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BackgroundDespite the high prevalence of polysubstance use, outcomes and potential risks associated with common drug combinations are not well characterized. Many individuals who use cocaine also use cannabis, yet little is known about how interactions between the two drugs might contribute to continued co-use.MethodsThe aim of this double-blind, placebo-controlled study was to determine the physiological and subjective effects of smoked cannabis with smoked cocaine, to identify variables that may contribute to the continued use of this drug combination. Healthy, non-treatment seeking volunteers who reported smoking both cocaine and cannabis (N=9, all males) completed a 13-day inpatient protocol. On session days, cannabis [0.0 or 5.6 % tetrahydrocannabinol (THC)] was administered 28min prior to cocaine (0, 12, or 25mg). Dependent measures included pharmacokinetic assessment of THC and cocaine and their respective metabolites, in addition to subjective and cardiovascular effects.ResultsActive cannabis (5.6 % THC) increased plasma levels of THC and the metabolite 11-nor-9-carboxy-Δ9-THC (THCCOOH), as well as subjective ratings of cannabis effects and heart rate relative to inactive cannabis. Cocaine dose-dependently increased plasma cocaine and metabolites and subjective ratings of cocaine effects. Active cannabis pre-treatment decreased plasma levels of cocaine and metabolites. Furthermore, active cannabis attenuated cocaine-related reductions in 'Hunger' and 'Calm.'ConclusionsCannabis pre-treatment altered the subjective experience of smoked cocaine and reduced peak plasma levels of cocaine. Future studies should explore additional doses of each drug and whether these changes also impact cocaine's reinforcing effects.

Background: Impulsive choice – the tendency to choose immediate over larger delayed rewards – is associated with both cocaine use and relapse. Little is known about the influence of transient states on impulsive choice in people who use cocaine (PWUC). This study investigated the direct effects of induced boredom on impulsive choice (i.e., temporal discounting) in PWUC relative to well-matched community controls. Methods: In a mixed within-between subject design, 41 PWUC (≥1x cocaine use in past 3 months; 7 females) and 38 demographically-matched controls (5 females) underwent two experimental conditions in counterbalanced order. Temporal discounting was assessed immediately after a standardized boredom induction task (peg-turning) and a self-selected video watched for the same duration (non-boredom). Subjective mood state and perceived task characteristics were assessed at baseline, during experimental manipulations, and after the choice task. Results: PWUC and controls were demographically well-matched and similar in reported drugs use other than cocaine, except for recent cigarette and alcohol use (PWUC>controls). As expected, peg-turning increased boredom in the sample overall, with higher boredom reported during peg-turning than the video (p.05, BF01=2.9). Conclusion: Experimentally-induced boredom increased state impulsivity irrespective of cocaine use status, suggesting a broad link between boredom and impulsive choice. This is the first study to show that transient boredom directly increases impulsive choice. Data support a viable laboratory method to further parse the effects of boredom on impulsive choice.

Attenuating enzymatic degradation of endocannabinoids (eCBs) by fatty acid amide hydrolase (FAAH) reduces cannabis withdrawal symptoms in preclinical and clinical studies. In mice, blocking cyclooxygenase-2 (COX-2) activity increases central eCB levels by inhibiting fatty acid degradation. This placebo-controlled study examined the effects of the FDA-approved COX-2 selective inhibitor, celecoxib, on cannabis withdrawal, ‘relapse,’ and circulating eCBs in a human laboratory model of cannabis use disorder. Daily, nontreatment-seeking cannabis smokers (12M,3F) completed a crossover study comprising two 11-day study phases (separated by >14 days for medication clearance). In each phase, the effects of daily BID placebo (0 mg) or celecoxib (200 mg) on cannabis (5.3% THC) intoxication, withdrawal symptoms (4 days of inactive cannabis self-administration) and ‘relapse’ (3 days of active cannabis self-administration following abstinence) were assessed. Outcome measures included mood, cannabis self-administration, sleep, food intake, cognitive performance, tobacco cigarette use, and circulating eCBs and related lipids. Under placebo maintenance, cannabis abstinence produced characteristic withdrawal symptoms (negative mood, anorexia, dreaming) relative to cannabis administration, and was associated with increased OEA (a substrate of FAAH) and oleic acid (metabolite of OEA), with no change in eCB levels. Compared to placebo, celecoxib improved subjective (but not objective) measures of sleep and did not affect mood or plasma levels of eCBs or associated lipids, and increased cannabis craving. The overall absence of effects on cannabis withdrawal symptoms, self-administration, or circulating eCBs relative to placebo, combined with an increase in cannabis craving, suggests celecoxib does not show promise as a potential pharmacotherapy for CUD.

