Optimally combining transcranial magnetic stimulation with antidepressants in major depressive disorder: A systematic review and Meta-analysis

There is a critical knowledge gap in optimally combining transcranial magnetic stimulation (TMS) and antidepressants to treat patients with major depressive disorder (MDD). TMS is effective in treating MDD in patients who have failed at least one antidepressant trial, with accelerated protocols showing faster remission in treatment-resistant depression (TRD). Although clinicians routinely augment antidepressants with TMS, there is a knowledge gap in stopping versus continuing antidepressants or the dosing strategies when starting or tapering TMS. These considerations are important when considering maintenance TMS (delivered alone or in combination with suitable antidepressants) to maintain remission in MDD after the index course of TMS. As the first step towards filling this knowledge gap, we reviewed randomized controlled trials (RCTs) and open-label trials from 2 databases (PubMed/Medline and EMBASE) that compared active TMS combined with a pre-specified antidepressant dosed in the same manner for adults with MDD versus sham TMS combined with the same antidepressant as in the active arm. All studies were published between January 1, 2000, and December 31, 2023. We excluded case reports, case series, and clinical studies that augmented TMS with antidepressants and vice versa. We found 10 RCTs (n = 654 participants) and performed a meta-analysis. This showed active TMS combined with pre-specified antidepressants had greater efficacy for MDD treatment than sham TMS combined with the same antidepressants as in the active arm (Hedge's g = 1; 95 % CI [0.27, 1.73]). The review and meta-analysis indicate greater short-term efficacy in combining antidepressants with TMS from the get-go in MDD. Given the increasing role of accelerated TMS protocols in expediting remission in MDD and the results of our meta-analysis, we advocate for RCTs examining the short-term and long-term effects of various antidepressant classes on these TMS protocols in MDD. This can also optimize and individualize maintenance TMS protocols to prevent relapse in MDD.

Intermittent theta burst stimulation and functional connectivity in people living with HIV/AIDS who smoke tobacco cigarettes: a preliminary pilot study

Background

People living with HIV (PLWHA) smoke at three times the rate of the general population and respond poorly to cessation strategies. Previous studies examined repetitive transcranial magnetic stimulation (rTMS) over left dorsolateral prefrontal cortex (L. dlPFC) to reduce craving, but no studies have explored rTMS among PLWHA who smoke. The current pilot study compared the effects of active and sham intermittent theta-burst stimulation (iTBS) on resting state functional connectivity (rsFC), cigarette cue attentional bias, and cigarette craving in PLWHA who smoke.

Methods

Eight PLWHA were recruited (single-blind, within-subject design) to receive one session of iTBS (n=8) over the L. dlPFC using neuronavigation and, four weeks later, sham iTBS (n=5). Cigarette craving and attentional bias assessments were completed before and after both iTBS and sham iTBS. rsFC was assessed before iTBS (baseline) and after iTBS and sham iTBS.

Results

Compared to sham iTBS, iTBS enhanced rsFC between the L. dlPFC and bilateral medial prefrontal cortex and pons. iTBS also enhanced rsFC between the right insula and right occipital cortex compared to sham iTBS. iTBS also decreased cigarette craving and cigarette cue attentional bias.

Conclusion

iTBS could potentially offer a therapeutic option for smoking cessation in PLWHA.

Adverse childhood experiences and early initiation of substance use: A survival analysis

OBJECTIVE

Early adversity, such as adverse childhood experiences (ACEs), is a risk factor for the development of substance use disorder (SUD). ACEs are associated with earlier initiation of substance use. This study examined the relationship between ACEs and age of initiation of substance use using survival analysis. It is hypothesized that individuals with higher ACEs will have an earlier age of initiation.

METHOD

Participants were recruited from the University of Kentucky's Laboratory for Human Behavioral Pharmacology. Participants were 18 years or older, English speaking, and actively engaged in substance use. Participants were not in substance abuse treatment nor were they seeking treatment. ACE scores were calculated, and age of substance use initiation was recorded. A Cox proportional hazard model was used to examine the effect of ACE score on age of substance use initiation.

RESULTS

A total of 107 participants completed the study. An average number of 2.3 ACEs (SD = 2.2) were endorsed with 24% of participants reporting 4 or more ACEs. Higher ACE scores were associated with cigarette smoking and non-medical prescription opioid use onset ( hazard ratio (HR) = 1.14, 95% CI=1.02-1.28, p = 0.02, and HR=1.19, 95% CI = 1.04-1.37, p = 0.01, respectively.

CONCLUSIONS

A significant association was found between higher ACE scores and earlier initiation of cigarette and non-medical prescription opioid use, consistent with prior research. Primary prevention of ACEs, screening for ACEs during childhood, and interventions for ACEs if detected, may help to reduce the risk of substance use/SUD in adulthood.

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.

Comparing cigarette-cue attentional bias between people with HIV/AIDS and people with opioid use disorder who smoke

Background

Special populations like people living with HIV/AIDS (PLWHA) and people with opioid use disorder (OUD) smoke tobacco cigarettes at rates three to four times greater than the general population. Patients with tobacco use disorder exhibit attentional bias (AB) for cigarette cues. Eye tracking can quantify this bias by measuring fixation time (FT) on cigarette and matched neutral cues, to calculate an AB score. Although previous studies have measured this bias in people who smoke without any other comorbid conditions, no study, to our knowledge, has measured or compared this bias in special populations.

