The influence of alternative reinforcers on cocaine use and abuse: a brief review

Intersections between environmental reward availability, loss aversion, and delay discounting as potential risk factors for cigarette smoking and other substance use

Behavioral theory suggests that density of environmental rewarding activities and biases in decision making influence risk for substance use disorder (SUD). To better understand intersections of these potential risk factors, this study examined whether environmental reward predicted smoking status or other drug use and whether such associations were independent of two decision-making biases known to predict SUD risk, namely loss aversion and delay discounting. Individuals that reported current daily cigarette smoking (n = 186; >10 cigarettes/day) and never-smoking (n = 241; <100 cigarettes lifetime) were recruited with standard crowdsourcing methods. Participants answered questions on alcohol and other drug use. Environmental reward was assessed using the Reward Probability Index (RPI), and loss aversion (LA) and delay discounting (DD) using a gamble-acceptance task and monetary choice questionnaire, respectively. Associations of RPI, LA, and DD with cigarette smoking, alcohol use, other drug use, and combinations of co-use were examined with logistic regression controlling for sociodemographic variables (educational attainment, gender, age). Low RPI (odds ratio[OR] = 0.97, p = .006), low LA (OR = 1.22, p < .001), and high DD (OR = 1.12, p = .03), were each independently associated with increased risk for cigarette smoking, as well as other substance use, and use combinations. We saw no evidence that RPI was significantly influencing associations between LA and DD with smoking status or other substance use. Finally, RPI, but not LA or DD, was significantly associated with depressed mood and sleep disturbance. These results provide new evidence on associations of RPI with smoking status and other substance use while further documenting independent associations between LA and DD and those outcomes.

Effects of episodic future thinking on reinforcement pathology during smoking cessation treatment among individuals with substance use disorders

RATIONALE

Reinforcer pathology (RP) is a theoretical model based on two processes: delay discounting (DD) and drug demand. Given that RP has been shown to have a predictive value on smoking behaviors, several studies have explored which interventions can reduce RP. Consistent with the RP framework, episodic future thinking (EFT) has shown effects on treatment outcomes and RP processes. The vast majority of studies that assess the effects of EFT on RP consist of experimental studies, and no previous research has tested these effects in a clinical sample of smokers.

OBJECTIVES

The primary aim of this study was to assess the effects of EFT on RP throughout the course of a smoking cessation intervention in smokers with substance use disorders (SUDs).

METHODS

Participants were randomized to cognitive behavior therapy (CBT) + EFT (n = 39) or CBT + EFT + contingency management (n = 33). Cotinine, frequency of EFT practices, cigarette purchase task (CPT), and DD were evaluated in treatment sessions. Mixed-effects model repeated measures analysis was used to explore DD and CPT in-treatment changes as a function of EFT practices and cotinine levels.

RESULTS

Greater practice of the EFT component significantly reduced cigarette demand (p < .020) as well as DD (p = .003). Additionally, a greater reduction in cotinine levels coupled with greater EFT practice led to a greater decrease in cigarette demand (p < .014).

CONCLUSIONS

EFT reduced the two facets of RP in treatment-seeking smokers with SUDs.

Animal Models of the Behavioral Symptoms of Substance Use Disorders

To more effectively manage substance use disorders, it is imperative to understand the neural, genetic, and psychological underpinnings of addictive behavior. To contribute to this understanding, considerable efforts have been made to develop translational animal models that capture key behavioral characteristics of addiction on the basis of DSM5 criteria of substance use disorders. In this review, we summarize empirical evidence for the occurrence of addiction-like behavior in animals. These symptoms include escalation of drug use, neurocognitive deficits, resistance to extinction, exaggerated motivation for drugs, increased reinstatement of drug seeking after extinction, preference for drugs over nondrug rewards, and resistance to punishment. The occurrence of addiction-like behavior in laboratory animals has opened the opportunity to investigate the neural, genetic, and psychological background of key aspects of addiction, which may ultimately contribute to the prevention and treatment of substance use disorders.

Factors mediating pain-related risk for opioid use disorder

Pain is a complex experience with far-reaching organismal influences ranging from biological factors to those that are psychological and social. Such influences can serve as pain-related risk factors that represent susceptibilities to opioid use disorder. This review evaluates various pain-related risk factors to form a consensus on those that facilitate opioid abuse. Epidemiological findings represent a high degree of co-occurrence between chronic pain and opioid use disorder that is, in part, driven by an increase in the availability of opioid analgesics and the diversion of their use in a non-medical context. Brain imaging studies in individuals with chronic pain that use/abuse opioids suggest abuse-related mechanisms that are rooted within mesocorticolimbic processing. Preclinical studies suggest that pain states have a limited impact on increasing the rewarding effects of opioids. Indeed, many findings indicate a reduction in the rewarding and reinforcing effects of opioids during pain states. An increase in opioid use may be facilitated by an increase in the availability of opioids and a decrease in access to non-opioid reinforcers that require mobility or social interaction. Moreover, chronic pain and substance abuse conditions are known to impair cognitive function, resulting in deficits in attention and decision making that may promote opioid abuse. A better understanding of pain-related risk factors can improve our knowledge in the development of OUD in persons with pain conditions and can help identify appropriate treatment strategies. This article is part of the special issue on 'Vulnerabilities to Substance Abuse.'.

Social interaction reward: A resilience approach to overcome vulnerability to drugs of abuse

Drug addiction is a multifactorial disorder resulting from the complex interaction between biological, environmental and drug-induced effects. Generally, stress is a well-known risk factor for the development of drug addiction and relapse. While most of the research focuses on risk factors that increase the vulnerability to drugs of abuse, recent studies are focusing on the areas of strength/positive coping approaches that can increase resistance to drugs of abuse. In this review, we concentrate on resilience, seen as a dynamic process, which can allow individuals to positively adapt within the context of a specific risk for psychiatric illness. Here, we discuss the effects of social stress in animal models on drug use, particularly cocaine. In contrast, we suggest social interaction reward when available as an alternative to drug use as an approach contracting negative stress effects and increasing resistance to drug use. Indeed, interventions, which aim at enhancing resilience to stress through the facilitation of social interaction and the enhancement of social support, could be particularly effective in helping people cope with stress and preventing drug use problems or relapse. Finally, understanding the neurobiological mechanisms underlying protective factors such as social interaction reward should provide the basis for future evidence-based interventions targeting substance abuse and stress-related pathologies.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

Voucher-Based Contingency Management is Efficacious but Underutilized in Treating Addictions

