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1.  Biphasic Effects of Alcohol on Delay and Probability Discounting 
Delay discounting and probability discounting are behavioral economic indices of impulsive and risky decision making that have been associated with addictive behavior, but the acute biphasic effects of alcohol on these decision-making processes are not well understood. This study sought to investigate the biphasic effects of alcohol on delay and probability discounting across the ascending and descending limbs of the breath alcohol concentration (BAC) curve, which are respectively characterized by the stimulant and sedative effects of alcohol. Delay and probability discounting were measured at four time points (Baseline, Ascending, Descending, and Endpoint) across the BAC curve at two target alcohol doses (40 mg/dl and 80 mg/dl) in healthy adults (N = 23 and 27, for both doses, respectively). There was no significant effect of alcohol on delay discounting at either dose. Alcohol significantly affected probability discounting, such that reduced discounting for uncertain rewards was evident during the descending limb of the BAC curve at the lower dose (p<.05) and during both the ascending and descending limb of the BAC curve at the higher dose (p<.05). Thus, alcohol resulted in increased risky decision making, particularly during the descending limb which is primarily characterized by the sedative effects of alcohol. These findings suggest that the biphasic effects of alcohol across the ascending and descending limbs of the BAC have differential effects on behavior related to decision-making for probabilistic, but not delayed, rewards. Parallels to and distinctions from previous findings are discussed.
PMCID: PMC4050433  PMID: 23750692
delay discounting; probability discounting; impulsivity; alcohol use; behavioral economics
2.  Behavioral Filter Vent Blocking on the First Cigarette of the Day Predicts Which Smokers of Light Cigarettes Will Increase Smoke Exposure From Blocked Vents 
Filter vent blocking on best-selling light cigarettes increases smoke yield during standard machine testing but not in clinical investigations of smokers. The purpose of the study was to investigate the effect of (a) manipulating cigarette filter vent blocking and (b) blocking status of first cigarette of the day on carbon monoxide (CO) boost. Participants (n = 25; Marlboro Lights nonmenthol cigarette smokers, age range 21–60 years, minimum 15 daily cigarettes, and daily smoking for a minimum 5 years) completed the laboratory-based, within-subject, double-blind, cross-over design of 2 smoking sessions, one utilizing a smoking topography device, one without. Each session consisted of smoking 4 cigarettes; 2 with filter vents blocked and 2 with filter vents unblocked. Spent first daily cigarette filters collected between sessions were scored for evidence of filter vent blocking. Smoking cigarettes with blocked filter vents significantly increased CO boost in both laboratory sessions ( p < .001). Those who blocked their first cigarette of the day (n = 10) had significantly greater CO boost when smoking a blocked cigarette, in relation to smoking an unblocked cigarette and in comparison with nonblockers ( p = .04). Total puff volume was a significant predictor of CO boost when smoking unblocked and blocked cigarettes ( ps < .04). Blocking filter vents significantly increased smoke exposure in relation to when filter vents are not blocked, particularly for those who block filter vents on their first cigarette of the day. Total puff volume predicted CO boost, and results suggest that smokers adjust their smoking behavior by cigarette blocking status. Those smokers who block filter vents may be increasing their exposure by 30%.
PMCID: PMC4047634  PMID: 19968405
smoking; light cigarette; filter vents; topography; carbon monoxide
3.  The Alternative Substance Paradigm:Effectiveness of Beverage Blinding and Effects on Acute Alcohol Responses 
A fundamental goal of double-blind alcohol challenge studies is to reduce alcohol expectancies, though there is little research on the effectiveness of blinding procedures and their relationship to acute alcohol responses. This study examined social drinkers’ perception of beverage content and related alcohol response during three separate double-blind experimental sessions with placebo, low dose alcohol (0.4 g/kg), and high dose alcohol (0.8 g/kg). Using the Alternative Substance Paradigm, participants (N=182) were informed that the beverage they consumed might contain alcohol, a stimulant, a sedative, or a placebo. At several timepoints, subjective and objective measures were obtained and participants were asked to identify which substance they received. During both placebo and low dose alcohol sessions, 33% and 50% of participants, respectively, did not correctly identify the beverage content; during the high dose alcohol session, 20% did not correctly identify the beverage. While correct and incorrect identifiers at any dose level did not differ on major background variables, drinking characteristics, or psychomotor performance during these sessions, they did differ on self-reported subjective responses, with greater sedation reported by incorrect identifiers in the placebo and high dose conditions. In sum, results suggest that the Alternative Substance Paradigm may be a viable option for alcohol laboratory studies, particularly for repeated sessions in within-subjects designs and in cases where the experimenter wants to reduce expectancy by not revealing a priori that alcohol is being administered.