Methods

We performed exploratory analyses on eye tracking data collected in two separate randomized clinical trials (RCTs) (NCT05049460, NCT05295953). We compared FT and cigarette-cue AB score (measured by subtracting FT on neutral cues from FT on cigarette cues) between PLWHA and people with OUD who smoke, using a visual probe task and Tobii Pro Fusion eye tracker. We used two cigarette cue types, one encompassing people smoking cigarettes and the other consisting of cigarette paraphernalia. We used two cue presentation times, 1000 and 2000 milliseconds (ms).

Results

Cues of people smoking cigarettes elicited greater AB than cues of cigarette paraphernalia across both subject groups when cues were presented for 2000 ms, but not 1000 ms. PLWHA who smoke exhibited greater AB for cues of people smoking cigarettes than cigarette paraphernalia when presented for 2000 ms compared to people with OUD who smoke.

Conclusion

We use cigarette-cue AB to quantify craving and cigarette consumption in two populations smoking at elevated rates. The addition of social cues potentiates cigarette cue AB, based on cue type and stimulus presentation time. Understanding the neurobiology of this relationship can help design novel smoking cessation treatments that target AB and prevent relapse in these populations with suboptimal response to smoking cessation treatments.

Trial registration

Clinical trials that provided the data for post hoc analyses are NCT05049460 and NCT05295953.

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.

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.

Intranasal Use of Prescription Stimulants Among Adults Aged 18 to 30: Results From A Crowdsourcing Platform

OBJECTIVE

Few studies of prescription stimulant non-oral, non-medical use (NMU) (defined by use not as prescribed) have been conducted in adults beyond the college population. The purpose of this study was to characterize prescription stimulant non-oral use, specifically intranasal (IN) use (snorting) in young adults.

METHOD

Amazon's MTurk platform was used to recruit participants for an online survey. Data were collected from March to April 2020.

RESULTS

Thirty-two percent (n = 157) of survey respondents (N = 975), aged 18 to 30, reported IN prescription stimulant use (average of 32.1 episodes of lifetime IN use). Adderall was the most-reported prescription stimulant used intranasally (89.2%). Most IN users (82%; n = 68) reported spending no more than 5 minutes tampering with prescription stimulants. Intranasal users said they would take the medication orally if unable to tamper or manipulate medication for IN use.

CONCLUSION

These data help quantify a complex public health issue of ongoing IN use of prescription stimulants and suggest a potential role for manipulation-deterrent medications.

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.

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.

Exercise Increases Attentional Bias Towards Food Cues in Individuals Classified as Overweight to Obese

BACKGROUND

The obesity epidemic continues to be a major public health concern. Although exercise is the most common weight loss recommendation, weight loss outcomes from an exercise program are often suboptimal. The human body compensates for a large percentage of the energy expended through exercise to maintain energy homeostasis and body weight. Increases in energy intake appear to be the most impactful compensatory behavior. Research on the mechanisms driving this behavior has not been fully elucidated.

PURPOSE

To determine if exercise influences the attentional processing towards food cues (attentional bias) and inhibitory control for food cues among individuals classified as overweight to obese who do not exercise.

METHODS

Thirty adults classified as overweight to obese participated in a counterbalanced, crossover trial featuring two assessment visits on separate days separated by at least one week. Attentional bias and inhibitory control towards food cues was assessed prior to and after a bout of exercise where participants expended 500 kcal (one assessment visit) and before and after a 60 min bout of watching television (second assessment visit). Attentional bias was conceptualized as the percentage of time fixated on food cues when both food and neutral (non-food) cues were presented during a food-specific dot-probe task. Inhibitory control, specifically motor impulsivity, was assessed as percentage of inhibitory failures during a food-specific Go/NoGo task.

RESULTS

A significant condition by time effect was observed for attentional bias towards food cues, independent of hunger, whereas attentional bias towards food cues was increased pre-post exercise but not after watching TV. Inhibitory control was not affected by exercise or related to attentional bias for food cues.

CONCLUSIONS

An acute bout of exercise increased attentional bias for food cues, pointing to a mechanism that may contribute to the weight loss resistance observed with exercise. Future trials are needed to evaluate attentional bias towards food cues over a longitudinal exercise intervention.

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).

Comparing Changes in Controlled Substance Prescribing Trends by Provider Type

BACKGROUND AND OBJECTIVES

Forty-nine out of 50 states have implemented Prescription Drug Monitoring Programs (PDMPs) to monitor controlled substance (CS) prescribing. PDMPs change health care provider behavior, but few studies have examined changes in CS prescription by health care provider type.

METHODS

Aggregated yearly data, including number of CS prescriptions, doses, and doses per prescription by health care provider type (physician, advanced practice registered nurse [APRN], and dentist) for each year from 2011 to 2017 was provided by the state PDMP, Kentucky All Schedule Prescription Electronic Reporting System (KASPER). In aggregate, this data set included 64,578,307 total prescriptions and 3,982,130,994 total doses of Schedule II-V medications.

RESULTS

Physicians and dentists showed a trend of decreasing prescriptions and doses for Schedule II opioids from 2012 to 2017 (27-32% reduction in 2017 compared to 2011). APRNs showed a substantive increase in the number of doses and prescriptions (121-204% increase in 2017 compared to 2011), with increases remaining when controlling for number of providers. Physicians increased doses and prescriptions of Schedule II stimulants (37% increase for both doses and prescriptions), but by a smaller magnitude than APRN increases in stimulants (334-360% increase). Dentists showed decreases in Schedule II stimulants prescribed (69-80% reduction). Similar trends, but more modest in magnitude, were observed for Schedule III-IV.

