Opioid craving does not incubate over time in inpatient or outpatient treatment studies: Is the preclinical incubation of craving model lost in translation?

Within addiction science, incubation of craving is an operational label used to describe time-dependent increases in drug seeking during periods of drug deprivation. The purpose of this systematic review was to describe the preclinical literature on incubation of craving and the clinical literature on craving measured over extended periods of abstinence to document this translational homology and factors impacting correspondence. Across the 44 preclinical studies that met inclusion criteria, 31 reported evidence of greater lever pressing, nose pokes, spout licks, or time spent in drug-paired compartments (i.e., drug seeking) relative to neutral compartments after longer periods of abstinence relative to shorter periods of abstinence, labelled as "incubation of craving." In contrast, no clinical studies (n = 20) identified an increase in opioid craving during longer abstinence periods. The lack of clinical evidence for increases in craving in clinical populations weakens the translational utility of operationalizing the time-dependent increase in drug-seeking behavior observed in preclinical models as models of incubation of "craving".

Impacts of xylazine on fentanyl demand, body weight, and acute withdrawal in rats: A comparison to lofexidine

The opioid use landscape has recently shifted to include xylazine, a veterinary anesthetic, as an adulterant in the fentanyl supply. The health impacts of xylazine as an emerging fentanyl adulterant has raised alarm regarding xylazine as a public health threat, warranting research on the impacts of xylazine on fentanyl's behavioral effects. No prior studies have evaluated the effects of xylazine on fentanyl consumption at various unit doses, fentanyl demand, or withdrawal as compared to the Food and Drug Administration-approved opioid withdrawal medication, lofexidine (Lucemyra®). This is important because lofexidine and xylazine are both adrenergic α2a (A2aR) agonists, however, lofexidine is not a noted fentanyl adulterant. Here we evaluated xylazine and lofexidine combined with self-administered fentanyl doses in male and female rats and evaluated fentanyl demand, body weight, and acute withdrawal. Consumption of fentanyl alone increased at various unit doses compared to saline. Xylazine but not lofexidine shifted fentanyl consumption downward at a number of unit doses, however, both lofexidine and xylazine suppressed fentanyl demand intensity as compared to a fentanyl alone control group. Further, both fentanyl + lofexidine and fentanyl + xylazine reduced behavioral signs of fentanyl withdrawal immediately following SA, but signs increased by 12 h only in the xylazine co-exposed group. Weight loss occurred throughout fentanyl SA and withdrawal regardless of group, although the xylazine group lost significantly more weight during the first 24 h of withdrawal than the other two groups. Severity of weight loss during the first 24 h of withdrawal was also correlated with severity of somatic signs of fentanyl withdrawal. Together, these results suggest that body weight loss may be an important indicator of withdrawal severity during acute withdrawal from the xylazine/fentanyl combination, warranting further translational evaluation.

A dose-ranging study of the physiological and self-reported effects of repeated, rapid infusion of remifentanil in people with opioid use disorder and physical dependence on fentanyl

RATIONALE

Understanding mechanisms of drug use decisions will inform the development of treatments for opioid use disorder (OUD). Decision-making experiments using neurobehavioral approaches require many trials or events of interest for statistical analysis, but the pharmacokinetics of most opioids limit dosing in humans.

OBJECTIVES

This experiment characterized the effects of repeated infusions of the ultra-short acting opioid remifentanil in people with OUD and physical opioid dependence.

METHODS

An inpatient study using a within-subjects, single-blind, escalating, within-session, pre-post design was conducted. Seven (3 female) subjects were maintained on oral oxycodone (40-60 mg, 4x/day = 160-240 total mg/day) for seven days prior to the dose-ranging session. Subjects received infusions of three ascending remifentanil doses (0.03, 0.1, 0.3 mcg/kg/infusion in 2 subjects; 0.1, 0.3, 1.0 mcg/kg/infusion in 5 subjects) every minute for 40 min per dose, with infusions administered over 5 s to model naturalistic delivery rates. End tidal carbon dioxide, respiration rate, oxygen saturation (SpO2) and heart rate were measured continuously. Blood pressure (BP), pupil diameter and self-reported drug effects were measured every 5 min.

RESULTS

Pupil diameter, SpO2 and systolic BP decreased, and ratings on prototypic subjective effects questionnaire items increased, as a function of remifentanil dose. The number of infusions held because of sedation or physiological parameters exceeding predetermined cutoffs also increased with dose.

CONCLUSIONS

This experiment established doses and procedures for the safe delivery of rapid, repeated remifentanil infusions to individuals with OUD and physical fentanyl dependence, which can be applied to the mechanistic study of opioid use decisions.

Oxycodone withdrawal is associated with increased cocaine self-administration and aberrant accumbens glutamate plasticity in rats

Individuals with opioid use disorder (OUD) frequently use other substances, including cocaine. Opioid withdrawal is associated with increased likelihood of cocaine use, which may represent an attempt to ameliorate opioid withdrawal effects. Clinically, 30% of co-using individuals take opioids and cocaine exclusively in a sequential manner. Preclinical studies evaluating mechanisms of drug use typically study drugs in isolation. However, polysubstance use is a highly prevalent clinical issue and thus, we established a novel preclinical model of sequential oxycodone and cocaine self-administration (SA) whereby rats acquired oxycodone and cocaine SA in an A-B-A-B design. Somatic signs of withdrawal were evaluated at 0, 22, and 24h following oxycodone SA, with the 24h timepoint representing somatic signs immediately following cocaine SA. Preclinically, aberrant glutamate signaling within the nucleus accumbens core (NAcore) occurs following use of cocaine or opioids, whereby medium spiny neurons (MSNs) rest in a potentiated or depotentiated state, respectively. Further, NAcore glial glutamate transport via GLT-1 is downregulated following SA of either drug alone. However, it is not clear if cocaine can exacerbate opioid-induced changes in glutamate signaling. In this study, NAcore GLT-1 protein and glutamate plasticity were measured (via AMPA/NMDA ratio) following SA. Rats acquired SA of both oxycodone and cocaine regardless of sex, and the acute oxycodone-induced increase in somatic signs at 22h was positively correlated with cocaine consumption during the cocaine testing phase. Cocaine use following oxycodone SA downregulated GLT-1 and reduced AMPA/NMDA ratios compared to cocaine use following food SA. Further, oxycodone SA alone was associated with reduced AMPA/NMDA ratio. Together, behavioral signs of oxycodone withdrawal may drive cocaine use and further dysregulate NAcore glutamate signaling.

Cocaine abstinence during the "critical period" of a contingency management trial predicts future abstinence in people with cocaine use disorder

BACKGROUND

Contingency Management (CM) is being piloted as a treatment for stimulant use disorder in several US states, highlighting the need for treatment optimization. One important goal of optimization is decreasing drug use during the early stages of treatment, which has predicted success in other interventions. However, this "critical period" has not been reported in CM trials. The purpose of this analysis was to determine if, after accounting for baseline abstinence and incentive condition, abstinence in a CM trial for people with Cocaine Use Disorder (CUD) could be predicted by cocaine use during a first-week critical period.

METHODS

Eighty-seven participants with CUD were randomized to receive contingent high or low value incentives for cocaine abstinence or were in a non-contingent control group. Generalized estimating equations (GEE) were used to analyze urine test results over 36 timepoints during the 12-week intervention. To assess for a critical period, the first three visits were included in the GEE as a covariate for remaining urine test results.

RESULTS

Participants who provided more negative samples during the critical period were significantly more likely to produce a negative urine sample during the remainder of the trial, though some effects of group remained after controlling for the critical period.

CONCLUSIONS

These results indicate that a critical period exists for CM trials, and it can explain a substantial amount of future performance. Early contact with an abstinence-contingent high magnitude alternative reinforcer may explain additional performance beyond the critical period, further justifying the use of high magnitude alternative reinforcers.