Risky decision-making is characteristic of drug users, but little is known about the effects of circumstances, such as abstinence, on risky choice behavior in human drug users. We hypothesized that cocaine users would make more risky choices for cocaine (defined as taking a chance to receive a large number of cocaine doses as opposed to choosing to receive a fixed amount of cocaine) after 3 or 7 days of cocaine abstinence, compared to 1 day of cocaine abstinence. Six male nontreatment-seeking current cocaine smokers were enrolled in a 21-day inpatient within-subject study. Participants repeatedly smoked six 25 mg doses of cocaine during a training session and were instructed that they would be making decisions about smoking this dose throughout the study. After 1, 3 and 7 days of cocaine abstinence, participants completed a computerized task in which they repeatedly decided between receiving a guaranteed number of cocaine doses (between 1 and 5; fixed option) or receiving a chance (0.13 to 0.75) to smoke a larger number of cocaine doses (probabilistic option). After completing the computerized task, one of the participants' choices was randomly implemented and they smoked either the fixed number of cocaine doses or had the specified chance to smoke the greater number of doses. Contrary to our hypothesis, 5 of the 6 participants made fewer risky choices after 3 and 7 days of cocaine abstinence compared to one day of abstinence suggesting greater risk-aversion. Thus, even during cocaine abstinence cocaine users make rational decisions related to their drug use.

Cannabis and synthetic cannabinoids are abused in spite of possible adverse health consequences. The current study investigated the reinforcing effects of an ecologically relevant mode of administration (inhalation) of delta-9-tetrahydrocannabinol (THC), the primary psychoactive component of cannabis, and three synthetic cannabinoids detected in synthetic cannabinoid products (JWH-018, JWH-073, and HU-210) in non-human primates (NHPs). Male and female (N = 4 each) rhesus macaques were trained to inhale warm air via a metal stem to receive a candy reinforcer, an alcohol aerosol vehicle was then paired with the candy. Dose-dependent responding for inhaled aerosols of THC (2.0-16.0 μg/kg/inhalation), JWH-018 (0.2-1.6 μg/kg/inhalation), JWH-073 (2.0-8.0 μg/kg/inhalation), and HU-210 (1.0-8.0 μg/kg/inhalation) was established using a fixed-ratio five schedule of reinforcement and compared to vehicle (alcohol) self-administration. Dose-dependent responding for inhaled heroin (25.0-100.0 μg/kg/inhalation), a known reinforcer in NHPs, was also established. Responding approximated vehicle levels for many drug doses tested, but at least half of the monkeys responded for ≥ one dose of each cannabinoid and heroin above vehicle, with the exception of THC. Drug deliveries calculated as percent vehicle followed a prototypical inverted-U shaped dose-response curve for cannabinoids and heroin except for THC and JWH-018 (in males). Grouped data according to sex demonstrated that peak percent of vehicle reinforcers earned for THC was greater in males than females, whereas peak percent of vehicle reinforcers earned for JWH-018, HU-210, and heroin were greater in females than males. These findings indicate minimal reinforcing effects of CB1 receptor agonists when self-administered by NHPs via aerosol inhalation. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