The United States lags far behind other industrialized countries on major markers of population health. Population health experts identify unhealthy behavior patterns (e.g., cigarette smoking, other substance use disorders, physical inactivity and poor food choices, nonadherence with recommended medical regimens) as the largest contributor to the status quo. Because these risk behaviors are overrepresented in socioeconomically disadvantaged and other vulnerable populations, they also increase health disparities. Hence, identifying evidence-based strategies to promote and sustain health-related behavior change is critical to improving U.S. population health. In this report, we review research demonstrating the efficacy of voucher-based contingency management delivered alone or in combination with other interventions for treating substance use disorders and other health-related behavior problems. The efficacy supporting these interventions is robust and discernible at the level of controlled randomized clinical trials and meta-analyses. Unfortunately, these evidence-based interventions are being underutilized in routine clinical care for substance use disorders, although they are used broadly in private-sector wellness programs and international programs to reduce chronic poverty. This report reviews the evidence supporting the efficacy of voucher-based contingency management using projects developed at the University of Vermont as exemplars and discusses dissemination of the model to public and private sector efforts to improve individual and population health.

Modeling cocaine relapse in rodents: Behavioral considerations and circuit mechanisms

Addiction is a chronic relapsing disorder, in that most addicted individuals who choose to quit taking drugs fail to maintain abstinence in the long-term. Relapse is especially likely when recovering addicts encounter risk factors like small "priming" doses of drug, stress, or drug-associated cues and locations. In rodents, these same factors reinstate cocaine seeking after a period of abstinence, and extensive preclinical work has used priming, stress, or cue reinstatement models to uncover brain circuits underlying cocaine reinstatement. Here, we review common rat models of cocaine relapse, and discuss how specific features of each model influence the neural circuits recruited during reinstated drug seeking. To illustrate this point, we highlight the surprisingly specific roles played by ventral pallidum subcircuits in cocaine seeking reinstated by either cocaine-associated cues, or cocaine itself. One goal of such studies is to identify, and eventually to reverse the specific circuit activity that underlies the inability of some humans to control their drug use. Based on preclinical findings, we posit that circuit activity in humans also differs based on the triggers that precipitate craving and relapse, and that associated neural responses could help predict the triggers most likely to elicit relapse in a given person. If so, examining circuit activity could facilitate diagnosis of subgroups of addicted people, allowing individualized treatment based on the most problematic risk factors.

Effects of alcohol dependence on discrete choice between alcohol and saccharin

Dependence on drugs has enduring effects on drug intake and relapse. The role of choice in enhanced susceptibility to drug use in drug dependence has been little studied. Here we determine the effects of alcohol dependence on the choice between alcohol and a non-drug reward, saccharin, using the discrete choice model in food-restricted male rats. We trained rats to self-administer alcohol (12% w/v) and saccharin (0.05, 0.1%), tested their choice of alcohol vs. saccharin, and determined the effects of deprivation and intertrial interval (ITI) duration on choice. We then determined the effects of alcohol dependence, induced by repeated intermittent exposure to alcohol vapor on choice of alcohol vs. saccharin (0.1%) in discrete choice trials as well as on the effects of adulteration of alcohol with quinine on choice. We trained another group of rats to self-administer intravenous (i.v.) nicotine (0.03 mg/kg/infusion) and oral saccharin (0.1%), determined their choice, and examined the roles of ITI duration and concurrent access on choice. Rats chose equivalent amounts of 0.05% saccharin and 12% alcohol, showed a stronger choice for 0.1% saccharin, and alcohol and saccharin choice were modestly decreased and increased, respectively, by deprivation. Alcohol dependence led to profound increases in the choice of alcohol over saccharin while adulteration of alcohol with quinine did not affect choice in non-dependent or dependent rats. Rats showed marked choice for 0.1% saccharin over i.v. nicotine. The strong effect that dependence had on alcohol choice is an important validation of the discrete choice procedure.

Diminished alternative reinforcement as a mechanism linking conduct problems and substance use in adolescence: a longitudinal examination

AIMS

To determine whether diminished alternative reinforcement (i.e. engagement and enjoyment from substance-free activities) mediated the longitudinal association of conduct problems with substance use in early-mid-adolescence.

DESIGN

Structural equation modeling tested whether the association between wave 1 (baseline) conduct problems and wave 3 (24-month follow-up) substance use outcomes was mediated by diminished alternative reinforcement at wave 2 (12-month follow-up). Additional analyses tested whether sex and socio-economic status moderated this association.

SETTING

Ten high schools in Los Angeles, CA, USA, 2013-15.

PARTICIPANTS

Students (n = 3396, 53.5% female, mean [standard deviation (SD)] age at wave 1 baseline = 14.1 (0.42) years).

MEASUREMENTS

Self-reported conduct problems (11-item questionnaire), alternative reinforcement (44-item questionnaire) and use of alcohol, marijuana and combustible cigarettes during the past 6 months (yes/no) and the past 30 days (nine-level ordinal response based on days used in past 30 days).

RESULTS

Significant associations of wave 1 conduct problems with wave 3 marijuana use during the past 6 months (β = 0.25) and past 30 days (β = 0.26) were mediated by wave 2 diminished alternative reinforcement (β_{indirect effect} : 6 months = 0.013, 30 days = 0.017, Ps < 0.001). Associations of conduct problems with alcohol or combustible cigarette use were not mediated by alternative reinforcement. All associations did not differ by sex and socio-economic status.

CONCLUSIONS

Diminished alternative reinforcement may be a modifiable mechanism linking early adolescent conduct problems and subsequent marijuana use that could be targeted in prevention programs to offset the adverse health and social sequelae associated with comorbid conduct problems and marijuana use in early-mid adolescence.

Crack cocaine users views regarding treatment with contingency management in Brazil

BACKGROUND

Contingency management (CM) has recently shown efficacy in promoting abstinence and retention in treatment among crack cocaine users in Brazil. However, partially because of unawareness and resistance among health care providers, CM has not been widely employed. The objective of this study was to conduct a secondary analysis in order to evaluate how CM participants perceive their treatment experience.

METHODS

Twenty-seven crack cocaine users, previously assigned to 12 weeks of CM treatment, were assessed with a structured questionnaire designed to assess their personal opinion of, difficulty in understanding, and acceptance of the CM intervention, as well as their opinion regarding its impact on their treatment responses.