Exponentiated model of drug demand is preferred over exponential models in people with daily/near daily cannabis use

Cannabis use is a growing health concern emphasizing the need to better understand the complexities of drug choice in people with daily/near daily cannabis use. Hypothetical purchasing tasks provide a means to collect data on drug consumption behavior without requiring drug administration and have been used to isolate behavioral economic factors of choice, including facets of drug demand in substance using populations. Various models are used for analyzing hypothetical purchasing task data, but challenges exist in modeling data sets with consumption values of zero. Additionally, a single model or approach may not be best for all commodities and drug classes. This study compared two common demand models (exponential vs. exponentiated) applied to identical hypothetical purchasing task data from 21 (n = 21) individuals with daily/near daily cannabis use. The exponential model was fit using three common levels of replacement values for zero consumption (.1, .01, .001) and compared to the exponentiated model without replacement values. We found that the exponentiated model produced significantly better model fits for individual data, compared to all exponential models. Additionally, significant differences for model derived values of demand elasticity and intensity were found between the exponentiated model and different levels of the exponential model. We conclude that the exponentiated model is preferred over the exponential model for performing demand analysis on hypothetical purchasing task data from individuals with daily/near daily cannabis use. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Progress and promise: A brief reflection on my time as editor of Experimental and Clinical Psychopharmacology

This editorial focuses on William W. Stoops time as editor of Experimental and Clinical Psychopharmacology. Stoops ends his time with gratitude for all who have contributed to the journal's success over the past years, pride for what they have accomplished, and excitement for the journal's future. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

The endowment effect and temporal discounting of drug and non-drug commodities

OBJECTIVES

Despite a rich history of behavioral economic research on substance use there remains a need for further exploration of behavioral mechanisms that may underlie the etiology or persistence of substance use disorder. The purpose of this study was to measure the association between delay discounting and the endowment effect in people who smoke cigarettes, use cocaine, and controls, using online crowdsourcing.

METHODS

Participants were categorized to a cocaine group (n = 36), cigarette group (n = 48), or control group (n = 47) based on recent reported drug use. Based on group, participants completed up to three delay discounting tasks (i.e., money, cigarettes and cocaine), an endowment effect task for multiple commodities, and other questionnaires.

RESULTS

Participants in the cocaine and cigarette group demonstrated an increased rate in discounting for money compared to controls. Participants in the cocaine group had a less pronounced endowment effect for beer, compared to controls, as suggested by willingness to accept less to sell beer. A significant negative association was found between endowment ratios for non-drug commodities and delay discounting for cigarettes, but not monetary or cocaine delay discounting, indicating an inconsistent relationship between the two measures.

CONCLUSIONS

These results support prior research demonstrating a relationship between cocaine and cigarette use and delay discounting and extend that work by measuring the association between delay discounting and the endowment effect. Future research should include both loss aversion and endowment effect tasks and compare their relationship with delay discounting among people that use drugs.

Use of drug purchase tasks in medications development research: orexin system regulation of cocaine and drug demand

Commodity purchase tasks provide a useful method for evaluating behavioral economic demand in the human laboratory. Recent research has shown how responding to purchase tasks for blinded drug administration can be used to study abuse liability. This analysis uses data from a human laboratory study to highlight how similar procedures may be particularly useful for understanding momentary changes in drug valuation when screening novel interventions. Eight nontreatment-seeking participants with cocaine use disorder (one with partial data) were enrolled in a cross-over, double-blind, randomized inpatient study. Participants were maintained on the Food and Drug Administration-approved insomnia medication suvorexant (oral; 0, 5, 10, 20 mg/day) in randomized order with experimental sessions completed after at least 3 days of maintenance on each suvorexant dose. Experimental sessions included administration of a sample dose of 0, 10 and 30 mg/70 kg intravenous cocaine. Analyses focused on purchase tasks for the blinded sample dose as well as alcohol, cigarettes and chocolate completed 15 min after the sample dose. As expected based on abuse liability, near zero demand was observed for placebo with dose-related increases in cocaine demand. Suvorexant maintenance increased cocaine demand in a dose-related manner with the greatest increase observed for the 10 mg/kg cocaine dose. Increased demand under suvorexant maintenance was also observed for alcohol. No effect of cocaine administration was observed for alcohol, cigarette, or chocolate demand. These data support the validity of demand procedures for measuring blinded drug demand. Findings also parallel self-administration data from this study by showing increases in cocaine use motivation under suvorexant maintenance.

Cognitive training and remediation interventions for substance use disorders: a Delphi consensus study

AIMS

Substance use disorders (SUD) are associated with cognitive deficits that are not always addressed in current treatments, and this hampers recovery. Cognitive training and remediation interventions are well suited to fill the gap for managing cognitive deficits in SUD. We aimed to reach consensus on recommendations for developing and applying these interventions.

DESIGN, SETTING AND PARTICIPANTS

We used a Delphi approach with two sequential phases: survey development and iterative surveying of experts. This was an on-line study. During survey development, we engaged a group of 15 experts from a working group of the International Society of Addiction Medicine (Steering Committee). During the surveying process, we engaged a larger pool of experts (n = 54) identified via recommendations from the Steering Committee and a systematic review.

MEASUREMENTS

Survey with 67 items covering four key areas of intervention development: targets, intervention approaches, active ingredients and modes of delivery.

FINDINGS

Across two iterative rounds (98% retention rate), the experts reached a consensus on 50 items including: (i) implicit biases, positive affect, arousal, executive functions and social processing as key targets of interventions; (ii) cognitive bias modification, contingency management, emotion regulation training and cognitive remediation as preferred approaches; (iii) practice, feedback, difficulty-titration, bias modification, goal-setting, strategy learning and meta-awareness as active ingredients; and (iv) both addiction treatment work-force and specialized neuropsychologists facilitating delivery, together with novel digital-based delivery modalities.

CONCLUSIONS

Expert recommendations on cognitive training and remediation for substance use disorders highlight the relevance of targeting implicit biases, reward, emotion regulation and higher-order cognitive skills via well-validated intervention approaches qualified with mechanistic techniques and flexible delivery options.

Cannabis Use Disorder Treatment Preferences: A Pilot Survey in Current Users of Cannabis

OBJECTIVES

Highly effective treatments for cannabis use disorder (CUD) are lacking, and patient preferences have not been considered during treatment development. We therefore conducted an exploratory crowdsourced survey of individuals reporting current cannabis use and a willingness to cut down or quit their cannabis use, to determine their interest in various treatment aspects.

METHODS

Subjects (n = 63) were queried about their willingness to take medications as a function of type, route, and regimen and to participate in adherence monitoring. Subjects were also asked about their willingness to engage in behavioral/psychosocial interventions as a function of type, setting, and duration. Measures theorized to be associated with treatment preferences were also collected, including cannabis use variables, readiness to change, reduction or cessation goal, perceived cessation barriers, and medication use beliefs and behaviors.

RESULTS

Survey responses indicated that efforts to develop CUD medications should focus on nonsynthetic compounds administered orally or by mouth spray no more than once per day to maximize patient acceptance. Remote adherence monitoring and one-on-one outpatient behavioral treatment approaches, especially contingency management, are also anticipated to enhance participation. Most subjects indicated a preference to reduce their cannabis use rather than quit.

CONCLUSIONS

These data provide guidance for the development of CUD interventions based on the preferences of individuals interested in treatment for their cannabis use. Additional research is needed to confirm these results in a larger sample and determine if matching CUD patients with their preferred treatments improves success rates.

Naltrexone-bupropion combinations do not affect cocaine self-administration in humans

The FDA has not yet approved a pharmacotherapy for cocaine use disorder despite nearly four decades of research. This study determined the initial efficacy, safety, and tolerability of naltrexone-bupropion combinations as a putative pharmacotherapy for cocaine use disorder. Thirty-one (31) non-treatment seeking participants with cocaine use disorder completed a mixed-design human laboratory study. Participants were randomly assigned to the naltrexone conditions (i.e., 0, 50 mg/day; between-subject factor) and maintained on escalating doses of bupropion (i.e., 0, 100, 200, 400 mg/day; within-subject factor) for at least four days prior to the conduct of experimental sessions. Cocaine self-administration (IN, 0, 40, 80 mg) was then determined using a modified progressive ratio and relapse procedure. Subjective and cardiovascular effects were also measured. Cocaine produced prototypical dose-related increases in self-administration, subjective outcomes (e.g., "Like Drug"), and cardiovascular indices (e.g., heart rate, blood pressure) during placebo maintenance. Naltrexone and bupropion alone, or in combination, did not significantly decrease self-administration on either procedure. Low doses of bupropion (i.e., 100 mg) blunted the effects of the cocaine on subjective measures of "Like Drug" and "Stimulated". No unexpected adverse effects were observed with naltrexone and bupropion, alone and combined, in conjunction with cocaine. Together, these results do not support the use of these bupropion-naltrexone combinations for the treatment of cocaine use disorder. Future research should determine if novel drug combinations may decrease cocaine self-administration.