There are no FDA-approved treatments for cannabis use disorder (CUD). Preclinical research has shown that the 5HT-2c agonist, lorcaserin, attenuates cue-induced reinstatement of THC-seeking and self-administration. The goal of this placebo-controlled, counterbalanced, within-subject human laboratory study was to examine lorcaserin’s effects on cannabis intoxication and self-administration. Lorcaserin (10 mg BID) was administered during one of two 13-day inpatient phases, and placebo during the other; each phase was separated by ≥ 7-days of washout. Inpatient phases comprised: 1) standardized cannabis administration (7.0% THC) at no financial cost (intoxication), counterbalanced with 2) the option to self-administer cannabis following either 0 or 3 days of abstinence. Cognitive task performance, food intake, subjective ratings of drug effects, objective/subjective sleep measures, and tobacco cigarette use were also assessed. Fifteen normal-weight, daily cannabis users (4F, 11M) not seeking treatment for CUD completed the study. Lorcaserin significantly reduced cannabis self-administration following 0 and 3 days of cannabis abstinence, and also reduced craving for cannabis during abstinence. Lorcaserin produced small but significant increases in positive cannabis ratings and body weight relative to placebo. Lorcaserin also reduced tobacco cigarette smoking on days of cannabis administration relative to placebo. During abstinence, subjective but not objective measures of sleep quality worsened during lorcaserin maintenance. Overall, lorcaserin’s ability to decrease drug-taking and cannabis craving in non-treatment seeking cannabis users supports further investigation of 5HT-2C agonists as potential pharmacotherapies for CUD.

Background The absence of an FDA-approved medication for the treatment of cocaine use disorder (CUD) may, in part, reflect the varying conditions present when the decision to use cocaine is made, with one medication unlikely to work under all conditions. The objective of this double-blind, placebo-controlled, human laboratory study was to test the effects of modafinil, a medication with mixed efficacy for the treatment of CUD, using a novel self-administration procedure designed to model distinct clinical scenarios. Methods During modafinil maintenance (0, 300 mg/day), participants chose to self-administer up to 7 doses of smoked cocaine (25 mg) under 9 conditions: immediately after exposure to: (a) cues associated with cocaine and a non-contingent cocaine administration, i.e. 'prime' (25 mg), (b) only cocaine cues, and (c) neither cues nor cocaine. Each condition was tested when self-administered cocaine cost $5, $10 and $15/dose. Results Nontreatment-seeking cocaine smokers (3 F,13 M), spending $388 ± 218/week on cocaine and with no history of alcohol use disorder, completed the study. Relative to placebo, modafinil robustly attenuated self-administration when cocaine was expensive ($10,$15/dose) and when there was no 'prime.' Modafinil had no effect on self-administration when cocaine was inexpensive ($5/dose) or when participants received a 'prime.' Conclusions Modafinil's effects on cocaine-taking varied substantially as a function of recent cocaine exposure and cost, which may help explain the mixed clinical findings. Modafinil may be most effective for preventing relapse in abstinent patients, particularly under conditions in which cocaine is costly, rather than initiating abstinence for those continuing to use cocaine.

Individuals who work nonstandard schedules, such as rotating or night shifts, are more susceptible to workplace injuries, performance decrements, and reduced productivity. This population is also almost twice as likely to use illicit drugs as individuals working a standard day shift. The purpose of this study was to examine the effects of smoked marijuana on performance, mood, and sleep during simulated shift work. Ten experienced marijuana smokers completed this 23-day, within-participant residential study. They smoked a single marijuana cigarette (0, 1.9, 3.56% Δ9-THC) one hour after waking for three consecutive days under two shift conditions: day shift and night shift. Shifts alternated three times during the study, and shift conditions were separated by an ‘off’ day. When participants smoked placebo cigarettes, psychomotor performance and subjective-effect ratings were altered during the night shift compared to the day shift: performance (e.g., vigilance) and a few subjective ratings were decreased (e.g., “Self-Confident”), whereas other ratings were increased (e.g., “Tired”). Objective and subjective measures of sleep were also disrupted, but to a lesser extent. Marijuana attenuated some performance, mood, and sleep disruptions: participants performed better on vigilance tasks, reported being less miserable and tired and sleep a greater number of minutes. Limited negative effects of marijuana were noted. These data demonstrate that abrupt shift changes produce performance, mood, and sleep decrements during night shift work and that smoked marijuana containing low to moderate Δ9-THC concentrations can offset some of these effects in frequent marijuana smokers.