PMCID: PMC4048031  PMID: 22867037
alcohol; social drinker; blinding procedures; alcohol expectancy; balanced-placebo design; alternative substance paradigm
4.  Predicting Extinction and Reinstatement of Alcohol and Sucrose Self-Administration in Outbred Rats 
Preventing relapse to drinking or escalation to excessive drinking could be aided by identifying factors that predict these behaviors. Animal models, particularly those that utilize operant self-administration techniques, can be useful. In a prior operant study, we noted a good deal of variability in behaviors during training and test sessions. We utilized data obtained from that study of two groups of rats, trained and tested identically except one responded for alcohol and the other for sucrose, to explore for associations related to relapse (reinstatement) or to excessive drinking (maintenance). Data were obtained from sessions conducted under fixed- and progressive-ratio schedules, as well as from extinction and reinstatement sessions. Variables assessed included active and inactive presses, head entries into the dipper trough, and automated recordings of body movements during these sessions, as well as alcohol preference prior to training. First, using multiple regression, we examined whether alcohol preference prior to training associated with any response variable among alcohol-responding rats. Second, using factor analysis, we identified a training variable, body movements, that associated with responses during tests. Using this measure, rats were divided into low and high response groups and compared on active lever presses and head entries across test sessions. Results show that among alcohol-responding rats, alcohol preference predicted head entries during extinction. High body movement rats emitted significantly fewer active lever presses and had fewer head entries across test sessions, particularly during reinstatement, compared to low body movement rats. Results from this exploratory study provide clues for future experimental studies.
PMCID: PMC4040462  PMID: 23421354
relapse; sign-tracking; conditioned approach; operant reinforcement
5.  Adult Rats Treated with Risperidone during Development Are Hyperactive 
Risperidone is an antipsychotic drug approved for use in children, but little is known about the long-term effects of early-life risperidone treatment. In animals, prolonged risperidone administration during development increases forebrain dopamine receptor expression immediately upon the cessation of treatment. A series of experiments was performed to ascertain whether early-life risperidone administration altered locomotor activity, a behavior sensitive to dopamine receptor function, in adult rats. One additional behavior modulated by forebrain dopamine function, spatial reversal learning, was also measured during adulthood. In each study, Long-Evans rats received daily subcutaneous injections of vehicle or one of two doses of risperidone (1.0 and 3.0 mg/kg per day) from postnatal days 14 – 42. Weight gain during development was slightly yet significantly reduced in risperidone-treated rats. In the first two experiments, early-life risperidone administration was associated with increased locomotor activity at one week post-administration through approximately nine months of age, independent of changes in weight gain. In a separate experiment, it was found that the enhancing effect of early-life risperidone on locomotor activity occurred in males and female rats. A final experiment indicated that spatial reversal learning was unaffected in adult rats administered risperidone early in life. These results indicate that locomotor activity during adulthood is permanently modified by early-life risperidone treatment. The findings suggest that chronic antipsychotic drug use in pediatric populations (e.g., treatment for the symptoms of autism) could modify brain development and alter neural set-points for specific behaviors during adulthood.
PMCID: PMC4041194  PMID: 23750695
antipsychotic drug; locomotor activity; reversal learning; development; gender; dopamine
6.  Acceptability of an Internet-based contingency management intervention for smoking cessation: Views of smokers, nonsmokers, and healthcare professionals 
The acceptability of an Internet-based contingency management (CM) intervention for cigarette-smoking was evaluated in two experiments. In Experiment 1, 67 participants completed an Internet-based CM intervention and then answered questions about the intervention. Experiment 2 assessed the acceptability of the intervention among potential treatment users (smokers, n = 164), non-smokers (n = 166), and healthcare providers (n = 139), who had never used the intervention. Participants in Experiment 2 were randomly assigned to either watch a video describing the standard CM intervention (No Deposit Group) or to watch a video about the standard intervention plus a deposit incentive (Deposit Group). Overall, results of both experiments indicated high acceptability across all dimensions of the intervention. Seventy-four percent of participants in Experiment 1, and 92% of those in Experiment 2, said they would use it if they needed to quit. Eighty one percent of healthcare providers reported that they would be very likely to recommend the intervention to patients. Participants in both experiments reported that monitoring their progress and earning vouchers were strengths of the intervention. The No Deposit group rated voucher earnings, cash earnings, and cost-effectiveness of the intervention higher than the Deposit Group. Healthcare professionals did not differ in their ratings across video conditions. Overall, the results suggest that Internet-based CM is acceptable as a method to help people quit smoking.
