.04, CI 0.37-0.51), Breakpoint (0.30 ± 0.03, CI 0.25-0.36), and Pmax (0.25 ± 0.04, CI 0.18-0.33). Patterns were largely consistent across substances. In conclusion, HPTs can be highly effective in revealing relationships between demand and substance-related correlates and outcomes, with Intensity and Omax exhibiting the greatest sensitivity.

Brief Assessment of Cigarette Demand (BACD): Initial development and correlational results in adults and adolescents

Developing briefer behavioral economic measures is an important priority to ensure that these measures can be used in a variety of different contexts and to reduce participant burden. We developed and sought to validate a Brief Assessment of Cigarette Demand (BACD). A 17-item Cigarette Purchase Task (CPT) and a 3-item BACD were completed concurrently in 2 community samples of smokers (Study 1, adult smokers [n = 80] with substance use disorders; Study 2, adolescent smokers [n = 81]). Responses on the CPT and BACD were compared on the following demand indices: (a) intensity (the number of cigarettes requested at no cost), (b) Omax (the maximum expenditure on cigarettes in a 24-hr period), and (c) breakpoint (the point at which consumption is totally suppressed/no cigarettes are purchased). Correlations of demand indices with cigarettes per day and nicotine dependence were calculated. Measures of cigarette demand on the CPT and BACD were significantly correlated, albeit at very different magnitudes, for all 3 indices in the adult sample (intensity, r = .86; breakpoint, r = .23; and Omax, r = .43) and for 2 of the indices in the adolescent sample (intensity, r = .97; breakpoint, r = .33). The CPT and BACD relationships with smoking and nicotine dependence were similar for breakpoint and intensity but not for Omax. As initial findings were mixed, additional validation work is recommended to improve psychometric properties before adoption. Valid brief measures of demand could have utility for research and treatment of addictive disorders. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Using behavioral economic variables to predict future alcohol use in a crowdsourced sample

BACKGROUND

Theoretical perspectives at the intersection of behavioral economics and operant theory have resulted in numerous advances for addiction science. Three mechanisms (i.e. behavioral economic demand [consumption-price relationships], delay discounting [reinforcer devaluation with delay], and proportionate alcohol-related reinforcement [relative reinforcement attributable to alcohol]) are proposed to contribute to problematic alcohol use. Limited research has evaluated the unique contribution of these mechanisms for predicting future alcohol consumption.

AIM

The purpose of this study was to evaluate the predictive relationship between these mechanisms and self-reported alcohol use frequency, quantity, and severity.

METHODS

Participants (n=223) sampled from the crowdsourcing website Amazon Mechanical Turk completed a survey containing behavioral economic measures. Weekly reports of daily alcohol use were then collected for 18 weeks. Unadjusted and adjusted models determined the association between behavioral economic variables and alcohol use.

RESULTS/OUTCOMES

Behavioral economic measures were associated with alcohol and soda use at baseline in a stimulus-selective manner (e.g. alcohol demand associated with alcohol, but not soda, variables). Predictive models adjusted for Alcohol Use Disorder Identification Test scores indicated that increased proportionate alcohol-related reinforcement and behavioral economic demand were uniquely and incrementally associated with frequency (e.g. adjusted odds ratio (AOR)=5.54 for proportionate alcohol-related reinforcement, p<0.05) and quantity-severity measures (e.g. AOR=7.58 for alcohol demand intensity, p<0.001), respectively. Test-retest reliability was generally acceptable (r_xx=0.42-0.76) with the exception of proportionate alcohol-related reinforcement (r_xx=0.29).

CONCLUSION/INTERPRETATION

These findings indicate the unique, predictive, and incremental validity of behavioral economic measures for evaluating future alcohol consumption, supporting their continued use in addiction science research.

Examining interrelationships between the Cigarette Purchase Task and delay discounting among pregnant women

Two common behavioral economic simulation tasks used to study cigarette smoking are the Cigarette Purchase Task, a measure of cigarette demand, and delay discounting, a measure of the subjective value of rewards as a function of delays to delivery. Few studies have evaluated whether combining these tasks enhances understanding of smoking beyond either alone. The current study represents an initial evaluation of the intersection between cigarette demand indices and delay discounting among pregnant smokers by examining associations between these measures and whether a woman makes antepartum quit attempts before entering prenatal care (a reliable predictor of eventual quitting). Participants were 159 pregnant women enrolled in a smoking-cessation trial. Low O max and shallow discounting were each associated with antepartum quit attempts. Participants were next categorized into four subgroups (low O max , shallow discounting; low O max , steep discounting; high O max , shallow discounting; high O max , steep discounting) using median splits. Those with shallow discounting and low O max were more likely to have made quit attempts than each of the other three subgroups. That is, steep discounting appears to undermine the association of low O max and efforts to quit smoking during pregnancy while high O max overshadows any protective influence associated with shallow discounting.

