Choice between variable and fixed cocaine injections in male rhesus monkeys.

RATIONALE: The schedule of drug availability may enhance choice of a drug. In non-human subjects, reinforcers are chosen more often when available under variable schedules of reinforcement relative to fixed schedules. OBJECTIVE: To determine whether variable-drug access is an important determinant of cocaine choice by manipulating the schedule, drug dose, and combination of schedule + dose. METHOD: Four male rhesus monkeys chose between cocaine doses (0.025-0.4 mg/kg/injection). In control conditions, the schedule and dose of each drug delivery were fixed. In other conditions, the reinforcement schedule (i.e., variable-ratio schedule), dose of each cocaine delivery, or both were variable on one lever while all aspects on the other lever remained fixed. RESULTS: When cocaine dose was equal on average (0.1 mg/kg/injection), 2 of 4 subjects chose cocaine associated with the variable schedule more than the fixed schedule. All subjects chose the variable dose that was equal on average to the fixed dose, and this difference was statistically significant. Three of 4 subjects chose cocaine associated with the variable combination over the fixed option (when the dose was equal on average). During dose-response determinations (when dose on the variable and fixed options were not equal), making the schedule, dose, or both variable generally did not alter cocaine's potency as a reinforcer. CONCLUSION: While many factors contribute to drug choice, unpredictable drug access is a feature that may be common in the natural environment and could play a key role in the allocation of behavior to drug alternatives by patients with substance-use disorders.

Perceptions about professionally and non-professionally trained hypoglycemia detection dogs.

AIMS: Patients with diabetes increasingly have questions about diabetes alert dogs. This study evaluated perceptions about dogs trained professionally or otherwise to detect glucose levels. METHODS: A link to a survey about glucose detecting dogs was announced on diabetes websites. RESULTS: 135 persons responded, with 63 answering about their child with diabetes. Most respondents obtained their dog from a professional trainer (n = 54) or trained it themselves (n = 51). Owners of self- and professionally-trained dogs were very positive about dogs' abilities to alert them to low and high glucose levels, while owners of dogs that learned entirely on their own (n = 15) reported lower frequencies of alerts and more missed hypoglycemic episodes, p<.01. Regardless of how dogs learned, perceptions about managing diabetes were improved during periods of dog ownership relative to times without, p<.001. Self-reported rates of diabetes-related hospitalizations, assistance from others for treating hypoglycemia, and accidents or near accidents while driving reduced during periods of dog ownership compared to periods without dogs, ps<.01. CONCLUSIONS: These data suggest potential effectiveness of and high satisfaction with glucose-detecting dogs. Clinicians can use these results to address pros and cons of dog ownership with patients who inquire about them.

Incentivizing behaviour change to improve diabetes care.

Behavioural economics refers to the study of psychological and cognitive factors that relate to decision-making processes. This field is being applied increasingly to health care settings, in which patients receive tangible reinforcers or incentives for meeting objective behavioural criteria consistent with healthy lifestyles. This article reviews the background and efficacy of reinforcement interventions in general, and then as applied to behaviours related to diabetes prevention and management. Specifically, reinforcement interventions have been applied with some notable success towards promoting greater attendance at medical appointments, enhancing weight loss efforts, augmenting exercising regimes, improving medication adherence and increasing blood glucose monitoring. Suggestions for promising areas of future research are provided, keeping in mind the controversial nature of these interventions.

Disordered gambling among racial and ethnic groups in the US: results from the national epidemiologic survey on alcohol and related conditions.