PMCID: PMC4000566  PMID: 23750691
Internet; contingency management; smoking cessation; acceptability; social validity; financial incentives
7.  Hypothetical Intertemporal Choice and Real Economic Behavior: Delay Discounting Predicts Voucher Redemptions During Contingency-Management Procedures 
Delay discounting rates are predictive of drug use status, the likelihood of becoming abstinent, and a variety of health behaviors. Rates of delay discounting may also be related to other relevant behaviors associated with addiction, such as the frequency at which individuals redeem contingency management voucher earnings. This study examined the discounting rates of 152 participants in a buprenorphine treatment program for opioid abuse. Participants received up to 12 weeks of buprenorphine treatment combined with contingency management. Participant’s drug use was measured via urine specimens submitted 3 times a week. Successive negative urine specimens were reinforced with increasing amounts of money. After each negative urine specimen, a participant could either redeem his or her earnings or accumulate it in an account. Analysis of the frequency of redemptions showed that participants with higher rates of delay discounting at study intake redeemed their earnings significantly more often than participants with lower rates of discounting. Age and income also predicted redemption rates. We suggest that delay discounting rates can be used to predict redemption behaviors in a contingency management treatment program and that these findings are consistent with the recent theory of the competing neurobehavioral decision systems.
PMCID: PMC4034533  PMID: 21186929
delay discounting; opioid; contingency management; impulsivity; competing neurobehavioral decision systems
8.  Placebo-Group Responders in Methamphetamine Pharmacotherapy Trials: The Role of Immediate Establishment of Abstinence 
Treatment responses of placebo groups in addiction medicine trials have important implications for research methodology and clinical practice, however, studies examining placebo group responses in addiction medicine is scarce. Extant data suggests the importance of early treatment responsiveness for long-term outcomes. Among methamphetamine (MA) dependent individuals randomized to placebo pill plus behavioral support conditions in pharmacotherapy development trials, we hypothesized that immediate abstinence would be a necessary but insufficient predictor for end-of-trial (EOT) abstinence.
The study is a secondary analysis of participants (N=184; 36% female) in the placebo condition of three randomized, placebo-controlled methamphetamine dependence pharmacotherapy trials. Receiver operating characteristic (ROC) curve analyses assessed the predictive power of initial abstinence, assessed by thrice weekly urine samples, for EOT abstinence.
Sixty percent of individuals with complete abstinence in the first two weeks of treatment were abstinent at EOT while 18% of people who failed to meet this standard were abstinent at EOT. Early response was related to retention at EOT and 12 month follow-up. Findings suggested that the inability to achieve at least three MA negative screenings in the first two weeks is associated with greater than 90% likelihood of treatment failure. A third week of screening added minimally to the prediction of EOT outcomes. The prediction of treatment failure was more precise than the prediction of treatment success.
The absence of a clinical response in the first two weeks of treatment among participants in the placebo group signals high risk of treatment failure. The vast majority of information regarding response in the placebo group from a12-week trial is obtained in early in the trial.
PMCID: PMC4035480  PMID: 22867036
methamphetamine dependence; placebo effects; early response; abstinence; treatment
9.  Smoking and the bandit: A preliminary study of smoker and non-smoker differences in exploratory behavior measured with a multi-armed bandit task 
Advantageous decision-making is an adaptive trade-off between exploring alternatives and exploiting the most rewarding option. This trade-off may be related to maladaptive decision-making associated with nicotine dependence; however, explore/exploit behavior has not been previously investigated in the context of addiction. The explore/exploit trade-off is captured by the multi-armed bandit task, in which different arms of a slot machine are chosen to discover the relative payoffs. The goal of this study was to preliminarily investigate whether smokers differ from non-smokers in their degree of exploratory behavior. Smokers (n = 18) and non-smokers (n = 17) completed a six-armed bandit task as well as self-report measures of behavior and personality traits. Smokers were found to exhibit less exploratory behavior (i.e. made fewer switches between slot machine arms) than non-smokers within the first 300 trials of the bandit task. The overall proportion of exploratory choices negatively correlated with self-reported measures of delay aversion and nonplanning impulsivity. These preliminary results suggest that smokers make fewer initial exploratory choices on the bandit task. The bandit task is a promising measure that could provide valuable insights into how nicotine use and dependence is associated with explore/exploit decision-making.