DISCUSSION AND CONCLUSIONS

Although monitoring and continuing education requirements are similar across all providers in Kentucky, differences in prescription trends for Schedule II opioids and stimulants were noted for physicians, APRNs, and dentists.

SCIENTIFIC SIGNIFICANCE

Changes in prescribing following introduction of mandatory use of KASPER markedly differed based on provider type, with increases observed for APRNs compared with physicians and dentists. These findings advance prior research by providing a detailed examination of prescribing trends by provider type subsequent to a PDMPs mandatory use law. (Am J Addict 2019;00:00-00).

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.

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.

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.

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 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.

Adverse Childhood Experiences, Tobacco Use, and Obesity: A Crowdsourcing Study

Background: Exposure to adverse childhood experiences (ACEs) increases health risk behavior in adulthood and is a risk for premature mortality. For example, ACEs are associated with both tobacco smoking and obesity, which remain significant health challenges for many adults, despite widespread knowledge about the risks. Objective: The present investigation used a novel online crowdsourcing platform (Amazon.com mechanical turk) to study the relationship between ACEs and later tobacco smoking and obesity. Methods: Participants were recruited based on smoking (n = 74 smokers; n = 75 nonsmokers) and stratified based on obesity (n = 52 BMI ≥ 30; n = 97 BMI < 30). Participants had no recent history of other substance use, except alcohol. The relationship between ACE score and smoking and obesity categories was analyzed using logistic regression. Results: The average age of the sample was 38.6-years old and was mostly female (66.4%), employed (82.6%) and college educated (63.1%). Those with 4+ ACEs had a significantly greater odds of cigarette use. Any ACEs exposure was associated with a significantly greater odds of obesity. Conclusions/Importance: Findings are concordant with previous studies and suggest crowdsourcing is a viable platform for studying ACEs and health behavior. Access to large samples and specific populations provided by crowdsourcing could help examine theoretical models about how exposure to ACEs could be connected to later adoption of high-risk behaviors such as tobacco cigarette smoking and obesity.

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.

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.

A pilot study of loss aversion for drug and non-drug commodities in cocaine users

BACKGROUND

Numerous studies in behavioral economics have demonstrated that individuals are more sensitive to the prospect of a loss than a gain (i.e., loss aversion). Although loss aversion has been well described in "healthy" populations, little research exists in individuals with substance use disorders. This gap is notable considering the prominent role that choice and decision-making play in drug use. The purpose of this pilot study was to evaluate loss aversion in active cocaine users.

METHODS

Current cocaine users (N=38; 42% female) participated in this within-subjects laboratory pilot study. Subjects completed a battery of tasks designed to assess loss aversion for drug and non-drug commodities under varying risk conditions. Standardized loss aversion coefficients (λ) were compared to theoretically and empirically relevant normative values (i.e., λ=2).

RESULTS

Compared to normative loss aversion coefficient values, a precise and consistent decrease in loss aversion was observed in cocaine users (sample λ≈1). These values were observed across drug and non-drug commodities as well as under certain and risky conditions.

CONCLUSIONS

These data represent the first systematic study of loss aversion in cocaine-using populations and provide evidence for equal sensitivity to losses and gains or loss equivalence. Futures studies should evaluate the specificity of these effects to a history of cocaine use as well as the impact of manipulations of loss aversion on drug use to determine how this phenomenon may contribute to intervention development efforts.

Influence of Cocaine-Related Images and Alcohol Administration on Inhibitory Control in Cocaine Users

BACKGROUND

Alcohol use and impulsivity, including decreased inhibitory control, predict poor treatment outcomes for individuals with cocaine use disorders. This study sought to determine the effects of alcohol administration on inhibitory control following cocaine-related and neutral cues on the Attentional Bias-Behavioral Activation (ABBA) task in cocaine users. We hypothesized that the proportion of inhibitory failures would increase following cocaine, compared to neutral, cues. We further hypothesized that there would be an interaction between alcohol administration and task version, such that alcohol would impair inhibitory control following cocaine, but not neutral cues.

METHODS

Fifty current cocaine users completed this mixed-model, double-blind, placebo-controlled, crossover study over 2 experimental sessions. The ABBA task was completed following alcohol administration (0.0 and 0.65 g/kg). Subject-rated drug effect and physiological measures were collected prior to and after alcohol administration.

RESULTS

Proportion of inhibitory failures was increased following cocaine-related cues compared to neutral cues independent of alcohol dose. Alcohol administration also produced prototypical subject-rated drug effects.

CONCLUSIONS

A better understanding of the relationship between alcohol consumption and inhibitory control in cocaine users could direct the development of interventions to decrease the risk of relapse in individuals who drink and display impaired inhibitory control.

N-Acetylcysteine reduces cocaine-cue attentional bias and differentially alters cocaine self-administration based on dosing order

BACKGROUND

Disrupted glutamate homeostasis is thought to contribute to cocaine-use disorder, in particular, by enhancing the incentive salience of cocaine stimuli. n-Acetylcysteine might be useful in cocaine-use disorder by normalizing glutamate function. In prior studies, n-acetylcysteine blocked the reinstatement of cocaine seeking in laboratory animals and reduced the salience of cocaine stimuli and delayed relapse in humans.