INTRODUCTION: Prior research suggests that racial minority groups in the United States are more vulnerable to develop a gambling disorder than whites. However, no national survey on gambling disorders exists that has focused on ethnic differences. METHODS: Analyses of this study were based on the National Epidemiologic Survey on Alcohol and Related Conditions, a large (N=43,093) nationally representative survey of the adult (> or =18 years of age) population residing in households during 2001-2002 period. Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition-Text Revision diagnoses of pathological gambling, mood, anxiety, drug use, and personality disorders were based on the Alcohol Use Disorder and Associated Disabilities Interview Schedule-DSM-IV Version. RESULTS: Prevalence rates of disordered gambling among blacks (2.2%) and Native/Asian Americans (2.3%) were higher than that of whites (1.2%). Demographic characteristics and psychiatric comorbidity differed among Hispanic, black, and white disordered gamblers. However, all racial and ethnic groups evidenced similarities with respect to symptom patterns, time course, and treatment seeking for pathological gambling. CONCLUSION: The prevalence of disordered gambling, but not its onset or course of symptoms, varies by racial and ethnic group. These varying prevalence rates may reflect, at least in part, cultural differences in gambling and its acceptability and accessibility. These data may inform the need for targeted prevention strategies for high-risk racial and ethnic groups.

Pathological gambling severity is associated with impulsivity in a delay discounting procedure.

Research and clinical expertise indicates that impulsivity is an underlying feature of pathological gambling. This study examined the extent to which impulsive behavior, defined by the rate of discounting delayed monetary rewards, varies with pathological gambling severity, assessed by the South Oaks Gambling Screen (SOGS). Sixty-two pathological gamblers completed a delay discounting task, the SOGS, the Eysenck impulsivity scale, the Addiction Severity Index (ASI), and questions about gambling and substance use at intake to outpatient treatment for pathological gambling. In the delay discounting task, participants chose between a large delayed reward (US $1000) and smaller more immediate rewards (US $1-$999) across a range of delays (6h to 25 years). The rate at which the delayed reward was discounted (k value) was derived for each participant and linear regression was used to identify the variables that predicted k values. Age, gender, years of education, substance abuse treatment history, and cigarette smoking history failed to significantly predict k values. Scores on the Eysenck impulsivity scale and the SOGS both accounted for a significant proportion of the variance in k values. The predictive value of the SOGS was 1.4 times that of the Eysenck scale. These results indicate that of the measures tested, gambling severity was the best single predictor of impulsive behavior in a delay discounting task in this sample of pathological gamblers.

Comparison of problem-gambling and non-problem-gambling youths seeking treatment for marijuana abuse.

OBJECTIVE: To evaluate the prevalence and correlates of problem gambling (PG) in marijuana-abusing adolescents. METHOD: A retrospective analysis was conducted of data collected from participants entering treatment for marijuana abuse in Philadelphia, Pennsylvania, and Hartford, Connecticut, between 1998 and 2000. RESULTS: Of 255 adolescents interviewed, 22% experienced gambling problems. Compared with non-problem gamblers (NPGs), PGs were more likely to be male, of African-American ethnicity, and to live in single-parent homes. Multivariate general linear models compared the two groups with respect to psychosocial problems. After controlling for age, gender, and race, differences between the groups emerged in drug use severity, legal difficulties, psychiatric problems, and human immunodeficiency virus risk behaviors. PGs reported a greater frequency of overall drug and alcohol use and greater intensity of marijuana use than their NPG counterparts. They had more illegal activity and greater somatization and anxiety symptoms, as well as higher levels of victimization. Compared with NPGs, PGs also reported more recent sexual partners. CONCLUSIONS: These data suggest that PG is common in marijuana-abusing youths and that they have increased psychosocial problems. These data suggest the need for early identification and treatment of PG in substance-abusing adolescents.

Contingency management in group treatment: a demonstration project in an HIV drop-in center.

This study describes a contingency management intervention applied in group treatment. In an HIV drop-in center, groups were held on Tuesdays and Thursdays for 35 weeks. An ABB'CA design was used, in which reinforcers were available in non-A phases. In the initial B phase, reinforcers were available only on Tuesdays, and they switched to Thursdays in the B' and C phases. The reinforcer was a drawing that was associated with the possibility of winning a prize. Reinforcers were provided for attending group and completing steps related to treatment goals. The number of drawings escalated with weeks of consecutive attendance and activity completion in the B phases; in the C phase, a fixed number of draws were provided. Overall, the procedure increased attendance, with an average of 0.7 clients (range 0-4) per session in the initial baseline phase to an average of seven clients (range 2-12) during reinforcement phases. The percentage of activities completed also rose from 25% during baseline to 65% during reinforcement phases. These data suggest the feasibility of a group-based contingency management intervention.