PMCID: PMC4028629  PMID: 23245198
exploration; exploitation; smoking; tobacco; multi-armed bandit task
10.  The short of it: Abbreviating the temporal discounting procedure 
A typical temporal discounting procedure determines the present, subjective value (indifference point) of a delayed outcome at 5 – 8 different delays to that outcome. These indifference points are used to determine a single index of discounting called a discounting rate. One concern that remains in the collection of this data is the high number of trials or choices, resulting in participant fatigue or other factors that may affect the validity of the data. In this report, we propose an abbreviated alternative to the more comprehensive and time-consuming discounting procedure. Specifically, we propose that fewer indifference points can be used to determine statistically equivalent discount rates with no loss in data sensitivity. We reanalyzed temporal discounting data obtained with 7 indifference points, and estimated discount rates from all combinations of 2, 3, and 4 of the 7 indifference points. Results indicate that valid and sensitive discounting indices can be obtained with fewer indifference points, and the most appropriate sets of indifference points are highlighted. The proposed abbreviated procedure is likely to be particularly useful when time constraints or participant fatigue is a concern, as well as in repeated-measures contexts.
PMCID: PMC4004783  PMID: 20695693
temporal discounting; discounting procedure; abbreviated procedure; discount rates
11.  Investigating Group Contingencies to Promote Brief Abstinence from Cigarette Smoking 
In contingency management (CM), monetary incentives are contingent on evidence of drug abstinence. Typically, incentives (e.g., “vouchers” exchangeable for goods or services) are contingent on individual performance. We programmed vouchers contingent on group performance to investigate whether these contingencies would promote brief abstinence from cigarette smoking. Thirty-two participants were divided into small teams (n = 3 per team). During three 5-day within-subject experimental conditions, participants submitted video recordings of breath carbon monoxide (CO) measures twice daily via Mōtiv8 Systems™, an Internet-based remote monitoring application. During the interdependent contingency condition, participants earned vouchers each time they and their teammates submitted breath CO samples indicative of abstinence (i.e., negative samples). During the independent contingency condition, participants earned vouchers each time they submitted negative samples, regardless of their teammates' performance. During the no vouchers condition, no monetary incentives were contingent on abstinence. In addition, half of the participants (n = 16) could communicate with their teammates through an online peer support forum. Although forum access did not appear to promote smoking abstinence, monetary incentives did promote brief abstinence. Significantly more negative samples were submitted when vouchers were contingent on individual performance (56%) or team performance (53%) relative to when no vouchers were available (35%; F = 6.9, p = 0.002). The results show that interdependent contingencies can promote brief abstinence from cigarette smoking. Moreover, the results suggest that these contingencies may help lower treatment costs and promote social support.
PMCID: PMC3657835  PMID: 23421358
contingency management; incentive; group contingency; cigarette; social support
12.  An Event-Level Examination of Sex Differences and Subjective Intoxication in Alcohol-Related Aggression 
Experimental and clinical psychopharmacology  2013;21(2):10.1037/a0031552.
Laboratory-based experimental research has demonstrated that the pharmacological effects of alcohol can increase aggressive responding. Given mixed findings and concerns regarding task validity, however, it remains uncertain whether this effect holds constant across men and women and whether variability in subjective alcohol intoxication contributes to alcohol-related aggression. In the present investigation, we used four years of event-level data in a sample of 1,775 college students (140,618 total observations) to provide a test of laboratory-derived findings on the link between alcohol and aggression in an alternative methodology. We found support for several such findings: 1) Within-person increases in alcohol intoxication, as assessed by estimated blood alcohol concentrations (eBACs), were associated with increases in the probability of aggression at the drinking-episode level; 2) This association was significantly stronger among men than among women; and 3) Within-person variability and between-persons individual differences in levels of subjective alcohol intoxication were associated with aggression over and beyond eBACs. Cross-methodological replication can reduce the impact of constraints specific to experimental studies on conclusions regarding alcohol’s relation with aggression.
PMCID: PMC3810171  PMID: 23421356
Aggression; Alcohol Use; Event-Level; Sex Differences; Subjective Intoxication
13.  Delay Discounting Decreases in Those Completing Treatment for Opioid Dependence 
Several studies examining both control and substance-dependent populations have found delay discounting to remain stable over time. In this report, we examine whether delay discounting changes in opioid-dependent individuals who complete a 12-week treatment. The 159 subjects who completed discounting assessments at baseline and treatment-end come from two separate clinical trials: 56 from Chopra et al. (2009) and 103 from Christensen et al. (2012). Mean discounting at 12 weeks significantly decreased to less than half (44.8%) of the baseline level (95% CIs (27.5, 73.2)). Analyzing each subject’s discounting data individually, over 3 times (95% CIs (1.9, 5.5)) as many subjects statistically decreased their discounting from their own baseline levels than those who exhibited a statistical increase. Though we failed to find any relationship among discounting measures and abstinence outcomes, the results from this large study suggest that treatment for substance dependence promotes decreases in delay discounting.