Substance use disorders and social determinants of health from electronic medical records obtained during Kentucky's "triple wave"

Social determinants of health (SDOH) play a critical role in the risk of harmful drug use. Examining SDOH as a means of differentiating populations with multiple co-occurring substance use disorders (SUDs) is particularly salient in the era of prevalent opioid and stimulant use known as the "Third Wave". This study uses electronic medical records (EMRs) from a safety net hospital system from 14,032 patients in Kentucky from 2017 to 2019 in order to 1) define three types of SUD cohorts with shared/unique risk factors, 2) identify patients with unstable housing using novel methods for EMRs and 3) link patients to their residential neighborhood to obtain quantitative perspective on social vulnerability. We identified patients in three cohorts with statistically significant unique risk factors that included race, biological sex, insurance type, smoking status, and urban/rural residential location. Adjusting for these variables, we found a statistically significant, increasing risk gradient for patients experiencing unstable housing by cohort type: opioid-only (n = 7385, reference), stimulant-only (n = 4794, odds ratio (aOR) 1.86 95 % confidence interval (CI): 1.66-2.09), and co-diagnosed (n = 1853, aOR = 2.75, 95 % CI: 2.39 to 3.16). At the neighborhood-level, we used 8 different measures of social vulnerability and found that, for the most part, increasing proportions of patients with stimulant use living in a census tract was associated with more social vulnerability. Our study identifies potentially modifiable factors that can be tailored by substance type and demonstrates robust use of EMRs to meet national goals of enhancing research on social determinants of health.

Building and implementing a quality assurance/quality improvement program for clinical research

Background

A major goal of the Clinical and Translational Science Award programs is to build and grow clinical and translational research, including the need to ensure that study teams are educated and adhere to best clinical research practices.

Objective

One of the primary objectives of the Center for Clinical and Translational Science at the University of Kentucky is to help investigators implement standard operating procedures and provide resources to conduct clinical research that is rigorous, ethical and safe.

Methods

The University of Kentucky Center for Clinical and Translational Science sought to establish a Quality Assurance/Quality Improvement program for Principal Investigator (PI) initiated clinical research studies using Center for Clinical and Translational Science services. Initiated in 2011, this program's goal was to improve research design quality and from the start of the project, "find it, fix it", leading to improved PI education, without being viewed as punitive.

Results

Since the initiation of our Quality Assurance/Quality Improvement program, PI acceptance has been good and we have expanded its footprint and adjusted our review style to better match the needs of our PIs. This article discusses our experiences with Quality Assurance/Quality Improvement program development and growth.

Conclusion

A Quality Assurance/Quality Improvement program can be developed that is efficient, effective, educational and well accepted by all clinical research stakeholders.

Influence of pregabalin maintenance on cannabis effects and related behaviors in daily cannabis users

No medications are approved for cannabis use disorder (CUD), though a small clinical trial demonstrated that the voltage-dependent calcium channel (VDCC) ligand gabapentin reduced cannabis use in treatment seekers. VDCCs are modulated by cannabinoid (CB) ligands, and there are shared effects between CB agonists and VDCC ligands. This overlapping neuropharmacology and the initial clinical results supported the evaluation of pregabalin, a "next-generation" VDCC ligand, as a CUD medication. Two separate placebo-controlled, double-blind, counterbalanced, within-subjects human laboratory studies tested placebo and 300 (N = 2 females, 11 males; Experiment [EXP] 1) or 450 (N = 3 females, 11 males; EXP 2) mg/day pregabalin in cannabis users who were not seeking treatment or trying to reduce/quit their cannabis use. The protocol consisted of two outpatient maintenance phases (11 days in EXP 1 and 15 days in EXP 2) that concluded with four experimental sessions within each phase. During experimental sessions, maintenance continued, and participants completed two 2-day blocks of sampling and self-administration sessions to determine the reinforcing effects of smoked cannabis (0% and 5.9% delta⁹-tetrahydrocannabinol [THC]), as well as subjective, attentional bias, performance, and physiological responses. In addition, naturalistic cannabis use, side effects, sleep quality, craving, and other self-reported substance use were measured during pregabalin maintenance. Cannabis was self-administered and produced prototypical effects, but pregabalin generally did not impact the effects of cannabis or alter naturalistic use. These human laboratory results in cannabis users not trying to reduce/quit their use do not support the efficacy of pregabalin as a stand-alone pharmacotherapy for CUD. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Suvorexant maintenance enhances the reinforcing but not subjective and physiological effects of intravenous cocaine in humans

Preclinical research has sought to understand the role of the orexin system in cocaine addiction given the connection between orexin producing cells in the lateral hypothalamus and brain limbic areas. Exogenous administration of orexin peptides increased cocaine self-administration whereas selective orexin-1 receptor antagonists reduced cocaine self-administration in non-human animals. The first clinically available orexin antagonist, suvorexant (a dual orexin-1 and orexin-2 receptor antagonist), attenuated motivation for cocaine and cocaine conditioned place preference, as well as cocaine-associated impulsive responding, in rodents. This study aimed to translate those preclinical findings and determine whether suvorexant maintenance altered the pharmacodynamic effects of cocaine in humans. Seven non-treatment seeking subjects with cocaine use disorder completed this within-subject human laboratory study, and a partial data set was obtained from one additional subject. Subjects were maintained for at least three days on 0, 5, 10 and 20 mg oral suvorexant administered at 2230 h daily in random order. Subjects completed experimental sessions in which cocaine self-administration of 0, 10 and 30 mg/70 kg of intravenous cocaine was evaluated on a concurrent progressive ratio drug versus money choice task. Subjective and physiological effects of cocaine were also determined. Cocaine functioned as a reinforcer and produced prototypic dose-related subjective and physiological effects (e.g., increased ratings of "Stimulated" and heart rate). Suvorexant (10, 20 mg) increased self-administration of 10 mg/70 kg cocaine and decreased oral temperature but did not significantly alter any other effects of cocaine. Future research may seek to evaluate the effects of orexin-1 selective antagonists in combination with cocaine.

A preliminary investigation of schedule parameters on cocaine abstinence in contingency management

Contingency management (CM) interventions are the most effective psychosocial interventions for substance use disorders. However, further investigation is needed to create the most robust intervention possible. This study investigated the effects of 1) reinforcer magnitude; and 2) fixed and escalating and resetting incentives on cocaine abstinence in an outpatient trial. In this analysis, 34 treatment-seeking individuals with Cocaine Use Disorder received either high or low value incentives for providing a benzoylecgonine-negative urine sample or were in a control condition and received incentives for providing a urine sample regardless of the results. Participants received either escalating and resetting incentives, wherein the value of each incentive increased with consecutive negative samples and reset to the initial level upon a positive sample (Experiment 1), or fixed incentives, wherein they received the same value incentive for each negative urine sample they provided (Experiment 2). Large incentives produced more abstinence, although escalating and resetting reinforcer values did not have a differential effect. Large, fixed incentives promoted abstinence faster than other reinforcers, whereas smaller incentives resulted in poor abstinence and took many visits to achieve initial abstinence. Future research comparing different schedules on cocaine abstinence in a randomized control trial with a larger sample size is required.

Human behavioral pharmacology of stimulant drugs: An update and narrative review

Stimulant use disorders present an enduring public health concern. Chronic stimulant use is associated with a range of health problems, with notable increases in stimulant overdose that disproportionately affect marginalized populations. With these persistent problems, it is important to understand the behavioral and pharmacological factors that contribute to stimulant use in humans. The purpose of this chapter is to provide an update and narrative review on recent human laboratory research that has evaluated the behavioral pharmacology of stimulant drugs. We focus on two prototypic stimulants: cocaine as a prototype monoamine reuptake inhibitor and d-amphetamine as a prototype monoamine releaser. As such, placebo controlled human laboratory studies that involved administration of doses of cocaine or d-amphetamine and were published in peer reviewed journals within the last 10 years (i.e., since 2011) are reviewed. Primary outcomes from these studies are subjective effects, reinforcing effects, cognitive/behavioral effects, and discriminative stimulus effects. Both cocaine and d-amphetamine produce classical stimulant-like behavioral effects (e.g., increase positive subjective effects, function as reinforcers), but there are notable gaps in the literature including understanding sex differences in response to stimulant drugs, cognitive-behavioral effects of stimulants, and influence of use history (e.g., relatively drug naïve vs drug experienced) on stimulant effects.