RESULTS

Descriptive analyses showed that 92.6% of the participants found it very easy to understand the CM protocol. All participants reported liking their CM experience quite a bit. For the perceived effects of CM on their treatment response, 81.5% of the participants stated that CM helped them considerably, the mean score for the impact of CM on treatment response (out of a maximum of 10) being 9 (SD = 1.5). When asked if they believed CM could help other people with crack cocaine dependence, 92.6% of the participants stated that CM could help such people a lot and 7.4% stated that it could help them a little.

CONCLUSIONS

From the perspective of the patients, CM was easily assimilated, easily accepted, and had a direct positive effect on treatment response. These findings provide additional support for the incorporation of CM into substance abuse treatment services in Brazil.

Is the concept of compulsion useful in the explanation or description of addictive behaviour and experience?

The concept of compulsion, in which addictive behaviour is said to be carried out against the will, is central to the disease theory of addiction and ubiquitous in modern definitions. The aims of this article are: (i) to describe various meanings of compulsion in the literature; (ii) to compare the part thought to be played by compulsion in addiction with its suggested role in obsessive-compulsive disorder; (iii) to critically examine the place of compulsion in influential neurobiological accounts of addiction; (iv) to summarise the empirical evidence bearing on the usefulness of the compulsion concept, evidence that seems at first sight incompatible with the notion of compulsion. This is followed by a discussion of which possible meanings of compulsion can survive an empirical test and what role they might play in understanding addiction, paying particular attention to a distinction between strong and weak senses of compulsion. A conclusion is that addictive behaviour cannot be considered compulsive at the time it is carried out, though other possible meanings of compulsion as an explanation or description of addictive behaviour and experience are discussed. Among other conclusions, it is suggested that, although in some senses of the term it may seem arbitrary whether or not 'compulsion' should be retained, its use has important consequences for the public understanding of addiction, and is likely to deter people's attempts to overcome their addictions and their chances of success.

Are Cocaine-Seeking "Habits" Necessary for the Development of Addiction-Like Behavior in Rats?

Drug self-administration models of addiction typically require animals to make the same response (e.g., a lever-press or nose-poke) over and over to procure and take drugs. By their design, such procedures often produce behavior controlled by stimulus-response (S-R) habits. This has supported the notion of addiction as a "drug habit," and has led to considerable advances in our understanding of the neurobiological basis of such behavior. However, to procure such drugs as cocaine, addicts often require considerable ingenuity and flexibility in seeking behavior, which, by definition, precludes the development of habits. To better model drug-seeking behavior in addicts, we first developed a novel cocaine self-administration procedure [puzzle self-administration procedure (PSAP)] that required rats to solve a new puzzle every day to gain access to cocaine, which they then self-administered on an intermittent access (IntA) schedule. Such daily problem-solving precluded the development of S-R seeking habits. We then asked whether prolonged PSAP/IntA experience would nevertheless produce "symptoms of addiction." It did, including escalation of intake, sensitized motivation for drug, continued drug use in the face of adverse consequences, and very robust cue-induced reinstatement of drug seeking, especially in a subset of "addiction-prone" rats. Furthermore, drug-seeking behavior continued to require dopamine neurotransmission in the core of the nucleus accumbens (but not the dorsolateral striatum). We conclude that the development of S-R seeking habits is not necessary for the development of cocaine addiction-like behavior in rats.SIGNIFICANCE STATEMENT Substance-use disorders are often characterized as "habitual" behaviors aimed at obtaining and administering drugs. Although the actions involved in consuming drugs may involve a rigid repertoire of habitual behaviors, evidence suggests that addicts must be very creative and flexible when trying to procure drugs, and thus drug seeking cannot be governed by habit alone. We modeled flexible drug-seeking behavior in rats by requiring animals to solve daily puzzles to gain access to cocaine. We find that habitual drug-seeking isn't necessary for the development of addiction-like behavior, and that our procedure doesn't result in transfer of dopaminergic control from the ventral to dorsal striatum. This approach may prove useful in studying changes in neuropsychological function that promote the transition to addiction.

Editorial: 3rd Special Issue on behavior change, health, and health disparities

This Special Issue of Preventive Medicine (PM) is the 3rd that we have organized on behavior change, health, and health disparities. This is a topic of critical importance to improving U.S. population health. There is broad scientific consensus that personal behaviors such as cigarette smoking, other substance abuse, and physical inactivity/obesity are among the most important modifiable causes of chronic disease and its adverse impacts on population health. Hence, effectively promoting health-related behavior change needs to be a key component of health care research and policy. There is also broad recognition that while these problems extend throughout the population, they disproportionately impact economically disadvantaged populations and other vulnerable populations and represent a major contributor to health disparities. Thus, behavior change represents an essential step in curtailing health disparities, which receives special attention in this 3rd Special Issue. We also devote considerable space to the longstanding challenges of reducing cigarette smoking and use of other tobacco and nicotine delivery products in vulnerable populations, obesity, and for the first time food insecurity. Across each of these topics we include contributions from highly accomplished policymakers and scientists to acquaint readers with recent accomplishments as well as remaining knowledge gaps and challenges.

Some current dimensions of the behavioral economics of health-related behavior change

Health-related behaviors such as tobacco, alcohol and other substance use, poor diet and physical inactivity, and risky sexual practices are important targets for research and intervention. Health-related behaviors are especially pertinent targets in the United States, which lags behind most other developed nations on common markers of population health. In this essay we examine the application of behavioral economics, a scientific discipline that represents the intersection of economics and psychology, to the study and promotion of health-related behavior change. More specifically, we review what we consider to be some core dimensions of this discipline when applied to the study health-related behavior change. Behavioral economics (1) provides novel conceptual systems to inform scientific understanding of health behaviors, (2) translates scientific understanding into practical and effective behavior-change interventions, (3) leverages varied aspects of behavior change beyond increases or decreases in frequency, (4) recognizes and exploits trans-disease processes and interventions, and (5) leverages technology in efforts to maximize efficacy, cost effectiveness, and reach. These dimensions are overviewed and their implications for the future of the field discussed.

Editorial: 2nd Special Issue on behavior change, health, and health disparities

This Special Issue of Preventive Medicine (PM) is the 2nd that we have organized on behavior change, health, and health disparities. This is a topic of fundamental importance to improving population health in the U.S. and other industrialized countries that are trying to more effectively manage chronic health conditions. There is broad scientific consensus that personal behavior patterns such as cigarette smoking, other substance abuse, and physical inactivity/obesity are among the most important modifiable causes of chronic disease and its adverse impacts on population health. As such behavior change needs to be a key component of improving population health. There is also broad agreement that while these problems extend across socioeconomic strata, they are overrepresented among more economically disadvantaged populations and contribute directly to the growing problem of health disparities. Hence, behavior change represents an essential step in curtailing that unsettling problem as well. In this 2nd Special Issue, we devote considerable space to the current U.S. prescription opioid addiction epidemic, a crisis that was not addressed in the prior Special Issue. We also continue to devote attention to the two largest contributors to preventable disease and premature death, cigarette smoking and physical inactivity/obesity as well as risks of co-occurrence of these unhealthy behavior patterns. Across each of these topics we included contributions from highly accomplished policy makers and scientists to acquaint readers with recent accomplishments as well as remaining knowledge gaps and challenges to effectively managing these important chronic health problems.