PMCID: PMC3972253  PMID: 22369670
stability; temporal discounting; impulsivity; opiate dependence; abstinence
14.  Effects of Alcohol on Tests of Executive Functioning in Men and Women: A Dose Response Examination 
Alcohol has been shown to affect performance on tasks associated with executive functioning. However, studies in this area have generally been limited to a single dose or gender or have used small sample sizes. The purpose of this study was to provide a more nuanced and systematic examination of alcohol's effects on commonly used tests of executive functioning at multiple dosages in both men and women. Research volunteers (91 women and 94 men) were randomly assigned to one of four drink conditions (alcohol doses associated with target blood alcohol concentrations of .000%, .050%, .075% and .100%). Participants then completed three tasks comprising two domains of executive functioning: two set shifting tasks, the Trail Making Test and a computerized version of the Wisconsin Card Sorting Task, and a response inhibition task, the GoStop Impulsivity Paradigm. Impaired performance on set shifting tasks was found at the .100% and .075% dosages, but alcohol intoxication did not impair performance on the GoStop. No gender effects emerged. Thus, alcohol negatively affects set shifting at moderately high levels of intoxication in both men and women, likely due to alcohol's interference with prefrontal cortex function. Although it is well-established that alcohol negatively affects response inhibition as measured by auditory stop-signal tasks, alcohol does not appear to exert a negative effect on response inhibition as measured by the GoStop, a visual stop-signal task.
PMCID: PMC3968820  PMID: 20939644
15.  Sex Differences in Negative Affect and Lapse Behavior During Acute Tobacco Abstinence: A Laboratory Study 
Heightened negative affect during acute tobacco abstinence in women relative to men could be an important factor underlying sex differences in smoking motivation. However, little controlled experimental work addresses this hypothesis. The current study investigated sex differences in withdrawal-related negative affect, time to start smoking on a lab analogue smoking lapse task, and the interrelation between sex, withdrawal-related negative affect, and smoking lapse behavior. Following a baseline session, current smokers (women: n = 68, men: n = 131) attended two counterbalanced lab sessions (16 hours smoking abstinence and ad libitum smoking) during which they completed self-report measures of mood and withdrawal symptoms followed by a laboratory analogue smoking lapse task. In this task participants are monetarily rewarded for delaying smoking. Performance on this task serves as an analogue model of smoking lapse behavior by measuring smoker’s capability to resist temptation to smoke under conditions where abstinence is advantageous. Females showed greater abstinence induced increases in composite negative affect as well as several particular negative affect states (i.e., POMS Anger, Anxiety, Depression, and Confusion, ps < .05) but no differences in abstinence induced changes in other forms of affect or craving. Females also exhibited marginally greater abstinence induced decreases in their willingness to delay smoking for money (p = .10), which was mediated by abstinence induced increases in anger (p < .05). These results suggest that differential sensitivity to abstinence induced negative affect, particularly anger, could underlie sex specific smoking patterns. Negative affect during tobacco abstinence may be an important factor for understanding and treating nicotine addiction in women.
PMCID: PMC3962304  PMID: 23834551
sex differences; negative affect; nicotine withdrawal; abstinence; smoking
16.  Test-Retest Reliability and Construct Validity of the Experiential Discounting Task 
Delay discounting (the devaluation of delayed rewards) has been studied extensively using animal models with psychophysical adjustment procedures. Similar procedures have been developed to assess delay discounting in humans and these procedures most often use hypothetical rewards and delays. The Experiential Discounting Task (EDT) was developed to assess human delay discounting using real rewards and delays. In the present study we examined the test-retest reliability and construct validity of the EDT. Construct validity was evaluated by comparing it to a standard delay discounting task. The EDT had poor test-retest reliability and discounting rates obtained with this task were uncorrelated with those obtained in the standard delay discounting task. Area under the EDT discounting curve was negatively correlated with scores on a measure of boredom proneness (i.e., individuals prone to boredom more steeply discounted delayed money in the EDT). This correlation may underlie previous reports that discounting in the EDT is correlated with addictions, as some evidence suggests boredom proneness is correlated with gambling, cigarette smoking, alcohol consumption, and sensation-seeking. Boredom proneness scores were correlated with no other measure of discounting. These findings suggest the EDT measures a different construct than that measured by traditional delay discounting tasks.
PMCID: PMC3959642  PMID: 23421359
Experiential discounting task; delay discounting; probability discounting; test-retest reliability; boredom proneness scale
17.  Is Expectancy Reality? Associations between Tension Reduction Beliefs and Mood Following Alcohol Consumption 
The present study investigated whether tension reduction (TR) expectancies were uniquely associated with self-reported mood following in-lab alcohol administration, given that little research has addressed this association. We also tested whether level of experience with alcohol, which may influence the learning of expectancies, moderated expectancy-mood associations.