METHODS

The present study determined the ability of maintenance on n-acetylcysteine (0 or 2400mg/day, counterbalanced) to reduce the incentive salience of cocaine stimuli, as measured by an attentional bias task, and attenuate intranasal cocaine self-administration (0, 30, and 60mg). Fourteen individuals (N=14) who met criteria for cocaine abuse or dependence completed this within-subjects, double-blind, crossover-design study.

RESULTS

Cocaine-cue attentional bias was greatest following administration of 0mg cocaine during placebo maintenance, and was attenuated by n-acetylcysteine. Cocaine maintained responding during placebo and n-acetylcysteine maintenance, but the reinforcing effects of cocaine were significantly attenuated across both maintenance conditions in participants maintained on n-acetylcysteine first compared to participants maintained on placebo first.

CONCLUSIONS

These results collectively suggest that a reduction in the incentive salience of cocaine-related stimuli during n-acetylcysteine maintenance may be accompanied by reductions in cocaine self-administration. These results are in agreement with, and link, prior preclinical and clinical trial results suggesting that n-acetylcysteine might be useful for preventing cocaine relapse by attenuating the incentive salience of cocaine cues.

A pilot investigation of acute inhibitory control training in cocaine users

BACKGROUND

Disrupted response inhibition and presence of drug-cue attentional bias in cocaine-using individuals have predicted poor treatment outcomes. Inhibitory control training could help improve treatment outcomes by strengthening cognitive control. This pilot study assessed the effects of acute inhibitory control training to drug- and non-drug-related cues on response inhibition performance and cocaine-cue attentional bias in cocaine-using individuals.

METHODS

Participants who met criteria for a cocaine-use disorder underwent five sessions of inhibitory control training to either non-drug-related cues (i.e., rectangles) or cocaine cues (n=10/condition) in a single day. Response inhibition and attentional bias were assessed prior to and following training using the stop-signal task and visual-probe task with eye tracking, respectively.

RESULTS

Training condition groups did not differ on demographics, inhibitory control training performance, response inhibition, or cocaine-cue attentional bias. Response inhibition performance improved as a function of inhibitory control training in both conditions. Cocaine-cue attentional bias was observed, but did not change as a function of inhibitory control training in either condition.

CONCLUSIONS

Response inhibition in cocaine-using individuals was augmented by acute inhibitory control training, which may improve treatment outcomes through better behavioral inhibition. Future studies should investigate longer-term implementation of inhibitory control training, as well as combining inhibitory control training with other treatment modalities.

Evaluation of the "Pipeline" for Development of Medications for Cocaine Use Disorder: A Review of Translational Preclinical, Human Laboratory, and Clinical Trial Research

Cocaine use disorder is a persistent public health problem for which no widely effective medications exist. Self-administration procedures, which have shown good predictive validity in estimating the abuse potential of drugs, have been used in rodent, nonhuman primate, and human laboratory studies to screen putative medications. This review assessed the effectiveness of the medications development process regarding pharmacotherapies for cocaine use disorder. The primary objective was to determine whether data from animal and human laboratory self-administration studies predicted the results of clinical trials. In addition, the concordance between laboratory studies in animals and humans was assessed. More than 100 blinded, randomized, fully placebo-controlled studies of putative medications for cocaine use disorder were identified. Of the 64 drugs tested in these trials, only 10 had been examined in both human and well-controlled animal laboratory studies. Within all three stages, few studies had been conducted for each drug and when multiple studies had been conducted conclusions were sometimes contradictory. Overall, however, there was good concordance between animal and human laboratory results when the former assessed chronic drug treatment. Although only seven of the ten reviewed drugs showed fully concordant results across all three types of studies reviewed, the analysis revealed several subject-related, procedural, and environmental factors that differ between the laboratory and clinical trial settings that help explain the disagreement for other drugs. The review closes with several recommendations to enhance translation and communication across stages of the medications development process that will ultimately speed the progress toward effective pharmacotherapeutic strategies for cocaine use disorder.

Effects of acute buspirone administration on inhibitory control and sexual discounting in cocaine users

OBJECTIVE

Cocaine users display deficits in inhibitory control and make impulsive choices that may increase risky behavior. Buspirone is an anxiolytic that activates dopaminergic and serotonergic systems and improves impulsive choice (i.e., reduces sexual risk-taking intent) in cocaine users when administered chronically. We evaluated the effects of acutely administered buspirone on inhibitory control and impulsive choice.

METHODS

Eleven subjects with a recent history of cocaine use completed this within-subject, placebo-controlled study. Subjects performed two cued go/no-go and a sexual risk delay-discounting task following oral administration of buspirone (10 and 30 mg), triazolam (0.375 mg; positive control), and placebo (negative control). Physiological and psychomotor performance and subject-rated data were also collected.

RESULTS

Buspirone failed to change inhibitory control or impulsive choice; however, slower reaction times were observed at the highest dose tested. Buspirone did not produce subject-rated drug effects but dose-dependently decreased diastolic blood pressure. Triazolam impaired psychomotor performance and increased ratings of positive subject-rated effects (e.g., Like Drug).

CONCLUSIONS

These findings indicate that acutely administered buspirone has little impact on behavioral measures of inhibitory control and impulsive sexual decision-making. Considering previous findings with chronic dosing, these findings highlight that the behavioral effects of buspirone differ as a function of dosing conditions.