Eating disorders are associated with a range of abnormalities in eating behavior. Some individuals consume large amounts of non-caloric artificial sweeteners, suggesting abnormalities in appetitive responding. The current study aimed to quantify hedonic and motivating effects of artificial sweetener in individuals with and without an eating disorder. Two laboratory studies were conducted. Hedonic preference was estimated using the number of artificial sweetener packets (0 to 10) added to unsweetened cherry flavored Kool-Aid (study 1). Motivation to obtain sweetener was assessed by a progressive ratio (PR) work task (study 2). Ninety-three participants (25 anorexia nervosa restricting type (AN-R), 23 AN binge/purge type (AN-B/P), 20 bulimia nervosa (BN), and 25 normal controls (NC)) completed the study. No significant difference in hedonic preference was found among participant groups. Work completed at the PR task ranged from 0 to 9500 key-board presses. The AN-B/P group had a significantly higher breakpoint and performed significantly more work for sweetener compared to the BN and NC groups. Among AN-B/P and AN-R participants, the preferred number of Equal packets was significantly correlated with the breakpoint and total work. The increased amount of work for sweetener among individuals with AN-B/P supports an enhanced reward value of sweet taste in this population, and suggests that the characteristic food avoidance in AN cannot be accounted for by decreased reward value of all taste-related stimuli. This study also supports the novel application of a PR ratio task to quantify the motivating effect of sweet taste among individuals with an eating disorder.

Research has suggested that subanesthetic doses of ketamine may work to improve cocaine-related vulnerabilities and facilitate efforts at behavioral modification. The purpose of this trial was to test whether a single ketamine infusion improved treatment outcomes in cocaine-dependent adults engaged in mindfulness-based relapse prevention.Fifty-five cocaine-dependent individuals were randomly assigned to receive a 40-minute intravenous infusion of ketamine (0.5 mg/kg) or midazolam (the control condition) during a 5-day inpatient stay, during which they also initiated a 5-week course of mindfulness-based relapse prevention. Cocaine use was assessed through self-report and urine toxicology. The primary outcomes were end-of-study abstinence and time to relapse (defined as first use or dropout).Overall, 48.2% of individuals in the ketamine group maintained abstinence over the last 2 weeks of the trial, compared with 10.7% in the midazolam group (intent-to-treat analysis). The ketamine group was 53% less likely (hazard ratio=0.47; 95% CI=0.24, 0.92) to relapse (dropout or use cocaine) compared with the midazolam group, and craving scores were 58.1% lower in the ketamine group throughout the trial (95% CI=18.6, 78.6); both differences were statistically significant. Infusions were well tolerated, and no participants were removed from the study as a result of adverse events.A single ketamine infusion improved a range of important treatment outcomes in cocaine-dependent adults engaged in mindfulness-based behavioral modification, including promoting abstinence, diminishing craving, and reducing risk of relapse. Further research is needed to replicate these promising results in a larger sample.

Repeated drug consumption may progress to problematic use by triggering neuroplastic adaptations that attenuate sensitivity to natural rewards while increasing reactivity to craving and drug cues. Using an established laboratory model aimed at evaluating behavioral shifts in the salience of cocaine now vs. money later, we evaluated the effect on cocaine use of a single sub-anesthetic dose of the N-methyl-D-aspartate receptor antagonist ketamine, which converging evidence suggests may work to correct problematic neuroadaptations and restore motivation for non-drug rewards. We found that ketamine, as compared to the control, significantly decreased cocaine self-administration by 67% relative to baseline at greater than 24 hours post-infusion, the most robust reduction observed to date in human cocaine users and the first to involve mechanisms other than stimulant or dopamine agonist effects. These findings signal new directions in medication development for substance use disorders.

The psycholinguistic analysis of client– counselor interactions indicates that how individuals talk about their substance use is associated with treatment outcome. However, the processes by which client speech influences out-of-session behaviors have not been clearly delineated. This study investigated the relationships between deriving relations–a key behavioral process by which language and cognition may come to influence behavior, shifts in the strength of client talk in favor of change, and treatment outcome among 75 cocaine-dependent participants (23% Female). Participants were trained to relate cocaine words, nonsense syllables, and negative-consequence words and were then assessed for a derived relation of equivalence before starting treatment. The DARN-C coding system was used to quantify the strength of participant speech during an early cognitive behavior therapy counseling session. Cocaine use during treatment was the outcome of interest. The analyses (a) characterized the process of deriving relations among individuals seeking help for their misuse of cocaine, (b) tested the relationships between shifts in the strength of participants’ speech in favor of change and treatment outcome, and (c) tested if deriving equivalence relations moderated the relationship between shifts in the strength of in-session speech and treatment response. Results indicated that a minority of participants derived equivalence relations, however increases in the strength of commitment language predicted less cocaine use during treatment only among those who did. The findings suggest deriving relations may be an important process by which changes in the strength of commitment language comes to influence substance use.