Regularly drinking college students (N = 145) recruited through advertisements completed self-report measures of positive alcohol expectancies, alcohol involvement, demographics, and pre- and post-drinking mood, and then consumed alcohol ad-lib up to 4 drinks in the laboratory.
Regression analyses controlling for pre-consumption mood, blood alcohol concentration (BAC), and all other positive expectancies showed TR expectancies to be a marginally significant positive predictor of negative mood post-drinking. This association was significant only for those who achieved lower BACs in lab and those who reported less involvement with alcohol (i.e., lower typical quantity, heavy episodic drinking frequency, and years of regular drinking).
Findings suggest that associations between expectations for mood and actual post-drinking mood outcomes may operate differently for less versus more involved drinkers. Clinical implications pertain to early intervention, when expectancies may be less ingrained and perhaps more readily modified.
PMCID: PMC3951403  PMID: 19968408
Tension Reduction; Expectancies; College students; Alcohol; Mood
18.  Self-Regulation, Daily Drinking, and Partner Violence in Alcohol Treatment-Seeking Men 
This study builds on research identifying deficits in behavioral self-regulation as risk factors for intimate partner violence (IPV). It also builds on alcohol administration research identifying these deficits as moderators of the association between acute alcohol consumption and aggression in laboratory paradigms. Participants analyzed were 97 men seeking residential treatment for alcohol dependence who were involved in a current or recent heterosexual relationship of at least one year. Participants completed a self-report measure of impulsivity, neuropsychological tests of executive function, and computerized delay discounting and behavioral inhibition tasks. With the exception of the self-report measure of impulsivity, performance on measures of behavioral self-regulation was not associated with the occurrence or frequency of past year IPV in this sample. Similarly, self-reported impulsivity moderated the association between daily drinking and IPV in multivariate models controlling for daily drug use, but deficits in performance on other measures did not. Performance on a tower task moderated the association between daily drinking and the occurrence of IPV, but contrary to hypotheses, better task performance was associated with greater likelihood of IPV on drinking days. These results suggest that self-perceived impulsivity is a better predictor of IPV in alcohol treatment seeking men than deficits in performance on behavioral measures of delay discounting, behavioral inhibition, and executive function.
PMCID: PMC3920985  PMID: 23379612
Intimate partner violence; alcohol use disorders; drinking; executive cognitive function; impulsivity; timeline followback
19.  Employment-Based Reinforcement of Adherence to Oral Naltrexone Treatment in Unemployed Injection Drug Users 
Naltrexone has high potential for use as a relapse prevention pharmacotherapy for opiate dependence; however suffers from notoriously poor adherence when prescribed for oral self-administration. This study evaluated whether entry to a therapeutic workplace could be used to reinforce adherence with oral naltrexone. Opiate-dependent and cocaine-using injection drug users were detoxified, inducted onto oral naltrexone, and randomly assigned to a Contingency (n=35) or Prescription (n=32) group for a 26-week period. Contingency participants were required to ingest naltrexone under staff observation to gain access to the therapeutic workplace. Prescription participants received a take-home supply of naltrexone and could access the workplace independent of naltrexone ingestion. Primary outcome measures were percent of urine samples positive for naltrexone at 30-day assessments and negative for opiates and cocaine at 30-day assessments. Contingency participants provided significantly more urine samples that were positive for naltrexone compared to Prescription participants (72% vs. 21%, P<.01), however no effect of experimental group was observed on percent opiate-negative (71% vs. 60%, P=.19.) or cocaine-negative (56% vs. 53%, P=.82) samples in the Contingency and Prescription groups, respectively. Opiate-positive samples were significantly more likely to occur in conjunction with cocaine (P<.001), and when not protected by naltrexone (P<.02), independent of experimental group. Overall, these results show that contingent access to a therapeutic workplace significantly promoted adherence to oral naltrexone, and that the majority of opiate use occurred in conjunction with cocaine use, suggesting that untreated cocaine use may limit the effectiveness of oral naltrexone in promoting opiate abstinence.