Comparing exponential and exponentiated models of drug demand in cocaine users

Drug purchase tasks provide rapid and efficient measurement of drug demand. Zero values (i.e., prices with zero consumption) present a quantitative challenge when using exponential demand models that exponentiated models may resolve. We aimed to replicate and advance the utility of using an exponentiated model by demonstrating construct validity (i.e., association with real-world drug use) and generalizability across drug commodities. Participants (N = 40 cocaine-using adults) completed Cocaine, Alcohol, and Cigarette Purchase Tasks evaluating hypothetical consumption across changes in price. Exponentiated and exponential models were fit to these data using different treatments of zero consumption values, including retaining zeros or replacing them with 0.1, 0.01, or 0.001. Excellent model fits were observed with the exponentiated model. Means and precision fluctuated with different replacement values when using the exponential model but were consistent for the exponentiated model. The exponentiated model provided the strongest correlation between derived demand intensity (Q0) and self-reported free consumption in all instances (Cocaine r = .88; Alcohol r = .97; Cigarette r = .91). Cocaine demand elasticity was positively correlated with alcohol and cigarette elasticity. Exponentiated parameters were associated with real-world drug use (e.g., weekly cocaine use) whereas these correlations were less consistent for exponential parameters. Our findings show that selection of zero replacement values affects demand parameters and their association with drug-use outcomes when using the exponential model but not the exponentiated model. This work supports the adoption of the exponentiated demand model by replicating improved fit and consistency and demonstrating construct validity and generalizability. (PsycINFO Database Record

Acute buspirone dosing enhances abuse-related subjective effects of oral methamphetamine

There is not an approved pharmacotherapy for treating methamphetamine use disorder. This study sought to determine the effects of acute buspirone treatment on the subjective and cardiovascular effects of oral methamphetamine in order to provide an initial assessment of the utility, safety, and tolerability of buspirone for managing methamphetamine use disorder. We predicted that acute buspirone administration would reduce the subjective effects of methamphetamine. We also predicted that the combination of buspirone and methamphetamine would be safe and well tolerated. Ten subjects completed the protocol, which tested three methamphetamine doses (0, 15, and 30mg) in combination with two buspirone doses (0 and 30mg) across 6 experimental sessions. Subjective effects and physiological measures were collected at regular intervals prior to and after dose administration. Methamphetamine produced prototypical subjective and cardiovascular effects. Acute buspirone administration increased some of the abuse-related subjective effects of methamphetamine and also attenuated some cardiovascular effects. The combination of oral methamphetamine and buspirone was safe and well tolerated. Acute buspirone administration may increase the abuse liability of oral methamphetamine. Chronic buspirone dosing studies remain to be conducted, but given preclinical findings and the outcomes of this work, the utility of buspirone for treating methamphetamine use disorder appears limited.

Human drug discrimination: A primer and methodological review

Drug-discrimination procedures empirically evaluate the control that internal drug states exert over behavior. They provide a highly selective method to investigate the neuropharmacological underpinnings of the interoceptive effects of drugs. Historically, drug discrimination has been one of the most widely used assays in the field of behavioral pharmacology. Drug-discrimination procedures have also 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 review gives some general history and background concerning the major theoretical concepts and principles of drug-discrimination research as well as its relevance to substance-use disorders. This article also provides a procedural overview and discusses key methodological issues that must be considered when designing and conducting a human drug-discrimination study. Although drug discrimination is unequivocally one of the most sophisticated and useful behavioral assays to investigate the underlying neuropharmacology of drugs in vivo, enthusiasm for its use has steadily declined in the last decade and a half. We conclude by commenting on the current state of drug-discrimination research and suggest potential avenues for future drug-discrimination research. (PsycINFO Database Record

Alcohol Administration Increases Cocaine Craving But Not Cocaine Cue Attentional Bias

BACKGROUND

Alcohol consumption is a known antecedent to cocaine relapse. Through associative conditioning, it is hypothesized that alcohol increases incentive motivation for cocaine and thus the salience of cocaine-related cues, which are important in maintaining drug-taking behavior. Cocaine-using individuals display a robust cocaine cue attentional bias as measured by fixation time during the visual probe task. The purpose of this study was to evaluate the influence of alcohol administration on cocaine cue attentional bias using eye-tracking technology to directly measure attentional allocation.

METHODS

Twenty current cocaine users completed a double-blind, placebo-controlled, within-subjects study that tested the effect of 3 doses of alcohol (0.00, 0.325, and 0.65 g/kg) on cocaine cue attentional bias using the visual probe task with eye-tracking technology. The participant-rated and physiological effects of alcohol were also assessed.

RESULTS

Participants displayed a robust cocaine cue attentional bias following both placebo and alcohol administration as measured by fixation time, but not response time. Alcohol administration did not influence cocaine cue attentional bias, but increased craving for cocaine in a dose-dependent manner. Alcohol produced prototypic psychomotor and participant-rated effects.

CONCLUSIONS

Alcohol administration increases cocaine craving but not cocaine cue attentional bias. Alcohol-induced cocaine craving suggests that alcohol increases incentive motivation for cocaine but not the salience of cocaine-related cues.

Safety and tolerability of intranasal cocaine during phendimetrazine maintenance

RATIONALE

Phendimetrazine appears to have limited abuse potential and reduces cocaine self-administration in preclinical studies. No human studies have evaluated the safety and tolerability of cocaine in combination with phendimetrazine, which is a necessary next step in evaluating the efficacy of phendimetrazine for treating cocaine use disorder.

OBJECTIVES

This study determined the safety and tolerability of acute cocaine doses during chronic phendimetrazine treatment.