Animal studies indicate that the kappa-opioid receptor/dynorphin system plays an important role in cocaine binges and stress-induced relapse. Our goal was to investigate changes in kappa-opioid receptor (KOR) availability in the human brain using positron emission tomography (PET), before and after a cocaine binge. We also investigated the correlation between KOR and stress-induced cocaine self-administration. PET imaging was performed with the KOR selective agonist [(11)C]GR103545. Subjects with cocaine-use disorder (CUD) underwent PET scans and performed two types of cocaine self-administration sessions in the laboratory as follows: (1) choice sessions following a cold pressor test, to induce stress, and (2) binge dosing of cocaine. This allowed us investigate the following: (1) the association between KOR binding and a laboratory model of stress-induced relapse and (2) the change in KOR binding following a 3-day cocaine binge, which is thought to represent a change in endogenous dynorphin. A group of matched healthy controls was included to investigate between group differences in KOR availability. A significant association between [(11)C]GR103545 binding and cocaine self-administration was seen: greater KOR availability was associated with more choices for cocaine. In addition, the 3-day cocaine binge significantly reduced [(11)C]GR103545 binding by 18% in the striatum and 14% across brain regions. No difference in [(11)C]GR103545 binding was found between the CUD subjects and matched controls. In the context of previous studies, these findings add to the growing evidence that pharmacotherapies targeting the KOR have the potential to significantly impact treatment development for cocaine-use disorder.

Cannabis is the most widely used illicit drugs and the changing legal, political and cultural climate will likely increase cannabis use further. One factor that may underlie the transition from recreational use to problematic use is stress. The hormone oxytocin (OXT) modulates stress and may have therapeutic efficacy for substance use disorders, but few studies have examined OXT in cannabis users. Another factor is sex; although more men smoke cannabis, the transition from recreational to problematic use is faster in women. Using a within-subjects design, the effects of intranasal (i.n.) oxytocin (OXT; 40 IU) administration on stress reactivity (using the Trier Social Stress Test; TSST) and cannabis (5.6% THC) self-administration was assessed in recreational cannabis using men (n = 31) and women (n = 32) relative to i.n. placebo (PBO) and no-stress (NST) conditions. The TSST produced expected subjective and cardiovascular effects compared to the NST. However, in the i.n. OXT-TSST condition, positive subjective effects were lower and negative subjective effects were higher in women compared to PBO administration and compared to men. Further, latency to self-administer cannabis was longer in women than men and women self-administered less cannabis than men regardless of stress condition. There were no differences in cannabis craving as a function of sex, stress, or medication. These results suggest that OXT administration may lead to greater stress reactivity in recreational cannabis users, particularly women, and support growing evidence that sex differences should be carefully considered when examining the therapeutic potential of OXT.

