Comparison of three measurement models of discounting among individuals with methamphetamine use disorder

Brain response in heavy drinkers during cross-commodity alcohol and money discounting with potentially real rewards: A preliminary study

Background

Alcohol use disorder (AUD) is associated with exaggerated preference for immediate rewards, a candidate endophenotype for use disorders. Addiction symptomology is often well-described by the preference for immediate intoxication over other delayed prosocial rewards. We measured brain activation in AUD-implicated regions during a cross-commodity delay discounting (CCD) task with choices for immediate alcohol and delayed money.

Methods

Heavy drinkers (n=24) experienced a brief intravenous alcohol infusion prime, regained sobriety, then chose between 'One Shot' and delayed money in an adjusting delay CCD task (sober and intoxicated); also during fMRI (sober). Participants also performed a behavioral sensation seeking task and completed self-report inventories of other risk factors. We assessed brain activation to choices representing immediate intoxication versus delayed money rewards in a priori regions of interest defined within the framework of Addictions NeuroImaging Assessment.

Results

Activation to CCD choice versus control trials activated paralimbic and ventral frontal cortical regions, including orbital and medial prefrontal cortex, posterior cingulate/retrosplenial cortex, angular and superior frontal gyri. We detected no differences between immediate or delayed choices. Left medial orbitofrontal cortex activation correlated with alcohol-induced wanting for alcohol; females showed greater activation than males. Behavioral sensation seeking correlated with right nucleus accumbens task engagement.

Conclusions

Alcohol decision-making elicited activation in regions governing reward, introspection, and executive decision-making in heavy drinkers, demonstrating the utility of laboratory tasks designed to better model real-world choice. Our findings suggest that the brain processes subserving immediate and delayed choices are mostly overlapping, even with varied commodities.

Developmental trajectories of delay discounting from childhood to young adulthood: longitudinal associations and test-retest reliability

Delay discounting (DD) indexes an individual's preference for smaller immediate rewards over larger delayed rewards, and is considered a form of cognitive impulsivity. Cross-sectional studies have demonstrated that DD peaks in adolescence; longitudinal studies are needed to validate this putative developmental trend, and to determine whether DD assesses a temporary state, or reflects a more stable behavioral trait. In this study, 140 individuals aged 9-23 completed a delay discounting (DD) task and cognitive battery at baseline and every-two years thereafter, yielding five assessments over approximately 10 years. Models fit with the inverse effect of age best approximated the longitudinal trajectory of two DD measures, hyperbolic discounting (log[k]) and area under the indifference-point curve (AUC). Discounting of future rewards increased rapidly from childhood to adolescence and appeared to plateau in late adolescence for both models of DD. Participants with greater verbal intelligence and working memory displayed reduced DD across the duration of the study, suggesting a functional interrelationship between these domains and DD from early adolescence to adulthood. Furthermore, AUC demonstrated good to excellent reliability across assessment points that was superior to log(k), with both measures demonstrating acceptable stability once participants reached late adolescence. The developmental trajectories of DD we observed from childhood through young adulthood suggest that DD may index cognitive control more than reward sensitivity, and that despite modest developmental changes with maturation, AUC may be conceptualized as a trait variable related to cognitive control vs impulsivity.

Single- and cross-commodity discounting among adults who use alcohol and cannabis: Associations with tobacco use and clinical indicators

BACKGROUND

Delay discounting assessments typically involve choices between an immediate outcome and a larger amount of the same outcome after a delay. Real-world choices, however, more often involve qualitatively different alternatives. The primary aim of this study was to examine single- and cross-commodity discounting of money, alcohol, and cannabis, along with clinical measures of alcohol and cannabis use among people who use both alcohol and cannabis, yet differ in tobacco cigarette smoking status (i.e., dual- versus tri-use).

METHODS

An online crowdsourced sample (N = 318) of people who reported using alcohol and cannabis in the past week completed single- and cross-commodity discounting assessments across each combination of money, alcohol, and cannabis. We recruited a balanced number of people who did and did not also use tobacco cigarettes and examined associations between discounting, tobacco use, and clinical indicators.

RESULTS

People who reported using tobacco cigarettes in addition to alcohol and cannabis tended to engage in significantly higher rates of harmful alcohol and cannabis use than those who reported using only alcohol and cannabis. Cross-commodity discounting was significantly associated with patterns of harmful alcohol and cannabis use while no associations emerged for single-commodity discounting.

CONCLUSIONS

Cross-commodity discounting provides a nuanced account of intertemporal choice by incorporating relative commodity valuation and appears to characterize harmful alcohol and cannabis use more clearly than single-commodity arrangements. Further cross-commodity research is needed to better understand the interplay between temporal location and relative commodity value among people who use multiple substances.

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).

At-Risk Drinking, Operant Demand, and Cross-Commodity Discounting as Predictors of Drunk Driving in Underage College Women

Behavioral economics offers unique tools for assessing value and motivation associated with college drinking. Tasks that model changes in consumption as a function of price (operant demand) or the decline in an outcome's subjective value as a function of time-to-occurrence (delay discounting) provide valuable information that may efficiently supplement clinical screening instruments when characterizing alcohol use severity. The first aim of this investigation was to examine the extent to which at-risk drinking, operant demand for alcohol, and single- and cross-commodity discounting of money and alcohol predict adverse consequences of past-month drinking in underage college women (N = 72). The second aim was to determine whether these clinical and behavioral economic measures could significantly predict the odds of past-month drunk driving, a serious public health concern due to the increasing prevalence of heavy episodic drinking among women in their first 1 - 2 years of college. Results showed that higher scores on the consumption factor of the Alcohol Use Disorder Identification Test (AUDIT-C), greater Persistence (consumption amidst constraint) and Amplitude (maximum consumption) of demand, as well as lower rates of discounting for choices between receiving alcohol now or double the amount after a delay (choosing the larger amount of alcohol even when it is delayed) significantly predicted adverse consequences of past-month drinking. Moreover, scores on the AUDIT-C, Amplitude of demand, and higher rates of discounting for choices between receiving alcohol now and money later (choosing immediately available alcohol at the expense of double the equivalent in delayed money) significantly predicted past-month drunk driving. We contend that operant demand along with single- and cross-commodity discounting can be viewed as intersecting measures of reinforcer value with clinical relevance to college women.