PMCID: PMC3641088  PMID: 23205722
naltrexone; contingency management; therapeutic workplace; incentive; injection drug use
20.  Delay Discounting in Adults Receiving Treatment for Marijuana Dependence 
Delay discounting is an index of impulsive decision-making and reflects an individual’s preference for smaller immediate rewards relative to larger delayed rewards. Multiple studies have indicated comparatively high rates of discounting among tobacco, alcohol, cocaine, and other types of drug users, but few studies have examined discounting among marijuana users. This report is a secondary analysis of data from a clinical trial that randomized adults with marijuana dependence to receive one of four treatments that involved contingency management (CM) and cognitive–behavioral therapy interventions. Delay discounting was assessed with the Experiential Discounting Task (Reynolds & Schiffbauer, 2004) at pretreatment in 93 participants and at 12 weeks posttreatment in 61 participants. Results indicated that higher pretreatment delay discounting (i.e., more impulsive decision-making) significantly correlated with lower readiness to change marijuana use (r = − 0.22, p = .03) and greater number of days of cigarette use (r = .21, p = .04). Pretreatment discounting was not associated with any marijuana treatment outcomes. CM treatment significantly interacted with time to predict change in delay discounting from pre- to posttreatment; participants who received CM did not change their discounting over time, whereas those who did not receive CM significantly increased their discounting from pre- to posttreatment. In this sample of court-referred young adults receiving treatment for marijuana dependence, delay discounting was not strongly related to treatment outcomes, but there was some evidence that CM may protect against time-related increases in discounting.
PMCID: PMC3659159  PMID: 23245197
marijuana; cannabis; delay discounting; impulsivity; marijuana treatment
21.  Alcohol Consumption and Urges to Smoke among Women during a Smoking Cessation Attempt 
Experimental and clinical psychopharmacology  2013;21(1):10.1037/a0031009.
Laboratory and ad libitum smoking studies have indicated that alcohol consumption increases the frequency and intensity of smoking urges. However, few studies have examined the relation between smoking urges and alcohol use in natural settings during a quit attempt. The purpose of this study was to examine the relationships between smoking urge and alcohol use in women who reported drinking on at least one occasion during the first 7 days of a smoking quit attempt (N = 134). Participants were asked to use a palmtop computer to complete assessments that recorded smoking urges and recent alcohol use. Multilevel analyses examined the relation between smoking urge parameters and alcohol use. Smoking urges were higher during assessments where alcohol had been recently consumed compared to assessments where no alcohol had been consumed. Interestingly, the first urge rating of the day was higher and urges were more volatile on days where alcohol would eventually be consumed as compared to days where no alcohol was consumed. A closer examination of urge parameters on drinking days indicated that smoking urge trajectory was significantly flatter and urge volatility was significantly higher following alcohol consumption. However, smoking urge trajectory also flattened later in the day on nondrinking days. The findings suggest that there may be reciprocal relations between smoking urge and alcohol use (e.g., higher initial urges and more volatile urges may increase the likelihood of alcohol use; and, alcohol use may impact within day smoking urge parameters), and these relations could potentially impact smoking cessation and relapse.
PMCID: PMC3854865  PMID: 23379613
Smoking; Smoking urge; Alcohol; Ecological Momentary Assessment; Multilevel Analysis
22.  Delay Discounting Predicts Adolescent Substance Abuse Treatment Outcome 
The purpose of the current study was to identify predictors of delay discounting among adolescents receiving treatment for marijuana abuse or dependence, and to test delay discounting as a predictor of treatment outcome. Participants for this study were 165 adolescents (88% male) between the ages of 12 and 18 (M =15.8; SD = 1.3) who enrolled in a clinical trial comparing three behavioral treatments for adolescent marijuana abuse or dependence. Participants completed a delay discounting task at treatment onset for $100 and $1,000 of hypothetical money and marijuana. Overall, smaller magnitude rewards were discounted more than larger magnitude rewards. Delay discounting rates were concurrently related to demographic variables (SES, race). Delay discounting of $1,000 of money predicted during treatment abstinence outcomes among adolescent marijuana abusers, over and above the effects of type of treatment received. Teens who show higher levels of discounting of the future may be an important subgroup to identify at treatment onset. Youth with a greater tendency to discount the future may require different intervention strategies that address their impulsivity (e.g., targeting executive function or inhibitory control) and/or different schedules of reinforcement to address their degree of preference for immediate rewards.