METHODS

Ten subjects completed this within-subject, placebo-controlled, inpatient study. Subjects were maintained on ascending oral phendimetrazine doses (0, 70, 140, and 210 mg/day). After at least seven maintenance days at each dose, subjects received ascending doses of intranasal cocaine (0, 10, 20, 40, and 80 mg), separated by 90 min, within one session.

RESULTS

Cocaine produced prototypical cardiovascular and subject-rated effects (e.g., increased blood pressure and ratings of like drug). The cardiovascular effects of cocaine alone were not clinically significant for an acute drug response (e.g., average heart rate did not approach tachycardia, 100 beats/min). Phendimetrazine enhanced peak heart rate following placebo and low cocaine doses, but these effects were also not clinically significant. Phendimetrazine was otherwise devoid of effects alone and did not alter the subject-rated effects of cocaine or hypothetical demand for cocaine on a purchase task.

CONCLUSIONS

Cocaine was safe and well tolerated during maintenance on a threefold range of phendimetrazine doses. Given this safety profile, the reduced abuse potential of phendimetrazine and promising preclinical research, future human laboratory studies, and possibly clinical trials should evaluate the efficacy of phendimetrazine for reducing cocaine use.

Buspirone reduces sexual risk-taking intent but not cocaine self-administration

Impulsive sexual decision-making may underlie sexual risk-taking behavior that contributes to the disproportionately high prevalence of HIV infection among cocaine users. Delay-discounting procedures measure impulsive decision-making and may provide insight into the underlying mechanisms of sexual risk-taking behavior. The anxiolytic drug buspirone reduces delay discounting in rats and blunts the reinforcing effects of cocaine in some preclinical studies suggesting that it might have utility in the treatment of cocaine-use disorders. This study determined whether buspirone mitigates impulsive risky sexual decision-making in cocaine users on a sexual delay-discounting procedure. The effects of buspirone maintenance on the abuse-related and physiological effects of cocaine were also tested. Nine (N = 9) current cocaine users completed a repeated-measures, inpatient protocol in which sexual delay discounting was assessed after 3 days of maintenance on placebo and buspirone (30 mg/day) in counterbalanced order. The reinforcing, subject-rated, and physiological effects of placebo and intranasal cocaine (15 and 45 mg) were also assessed during buspirone and placebo maintenance. Buspirone increased the likelihood of condom use for hypothetical sexual partners that were categorized as most likely to have a sexually transmitted infection and least sexually desirable. Cocaine functioned as a reinforcer and increased positive subjective effects ratings, but buspirone maintenance did not impact these effects of cocaine. Buspirone was also safe and tolerable when combined with cocaine and may have blunted some its cardiovascular effects. The results from the sexual delay-discounting procedure indicate that buspirone may reduce preference for riskier sex in cocaine users. (PsycINFO Database Record

Cigarette Cue Attentional Bias in Cocaine-Smoking and Non-Cocaine-Using Cigarette Smokers

INTRODUCTION

Cigarette smoking in cocaine users is nearly four times higher than the national prevalence and cocaine use increases cigarette smoking. The mechanisms underlying cigarette smoking in cocaine-using individuals need to be identified to promote cigarette and cocaine abstinence. Previous studies have examined the salience of cigarette and cocaine cues separately. The present aim was to determine whether cigarette attentional bias (AB) is higher in cigarettes smokers who smoke cocaine relative to individuals who only smoke cigarettes.

METHODS

Twenty cigarette smokers who smoke cocaine and 20 non-cocaine-using cigarette smokers completed a visual probe task with eye-tracking technology. During this task, the magnitude of cigarette and cocaine AB was assessed through orienting bias, fixation time, and response time.

RESULTS

Cocaine users displayed an orienting bias towards cigarette cues. Cocaine users also endorsed a more urgent desire to smoke to relieve negative affect associated with cigarette craving than non-cocaine users (g = 0.6). Neither group displayed a cigarette AB, as measured by fixation time. Cocaine users, but not non-cocaine users, displayed a cocaine AB as measured by orienting bias (g = 2.0) and fixation time (g = 1.2). There were no significant effects for response time data.

CONCLUSIONS

Cocaine-smoking cigarettes smokers display an initial orienting bias toward cigarette cues, but not sustained cigarette AB. The incentive motivation underlying cigarette smoking also differs. Cocaine smokers report more urgent desire to smoke to relieve negative affect. Identifying differences in motivation to smoke cigarettes may provide new treatment targets for cigarette and cocaine use disorders.

IMPLICATIONS

These results suggest that cocaine-smoking cigarette smokers display an initial orienting bias towards cigarette cues, but not sustained attention towards cigarette cues, relative to non-cocaine-using smokers. Smoked cocaine users also report a more urgent desire to smoke to relieve negative affect than non-cocaine users. Identifying differences in motivation to smoke cigarettes may provide new treatment targets for both cigarette and cocaine use disorders.

Profile of internet access in active cocaine users

BACKGROUND AND OBJECTIVES

Web-based interventions have received attention for substance abuse treatment. Few studies have examined Internet use among substance users.

METHODS

Internet-use data were examined for 66 participants screened to participate in behavioral pharmacology studies.

RESULTS

A majority of active cocaine users reported regular Internet use. Demographic profiles generally did not impact Internet use, but Internet users were more likely to be younger and report other drug use.

DISCUSSION AND CONCLUSIONS

Active cocaine users have similar rates of Internet access as the general population.