Differential vulnerability to the punishment of cocaine related behaviours: effects of locus of punishment, cocaine taking history and alternative reinforcer availability

BACKGROUND

The availability of alternative reinforcement has been shown to reduce drug use, but it remains unclear whether it facilitates a reduction or cessation of drug seeking or taking.

OBJECTIVES

We compared the effects of punishment of cocaine seeking or taking behaviour after brief or extended cocaine-taking histories when behavioural reallocation was facilitated or not by making available an alternative ingestive reinforcer (sucrose).

METHODS

In the first experiment, punishment of either seeking or taking responses was introduced immediately after training on the seeking-taking chained schedule. In the second experiment, punishment of cocaine seeking was introduced after 12 additional days of either 1 or 6 h daily access to cocaine self-administration. In both experiments, beginning 1 week before the introduction of punishment, a subset of rats had concurrent nose poke access to sucrose while seeking or taking cocaine.

RESULTS

The presence of an alternative source of reinforcement markedly facilitated behavioural reallocation from punished cocaine taking after acquisition. It also facilitated punishment-induced suppression of cocaine seeking after an extensive cocaine self-administration history likely by prompting goal-directed motivational control over drug use. However, a significant proportion of rats were deemed compulsive-maintaining drug use after an extensive cocaine history despite the presence of abstinence-promoting positive and negative incentives.

CONCLUSION

Making available an alternative reinforcer facilitates disengagement from punished cocaine use through at least two different processes but remains ineffective in a subpopulation of vulnerable animals, which continued to seek cocaine despite the aversive consequence of punishment and the presence of the alternative positive reinforcer.

Comparison of behavioral treatment conditions in buprenorphine maintenance

BACKGROUND AND AIMS

The Controlled Substances Act requires physicians in the United States to provide or refer to behavioral treatment when treating opioid-dependent individuals with buprenorphine; however, no research has examined the combination of buprenorphine with different types of behavioral treatments. This randomized controlled trial compared the effectiveness of four behavioral treatment conditions provided with buprenorphine and medical management (MM) for the treatment of opioid dependence.

DESIGN

After a 2-week buprenorphine induction/stabilization phase, participants were randomized to one of four behavioral treatment conditions provided for 16 weeks: cognitive behavioral therapy (CBT = 53); contingency management (CM = 49); both CBT and CM (CBT + CM = 49); and no additional behavioral treatment (NT = 51).

SETTING

Study activities occurred at an out-patient clinical research center in Los Angeles, California, USA.

PARTICIPANTS

Included were 202 male and female opioid-dependent participants.

MEASUREMENTS

Primary outcome was opioid use, measured as a proportion of opioid-negative urine results over the number of tests possible. Secondary outcomes include retention, withdrawal symptoms, craving, other drug use and adverse events.

FINDINGS

No group differences in opioid use were found for the behavioral treatment phase (χ2  = 1.25, P = 0.75), for a second medication-only treatment phase, or at weeks 40 and 52 follow-ups. Analyses revealed no differences across groups for any secondary outcome.

CONCLUSION

There remains no clear evidence that cognitive behavioural therapy and contingency management reduce opiate use when added to buprenorphine and medical management in opiate users seeking treatment.

Delay discounting of food and remifentanil in rhesus monkeys

RATIONALE

Drug abuse can be conceptualized as choice between drug and nondrug reinforcers in which drug choice is excessive; factors impacting drug taking can be examined using procedures in which subjects choose between drug and an alternative reinforcer.

OBJECTIVE

This experiment examined the effects of delayed reinforcement on choice between food and the mu-opioid receptor agonist remifentanil.

METHODS

Rhesus monkeys responded under a concurrent fixed-ratio 5, fixed-ratio 5 schedule in which responding on one lever delivered one food pellet and responding on another lever delivered an i.v. infusion.

RESULTS

With no delay, monkeys responded predominantly for food rather than saline or small doses of remifentanil; as the dose of remifentanil increased (0.1-1.0 μg/kg/infusion), monkeys responded more for drug. Delaying delivery (30-240 s) of 0.32 and not 1.0 μg/kg/infusion of remifentanil (food delivered immediately) decreased responding for drug and increased responding for food, resulting in a rightward shift in the remifentanil dose-effect curve. Delaying delivery of food (60-240 s) when doses of remifentanil smaller than 0.32 μg/kg/infusion (but not saline) were available decreased responding for food and increased responding for drug, resulting in a leftward shift in the remifentanil dose-effect curve.

CONCLUSION

These results provide evidence that delaying the delivery of a mu-opioid receptor agonist reduces its potency as a positive reinforcer; more importantly, delaying the delivery of an alternative nondrug reinforcer (e.g., food) enhances the reinforcing potency of the agonist. Thus, understanding the factors that control substance abuse requires examination of contingencies for both drug and nondrug reinforcers.

Duration effects in contingency management treatment of methamphetamine disorders

The primary aim of this study was to determine whether different durations of contingency management (CM) in conjunction with psychosocial treatment produced different rates of abstinence among methamphetamine dependent individuals. Participants were randomized to one of the four 16-week treatment conditions: standard psychosocial treatment or psychosocial treatment plus one of the three durations of CM (one-month, two-month, or four-month). A total of 118 participants were randomized to the four treatment conditions. There were significant differences across treatment conditions for number of consecutive days of methamphetamine abstinence (p<0.05). These differences were in the hypothesized direction, as participants were more likely to remain abstinent through the 16-week trial as CM duration increased. A significant effect of treatment condition (p<0.05) and time (p<0.05) on abstinence over time was also found. Longer durations of CM were more effective for maintaining methamphetamine abstinence.

A history of alternative reinforcement reduces stimulus generalization of ethanol-seeking in a rat recovery model

BACKGROUND

Longer periods of recovery reduce the likelihood of relapse, which may be due to a reduced ability of various stimuli to occasion alcohol or drug seeking. However, this hypothesis remains largely uninvestigated.