Background The hypocretin/orexin system is involved in regulating arousal, and much recent work demonstrates that decreasing hypocretin receptor-1 (HCRTr1) activity using antagonists decreases appetitive behavior, including stimulant drug self-administration and reinstatement. Methods The present study determined the effects of hypocretin-1 and HCRTr1 antagonists on responding reinforced by intravenous (i.v.) cocaine self-administration (0.0125 – 0.05 mg/kg/infusion) in 5 female rhesus monkeys. Responding was examined using 3 schedules of reinforcement: 1) a Fixed interval 1 min, Fixed ratio 10 Chain schedule [FI 1-min (FR10:S)], 2) a Progressive Ratio (PR) schedule, and 3) a cocaine vs. candy. Results Choice schedule: the HCRTr1 antagonist SB-334867 (8–24 mg/kg, i.m.) decreased cocaine taking under the Chain schedule and PR schedule in all 5 monkeys and in 4 of the 5 monkeys under the Choice schedule. d- Amphetamine (0.06 – 0.25 mg/kg, i.m.), tested as a control manipulation, decreased cocaine taking in all 5 monkeys under the Chain schedule. The peptide hypocretin-1 (0.072 mg/kg, i.v.) increased cocaine taking in the monkeys with low rates of cocaine taking under the Chain (3/4) and Choice (4/5) schedules. Reinstatement of extinguished cocaine responding following response-independent delivery of a large dose of cocaine (0.3 mg/kg) was attenuated in 3 of the 5 monkeys by the HCRTr1 antagonist SB-334867. Conclusions These data expand upon work accomplished in predominantly male rodents suggesting that the hypocretin system modulates the response to appetitive stimuli. A better understanding of this system offers promise as a novel approach in medication development for appetitive disorders.

The anorexigenic effects of intramuscular d-amphetamine HCl (0.06-0.50 mg/kg) and dexfenfluramine HCl (0.25-2.0 mg/kg) were determined in experimentally naive baboons. A group of 8 adult male baboons was tested prior to a group of 7 adult female baboons. A 120-min session occurred at 9:00 a.m. during which baboons could respond for food pellets. Drug was given 30 min prior to the 9:00 a.m. morning session. Beginning at 11:00 a.m., baboons had a 6-hr multiple-meal session during which they could have up to 4 food pellet meals. Food was not available overnight, but food was available for 90 min upon awakening such that drug effects were evaluated in non-food-deprived animals. Under baseline conditions baboons earned between 30 and 70 pellets during the morning session and another 175-225 pellets during the remainder of the day. Amphetamine and dexfenfluramine produced dose-dependent decreases in food pellet intake during both the morning food session and the later multiple-meal session. Whereas there were minimal sex differences in the effects of dexfenfluramine, many of the amphetamine doses produced greater decreases in pellet intake in males than females. These results are discordant with much of the rodent literature on abuse-related drug effects that generally reports greater effects of amphetamine in females than males. Additional work is needed to replicate the current findings in nonhuman primates. (PsycINFO Database Record

The reinforcing efficacy of vaporized methamphetamine HCl (0.3 mg/kg) was determined in baboons with minimal previous drug exposure. A group of 8 adult male baboons was tested prior to a group of 7 adult female baboons. Baboons were initially trained to suck on a brass stem activating a pressure-sensitive relay (i.e., puff), to receive one M&M® candy. Five of the 8 males and 6 of the 7 females learned to activate the relay. 0.05 ml of 95% ethyl alcohol containing 0.3 mg/kg methamphetamine was vaporized and delivered to the mouth of the baboon after he/she completed 2 puffs; a single candy was given after an additional 5 puffs to ensure that baboons continued puffing after the aerosol entered their mouths. Puffing was recorded but not reinforced by candy or drug for 2 min after each aerosol delivery for males and 1 minute for females. Males could earn 10 and females could earn 20 aerosol deliveries. Males made between 225 and 650 puffs each session. Females made between 200 and 400 puffs each session. When only candy and placebo aerosol were delivered the number of puffs decreased in all 6 females but increased in all 5 males. When candy was delivered without aerosol, puffing decreased in 4 of 5 males, but this manipulation was not tested in females. Methamphetamine aerosol delivery maintained lower rates of puffing behavior in females than males, but procedural differences weaken interpretation of this sex comparison. Although training non-human primates to inhale drug vapors is time consuming, if successful, their long lifespan could provide years of valuable data justifying further work with non-human primates using models of vaporized drug self-administration.