Logical fallacies and misinterpretations that hinder progress in translational addiction neuroscience

Substance use disorders (SUDs) are heterogeneous and complex, making the development of translationally predictive rodent and nonhuman primate models to uncover their neurobehavioral underpinnings difficult. Neuroscience-focused outcomes have become highly prevalent, and with this, the notion that SUDs are disorders of the brain embraced as a dominant theoretical orientation to understand SUD etiology and treatment. These efforts, however, have led to few efficacious pharmacotherapies, and in some cases (as with cocaine or methamphetamine), no pharmacotherapies have translated from preclinical models for clinical use. In this theoretical commentary, we first describe the development of animal models of substance use behaviors from a historical perspective. We then define and discuss three logical fallacies including 1) circular explanation, 2) affirming the consequent, and 3) reification that can apply to developed models. We then provide three case examples in which conceptual or logical issues exist in common methods (i.e., behavioral economic demand, escalation, and reinstatement). Alternative strategies to refocus behavioral models are suggested for the field to better bridge the translational divide between animal models, the clinical condition of SUDs, and current and future regulatory pathways for intervention development.

Differential impacts of economic and demographic variables on substance use patterns during the COVID-19 pandemic

Background: The COVID-19 pandemic and subsequent economic crisis has provided a unique opportunity to investigate the effects of economic shifts on substance use. Existing literature on this relationship is limited and conflicting, warranting further exploration.Objective: This study aimed to identify relationships between socioeconomic status (SES), demographic variables, and substance use patterns before and after government-mandated business closures due to COVID-19.Methods: Participants were recruited based on self-reported substance use through Amazon's Mechanical Turk (MTurk). Qualifying participants (N = 315, 43% female, mean age = 35.35) reported their substance use and SES for two-week periods before and after pandemic-related business closures. Regression models analyzed relationships between substance use and study variables.Results: Regression models found that, during COVID-19 closures, greater financial strain predicted decreased benzodiazepine (β = -1.12) and tobacco (β = 1.59) use. Additionally, certain predictor variables (e.g., participants' age [β = 1.22], race [β = -4.43], psychiatric disorders including ADHD [β = -2.73] and anxiety [β = 1.53], and concomitant substance use [β = 3.38]) predicted changes in substance use patterns; however, the directionality of these associations varied across substances.Conclusion: Specific substance use patterns were significantly and differentially impacted by economic strain, psychiatric diagnoses, and concomitant substance use. These results can help direct harm reduction efforts toward populations at greatest risk of harmful substance use following the pandemic.

Clinical neuropharmacology of cocaine reinforcement: A narrative review of human laboratory self-administration studies

Cocaine use is an unrelenting public health concern. To inform intervention and prevention efforts, it is crucial to develop an understanding of the clinical neuropharmacology of the reinforcing effects of cocaine. The purpose of this review is to evaluate and synthesize human laboratory studies that assess pharmacological manipulations of cocaine self-administration. Forty-one peer-reviewed, human cocaine self-administration studies in which participants received a pretreatment drug were assessed. The pharmacological action and treatment regimen for all drugs reviewed were considered. Drugs that increase extracellular dopamine tend to have the most consistent effects on cocaine self-administration. The ability of nondopaminergic drugs to impact cocaine reinforcement might be related to their downstream effects on dopamine, though it is difficult to draw conclusions because pharmacologically selective compounds are not widely available for human testing. The ability of acute versus chronic drug treatment to differentially affect human cocaine self-administration was not determined because buprenorphine was the only pretreatment drug that was assessed under both acute and chronic dosing regimens. Future research directly comparing acute and chronic drug treatment and/or comparing drugs with different mechanisms of action, is needed to make more conclusive determinations about the clinical neuropharmacology of cocaine reinforcement.

A Brief Introduction to Human Behavioral Pharmacology: Methods, Design Considerations and Ethics

Human behavioral pharmacology methods have been used to rigorously evaluate the effects of a range of centrally acting drugs in humans under controlled conditions for decades. Methods like drug self-administration and drug discrimination have been adapted from nonhuman laboratory animal models. Because humans have the capacity to communicate verbally, self-report methods are also commonly used to understand drug effects. This perspective article provides an overview of these traditional human behavioral pharmacology methods and introduces some novel methodologies that have more recently been adapted for use in the field. Design (e.g., using placebo controls, testing multiple doses) and ethical (e.g., avoiding enrollment of individuals seeking treatment, determining capacity to consent) considerations that must be addressed when conducting these types of studies are also described.

The continued rise of methamphetamine use among people who use heroin in the United States

BACKGROUND

Methamphetamine use is a growing public health concern in the United States. Prior analyses with nationally representative data from 2015 to 2017 suggested that increases in methamphetamine use appeared largely selective to people using heroin. This analysis updated prior estimates to determine if trends are selectively persistent and how they compare to historical trends. We also evaluate sociodemographic risk factors associated with methamphetamine use among people using heroin.

METHODS

Data from the 2015-2019 National Surveys on Drug Use and Health (NSDUH) were analyzed. Data from the 2006-2014 NSDUH were summarized for historical trends. Past month and past year methamphetamine use prevalence was determined within populations using heroin as well as those using other drugs (e.g., cocaine, cannabis). Multivariable logistic models accounting for complex survey design evaluated predictors of methamphetamine use among people using heroin.

RESULTS

From 2015 to 2019, past month methamphetamine use increased from 9.0% to 44.0% within the population of people reporting past month heroin use. Similarly, past year methamphetamine use increased from 22.5% to 46.7% among those reporting past year heroin use. Risk factors for methamphetamine use among people using heroin included rurality, past year injection drug use, and serious mental illness.

CONCLUSIONS

A rapid, selective, and sustained increase in methamphetamine use is evident among people using heroin. These findings combined with similar findings in treatment admission and overdose data emphasize the need for increased attention to a specific type of high-risk use pattern in the United States, an issue that appears increasingly unlikely to naturally resolve.

An evaluation of fixed and randomized price sequence on the alcohol purchase task

Factors influencing drug consumption can be effectively evaluated in the context of behavioral economic demand. Specifically, hypothetical purchase tasks (HPTs) allow for estimated drug consumption at a range of prices in which drug administration is not ethically or feasibly possible. With the marked increase of HPTs in behavioral research, understanding methodological influences on responding is paramount. One such methodological consideration is the price sequence, which can be presented in a fixed, ascending order or a randomized sequence. This study compared fixed and fully randomized sequence order with college student drinkers using a within-subjects design. Self-reported consumption revealed that despite some small differences between the fixed and random sequences, consumption preferences were highly similar, regardless of presentation order. These results suggest participants are likely not anchoring their responses to the prior price on a fixed-order sequence. We conclude with a discussion on how these findings provide implications for HPTs and future research. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Researcher perspectives on including people who use drugs in clinical research

Background: People who use drugs are commonly excluded from clinical research despite being disproportionately impacted by numerous health conditions. Recent work indicates that community-recruited individuals report low support of research inclusion for persons reporting substance use.Objective: This study conducted a mixed-method assessment of researchers' attitudes on including persons reporting substance use in clinical research.Methods: Respondents (N = 168; 58% female; 58% psychologists) recruited via scientific society listservs and Twitter completed a survey containing two hypothetical research vignettes. Quantitative items evaluated respondents' endorsement of research participation by healthy adults, people who use drugs, and vulnerable populations. Qualitative items included open-ended questions asking reasons why people who use drugs should and should not participate in research.Results: Respondents reported significantly lower support for research participation by people who use drugs compared to healthy adults (p <.001). Open-ended responses concerning the inclusion of people who use drugs included themes relevant to the Belmont Principles (e.g., capacity to consent) and data quality (e.g., "bad data," poor compliance).Conclusion: Although lower support for research participation by people who use drugs was observed compared to healthy adults, the magnitude of this difference was smaller than reported for prior community-recruited respondents. These findings emphasize salient factors that may serve as both protections for and barriers to inclusion of people who use drugs in research. Initiatives including adoption of person-first language, addressing stereotyping of people who use drugs, and emphasizing the benefits of including these populations in clinical research should be explored to reduce bias while retaining needed protections.