METHODS

Here we assessed the ability of intermediate stimuli to occasion responding for ethanol in rats trained to discriminate an 8 kHz tone signaling a food fixed-ratio (FR) of 5 and an ethanol FR5, from a 16 kHz tone signaling a food FR150 and ethanol FR5. In the presence of the 8 kHz tone responding for food predominates, and in the presence of the 16 kHz tone, responding for ethanol predominates.

RESULTS

In the context of alternation between these conditions, varying the tone from 8 to 16 kHz produces a graded increase in ethanol (versus food) responding, consistent with a stimulus generalization function. A recent history of responding under food-predominant choice conditions, either during the test session or in the four sessions that precede it shifts the generalization function downwards. Extending this history to nine sessions shifts the curve further downwards. The stimulus generalization function was similar in a separate group, trained with different relative ratios for food and ethanol, but with similar behavioral allocation under each discriminative stimulus. Finally, withholding access to food and ethanol for 4 or 16 sessions did not affect the stimulus generalization gradient.

CONCLUSION

These results suggest that longer histories of reinforced alternative behavior might reduce the likelihood of relapse by decreasing the control exerted over alcohol- or drug-seeking by stimuli similar to those that previously occasioned alcohol- or drug-seeking.

Financial incentives for smoking cessation among pregnant and newly postpartum women

OBJECTIVE

Smoking during pregnancy is the leading preventable cause of poor pregnancy outcomes in the U.S., causing serious immediate and longer-term adverse effects for mothers and offspring. In this report we provide a narrative review of research on the use of financial incentives to promote abstinence from cigarette smoking during pregnancy, an intervention wherein women earn vouchers exchangeable for retail items contingent on biochemically-verified abstinence from recent smoking.

METHODS

Published reports based on controlled trials are reviewed. All of the reviewed research was conducted by one of two research groups who have investigated this treatment approach.

RESULTS

Results from six controlled trials with economically disadvantaged pregnant smokers support the efficacy of financial incentives for increasing smoking abstinence rates antepartum and early postpartum. Results from three trials provide evidence that the intervention improves sonographically estimated fetal growth, mean birth weight, percent of low-birth-weight deliveries, and breastfeeding duration.

CONCLUSIONS

The systematic use of financial incentives has promise as an efficacious intervention for promoting smoking cessation among economically disadvantaged pregnant and recently postpartum women and improving birth outcomes. Additional trials in larger and more diverse samples are warranted to further evaluate the merits of this treatment approach.

Drug treatments in criminal justice settings

The available evidence suggests that drug treatment can lead to modest, but real, reductions in criminal offending for drug-using criminal offenders. Considering the scope of the problem of drug-related crime and the expense of dealing with these issues, even marginal improvements can lead to important aggregate savings in both economic and humanitarian terms. More randomized, controlled trials of drug treatment in criminal justice programs will lead to a more sophisticated understanding of what kind of treatment works best for this group.

Comparison of intranasal methamphetamine and d-amphetamine self-administration by humans

AIMS

There are no studies directly comparing self-administration of methamphetamine and d-amphetamine by humans. This study compared intranasal methamphetamine- and d-amphetamine self-administration and characterized the mood, performance and physiological effects produced by the drugs.

DESIGN

A randomized, double-blind, placebo-controlled, cross-over study.

SETTING

An out-patient research unit at the New York State Psychiatric Institute.

PARTICIPANTS

Male recreational methamphetamine users (n = 13).

MEASUREMENTS

Five 2-day blocks of sessions were conducted. On the first day of each block, participants 'sampled' a single methamphetamine or d-amphetamine dose (0, 12, 50 mg/70 kg) and a monetary reinforcer ($5 or $20). Amphetamine plasma levels, cardiovascular, mood, and psychomotor performance effects were assessed before drug administration and repeatedly thereafter. On the second day of each block, participants chose between the sampled reinforcers (drug or money).

FINDINGS

There were no significant differences between the drugs on the majority of measures. Under the $5 condition, both amphetamines increased self-administration dose-dependently, with 41% drug choices overall. Under the $20 condition, only 17% drug options were selected. Both drugs increased cardiovascular activity and 'positive' mood, although methamphetamine produced more prominent effects on some measures (e.g. heart rate and ratings of 'high').

CONCLUSIONS

Methamphetamine and d-amphetamines appear to produce a similar dose-related profile of effects in humans, which supports their equivalence for abuse potential.

Exercise as a potential treatment for drug abuse: evidence from preclinical studies

Epidemiological studies reveal that individuals who engage in regular aerobic exercise are less likely to use and abuse illicit drugs. Until recently, very few studies had examined the causal influences that mediate this relationship, and it was not clear whether exercise was effective at reducing substance use and abuse. In the past few years, several preclinical studies have revealed that exercise reduces drug self-administration in laboratory animals. These studies have revealed that exercise produces protective effects in procedures designed to model different transitional phases that occur during the development of, and recover from, a substance use disorder (e.g., acquisition, maintenance, escalation, and relapse/reinstatement of drug use). Moreover, recent studies have revealed several behavioral and neurobiological consequences of exercise that may be responsible for its protective effects in these assays. Collectively, these studies have provided convincing evidence to support the development of exercise-based interventions to reduce compulsive patterns of drug intake in clinical and at-risk populations.

Alternative reinforcer response cost impacts cocaine choice in humans

Cocaine use disorders are an unrelenting public health concern. Behavioral treatments reduce cocaine use by providing non-drug alternative reinforcers. The purpose of this human laboratory experiment was to determine how response cost for non-drug alternative reinforcers influenced cocaine choice. Seven cocaine-using, non-treatment-seeking subjects completed a crossover, double-blind protocol in which they first sampled doses of intranasal cocaine (5, 10, 20 or 30 mg) and completed a battery of subject-rated and physiological measures. Subjects then made eight discrete choices between the sampled dose and an alternative reinforcer (US$0.25). The response cost to earn a cocaine dose was always a fixed ratio (FR) of 100 responses. The response cost for the alternative reinforcer varied across sessions (FR1, FR10, FR100, FR1000). Dose-related increases were observed for cocaine choice. Subjects made fewer drug choices when the FR requirements for the alternative reinforcers were lower than that for drug relative to when the FR requirements were equal to or higher than that for drug. Intranasal cocaine also produced prototypical stimulant-like subject-rated and physiological effects (e.g., increased ratings of Like Drug; elevated blood pressure). These data demonstrate that making alternative reinforcers easier to earn reduces cocaine self-administration, which has implications for treatment efforts.