Pathological gamblers, with and without substance use disorders, discount delayed rewards at high rates.

Pathological gambling is classified as a disorder of impulse control, yet little research has evaluated behavioral indices of impulsivity in gamblers. The rates at which rewards delayed in time are subjectively devalued may be a behavioral marker of impulsivity. This study evaluated delay discounting in 60 pathological gamblers and 26 control participants. Gamblers were divided into those with (n = 21) and without (n = 39) substance use disorders. A hypothetical $1,000 reward was delayed at intervals ranging from 6 hr to 25 years, and immediate rewards varied from $1 to $999. Pathological gamblers discounted delayed rewards at higher rates than control participants, and gamblers with substance use disorders discounted delayed rewards at higher rates than non-substance-abusing gamblers. These data provide further evidence that rapid discounting of delayed rewards may be a feature central to impulse control and addictive disorders, including pathological gambling.

Challenges in the transfer of contingency management techniques: comment on Silverman et al. (2001).

This article critiques K. Silverman, D. Svikis, E. Robles, M. L. Stitzer, and G. E. Bigelow's (2001) study of a contingency management intervention for reinforcing development of job-related skills in substance abusing women. The strengths of Silverman et al.'s study include studying a patient population of major public health concern, expanding contingency management techniques to a vocational training setting, reinforcing gradual approximations, implementing the intervention for a long duration, and carefully designing and executing the experimental procedures. However, many of these strengths may also be interpreted as weaknesses if the ultimate goal is to apply contingency management techniques in self-sustaining, community-based settings. The need to evaluate long-term cost-effectiveness of these procedures is described, and the difficulties in transferring contingency management techniques to real-world settings is discussed.

The effects of housing costs on polydrug abuse patterns: a comparison of heroin, cocaine, and alcohol abusers.

This study evaluated how price of housing affects hypothetical purchasing decisions. Participants (26 heroin, 28 cocaine, and 15 alcohol abusers, and 25 controls) were exposed to 4 conditions in which they "purchased" drugs, food, housing, and entertainment. Whereas income remained constant, housing prices varied across conditions. Except for 23% of heroin abusers, participants purchased housing regardless of cost, so that income increased as housing cost decreased. Demand for food was income inelastic, whereas demand for entertainment was income elastic. Each group showed income elastic demand for their drug of choice. Hypothetical choices were reliable; drug choices were correlated with urinalysis results, and willingness to forgo housing in the simulation was correlated with time spent homeless in real life. This study shows that changes in housing prices may affect choices for drug and nondrug reinforcers.

A behavioral approach to understanding and treating pathological gambling.

This report provides a behavioral account of gambling and its treatment. It describes the similarities between gambling and other behaviors maintained by intermittent schedules of reinforcement, the relationship between response cost and gambling behaviors, and how magnitudes of reinforcers affect gambling behaviors. In addition, the relationship between immediacy of reinforcement and behavior is described. Using these behavioral phenomena, behavioral and cognitive-behavioral treatments of pathological gambling are described. Finally, we present the rationale and framework for our cognitive-behavioral treatment, and we provide a behavioral interpretation of 12-step groups.

Limits to buprenorphine dosing: a comparison between quintuple and sextuple the maintenance dose every 5 days.

The relative efficacy of quintuple and sextuple buprenorphine dosing in abating withdrawal symptoms for 120 h was compared in opioid-dependent outpatients. Fourteen subjects received buprenorphine in a double-blind, placebo-controlled, cross-over design. Daily sublingual maintenance doses were 4 mg/70 kg (n=4) and 8 mg/70 kg (n=10). After a stabilization period of daily maintenance administration, subjects received quintuple (5x daily maintenance dose) and sextuple (6x daily maintenance dose) doses every 120 h. Measures of opioid agonist and withdrawal effects were assessed daily. Subjective ratings of withdrawal were significantly greater than baseline ratings beyond 96-h post dosing under both regimens. There was no evidence, however, that those subjective ratings of withdrawal differed between the two regimens. Thus, these data suggest that sextuple buprenorphine dosing, administered every 5 days, does not abate opioid-withdrawal beyond 96 hours.