Behavioral economics and the aggregate versus proximal impact of sociality on heavy drinking

BACKGROUND

Behavioral economic theory predicts decisions to drink are cost benefit analyses, and heavy episodic drinking occurs when benefits outweigh costs. Social interaction is a known benefit associated with alcohol use. Although heavy drinking is typically considered more likely during more social drinking events, people who drink heavily in isolation tend to report greater severity of use. This study explicitly disaggregates between-person and within-person effects of sociality on heavy episodic drinking and examines behavioral economic moderators.

METHODS

We used day-level survey data over an 18-week period in a community adult sample recruited through crowdsourcing (mTurk; N = 223). Behavioral economic indices were examined to determine if macro person-level variables (alcohol demand, delay discounting, proportionate alcohol-related reinforcement [R-ratio]) interact with event-level social context to predict heavy drinking episodes.

RESULTS

Mixed effect models indicated significant between-person and within-person social context associations. Specifically, people with a higher proportion of total drinking occasions in social contexts had decreased odds of heavy drinking, whereas being in a social context for a specific drinking occasion was associated with increased odds of heavy drinking. Person-level R-Ratio, demand elasticity, and breakpoint variables interacted with social context to predict heavy episodic drinking, such that the event-level social context association was stronger when R-Ratios, alcohol price insensitivity, and demand breakpoints were high.

CONCLUSIONS

These results demonstrate an ecological fallacy, in which the size and direction of effects were divergent at different levels of analysis, and highlight the potential for merging behavioral economic variables with proximal contextual effects to predict heavy drinking.

E-Cigarette Demand: Impact of Commodity Definitions and Test-Retest Reliability

INTRODUCTION

Behavioral economic demand provides a multidimensional understanding of reinforcement. Commodity purchase tasks are an efficient method for measuring demand in human participants. One challenge in translating these procedures to electronic nicotine delivery systems (ENDS or e-cigarettes) is defining commodity units given the lack of standardization in the e-cigarette marketplace.

AIMS AND METHODS

The purpose of this study was to directly compare methods of operationalizinge-cigarette purchases, puffs, cartridges, and mLs liquid, using a within-subject design. Participants (N = 132) reporting past week e-cigarette use were recruited using crowdsourcing. Purchase tasks were completed operationalizing e-cigarette units as puffs or cartridges at baseline and puffs or mLs liquid at a 3-month follow-up.

RESULTS

Bivariate associations supported convergent and discriminant validity with the largest effect size correlations for intensity and elasticity observed for the puff version. Interaction models suggested that product preferences moderated the relationship between time-to-first use and cartridge demand with larger effect size correlations among persons reporting a preference for JUULs, but weaker relationships among persons reporting other device preferences. Puff intensity (rxx = .61) and elasticity (rxx = .62) showed good test-retest reliability for participants reporting stable consumption, but poor test-retest reliability for individuals with changed consumption levels (intensity rxx = -.08; elasticity rxx = -.10).

CONCLUSIONS

This study highlights the relevance of commodity definitions in the e-cigarette purchase task. Puffs as an experimental commodity may provide flexibility for studying e-cigarette demand in heterogenous or unknown populations, whereas more tailored or personalized approaches like cartridge or mL-based tasks will likely be helpful when studying known subgroups.

IMPLICATIONS

The commodity purchase task procedure is widely used for understanding cigarette and e-cigarette demand in nicotine dependence research. This study evaluates the importance of operational definitions of e-cigarette commodities in the purchase task (ie, puffs, cartridges, or mLs liquid). Puffs may provide a more flexible commodity unit when evaluating e-cigarette demand in general or heterogenous populations, whereas device-specific units may prove more valuable when studying populations with consistent and known product use.

Topiramate-phentermine combinations reduce cocaine self-administration in humans

RATIONALE

Cocaine use disorder is an unrelenting public health concern. Despite nearly four decades of research, an FDA approved medication is not yet available.

OBJECTIVES

The objective of this human laboratory study was to demonstrate the initial efficacy, safety and tolerability of topiramate-phentermine combinations for cocaine use disorder.

METHODS

Thirty-one (31) participants with cocaine use disorder completed this mixed-model inpatient laboratory study. Participants were maintained on topiramate (0 [N = 11], 50 [N = 9] or 100 [N = 11] mg/day). Each topiramate group was concurrently maintained on phentermine (0, 15, 30 mg). Drug self-administration, subjective responses and cardiovascular effects following acute doses of intranasal cocaine (0, 40, 80 mg) were determined during separate experimental sessions after at least seven (7) days of maintenance on each condition.

RESULTS

The three groups of participants were well matched demographically and generally did not differ significantly in their responses to a range of doses of intranasal cocaine (0, 10, 20, 40, 80 mg) during a medical safety session. Maintenance on topiramate and phentermine alone significantly decreased cocaine self-administration although these effects were modest in magnitude. Combining topiramate and phentermine robustly decreased cocaine self-administration. Topiramate and phentermine were well tolerated alone and combined, as well as in conjunction with cocaine.

CONCLUSIONS

The results of the present study support advancing topiramate-phentermine combinations as a putative pharmacotherapeutic for cocaine use disorder.

Acute methylphenidate administration reduces cocaine-cue attentional bias

Mechanistic research on behavioral processes underlying substance use disorder might help identify novel targets for interventions development. Drug-related attentional bias and response inhibition deficits have received a great deal of consideration in substance use research, broadly, and cocaine use research, specifically. Studies investigating pharmacological mechanisms that may ameliorate, or further impair, these behaviors relevant to cocaine use are relatively lacking. This study evaluated the impact of acute administration of methylphenidate, a dopamine-favoring reuptake inhibitor, on both gaze-related cocaine-cue-attentional bias and cocaine-cue related disruptions in response inhibition among individuals with cocaine use disorder. Participants (N = 12; 33% female) completed a within-subject, outpatient, acute dosing study. Two sessions were completed in which methylphenidate (60 mg) or placebo were administered followed by completion of an attentional bias task using eye-tracking technology and neutral-cue and cocaine-cue response inhibition tasks. Subjective and physiological effects were also recorded. Significant cocaine cue attentional bias and response inhibition failures were observed during placebo administration. Acute methylphenidate administration reduced cocaine-cue attentional bias as measured by cocaine-cue gaze fixations (d_z = 1.04; Bayes Factor = 12.37). No statistically significant effects of methylphenidate were observed on response inhibition (Bayes Factors = 0.17-1.04). Methylphenidate produced prototypical subjective and physiological effects. Although the small sample should be considered, these findings indicate acute manipulation of dopaminergic activity reduced cue-related attentional allocation related to cocaine use disorder. Future research evaluating alternative dopaminergic agents and applications within a clinical setting are needed to determine the clinical significance of targeting this neurobehavioral mechanism.

An update on the clinical pharmacology of methylphenidate: therapeutic efficacy, abuse potential and future considerations

INTRODUCTION

Methylphenidate remains a first-line medication for treating ADHD in children and adults. However, its behavioral pharmacological similarities to methamphetamine and cocaine have historically created concern for its potential as a drug of abuse. In September 2019, the FDA published a docket requesting comments for the development of abuse deterrent formulations for CNS stimulants, emphasizing the abuse of methylphenidate as a public health concern.

AREAS COVERED

We conducted a narrative review of research on the clinical pharmacology, therapeutic efficacy, and abuse potential of methylphenidate.

EXPERT OPINION

Several studies indicate that methylphenidate has at least some abuse potential. Methylphenidate, amphetamine, methamphetamine, and cocaine overlap in their subjective, reinforcing, and discriminative stimulus effects. Regardless, methylphenidate remains an efficacious treatment for ADHD in children and adults when properly adhered to, especially when paired with non-pharmacological treatments. The development of abuse deterrent formulations of methylphenidate is warranted.