SCIENTIFIC SIGNIFICANCE

Our findings contribute to the limited data on Internet use in active drug users by demonstrating Internet access in cocaine-using populations, supporting the use of this medium to conduct research and clinical interventions.

Cocaine-related stimuli impair inhibitory control in cocaine users following short stimulus onset asynchronies

BACKGROUND AND AIMS

Cocaine users display a significant increase in inhibitory failures following cocaine-related images compared with neutral images in a modified cued Go/No-Go task, the Attentional Bias-Behavioral Activation (ABBA) task. The aim of this study was to demonstrate that stimulus onset asynchrony (SOA) impacts inhibitory failures on the ABBA task.

DESIGN

A between-subjects experiment.

SETTING

An out-patient research unit in the United States.

PARTICIPANTS

Ninety-one cocaine users recruited from the community.

MEASUREMENTS

Participants were assigned to groups in which they saw either cocaine (n=46) or neutral (n=45) images as the go condition. Cues were presented for one of five SOAs (i.e. 100, 200, 300, 400 or 500 ms) before a go or no-go target was displayed.

FINDINGS

Participants in the cocaine go condition had a significantly higher proportion of inhibitory failures to no-go targets (F4,356=2.50, P=0.04) with significantly more inhibitory failures following all SOAs (P<0.05) than those in the neutral go condition. Within the cocaine go condition, significantly more inhibitory failures were observed following the 100 and 200 ms SOAs than after the 300, 400 or 500 ms SOAs (P<0.05).

CONCLUSIONS

Cocaine-related stimuli appear to decrease inhibitory control in cocaine users at short (100 and 200 ms) stimulus onset asynchronies (SOAs: the amount of time between the start of one stimulus and the start of another stimulus), but not at longer (300, 400 and 500 ms) SOAs.

The magnitude of drug attentional bias is specific to substance use disorder

The visual probe task with eye tracking is a sensitive measure of cocaine and alcohol cue attentional bias. Despite the high comorbidity between cocaine and alcohol dependence, attentional bias studies have examined the influence of cocaine- and alcohol-related cues separately. The aim of this experiment was to directly compare the magnitude of cocaine and alcohol cue attentional bias in individuals dependent on cocaine or cocaine and alcohol. Individuals who met criteria for cocaine dependence (n = 20) or both cocaine and alcohol dependence (n = 20) completed a visual probe task with eye tracking. Cocaine-dependent participants displayed an attentional bias toward cocaine, but not alcohol. In contrast, cocaine-alcohol dependent participants displayed an attentional bias to both cocaine and alcohol, and the magnitude of these biases did not differ. The magnitude of cocaine cue attentional bias, however, was significantly smaller in the cocaine-alcohol dependent group compared to the cocaine-dependent group. These results suggest that fixation time during the visual probe task is sensitive to clinically relevant differences in substance use disorders. The incentive value of cocaine-related cues, however, may differ for individuals who are also dependent on alcohol.

Mu opioid mediated discriminative-stimulus effects of tramadol: an individual subjects analysis

Drug discrimination procedures use dose-dependent generalization, substitution, and pretreatment with selective agonists and antagonists to evaluate receptor systems mediating interoceptive effects of drugs. Despite the extensive use of these techniques in the nonhuman animal literature, few studies have used human participants. Specifically, human studies have not routinely used antagonist administration as a pharmacological tool to elucidate the mechanisms mediating the discriminative stimulus effects of drugs. This study evaluated the discriminative-stimulus effects of tramadol, an atypical analgesic with monoamine and mu opioid activity. Three human participants first learned to discriminate 100 mg tramadol from placebo. A range of tramadol doses (25 to 150 mg) and hydromorphone (4 mg) with and without naltrexone pretreatment (50 mg) were then administered to participants after they acquired the discrimination. Tramadol produced dose-dependent increases in drug-appropriate responding and hydromorphone partially or fully substituted for tramadol in all participants. These effects were attenuated by naltrexone. Individual participant records indicated a relationship between mu opioid activity (i.e., miosis) and drug discrimination performance. Our findings indicate that mu opioid activity may mediate the discriminative-stimulus effects of tramadol in humans. The correspondence of generalization, substitution, and pretreatment findings with the animal literature supports the neuropharmacological specificity of the drug discrimination procedure.

Test-retest reliability of eye tracking during the visual probe task in cocaine-using adults

BACKGROUND

Stimuli associated with cocaine use capture attention. Evidence suggests that fixation time measured on the visual probe task is a valid measure of cocaine cue attentional bias. The aim of this experiment was to demonstrate the test-retest reliability of cocaine cue attentional bias as measured by fixation time during the visual probe task.

METHODS

In a within-subject, repeated-measures design, thirty-six non-treatment seeking cocaine-using adults completed a visual probe task with eye tracking.

RESULTS

Participants displayed an attentional bias to cocaine-related images as measured by fixation time across two occasions (F (1, 35) = 56.5, p < 0.0001). A Pearson correlation indicated significant test-retest reliability for this effect (r = 0.51, p = 0.001). Response time failed to detect an attentional bias and test-retest reliability was low (r = 0.24, p = 0.16).

CONCLUSION

Fixation time during the visual probe task is a reliable measure of cocaine cue attentional bias in cocaine-using adults across time.