Examining the limits of the buprenorphine interdosing interval: daily, every-third-day and every-fifth-day dosing regimens.

AIMS: Opioid-dependent outpatients may be more likely to present for pharmacological treatment if less than daily dosing can be arranged. These studies compared opioid withdrawal symptoms during 24-, 72-, and 120-hour buprenorphine dosing regimens and evaluated participants' preferences for these different dosing regimens. PARTICIPANTS: Thirty-three opioid-dependent participants received daily sublingual maintenance doses of 4 mg/70 kg (n = 14) or 8 mg/70 kg (n = 19) of liquid buprenorphine. METHODS: In Study I participants received, in a random order, three dosing regimens for five repetitions of each: daily maintenance doses every 24 hours (4 or 8 mg/70 kg), triple the daily maintenance dose every 72 hours (12 or 24 mg/70 kg) and quintuple the daily maintenance dose every 120 hours (20 or 40 mg/70 kg). Doses were administered under double-blind procedures, and placebos were administered on the interposed days during the latter two regimens. Subjective and observer ratings of opioid withdrawal symptoms were assessed daily prior to receipt of each dose. In Study II, a new group of participants received each of the three dosing regimens under open-dosing procedures and then chose between the different dosing regimens. FINDINGS: Opioid withdrawal symptoms increased significantly during the every-fifth-day dosing regimen in both the blind- and open-dosing studies. In the choice phase of Study II, only one participant (7%) chose quintuple-every-fifth-day dosing over all other dosing options. CONCLUSIONS: These results suggest that the maximum duration of action of buprenorphine is less than 5 days when five times the daily maintenance dose is provided.

Delay discounting of money and alcohol in actively using alcoholics, currently abstinent alcoholics, and controls.

RATIONALE: Impulsivity is implicated in alcohol dependence, and discounting of delayed rewards may be an objective indicator of impulsiveness. OBJECTIVES: This study evaluated delay discounting functions in alcoholics and controls. It compared discounting rates between different magnitudes ($1000 and $100) and different types (money and alcohol) of rewards. METHODS: Active alcoholics (n = 19), currently abstinent alcoholics (n = 12) and controls (n = 15) indicated preferences for immediate versus delayed rewards using a titration procedure that determined indifference points at various delays. Four conditions were presented, and the delayed rewards in the four conditions were $1000, $100, 150 bottles of an alcoholic beverage, and 15 bottles of an alcoholic beverage. RESULTS: In all three groups across all four conditions, hyperbolic discounting functions provided a good fit of the data. Linear contrasts, predicting the most rapid discounting rates in active alcoholics, intermediary rates in currently abstinent alcoholics, and the least rapid rates in controls, were significant for three of the four conditions. Alcohol was discounted more rapidly than money. CONCLUSIONS: These data provide further evidence of more rapid discounting of delayed rewards in alcohol abusers compared to controls, and especially steep discounting among current users. Rapid discounting of delayed rewards may be a feature related to addictive disorders. A better understanding of how delaying rewards in time impacts their value may have implications for treatment.

Substance abuse, pathological gambling, and impulsiveness.