Pharmacological validation of a translational model of cocaine use disorder: Effects of d-amphetamine maintenance on choice between intravenous cocaine and a nondrug alternative in humans and rhesus monkeys

Drug self-administration procedures are the gold standard for laboratory research to study mechanisms of drug use disorders and evaluate candidate medications. However, preclinical-to-clinical translation has been hampered by a lack of coordination. To address this limitation, we previously developed homologous intravenous (IV) cocaine choice self-administration procedures in rhesus monkeys and humans, and then demonstrated their functional equivalence. The present studies sought to determine the sensitivity of these procedures to d-amphetamine maintenance. Three (N = 3) rhesus monkeys with histories of cocaine self-administration and 16 (N = 16) humans with cocaine use disorder completed the studies. Monkeys were maintained on IV d-amphetamine (0, 0.019, 0.037 and 0.074 mg/kg/h), and then completed 7 sessions during each condition in which they completed 9 choice trials to receive 0.14 mg/kg/injection IV cocaine (corresponding to 10 mg/70 kg in humans) or 10 food pellets under independent, concurrent progressive-ratio schedules. Humans were maintained on oral extended release d-amphetamine (0, 30 and 60 mg/day, corresponding to the lowest 3 doses in monkeys) and participated in 12 sessions in which they chose money ($6.00) or IV cocaine (0, 3, 10 and 30 mg/70 kg). Blood samples were taken to compare d-amphetamine plasma levels across species. In monkeys and humans, d-amphetamine reduced the number of cocaine choices and produced comparable blood levels at equivalent daily doses. d-Amphetamine had similar efficacy, though lower potency, at reducing choice for an equivalent cocaine dose in monkeys relative to humans. These coordinated studies support the utility of these procedures as a translational model for cocaine use disorder. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

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.

Inhibitory-control training for cocaine use disorder and contingency management for clinic attendance: A randomized pilot study of feasibility, acceptability and initial efficacy

BACKGROUND

Cocaine abusers have impaired inhibitory Cocaine use is associated with impaired inhibitory control. This study determined the feasibility, acceptability, and initial efficacy of inhibitory-control training to cocaine or neutral images in cocaine use disorder patients.

METHODS

Participants were randomly assigned to inhibitory-control training to cocaine (N = 20) or neutral (N = 20) images. Feasibility was assessed by percent of patients eligible for participation after a behavioral qualification session, time-to-target enrollment, percent of clinic visits attended, percent of participants who completed 80 % or more training sessions, and percent of follow-up visits attended. Acceptability was determined using a Treatment Acceptability Questionnaire. Initial efficacy was determined during training and a follow-up phase with urine samples tested qualitatively and quantitatively for cocaine. Participants in both conditions received monetary incentives delivered on an escalating schedule for clinic attendance.

RESULTS

The groups were well matched and no differences on demographic or substance use variables were observed. Attendance was stable during the treatment period with high overall attendance in both groups (average sessions attended: cocaine image group = 97 %; neutral image group = 90 %). No group differences were observed in the percentage of follow-up sessions attended (95 % for the cocaine-image group; 88 % of neutral-image group). Ratings on the Treatment Acceptability Questionnaire were high (i.e., mean scores ≥ 80 for all items rated on 101-unit visual analog scales). Participants in the cocaine- and neutral-image conditions did not differ significantly in terms of cocaine use during the training nor follow-up phase. Inhibitory-control training improved stop signal performance but not delay discounting.

CONCLUSION

The procedures were feasible and acceptable. Inhibitory-control training to cocaine images did not reduce cocaine use relative to the neutral image training condition. The inability to detect significant differences in cocaine use across the groups is not surprising given the small sample size. More research is needed to determine the utility of inhibitory-control training for cocaine use disorder. Future trials should determine whether inhibitory-control training to cocaine images augments the efficacy of other behavioral interventions.

Utilizing content-knowledge questionnaires to assess study eligibility and detect deceptive responding

Background: Deceptive responding during eligibility screening presents a significant concern for assessing inclusion/exclusion criteria. This problem is compounded in settings for which biomarkers or other objective verification (e.g., urinalysis) are not feasible.Objectives: Introduce and describe content-knowledge questionnaires as an objective method for collaterally assessing study eligibility.Methods: Participants (N = 3772; 66.1% female) recruited using the crowdsourcing resource Amazon Mechanical Turk (mTurk) completed a Cannabis Knowledge Questionnaire (CKQ). The CKQ contained four-items indexing knowledge of typical cannabis costs, weights, and terminology. Self-reported cannabis use history was collected and compared to individual item and total scale scores. A separate in-laboratory assessment evaluated participants during in-person screening for cannabis, alcohol, and cocaine research protocols (N = 43).Results: Good internal consistency (α = .74) was observed. The most common correctly answered question was about dabbing (41.4%) followed by cannabis cost (37.6%), hybrid strains (36.6%), and estimated weight (29.7%). Current cannabis use was associated with large effect size increases in the rate of correct responses (RR = 3.64) as well as odds of a correct response on individual items (OR = 5.88-21.48). In the laboratory study, participants with a positive urine drug test for cannabis or those reporting lifetime regular cannabis use scored higher than those without this history (RR = 1.89-2.61).Conclusion: These findings highlight the efficiency and efficacy of including content-knowledge questionnaires for collateral assessment of study eligibility, especially when biomarkers are not possible. Future studies will be useful for extending this initial demonstration to alternative settings and substances.

A nationally representative analysis of "twin epidemics": Rising rates of methamphetamine use among persons who use opioids

BACKGROUND

Recent data suggest increases in methamphetamine potency, affordability, and availability in the US. Other data indicate rising rates of methamphetamine use among patients seeking treatment for opioid use disorder. The extent to which similar increases in methamphetamine use have occurred for populations outside of a treatment context and for those reporting other substance use is unknown.

PURPOSE

The current analysis used a nationally representative data source to evaluate recent trends in past month methamphetamine use based on opioid use history.

METHODS

Data from the 2015-2017 National Survey on Drug Use and Health (NSDUH) were analyzed for yearly variations in past month methamphetamine use by opioid use history. Sensitivity analyses assessed if these trends were specific to methamphetamine use and to persons reporting opioid use.

RESULTS

Significant increases in past month methamphetamine use were observed for persons reporting past month heroin use, past year heroin use disorder, and past year prescription opioid use disorder. Among individuals reporting past month heroin use, for example, methamphetamine use tripled from 9.0% in 2015 to 30.2% in 2017. These associations were specific to methamphetamine with little change in other substance use. Similar increases in methamphetamine use were not observed for populations reporting other illicit substance use with the exception of prescription tranquilizers.

CONCLUSIONS

These results provide data corroborating evidence of emergent concerns related to methamphetamine use in the US. Such findings highlight the importance of considering global drivers of substance use to avoid cyclic waves of new and emerging substance use crises.

Influence of phendimetrazine maintenance on the reinforcing, subjective, performance, and physiological effects of intranasal cocaine

RATIONALE

No pharmacotherapies are approved for cocaine use disorder. Phendimetrazine, a prodrug of the monoamine-releaser phenmetrazine, attenuates the reinforcing effects of cocaine in preclinical models, has minimal abuse potential, and is safe when combined with cocaine.

OBJECTIVES

This study determined the influence of phendimetrazine maintenance on the reinforcing effects of cocaine (i.e., choice to self-administer cocaine), along with the subjective, performance, and physiological effects of cocaine. We hypothesized that phendimetrazine would attenuate the reinforcing effects of cocaine.

METHODS

Twenty-nine subjects with cocaine use disorder completed this within-subject, inpatient study. The subjects were maintained on placebo and 210 mg phendimetrazine in a counterbalanced order. After at least 7 days of maintenance on the target dose, the subjects completed experimental sessions in which the effects of single doses of 0, 20, 40, and 80 mg of intranasal cocaine were determined.

RESULTS

Cocaine functioned as a reinforcer, producing significant dose-related increases in self-administration. Cocaine increased prototypic effects (e.g., ratings of stimulated and blood pressure). Phendimetrazine attenuated ratings on a select set of subjective outcomes (e.g., ratings of talkative/friendly), but failed to reduce the reinforcing effects of cocaine or a majority of positive subjective cocaine effects. Phendimetrazine increased heart rate, indicating a physiologically active dose was tested, but heart rate increases were not clinically significant.

CONCLUSIONS

These results indicate that although phendimetrazine can safely be combined with cocaine, it does not attenuate the abuse-related effects of cocaine. It is unlikely, then, that phendimetrazine will be an effective standalone treatment for cocaine use disorder.