Contingency management with community reinforcement approach or twelve-step facilitation drug counseling for cocaine dependent pregnant women or women with young children

BACKGROUND

Cocaine abuse among women of child-bearing years is a significant public health problem. This study evaluated the efficacy of contingency management (CM), the community reinforcement approach (CRA), and twelve-step facilitation (TSF) for cocaine-dependent pregnant women or women with young children.

METHODS

Using a 2×2 study design, 145 cocaine dependent women were randomized to 24 weeks of CRA or TSF and to monetary vouchers provided contingent on cocaine-negative urine tests (CM) or non-contingently but yoked in value (voucher control, VC). Primary outcome measures included the longest consecutive period of documented abstinence, proportion of cocaine-negative urine tests (obtained twice-weekly), and percent days using cocaine (PDC) during treatment. Documented cocaine abstinence at baseline and 3, 6, 9 and 12 months following randomization was a secondary outcome.

FINDINGS

CM was associated with significantly greater duration of cocaine abstinence (p<.01), higher proportion of cocaine-negative urine tests (p<0.01), and higher proportion of documented abstinence across the 3-, 6-, 9- and 12-month assessments (p<0.05), compared to VC. The differences between CRA and TSF were not significant for any of these measures (all p values ≥0.75). PDC decreased significantly from baseline during treatment in all four groups (p<0.001) but did not differ significantly between CM and VC (p=0.10) or between TSF and CRA (p=0.23).

INTERPRETATION

The study findings support the efficacy of CM for cocaine dependent pregnant women and women with young children but do not support greater efficacy of CRA compared to TSF or differential efficacy of CM when paired with either CRA or TSF.

Stress decreases the ability to resist smoking and potentiates smoking intensity and reward

We have developed a novel human laboratory model to examine two primary aspects of stress-precipitated tobacco relapse: (1) Does stress reduce the ability to resist the first cigarette? (2) Once the first cigarette is initiated, does stress facilitate subsequent smoking? Using a within-subject design, daily smokers (n = 37) who were nicotine deprived overnight received a personalized imagery induction (stress or neutral) on two separate days, and then had the option of initiating a tobacco self-administration session or delaying initiation for up to 50 min in exchange for three levels of monetary reinforcement. Subsequently, the tobacco self-administration session entailed a 1-hour period in which subjects could choose to smoke using a smoking topography system. Following the stress induction, subjects were less able to resist smoking, smoked more intensely (increased puffs, shorter inter-puff interval, and greater peak puff velocity), and perceived greater satisfaction and reward from smoking. Stress significantly increased hypothalamus-pituitary-adrenal (HPA) axis reactivity, tobacco craving, negative emotion, and physiologic reactivity relative to the neutral condition. In addition, increased cortisol, ACTH, and tobacco craving were associated with reduced ability to resist smoking following stress. These findings have implications for understanding the impact of stress on smoking relapse and model development to assess smoking lapse behavior.

Intranasal cocaine functions as reinforcer on a progressive ratio schedule in humans

Cocaine dependence continues to be a worldwide public health concern. Although the majority of individuals reporting cocaine use do so via the intranasal route, relatively few laboratory experiments have examined the reinforcing effects of cocaine administered intranasally. The purpose of this experiment was to measure the reinforcing effects of intranasal cocaine using a progressive ratio schedule in which eight cocaine-using subjects chose between doses of cocaine (4 [placebo], 15, 30 and 45 mg) and an alternative reinforcer ($0.25). During each session, subjects first sampled the dose of cocaine available that day and then made six choices between that dose and money, which were available on concurrent progressive ratio schedules of responding. Break points for active cocaine doses were higher than those for placebo but no statistically significant active versus placebo dose effects were observed on subject-rated or physiological measures. These data demonstrate that intranasal cocaine functions as a reinforcer under a progressive ratio schedule in humans. Future research should test higher cocaine doses and larger values of the alternative reinforcer. These procedures may be useful for examining the influence of putative pharmacological and behavioral interventions on intranasal cocaine self-administration.

Using a novel alternative to drug choice in a human laboratory model of a cocaine binge: a game of chance

Human laboratory studies have shown that, once initiated, cocaine self-administration is difficult to disrupt using non-drug alternatives. This inpatient study examined whether binge self-administration of cocaine could be altered by an immediate, non-drug reinforcer. Ten cocaine-dependent participants completed 5 consecutive laboratory session days with 2 sessions per day (a model binge), 9 days where cocaine was not available, and subsequent 2 laboratory session days where cocaine was again available (a second model binge). In each laboratory session, participants could choose to either self-administer smoked cocaine or play a game of chance by drawing a pre-determined number of balls from a bingo wheel. Balls were worth monetary amounts from $0 to $20. Participants' choice to smoke cocaine varied as a function of number of balls drawn. Thus, this game of chance served as an alternative reinforcer to smoking cocaine. Choice varied lawfully as a function of the number of opportunities to earn money indicating that an immediate behavioral alternative can reduce cocaine self-administration after initiation of use. The current model could be used to evaluate whether behavioral and pharmacological manipulations shift choice from cocaine to a non-drug alternative.

Reduction of extinction and reinstatement of cocaine seeking by wheel running in female rats

RATIONALE AND OBJECTIVES

Previous work has shown that wheel running reduced the maintenance of cocaine self-administration in rats. In the present study, the effect of wheel running on extinction and reinstatement of cocaine seeking was examined. Female rats were trained to run in a wheel during 6-h sessions, and they were then catheterized and placed in an operant conditioning chamber where they did not have access to the wheel but were allowed to self-administer iv cocaine. Subsequently, rats were divided into four groups and were tested on the extinction and reinstatement of cocaine seeking while they had varying access to a wheel in an adjoining compartment. The four groups were assigned to the following wheel access conditions: (1) wheel running during extinction and reinstatement (WER), (2) wheel running during extinction and a locked wheel during reinstatement (WE), (3) locked wheel during extinction and wheel running during reinstatement (WR), and (4) locked wheel during extinction and reinstatement (WL). WE and WR were retested later to examine the effect of one session of wheel access on cocaine-primed reinstatement.

RESULTS

There were no group differences in wheel revolutions, in rate of acquisition of cocaine self-administration, or in responding during maintenance when there was no wheel access. However, during extinction, WE and WER responded less than WR and WL. WR and WER had lower cocaine-primed reinstatement than WE and WL. One session of wheel exposure in WE also suppressed cocaine-primed reinstatement.