PMCID: PMC3906638  PMID: 22182419
delay discounting; adolescent substance abuse; marijuana
23.  Effects of transdermal nicotine and concurrent smoking on cognitive performance in tobacco-abstinent smokers 
Smokers experience cognitive decrements during tobacco abstinence and boosts in performance upon resumption of smoking. Few studies have examined whether smoking cessation treatments such as transdermal nicotine ameliorate these decrements and/or attenuate the cognitive effects of smoking. Identifying the effects of nicotine on these tobacco-related changes in performance could guide the development of more efficacious treatments. The purpose of this double-blind, randomized, laboratory study was to use process-specific cognitive tasks to examine the effects of transdermal nicotine (TN) and tobacco smoking on attention and working memory in overnight-abstinent smokers (N=124; 54 women). Each participant completed four, 6.5-hour sessions corresponding to 0, 7, 14, or 21 mg TN doses, and smoked a single cigarette four hours after TN administration. Outcome measures were administered before and after smoking, and included tasks measuring attention (alerting, orienting, and executive function), working memory (verbal and spatial), and psychomotor function. Analysis of variance (p < .05) revealed that TN improved verbal and spatial working memory performance, as well as psychomotor function. Smoking, independent of TN dose, improved alerting, verbal working memory, and psychomotor function. Lastly, TN partially attenuated the effects of smoking on some working memory outcomes. These findings lend evidence to the idea that TN ameliorates some abstinence-related cognitive decrements and suggest that TN does not completely attenuate the cognitive effects of a concurrently smoked cigarette. Consequently, TN’s efficacy as a smoking cessation treatment might be improved should these limitations be better addressed by either modifying or supplementing existing treatments.
PMCID: PMC3894826  PMID: 21341925
24.  Comparative abuse liability of GHB and ethanol in humans 
Experimental and clinical psychopharmacology  2013;21(2):10.1037/a0031692.
Gamma-hydroxybutyric acid (GHB; sodium oxybate) is approved for narcolepsy symptom treatment, and it is also abused. This study compared the participant-rated, observer-rated effects, motor/cognitive, physiological, and reinforcing effects of GHB and ethanol in participants with histories of sedative (including alcohol) abuse. Fourteen participants lived on a residential unit for ~1 month. Sessions were conducted Monday through Friday. Measures were taken before, and repeatedly up to 24 hours after drug administration. Participants were administered GHB (1, 2, 4, 6, 8, and 10 g/70kg), ethanol (12, 24, 48, 72, 96, and 120 g/70kg), or placebo in a double-blind, within-subjects design. For safety, GHB and ethanol were administered in an ascending dose sequence, with placebos and both drugs intermixed across sessions. The sequence for each drug was stopped if significant impairment or intolerable effects occurred. Only 9 and 10 participants received the full dose range for GHB and ethanol, respectively. The highest doses of GHB and ethanol showed onset within 30 minutes, with peak effects at 60 minutes. GHB effects dissipated between 4 and 6 hours, while ethanol effects dissipated between 6 and 8 hours. Dose-related effects were observed for both drugs on a variety of measures assessing sedative drug effects, abuse liability, performance impairment, and physiological effects. Within-session measures of abuse liability were similar between the two drugs. However, post-session measures of abuse liability, including a direct preference test between the highest tolerated doses of each drug, suggested somewhat greater abuse liability for GHB, due most likely to the delayed aversive ethanol effects (e.g., headache).
PMCID: PMC3886725  PMID: 23421353
Gamma-hydroxybutyric acid; GHB; sodium oxybate; ethanol; alcohol
25.  Test-retest reliability and gender differences in the Sexual Discounting Task among cocaine-dependent individuals 
Experimental and clinical psychopharmacology  2013;21(4):10.1037/a0033071.
The Sexual Discounting Task uses the delay discounting framework to examine sexual HIV risk behavior. Previous research showed task performance to be significantly correlated with self-reported HIV risk behavior in cocaine dependence. Test-retest reliability and gender differences had remained unexamined. The present study examined the test-retest reliability of the Sexual Discounting Task. Cocaine-dependent individuals (18 men, 13 women) completed the task in two laboratory visits ~7 days apart. Participants selected photographs of individuals with whom they were willing to have casual sex. Among these, participants identified the individual most (and least) likely to have a sexually transmitted infection (STI), and the individual with whom he/she most (and least) wanted to have sex. In reference to these individuals, participants rated their likelihood of having unprotected sex vs. waiting to have sex with a condom, at various delays. A money delay discounting task was also completed at the first visit. Significant differences in discounting among partner conditions were shown. Differential stability was demonstrated by significant, positive correlations between test and retest for all four partner conditions. Absolutely stability was demonstrated by statistical equivalence tests between test and retest, and also supported by a lack of significant differences between test and retest. Men generally discounted significantly more than women for sexual outcomes but not money. Results suggest the Sexual Discounting Task to be a reliable measure in cocaine-dependent individuals, which supports its use as a repeated measure in clinical research, e.g., studies examining acute drug effects on sexual risk, and the effects of of addiction treatment and HIV prevention interventions on sexual risk.
PMCID: PMC3880114  PMID: 23834552
cocaine; delay discounting; gender differences; HIV; reliability; sex characteristics; unsafe sex

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