Behavioral economic demand metrics for abuse deterrent and abuse potential quantification

INTRODUCTION

Behavioral economics provides a framework for quantifying drug abuse potential that can inform public health risk, clinical treatment, and research. Hypothetical purchase task (HPT) questionnaires may provide a low-cost and sensitive method by which to measure and predict the appeal of pharmaceutical drugs that differ by formulation. However, the validity of this type of analysis must be empirically established by comparing the "essential value" (EV) of different drugs across subgroups.

PROCEDURES

This pilot study used HPT assessments and the Exponential Model of Demand to quantify the EV of opioid medications-specifically, easily tampered formulations versus (vs.) abuse-deterrent formulations-in patients with a history of opioid abuse.

MAIN FINDINGS

Participants had more inelastic demand for opioid pills than for cigarettes and alcohol. Participants with experience manipulating pills (M group) had more inelastic demand for standard pills vs. participants with no manipulation experience (NM group), and the M group had a more elastic demand for the abuse-deterrent opioid pill than for the standard pill. There was no effect of formulation in the NM group and there was no difference in demand elasticity for abuse-deterrent pills between the two groups. There was a positive correlation between the EVs of different drugs, and between some behavioral economic indices and treatment variables.

CONCLUSIONS

Our results suggest that HPTs may provide a sensitive measure of abuse potential that can distinguish between different formulations in at-risk populations.

Measurement of substance-free reinforcement in addiction: A systematic review

A robust body of theoretical and experimental work highlights the influence of alternative, substance-free rewards on decisions to use alcohol and other drugs. However, translational applications have been limited in part by the lack of consensus on how to measure substance-free reinforcement in applied and clinical settings. The current study summarizes extant research utilizing self-report reinforcement or reward methodologies, and critically reviews the psychometric properties of the available measures. These studies (N = 50) fell into three categories: measures of recent substance-related and substance-free activity participation and enjoyment (n = 32), measures of time or monetary resource allocation (n = 15), and rating scale measures of reward availability and experience (n = 8). The available research suggests that, consistent with experimental laboratory research and with behavioral economic predictions, there is an inverse relation between substance-free reinforcement and substance use. These studies also support the clinical utility of these measures in predicting substance use severity and course. Reinforcement measures could be improved by enhancing content validity, multimethod convergent validity, and generalizability.

A dual process perspective on advances in cognitive science and alcohol use disorder

There is a tremendous global and national (US) burden associated with alcohol misuse and alcohol use disorder (AUD). Further, of the mental health disorders, AUD has the widest treatment gap. Thus, there is a critical need for improved understanding of the etiology, maintenance, and treatment of AUD. The application of cognitive science to the study of AUD has a longstanding history of attempting to meet this need. In this selective review, we identified and focused on four domains of recent (i.e., in the last decade) applications of cognitive science to the study of AUD: implicit cognitive biases, executive function, behavioral economic approaches to alcohol decision making, and functional connectivity neuroimaging. We highlighted advances within these four domains and considered them in the context of dual process models of addiction, which focus on the contribution and interplay of two complementary neurocognitive systems (impulsive and control systems). Findings across the domains were generally consistent with dual process models. They also suggest the need for further model refinements, including integrating behavioral economic approaches and findings from functional connectivity neuroimaging studies. Research evaluating candidate interventions associated with these domains is emergent but promising, suggesting important directions for future research.

Experimental reductions of delay discounting and impulsive choice: A systematic review and meta-analysis

Many behaviors posing significant risks to public health are characterized by repeated decisions to forego better long-term outcomes in the face of immediate temptations. Steeply discounting the value of delayed outcomes often underlies a pattern of impulsive choice. Steep delay discounting is correlated with addictions (e.g., substance abuse, obesity) and behaviors such as seatbelt use and risky sexual activity. As evidence accumulates suggesting steep delay discounting plays a causal role in these maladaptive behaviors, researchers have begun testing methods for reducing discounting. In this first systematic and comprehensive review of this literature, the findings of 92 articles employing different methodologies to reduce discounting are evaluated narratively and meta-analytically. Although most of the methods reviewed produced significant reductions in discounting, they varied in effect sizes. Most methods were ideal for influencing one-off choices (e.g., framing and priming manipulations), although other successful manipulations, such as episodic future thinking, could be incorporated into existing therapies designed to produce longer-lasting changes in decision-making. The largest and longest-lasting effects were produced by learning-based manipulations, although translational research is needed to determine the generality and clinical utility of these methods. Methodological shortcomings in the existing literature and suggestions for ameliorating these issues are discussed. This review reveals a variety of methods with translational potential, which, through continued refinement, may prove effective in reducing impulsive choice and its associated maladaptive decisions that negatively impact quality of life. (PsycINFO Database Record