Background: Previous studies have shown that repetitive transcranial magnetic stimulation (rTMS) to the dorsolateral prefrontal cortex may serve as a potential treatment for cocaine use disorder (CUD), which remains a public healthy problem that is refractory to treatment. The goal of this pilot study was to investigate the effect of rTMS on cocaine self-administration in the laboratory. In the self-administration sessions, CUD participants chose between cocaine and an alternative reinforcer (money) in order to directly measure cocaine-seeking behavior. The rTMS was delivered with the H7 coil, which provides stimulation to the medial prefrontal cortex (mPFC) and anterior cingulate cortex (ACC). These brain regions were targeted based on previous imaging studies demonstrating alterations in their activation and connectivity in CUD. Methods: Volunteers with CUD were admitted to an inpatient unit for the entire study and assigned to one of three rTMS groups: high frequency (10 Hz), low frequency (1 Hz), and sham. Six participants were included in each group and the rTMS was delivered on weekdays for three weeks. The cocaine self-administration sessions were performed at three time points: at baseline (pre-TMS, session 1), after 4 days of rTMS (session 2), and after 13 days of rTMS (session 3). During each self-administration session, participants outcome measure was the number of choices for cocaine. Results: The results showed a significant group by time effect (p = .02), where the choices for cocaine decreased between sessions 2 and 3 in the high frequency group. There was no effect of rTMS on cocaine self-administration the low frequency or sham groups. Conclusion: Taken in the context of the existing literature, these results contribute to the data showing that high frequency rTMS to the prefrontal cortex may serve as a potential treatment for CUD. □

Human drug use involves repeated choices to take drugs or to engage in alternative behaviors. The purpose of this study was to examine how response cost for cocaine and the value of an alternative reinforcer (opportunity to play a game of chance) and how ‘free’ doses (with minimal response cost) affected cocaine choice. Two laboratory studies of cocaine self-administration were conducted in a group of humans who were habitual cocaine smokers and in a group of rhesus monkeys that intravenously self-administered cocaine. Nine human cocaine smokers who were not seeking treatment for their cocaine were repeatedly presented with the choice to smoke 25 mg cocaine base or play a game of chance for a monetary bonus paid at study completion. The response cost for choosing cocaine varied (up to 4000 responses/dose) and the number of game plays varied (up to 8). In this sample of humans, increasing either the response cost for cocaine or increasing the value of the alternative reinforcer did not significantly affect cocaine choice, while increasing both simultaneously slightly decreased cocaine choice and increased choice of the alternative. In monkeys, the dose–response function for cocaine self-administration (10 choices of 0.0125–0.1 mg/kg/infusion vs. candy coated chocolate) was steep and we failed to achieve a 50/50 cocaine/candy choice even after substantially manipulating cost and number of candies available. Providing a large ‘free’ self-administered cocaine dose to humans did not significantly affect cocaine choice, whereas in monkeys, a large free dose of cocaine decreased cocaine choice when higher doses of cocaine were available for self-administration. The present results demonstrate that in the laboratory, it is difficult to modify on-going cocaine self-administration behavior in both humans and non-human primates.

The α2a-adrenergic agonist, lofexidine, reduced cannabis withdrawal-related sleep disruption in the laboratory, but side effects (e.g. fatigue, hypotension) limit its utility as a treatment for cannabis use disorder. This study tested the potential efficacy and tolerability of a daily bedtime administration of the FDA-approved α2a-adrenergic agonist, guanfacine, in a human laboratory model of cannabis use disorder. Daily, nontreatment-seeking cannabis smokers (13M, 2F) completed a within-subject study comprising two 9-day inpatient study phases. Each phase tested the effects of daily placebo or immediate-release guanfacine (2 mg) on cannabis intoxication (5.6 percent THC; 2 days), withdrawal (4 days of abstinence) and subsequent 'relapse' (3 days of cannabis self-administration). Ratings of mood, sleep, cardiovascular effects, food intake, psychomotor performance and cannabis self-administration were assessed. An outpatient phase preceded each inpatient phase for medication clearance or dose induction. Under placebo medication conditions, cannabis abstinence produced significant withdrawal, including irritability, sleep disruption and anorexia. Guanfacine reduced ratings of irritability and improved objective measures of sleep during cannabis withdrawal relative to placebo but did not reduce cannabis self-administration. Guanfacine was well tolerated with little evidence of fatigue and only small decreases in blood pressure: no dose was held due to hypotension. Thus, a single daily administration of guanfacine at bedtime improved sleep and mood during cannabis withdrawal relative to placebo. This positive signal supports further studies varying the guanfacine dose, formulation or frequency of administration, or combining it with other medications to increase the likelihood of having an impact on cannabis use.