This study evaluated behavioral and self-report indices of impulsiveness in pathological gambling substance abusers (n=27), non-pathological gambling substance abusers (n=63), and non-pathological gambling/non-substance abusing controls (n=21). The Bechara card task measured preferences for decks of cards that ranged in magnitude and probability of delayed and immediate rewards and punishers. The Stanford Time Perception Inventory (STPI) assessed orientation to the future, the Zuckerman Sensation Seeking Scale evaluated sensation seeking, and the Eysenck and Barratt scales measured impulsivity. A Principal Components analysis revealed that these personality measures comprised three distinct measures of impulsivity: impulse control, novelty seeking and time orientation. Linear contrast analyses revealed that substance abuse and pathological gambling resulted in additive effects on the impulse control and time orientation factors, but not on the novelty-seeking scale. Performance on the card task did not correlate with any of the three factors derived from the personality scale scores, but the presence of both substance abuse and pathological gambling had an additive effect on preferences for decks containing greater immediate gains but resulting in large punishers and overall net losses. These results provide further evidence of an association among substance abuse, pathological gambling, and impulsivity.

Reinforcing compliance with non-drug-related activities.

Contingency management (CM) procedures, that provide incentives for specific behaviors, are efficacious in treating substance use disorders. Typically, CM interventions reinforce submission of urine specimens negative for the targeted drug(s) of abuse, but other behaviors can be reinforced as well, such as compliance with non-drug-related activities. This article describes 1,059 activities chosen by 46 subjects participating in one of two CM studies. The most frequently chosen activities were related to recreational activities (going to movies, library, or church) and sobriety (attending Alcoholics Anonymous meetings, completing worksheets). Over 95% of subjects participated in at least one of these types of activities, and together they accounted for over 70% of the activities selected. Over half the subjects participated in at least one activity related to employment, health, family, and personal improvement, such as applying for a job, attending a medical appointment, taking their child to an event, or creating weekly to-do lists. A detailed description of activity selection and verification procedures may assist in developing consistent approaches across treatment settings, and future research may evaluate further the efficacy of this contingency management approach in treating substance abusers.

A behavioral economic analysis of polydrug abuse in alcoholics: asymmetrical substitution of alcohol and cocaine.

Economic concepts can be used to assess how drug prices affect consumption patterns. Increases in price for a commodity typically result in reductions in consumption. Demand is considered elastic if decreases in consumption are proportionally greater than increases in price, and inelastic if they are proportionally smaller than rises in price. The price of one commodity can also affect consumption of others. Commodities can function as substitutes, complements or independents, and these concepts refer to increases, decreases, or no change in the consumption of one item as the price of another increases. This study evaluated the effects of drug prices on hypothetical drug-purchasing decisions in 53 alcohol abusers. Experiments 1, 2, and 3 examined how alcohol, cocaine, and Valium prices, respectively, influenced purchases of alcohol, cocaine, Valium, heroin, marijuana and nicotine. As price of alcohol rose in Experiment 1, alcohol purchases decreased and demand for alcohol was inelastic. Cocaine was a complement to alcohol, but other drugs purchases were independent of alcohol prices. In Experiment 2, demand for cocaine was elastic as its price increased. Alcohol was a substitute for cocaine, but other drug purchases did not change significantly. In Experiment 3, demand for Valium was elastic as its price rose, and all other drug purchases were independent of Valium prices. Hypothetical choices were reliable between and within subjects and associated with urinalysis results and lifetime histories of drug abuse. These results suggest that, among alcohol abusers, cocaine is a complement to alcohol, but alcohol is a substitute for cocaine.

Reliability of drug users' self-reported HIV risk behaviors using a brief, 11-item scale.

This study evaluated the reliability of self-reported HIV risk behaviors in 84 substance misusers. The 11-item HIV Risk Behavior Scale was, used to evaluate lifetime, past month, and past week risk behaviors. Cronbach's alpha ranged from .75 to .80 for the three versions. Test-retest reliability for the lifetime version was excellent, with correlations of .90. In addition, 44 clients completed the weekly version once a week for four weeks, as well as the monthly version at the end of the same month. Reliability of responses collected weekly and monthly was good (r=.67, p < .001). Principal component analysis of the items confirmed that the scale measures two distinct HIV risk factors: one related to injecting behaviors and the other to sexual behaviors. These data suggest that the HRBS has satisfactory psychometric properties for measuring lifetime as well as recent HIV risk behaviors in substance misusers. Due to its brevity, this instrument may be a useful clinical and research tool.