Evaluating non-medical prescription opioid demand using commodity purchase tasks: test-retest reliability and incremental validity

RATIONALE

Non-medical prescription opioid use and opioid use disorder (OUD) present a significant public health concern. Identifying behavioral mechanisms underlying OUD will assist in developing improved prevention and intervention approaches. Behavioral economic demand has been extensively evaluated as a measure of reinforcer valuation for alcohol and cigarettes, whereas prescription opioids have received comparatively little attention.

OBJECTIVES

Utilize a purchase task procedure to measure the incremental validity and test-retest reliability of opioid demand.

METHODS

Individuals reporting past year non-medical prescription opioid use were recruited using the crowdsourcing platform Amazon Mechanical Turk (mTurk). Participants completed an opioid purchase task as well as measures of cannabis demand, delay discounting, and self-reported pain. A 1-month follow-up was used to evaluate test-retest reliability.

RESULTS

More intense and inelastic opioid demand was associated with OUD and more intense cannabis demand was associated with cannabis use disorder. Multivariable models indicated that higher opioid intensity and steeper opioid delay discounting rates each significantly and uniquely predicted OUD. Increased opioid demand intensity, but not elasticity, was associated with higher self-reported pain, and no relationship was observed with perceived pain relief from opioids. Opioid demand showed acceptable-to-good test-retest reliability (e.g., intensity rxx = .75; elasticity rxx = .63). Temporal reliability was lower for cannabis demand (e.g., intensity rxx = .53; elasticity rxx = .58) and discounting rates (rxx = .42-.61).

CONCLUSIONS

Opioid demand was incrementally valid and test-retest reliable as measured by purchase tasks. These findings support behavioral economic demand as a clinically useful measure of drug valuation that is sensitive to individual difference variables.

Feasibility of Collecting Saliva for Biological Verification of Tobacco Use Status in Dental Practices and Patients' Homes: Results from the National Dental PBRN

OBJECTIVE

To evaluate the feasibility of collecting and analyzing saliva samples from dental practices and patients' homes for biochemical verification of tobacco use status.

BASIC RESEARCH DESIGN

Sub-study within single-arm, multi-center, longitudinal clinical study.

CLINICAL SETTING

Dental practices in the South Central region of the United States National Dental Practice-Based Research Network and patients' homes.

PARTICIPANTS

Fifty-five patients recruited from 30 dental practices.

INTERVENTIONS

Participants in the sub-study were instructed on saliva collection for cotinine analysis in dental practices where they enrolled in the primary study. Saliva was collected at the practices and then from patients' homes.

MAIN OUTCOME MEASURES

Feasibility for dental practice collection was define as 80% of enrolled participants having analyzable samples. For patients' home collection, feasibility was defined as 70%.

RESULTS

Forty-seven samples (i.e., 86% of those enrolled) collected in dental practices were analyzable. Twenty-one samples (i.e. 38% of those enrolled) collected in patients' homes were analyzable.

CONCLUSIONS

Collecting saliva samples for cotinine analysis from dental practices, but not from patients' homes, was feasible. Dental practices may provide an advantageous setting for biochemically verifying tobacco use status as part of clinical trials for tobacco cessation.

Creation of an institutional semi-independent data monitoring committee

BACKGROUND

A major goal of the National Institutes of Health's Clinical and Translational Science Award program is to facilitate clinical research and enhance the transition of basic to clinical research. As such, a number of Clinical and Translational Science Award centers have developed services to facilitate the conduct of clinical research, including support with fulfilling regulatory requirements.

METHODS

The University of Kentucky sought to establish an institutional semi-independent monitoring committee to provide oversight for clinical research studies per National Institutes of Health requirements and recommendations. Our semi-independent monitoring committee was initiated in 2010.

RESULTS

Since the inception of our semi-independent monitoring committee we have restructured its operations and protocols to improve efficiency. This article discusses our experiences with semi-independent monitoring committee creation and growth.

CONCLUSION

This article summarizes our experience in creating and maturing an institutional data monitoring committee.

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.

Contribution of cannabis-related cues to concurrent reinforcer choice in humans

BACKGROUND

Drug-related cues play a critical role in the development and persistence of substance use disorder. Few human laboratory studies have evaluated how these cues contribute to decisions between concurrently presented reinforcers, and none have examined the specific role of cannabis cues. This study evaluated the contribution of cannabis-related cues to concurrent monetary reinforcer choice in humans.

METHODS

Participants with a cannabis use history (i.e., use in the past two weeks and 50 or more lifetime uses; n = 71) and controls without this history (i.e., 5 or less lifetime uses; n = 79) were recruited using Amazon Mechanical Turk. A cued concurrent choice task was used in which cannabis trials presented two cues (one cannabis and one neutral) side-by-side followed by concurrent monetary offers below each image. The primary dependent measure was choice for cannabis-cued monetary reinforcers on equal value trials. Secondary analyses evaluated individual difference variables related to choice bias.

RESULTS

Participants in the cannabis group showed a significant bias for cannabis-cued choices (mean 76.0%) whereas participants in the control group showed a significant bias against cannabis-cued choices (mean 30.3%). Reaction times on cannabis trials were faster than neutral filler trials and did not differ by group. Cannabis-cued choice was significantly associated with more frequent cannabis use (r = .44), higher cannabis demand intensity (r = .28), and lower cannabis elasticity (r = -.30).

CONCLUSIONS

These findings suggest that cannabis-related cues can influence reinforcer choice and potentially promote disadvantageous decision-making related to non-drug reinforcers.

Feasibility, Acceptability, and Initial Efficacy of Delivering Alcohol Use Cognitive Interventions via Crowdsourcing

BACKGROUND

Inhibitory control training and working memory training are 2 cognitive interventions that have been considered for alcohol use disorder (AUD). Existing studies have typically relied on small samples that preclude the evaluation of small effects. Crowdsourcing is a sampling method that can address these limitations by effectively and efficiently recruiting large samples with varying health histories. This study tested the feasibility and acceptability of delivering cognitive training interventions via crowdsourcing.

METHODS

Participants with AUD were recruited from the crowdsourcing website Amazon Mechanical Turk (mTurk) (ClinicalTrials.gov; NCT03438539). Following completion of a baseline survey, participants were randomized to an inhibitory control, working memory, or control training condition. Participants were asked to complete training tasks daily over a 2-week period. Follow-up assessments evaluating acceptability measures and alcohol and soda consumption were completed immediately following and 2 weeks after training.

RESULTS

Response rates were satisfactory over the 2-week intervention period (65% of training tasks completed), and performance on training tasks was consistent with expected effects. A majority of participants indicated that they were satisfied with the study procedures (94.6%), would participate again (97.4%), and would consider incorporating the training task in their daily life (81.1%). Modest reductions in alcohol consumption were observed (e.g., 0.5 drinking day/wk), primarily in the inhibitory control group, and these effects were selective to alcohol use and did not extend to soda consumption.

CONCLUSIONS

These findings demonstrate the feasibility and acceptability of utilizing crowdsourcing methods for interventions development. Such a demonstration helps establish the crowdsourcing setting for future large sample studies testing novel interventions for AUD and other substance use disorders.

Synthetic Cathinone Use Among Polysubstance Users: Indirect Indicator of Indiscriminate Drug Taking or Preferred Drug of Abuse?

A survey pertaining to synthetic cathinone (SC) use was completed by 499 polysubstance users enrolled in a residential recovery program in the Southeastern United States. Of the final sample, 28% reported ever SC use. SC-users, compared with nonusers, were more often younger (32.7 vs. 36.0, p = .001), White (93.4% vs. 80.8%, p = .001), and on probation/parole since 2010 (80.9% vs. 70.9%, p = .032). SC-users evidenced extensive drug histories and were less likely to be enrolled in an urban-based program, compared to a rural, Appalachian-based program (73.8% vs. 86.6%, p = .001). Use of synthetic cannabinoids (adjusted odds ratio [AOR] = 1.9, p = .044), kratom (AOR = 1.7, p = .045), and inhalants (AOR = 2.3, p = .001) were significantly associated with SC use. Approximately 23% of SC-users preferred SCs to amphetamines or cocaine; however, only 3.6% ranked SC as their most preferred drug. Past-year SC use declined to 6.6%. Among polysubstance users in this sample, SC use may be a potential indicator of versatile and indiscriminate drug-taking.