Fixation time is a sensitive measure of cocaine cue attentional bias

BACKGROUND AND AIMS

Attentional bias has been demonstrated to a variety of substances. Evidence suggests that fixation time is a more direct measure of attentional bias than response time. The aims of this experiment were to demonstrate that fixation time during the visual probe task is a sensitive and stable measure of cocaine cue attentional bias in cocaine-using adults compared to controls.

DESIGN

A between-subject, repeated-measures experiment.

SETTING

An out-patient research unit.

PARTICIPANTS

Fifteen cocaine using and 15 non-cocaine-using adults recruited from the community.

MEASUREMENTS

Participants completed a visual probe task with eye tracking and a modified Stroop during two experimental sessions.

FINDINGS

A significant interaction between cue type and group (F = 13.5; P < 0.05) indicated that cocaine users, but not controls, displayed an attentional bias to cocaine-related images as measured by fixation time. There were no changes in the magnitude of attentional bias across sessions (F = 3.4; P > 0.05) and attentional bias correlated with self-reported life-time cocaine use (r = 0.64, P < 0.05). Response time on the visual probe (F = 1.1; P > 0.05) as well as on the modified Stroop (F = 0.1; P > 0.05) failed to detect an attentional bias.

CONCLUSIONS

Fixation time on cocaine-related stimuli (propensity to remain focused on the stimulus) is a sensitive and stable measure of cocaine cue attentional bias in cocaine-using adults.

Agonist replacement for stimulant dependence: a review of clinical research

Stimulant use disorders are an unrelenting public health concern worldwide. Agonist replacement therapy is among the most effective strategies for managing substance use disorders including nicotine and opioid dependence. The present paper reviewed clinical data from human laboratory self-administration studies and clinical trials to determine whether agonist replacement therapy is a viable strategy for managing cocaine and/or amphetamine use disorders. The extant literature suggests that agonist replacement therapy may be effective for managing stimulant use disorders, however, the clinical selection of an agonist replacement medication likely needs to be based on the pharmacological mechanism of the medication and the stimulant abused by patients. Specifically, dopamine releasers appear most effective for reducing cocaine use whereas dopamine reuptake inhibitors appear most effective for reducing amphetamine use.

Relationship between intranasal cocaine self-administration and subject-rated effects: predictors of cocaine taking on progressive-ratio schedules

OBJECTIVE

Subject-rated measures and drug self-administration represent two of the most commonly used methods of assessing abuse potential of drugs, as well as screening intervention efficacy in the human laboratory. Although the results from these methods are often consistent, dissociations between subject-rated and self-administration data have been observed. The purpose of the present retrospective analysis was to examine the relationship between subject-rated effects and intranasal cocaine self-administration to help guide future research design and intervention assessment.

METHODS

Data were combined from two previous studies in which drug and an alternative reinforcer (i.e., money) were available on concurrent progressive-ratio schedules of reinforcement. Pearson correlation coefficients and regression model selection utilizing corrected Akaike information criterion were used to determine which subject-rated measures were associated with and best predicted cocaine self-administration.

RESULTS

Eleven subject-rated effects were positively associated with cocaine-maintained breakpoints. A combination of three of these subject ratings (i.e., Like Drug, Performance Improved, and Rush) best predicted cocaine taking.

CONCLUSIONS

The present findings suggest that, at least under certain conditions with intranasal cocaine, some, but not all, positive subject-rated effects may predict drug self-administration. These findings will be useful in guiding future examinations of putative interventions for cocaine-use disorders.

Combination pharmacotherapies for stimulant use disorder: a review of clinical findings and recommendations for future research

Despite concerted efforts to identify a pharmacotherapy for managing stimulant use disorders, no widely effective medications have been approved. Innovative strategies are necessary to develop successful pharmacotherapies for stimulant use disorders. This manuscript reviews human laboratory studies and clinical trials to determine whether one such strategy, use of combination pharmacotherapies, holds promise. The extant literature shows that combination pharmacotherapy produced results that were better than placebo treatment, especially with medications shown to have efficacy as monotherapies. However, many studies did not compare individual constituents to the combination treatment, making it impossible to determine whether combination treatment is more effective than monotherapy. Future research should systematically compare combined treatments with individual agents using medications showing some efficacy when tested alone.

Drug-related stimuli impair inhibitory control in cocaine abusers

BACKGROUND

Cocaine users show impaired inhibitory control on cued go/no-go tasks and attention bias to drug-related stimuli in the emotional Stroop task. The results of a previous study suggested that there is a relationship between inhibitory control and attention bias in alcohol drinkers such that the presentation of alcohol-related images as a go cue in a cued go/no-go task significantly impaired inhibitory control compared to neutral images as a go cue. The present study determined the generality of these previous findings by assessing inhibitory control in cocaine users utilizing a modified cued go/no-go task with cocaine or neutral images as the cues.

METHODS

Non-treatment seeking cocaine users (N=30) completed the modified task after completing detailed measures of demographics and drug use. Participants were matched on basic demographic factors and were assigned to groups in which they saw either a cocaine or neutral image as the go cue.

RESULTS

Participants assigned to the cocaine image go cue condition had a significantly higher proportion of inhibitory failures to the no-go target than their counterparts assigned to the neutral cue condition, but there were no group differences on reaction time (i.e., accuracy was not traded for speed).

CONCLUSIONS

Cocaine users were less able to inhibit pre-potent responses when a cocaine-related image served as the go cue than when a neutral image served as the go cue, consistent with previous research in alcohol users. The outcomes suggest that cocaine-related cues produce disinhibition, perhaps contributing to the high incidence of relapse or continued cocaine use.