CONCLUSIONS

Wheel running immediately and effectively reduced cocaine-seeking behavior, but concurrent access to running was necessary. Thus, exercise is a useful and self-sustaining intervention to reduce cocaine-seeking behavior.

Monetary alternative reinforcers more effectively decrease intranasal cocaine choice than food alternative reinforcers

Cocaine dependence continues to be a significant public health concern. Contingency management, wherein alternative reinforcers are made available upon cocaine abstinence, has shown promise for decreasing cocaine use. Other research has modeled this effect and demonstrated that alternative reinforcers also reduce cocaine self-administration in the laboratory. Results from both clinical and laboratory studies suggest that the type and value of alternative reinforcers influences their ability to decrease drug choice. The purpose of the present experiment was to determine the effect of money or food alternative reinforcers, valued at $0.01, 0.25, 0.50 and 1.00, on intranasal cocaine (4 [placebo] and 30 mg) choice. Cocaine was chosen to a greater extent than placebo across alternative reinforcer types and values, but the monetary alternative reinforcer suppressed drug choice to a greater degree than the food reinforcer. These results are concordant with previous findings and suggest that money may be a more effective alternative reinforcer for decreasing cocaine use. Future research should determine the sensitivity of this model to specific behavioral aspects of contingency management and whether food could compete with drugs as reinforcers in humans under laboratory conditions.

Delay of smoking gratification as a laboratory model of relapse: effects of incentives for not smoking, and relationship with measures of executive function

Nineteen nicotine-deprived cigarette smokers received monetary rewards for each minute they chose not to initiate smoking in 2-h laboratory sessions followed by a 30-min period of enforced abstinence from smoking. Reinforcer amounts were delivered according to one of three schedules: increasing, decreasing, and constant. Relapse time (time until first cigarette) was shortest in the decreasing condition, longest in the increasing condition, and intermediate in the constant condition. All differences were significant except in the constant-decreasing comparison. The relationships between a battery of baseline assessments and relapse times were examined. Relapse times were predicted by delay-discounting coefficients (k) for $10 and $1000 in money and for $1000 of cigarettes. Relapse times were also predicted by the number of cigarettes smoked daily and a Wisconsin Card Sorting Test score. Performance on the Stroop Task and the Fagerström Test for Nicotine Dependence differentiated participants dichotomized into those who relapsed 'earlier' in sessions versus those who first smoked 'later'. The variability in some scores from smoking-urges and affect questionnaires administered after smoking-room sessions was explained by measures related to in-session nicotine intake. Results are discussed as they relate to contingency-management procedures, predictors of relapse, and the competing neurobehavioral decision systems theory of addiction.

Social experiences affect reinstatement of cocaine-induced place preference in mice

RATIONALE

Drug addiction is a multifactorial disorder resulting from an interaction between genetic and environmental factors, and negative and positive environmental conditions may increase or reduce, respectively, vulnerability to drug addiction.

OBJECTIVES

The influence of different social experiences on the acquisition, extinction, and reinstatement of a cocaine-induced conditioned place preference (CPP) was evaluated.

METHODS

In experiment 1, adolescent and adult male OF1 mice housed under four different conditions (grouped, isolated, crowded, and cohabitating with a female) were conditioned with 50, 12.5, or 3.125 mg/kg of cocaine. All mice underwent extinction sessions until the CPP was extinguished. The effects of cocaine priming injections on the reinstatement of CPP were then evaluated. In experiment 2, the effect of different social experiences on the maintenance and reinstatement of cocaine-CPP in adult mice was studied.

RESULTS

Although housing conditions did not affect the acquisition of cocaine-CPP, it did modify reinstatement after extinction. Adolescent mice living in crowded conditions or cohabitating with a female did not present reinstatement after cocaine priming. Similarly, neither isolated adult mice nor adults cohabitating with a female presented reinstatement. In grouped adult mice, isolation after acquisition of the CPP and social defeat before reinstatement increased the vulnerability to reinstatement induced by cocaine priming. Conversely, both exposure to females and a brief social interaction undermined cocaine-induced reinstatement.

CONCLUSIONS

Social experiences modify vulnerability to reinstatement, acting as prevention or risk factors in the development of drug addiction.

An overview of the emergence of disparities in smoking prevalence, cessation, and adverse consequences among women

This report reviews epidemiologic findings demonstrating the emergence of disparities in smoking prevalence against the backdrop of general declines in smoking over time among women in the United States. In addition to socioeconomic differences in overall smoking prevalence, this report examines evidence of emerging disparities for specific stages of smoking, including progression to heavy smoking, smoking cessation, and lung cancer mortality. Findings from population-based studies indicate that social disadvantage signals higher likelihood of involvement with each stage of smoking and the gap by level of disadvantage is increasing over time. Disparities in smoking outcomes have been observed for both men and women but in many cases appear to be greater for women. This pattern of results in which disparities emerge in a dynamic system of change in smoking are consistent with Link and Phelan's theory of social conditions as a fundamental cause of disease, and has important implications for approaches to reduce the public health burden of smoking.

Financing a voucher program for cocaine abusers through community donations in Spain

This study analyzed the viability of financing a voucher program for cocaine addicts in Spain through public and private donations. Of the 136 companies contacted, 52 (38%) provided donations. The difference between the benefits (15,670 Euro/ $20,371) and the costs (3734 Euro/ $4854) was 11,936 Euro/ $15,517. The type of reinforcer a company can offer, the size of the company, and the time elapsed before responding may be determining variables in a company's decision whether to collaborate.

Developing human laboratory models of smoking lapse behavior for medication screening

Use of human laboratory analogues of smoking behavior can provide an efficient, cost-effective mechanistic evaluation of a medication signal on smoking behavior, with the result of facilitating translational work in medications development. Although a number of human laboratory models exist to investigate various aspects of smoking behavior and nicotine dependence phenomena, none have yet modeled smoking lapse behavior. The first instance of smoking during a quit attempt (i.e. smoking lapse) is highly predictive of relapse and represents an important target for medications development. Focusing on an abstinence outcome is critical for medication screening as the US Food and Drug Administration approval for cessation medications is contingent on demonstrating effects on smoking abstinence. This paper outlines a three-stage process for the development of a smoking lapse model for the purpose of medication screening. The smoking lapse paradigm models two critical features of lapse behavior: the ability to resist the first cigarette and subsequent ad libitum smoking. Within the context of the model, smokers are first exposed to known precipitants of smoking relapse (e.g. nicotine deprivation, alcohol, stress), and then presented their preferred brand of cigarettes. Their ability to resist smoking is then modeled and once smokers 'give in' and decide to smoke, they participate in a tobacco self-administration session. Ongoing and completed work developing and validating these models for the purpose of medication screening is discussed.