Assessment of demand for methamphetamine and cigarettes among individuals with methamphetamine use disorder

Methamphetamine (MA) is a highly addictive stimulant with recent upward trends in prevalence and associated public health problems. Drug demand, as assessed by hypothetical purchasing tasks, has been useful in addictions research and may help our understanding of the factors influencing MA use. However, no studies have assessed MA demand using current models of demand. The purpose of the current study was to assess demand for MA using a hypothetical drug purchasing task. Given high rates of cigarette smoking among MA users, it was of interest also to assess and compare demand for MA relative to cigarettes. Participants consisted of non-treatment-seeking volunteers with MA use disorder (N = 18), of whom 17 reported daily smoking. Results showed the exponentiated demand model provided a good fit to consumption data. Results from Bayesian generalized linear modeling demonstrated multiple positive relationships (posterior probability ≥75%) between self-reported drug use (days MA used in the past 30 days, cigarettes smoked per day) and indices of demand for each drug (Qo, Omax, Pmax, and break point). Comparing MA to cigarettes, results from Bayesian generalized linear mixed modeling revealed greater abuse liability for MA compared to cigarettes (posterior probability ≥99%) based on α and essential value. Overall, the findings of the current study support the feasibility and validity of the exponentiated demand model for assessing demand for drugs among individuals with MA use disorder. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Single- and cross-commodity delay discounting of money and e-cigarette liquid in experienced e-cigarette users

BACKGROUND

Delay discounting (DD) research has improved our understanding of important behavioral processes associated with tobacco use. Little research has explored DD among e-cigarette users, and these studies have exclusively examined money as the only available commodity. This secondary analysis of a laboratory study explored discounting for money and e-liquid among e-cigarette users using two single-commodity discounting (SCD) tasks and one cross-commodity discounting (CCD) task. A secondary goal was to explore the extent to which results from the SCD and CCD tasks were correlated to each other and with measures of e-cigarette use.

METHODS

E-cigarette users (N = 27) completed two SCD tasks and one CCD task. The SCD tasks assessed choices between various amounts of either money now versus money later (M-M) or e-liquid now versus e-liquid later (mL-mL). The CCD task assessed choices between e-liquid now versus money later (mL-M). Discounting results were compared using logk and AUClog.

RESULTS

Discounting was greatest in the mL-mL task, followed by the M-M task, and then the mL-M task. AUClog and logk were significantly correlated across all discounting tasks. Attempts to quit vaping was positively associated with logk and negatively associated with AUClog and in both SCD tasks.

CONCLUSIONS

E-cigarette users discount e-liquid more than money in a SCD task. However, when the two commodities, money and e-liquid (CCD), are compared the substance of abuse is discounted to a lesser extent. Interventions that provide alternative reinforcers to compete with the reinforcing effects of nicotine intake may be especially indicated for treating e-cigarette dependence.

Probabilistic Reversal Learning Deficits in Patients With Methamphetamine Use Disorder-A Longitudinal Pilot Study

Methamphetamine use disorder (MUD) is increasing worldwide and commonly associated with learning deficits. Little is known the about underlying trajectories, i.e., how the affected higher-order cognitive functions develop over time and with respect to abstinence and relapse. A probabilistic reversal learning (PRL) paradigm was implemented to uncover the microstructure of impulsive choice and maladaptive learning strategies in 23 patients with MUD in comparison with 24 controls. Baseline data revealed fewer optimal choices and a pattern of altered learning behavior from negative and positive feedback in patients suggesting impairments in flexibly-adapting behavior to changes of reward contingencies. Integrating longitudinal data from a follow-up assessment after 3 months of specific treatment revealed a group-by-time interaction indicating a normalization of these cognitive impairments in patients with MUD. In summary, our study demonstrates behavioral correlates of maladaptive decision-making processes in patients with MUD, which may recover after 3 months of MUD-specific therapy paving the way for further learning-based interventions. Limited by a small sample size, the results of this pilot study warrant replication in larger populations.

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.

A Monte Carlo method for comparing generalized estimating equations to conventional statistical techniques for discounting data

Discounting is the process by which outcomes lose value. Much of discounting research has focused on differences in the degree of discounting across various groups. This research has relied heavily on conventional null hypothesis significance tests that are familiar to psychologists, such as t-tests and ANOVAs. As discounting research questions have become more complex by simultaneously focusing on within-subject and between-group differences, conventional statistical testing is often not appropriate for the obtained data. Generalized estimating equations (GEE) are one type of mixed-effects model that are designed to handle autocorrelated data, such as within-subject repeated-measures data, and are therefore more appropriate for discounting data. To determine if GEE provides similar results as conventional statistical tests, we compared the techniques across 2,000 simulated data sets. The data sets were created using a Monte Carlo method based on an existing data set. Across the simulated data sets, the GEE and the conventional statistical tests generally provided similar patterns of results. As the GEE and more conventional statistical tests provide the same pattern of result, we suggest researchers use the GEE because it was designed to handle data that has the structure that is typical of discounting data.