Human Drug Discrimination: Elucidating the Neuropharmacology of Commonly Abused Illicit Drugs

Drug-discrimination procedures empirically evaluate the control that internal drug states have over behavior. They provide a highly selective method to investigate the neuropharmacological underpinnings of the interoceptive effects of drugs in vivo. As a result, drug discrimination has been one of the most widely used assays in the field of behavioral pharmacology. Drug-discrimination procedures have been adapted for use with humans and are conceptually similar to preclinical drug-discrimination techniques in that a behavior is differentially reinforced contingent on the presence or absence of a specific interoceptive drug stimulus. This chapter provides a basic overview of human drug-discrimination procedures and reviews the extant literature concerning the use of these procedures to elucidate the underlying neuropharmacological mechanisms of commonly abused illicit drugs (i.e., stimulants, opioids, and cannabis) in humans. This chapter is not intended to review every available study that used drug-discrimination procedures in humans. Instead, when possible, exemplary studies that used a stimulant, opioid, or Δ9-tetrahydrocannabinol (the primary psychoactive constituent of cannabis) to assess the discriminative-stimulus effects of drugs in humans are reviewed for illustrative purposes. We conclude by commenting on the current state and future of human drug-discrimination research.

The use of crowdsourcing in addiction science research: Amazon Mechanical Turk

Crowdsourcing, the use of the Internet to outsource work to a large number of people, has witnessed a dramatic growth over the past decade. One popular crowdsourcing option, Amazon Mechanical Turk (MTurk), is now commonly used to sample participants for psychological research. Addiction science is positioned to benefit greatly from crowdsourced sampling due to the ability to efficiently and effectively tap into populations with specific behavioral and health histories. The primary objective of this review is to describe the utility of crowdsourcing, broadly, and MTurk, specifically, for conducting research relevant to substance use and misuse. Studies in psychological and other health science have supported the reliability and validity of data gathered using crowdsourced samples. Promising research relevant to addiction science has also been conducted, including studies using cross-sectional designs and those for measure development purposes. Preliminary work using longitudinal methods and for interventions development has also revealed the potential of MTurk for studying alcohol and other drug use through these designs. Additional studies are needed to better understand the benefits, as well as the limits and constraints, of research conducted through crowdsourced online platforms. Crowdsourcing, such as on MTurk, can ultimately provide an important complement to existing methods used in human laboratory, clinical trial, community intervention, and epidemiological research. The combinations of these methodological approaches could help improve the rigor, reproducibility, and overall scope of research conducted in addiction science. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

The impact of financial strain on medication non-adherence: Influence of psychiatric medication use

Non-adherence to prescribed medications is a systemic public health concern. Financial strain, the extent to which an individual is unable to afford necessary items, may represent an important factor related to adherence. This study evaluated the association between financial strain and medication adherence as a function of medication type. Participants reporting a daily prescription for psychiatric or other chronic health conditions (N = 231) were sampled from the crowdsourcing website Amazon Mechanical Turk (mTurk). All participants completed measures of financial strain and other individual-difference factors related to adherence. Medication adherence was evaluated using a subjective scale (i.e., ARMS) and past month non-adherence rates. General financial strain showed a modest relationship with subjective scales of adherence, but not past month non-adherence rates. Medication-specific financial strain was associated with greater non-adherence, even after controlling for relevant demographic, socio-economic, and personality factors. Medication-specific financial strain also disproportionately affected individuals taking psychiatric medications relative to those not taking psychiatric medications. These findings emphasize the role that financial strain plays in medication adherence, and in particular, in psychiatric conditions. Future studies could design interventions targeting financial strain to improve clinical adherence, broadly, and psychiatric medication adherence, specifically.

Attentional bias to cannabis cues in cannabis users but not cocaine users

Attentional bias to drug cues has been associated with the problematic use of drugs, including cannabis. The cognitive mechanisms underlying this bias are not fully understood. The purpose of this study was to determine whether cannabis-cue attentional bias is associated with disruptions in attentional processing. To this end, a novel cannabis-cue visual probe task that incorporated eye tracking technology and attention-based metrics derived from signal detection theory was administered to seventeen individuals who reported daily/near-daily cannabis use. Seventeen individuals with cocaine use disorder were also enrolled as a clinical-control group. Cannabis and neutral images were briefly presented side-by-side on a computer screen, followed by the appearance of a "go" or "no-go" target upon offset of both images to permit assessment of attention-based performance. Cannabis users exhibited attentional bias to cannabis cues, as measured by fixation time and response time, but not cue-dependent disruptions on subsequent attentional performance. Cocaine users did not display an attentional bias to cannabis cues but did display poorer attentional performance relative to cannabis users. These results indicate that attentional bias to cannabis cues is selective to cannabis use history and not associated with impaired attentional processing.

Association of exercise with smoking-related symptomatology, smoking behavior and impulsivity in men and women

INTRODUCTION

Despite extensive efforts to develop effective smoking cessation interventions, 70-85% of American cigarette smokers who quit relapse within one year. Exercise has shown promise as an intervention; however, many results have been equivocal. This study explored how exercise is associated with smoking-related symptomatology, smoking behavior and impulsivity in male and female smokers.

METHODS

Participants were recruited throughout the United States using the on-line crowdsourcing platform, Amazon's Mechanical Turk. They completed a survey with self-report measures assessing exercise, smoking-related symptomatology, smoking behavior and impulsivity. Differences between men and women were tested using t- and chi-square tests. Regression analyses tested for associations between exercise and smoking-related symptomatology, smoking behavior and impulsivity.

RESULTS

Participants (N = 604) were, on average, 32 (SD = 6.2) years old, mostly Caucasian, with at least some college education and approximately half were women. Women exercised slightly less than men and had more negative affect, craving, physical symptoms and withdrawal. Women smoked more cigarettes per day, had greater nicotine dependency and more years of smoking. Positive affect was positively associated with exercise for both men and women; however, this association was significantly stronger in women. Negative affect and withdrawal were inversely associated with exercise for women only. Impulsivity was inversely associated with exercise for both men and women.

CONCLUSION

Exercise was significantly associated with several smoking-related symptomatology, smoking behavior and impulsivity variables for both men and women, suggesting that exercise may be a useful intervention for smoking cessation. Future prospective research should determine how exercise directly impacts smoking cessation.

Contribution of cocaine-related cues to concurrent monetary choice in humans

RATIONALE

Theoretical accounts highlight the importance of drug-related cues for the development and persistence of drug-taking behavior. Few studies have evaluated the ability of spatially contiguous drug cues to bias decisions between two concurrently presented non-drug reinforcers.

OBJECTIVE

Evaluate the contribution of spatially contiguous cocaine cues to choice between two concurrently presented monetary reinforcers METHODS: Participants with cocaine use disorder completed a cued concurrent choice task. Two cues (one cocaine and one control image) were presented side-by-side followed by concurrent monetary offers below each image. Concurrent choice was measured for cocaine-side advantageous, equal, and disadvantageous concurrent monetary offers. The primary dependent measure was bias for selecting cocaine-cued monetary reinforcers. Three experiments tested selectivity of cocaine-cued bias in individuals with a cocaine use history (Experiment 1), replication when including additional control trials (Experiment 2), and a potential attentional mechanism evaluated using eye-tracking technology (Experiment 3).

RESULTS

Significant and robust cocaine-cued bias at equal monetary value was observed in three experiments (mean percent choice = 65-77%) and higher Drug Abuse Screening Test (DAST) scores were associated with greater cocaine-choice bias. These experiments demonstrated that cocaine-cued bias was (1) selective to individuals with a cocaine use history, (2) specific to trials involving a cocaine cue, and (3) partially associated with attentional bias.

CONCLUSIONS

These experiments provide evidence that drug-related cues can influence choice and potentially promote maladaptive decision making during concurrent choice events. Future research evaluating prospective associations of drug-cued bias with drug-associated behaviors will help reveal the clinical relevance for substance use disorder.

Decision-making in addiction: Current knowledge, clinical implications and future directions

This article serves to summarize this special issue on "Decision-making in Addiction." The manuscripts included in this issue cover topics as diverse as theory, types of models used to study decision-making, underlying pharmacological, behavioral and brain mechanisms, and individual differences. Together, these papers can serve as a comprehensive resource outlining our contemporary understanding of how decision-making processes contribute to addictive behavior. The knowledge included here can inform treatment development, clearly pointing to the need for tailored interventions based on individual differences.