Review. Positron emission tomography imaging studies of dopamine receptors in primate models of addiction

Animal models have provided valuable information related to trait and state variables associated with vulnerability to drug addiction. Our brain imaging studies in monkeys have implicated D2 receptors in cocaine addiction. For example, an inverse relationship between D2 receptor availability and rates of cocaine self-administration has been documented. Moreover, environmental variables, such as those associated with formation of the social hierarchy, can impact receptor availability and sensitivity to the abuse-related effects of cocaine. Similarly, both D2 receptor availability and cocaine self-administration can be altered by chronic drug administration and fluctuations in hormone levels. In addition, cocaine self-administration can be altered in an orderly fashion by presentation of an acute stressor, such as acting as an intruder into an unfamiliar social group, which can shift the cocaine dose-response curve to the left in subordinate monkeys and to the right in dominant animals, suggesting an interaction between social variables and acute stressors. Conversely, irrespective of social rank, acute environmental enrichment, such as increasing the size of the living space, shifts the cocaine dose-response curve to the right. These findings highlight a pervasive influence of the environment in modifying the reinforcing effects of cocaine and strongly implicate brain D2 receptors.

Effect of transdermal nicotine replacement on alcohol responses and alcohol self-administration

RATIONALE

Nicotine replacement is commonly used to treat tobacco use in heavy-drinking smokers. However, few studies have examined the effect of nicotine replacement on subjective and physiological responses to alcohol and alcohol drinking behavior.

OBJECTIVE

The primary aim of this within-subject, double-blind study was to examine whether transdermal nicotine replacement (0 mg vs 21 mg/day) altered response to a low-dose priming drink and subsequent ad libitum drinking behavior.

MATERIALS AND METHODS

Subjects (n=19) were non-treatment-seeking, non-dependent heavy drinkers who were daily smokers. Six hours after transdermal patch application, subjective and physiological responses to a priming drink [designed to raise blood alcohol levels (BALs) to 0.03 g/dl] were assessed. This was followed by a 2-h self-administration period where subjects could choose to consume up to eight additional drinks (each designed to raise BALs by 0.015 g/dl) or to receive monetary reinforcement for drinks not consumed.

RESULTS

We found that 6 h after patch application, tobacco craving associated with withdrawal relief was decreased, and systolic blood pressure and heart rate were increased in the active patch condition compared to the placebo patch condition. Subjective intoxication in response to the priming drink was attenuated in the active nicotine patch condition compared to 6 h of nicotine deprivation (i.e., placebo patch). During the self-administration period, subjects had longer latencies to start drinking and consequently appeared to consume fewer drinks when administered the active patch compared to the placebo patch.

CONCLUSIONS

In heavy drinkers, transdermal nicotine replacement compared to mild nicotine deprivation attenuated subjective and physiological alcohol responses and delayed the initiation of drinking.

Effects of ambient temperature on the relative reinforcing strength of MDMA using a choice procedure in monkeys

RATIONALE

3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) is frequently used in hot environments, such as rave parties. Studies in laboratory animals have shown that ambient temperature can alter the behavioral and neurochemical effects of MDMA.

OBJECTIVE

To examine the influence of ambient temperature on the relative reinforcing strength of MDMA and reinstatement of behavior previously maintained by MDMA is the objective of the study.

METHODS

The effects of cool (18 degrees C), room (24 degrees C), and warm (31 degrees C) temperatures were examined when MDMA was available under a concurrent fixed-ratio 30 schedule of MDMA (saline, 0.03-0.3 mg/kg/injection) and food choice in rhesus monkeys (n = 5). During saline substitutions, the effect of noncontingent MDMA (0.03-0.3 mg/kg) on response allocation was examined at each ambient temperature.

RESULTS

At room temperature, MDMA choice increased as a function of dose, such that food was preferred over a low MDMA dose (0.03 mg/kg/injection), whereas higher doses were preferred over food. Elevating the ambient temperature significantly increased the relative reinforcing strength of 0.03 mg/kg/injection MDMA, and lowering the ambient temperature significantly attenuated the choice of 0.1 mg/kg/injection MDMA. Noncontingent injections of MDMA administered before a session in which saline was the alternative to food dose-dependently increased injection-lever responding; this effect was not influenced by ambient temperature.

CONCLUSIONS

These results suggest that ambient temperature can affect the relative reinforcing strength of MDMA, but not MDMA-induced reinstatement. Furthermore, these results suggest environmental strategies for decreasing the reinforcing strength of MDMA.

A Double-Blind Evaluation of Gabapentin on Alcohol Effects and Drinking in a Clinical Laboratory Paradigm

INTRODUCTION

There has been increasing interest in the use of anticonvulsant agents in the treatment of alcoholism. Anticonvulsant agents have mostly been evaluated as an alternative to benzodiazepines in the treatment of alcohol withdrawal. Among the advantages of using anticonvulsant agents in this capacity is their purported lack of interaction with alcohol (i.e., interactions that could increase psychomotor deficits, cognitive impairment, and increase intoxication). This is particularly important in the treatment of alcohol withdrawal and relapse prevention in outpatients. Unfortunately, these untoward clinical interactions between anticonvulsants and alcohol in alcoholic patients have not been thoroughly assessed. The current clinical laboratory study was conducted to evaluate the safety and tolerability of the anticonvulsant gabapentin in alcoholic subjects. In addition, the ability of gabapentin to reduce alcohol craving and consumption was evaluated.

METHODS

Thirty-five non-treatment-seeking alcoholic subjects were enrolled in a subacute human laboratory study and received double-blind treatment with up to 1,200 mg of gabapentin (n=18) or placebo (n=17) for 8 days. The safety and tolerability of gabapentin were monitored in the natural environment during the first 5 days of medication treatment and during a free-choice limited access consumption paradigm following an initial drink of alcohol in a bar-lab setting on Day 7.

RESULTS

There was no overall effect of gabapentin on drinking or craving; however, it was tolerated (e.g., mood and sedation) as well as placebo over 5 days of natural drinking. During the bar-lab drinking session, there were no differences in subjective high or intoxication between subjects treated with gabapentin or placebo.

DISCUSSION

This study provides initial evidence that the anticonvulsant gabapentin is safe if used in conjunction with alcohol consumption in alcoholic individuals. Further study is needed with this and other lab models to determine the utility and safety of gabapentin in the treatment of alcoholism.