Background Cocaine dependence involves problematic neuroadaptations that might be responsive to modulation of glutamatergic circuits. This investigation examined the effects of subanesthetic ketamine infusions on motivation for quitting cocaine and on cue-induced craving in cocaine-dependent participants, 24 hours postinfusion. Methods Eight volunteers with active DSM-IV cocaine dependence not seeking treatment or abstinence were entered into this crossover, double-blind trial. Three 52-min intravenous infusions were administered: ketamine (.41 mg/kg or .71 mg/kg) or lorazepam 2 mg, counterbalanced into three orderings in which ketamine .41 mg/kg always preceded the .71 mg/kg dose. Infusions were separated by 48 hours, and assessments occurred at baseline and at 24 hours postinfusion. Outcomes were change between postinfusion and preinfusion values for: 1) motivation to quit cocaine scores with the University of Rhode Island Change Assessment; and 2) sums of visual analogue scale craving ratings administered during cue exposure. Results Compared with the active control lorazepam, a single ketamine infusion (.41 mg/kg) led to a mean 3.9-point gain in University of Rhode Island Change Assessment ( p = .012), which corresponds to an approximately 60% increase over preceding values. There was a reduction of comparable magnitude in cue-induced craving ( p = .012). A subsequent ketamine infusion (.71 mg/kg) led to further reductions in cue-induced craving compared with the control. Infusions were well-tolerated. Conclusions Subanesthetic ketamine demonstrated promising effects on motivation to quit cocaine and on cue-induced craving, 24 hours postinfusion. Research is needed to expand on these preliminary results and to evaluate the efficacy of this intervention in clinical settings.

Adult hippocampal neurogenesis is critically implicated in rodent models of stress and anxiety as well as behavioral effects of antidepressants. Whereas similar factors such as psychiatric disorder and antidepressant administration are correlated with hippocampal volume in humans, the relationship between these factors and adult neurogenesis is less well understood. To better bridge the gap between rodent and human physiology, we examined the numbers of proliferating neural precursors and immature cells in the hippocampal dentate gyrus (DG) as well as in vivo magnetic resonance imaging (MRI)-estimated whole hippocampal volume in eight socially dominant- or subordinate-like (SL) baboons administered the antidepressant fluoxetine or vehicle. SL baboons had lower numbers of proliferating cells and immature neurons than socially dominant-like baboons. Fluoxetine treatment was associated with a larger whole hippocampal volume but surprisingly resulted in lower numbers of immature neurons. These findings are the first to indicate that adult neurogenesis in the baboon hippocampal DG may be functionally relevant in the context of social stress and mechanisms of antidepressant action.

Objective This study examined learning functions in short-term cocaine users and control participants. Method Seventeen active cocaine users (reporting 3.5 mean years of cocaine use) and seventeen non-cocaine-using controls (with similar reported levels of alcohol and marijuana use) were compared on tasks measuring different aspects of learning. Results The cocaine users performed more poorly on the Weather Prediction and List-Learning tasks, as well as supplementary executive and psychomotor function tasks, than controls. Conclusions Individuals with a relatively short duration of cocaine use exhibited moderate weaknesses in probabilistic category learning, verbal learning and psychomotor functions, relative to controls. These weaknesses may underpin difficulty in learning from the probabilistic consequences of behavior and hinder the ability to respond to cognitive-behavioral treatments., Highlights • Learning functions in short-term cocaine users have been understudied. • Short-term cocaine users performed worse than controls on probabilistic category and verbal learning tasks. • Short-term cocaine users performed similarly to controls on an equivalence learning task. • Clinicians should be aware that even short-term cocaine use may be associated with cognitive weaknesses.

Objective Activity-based anorexia is a translational rodent model that results in severe weight loss, hyperactivity, and voluntary self-starvation. The goal of our investigation was to identify vulnerable and resistant phenotypes of activity-based anorexia in adolescent female rats. Method Sprague-Dawley rats were maintained under conditions of restricted access to food (N = 64; or unlimited access, N = 16) until experimental exit, predefined as a target weight loss of 30–35% or meeting predefined criteria for animal health. Nonlinear mixed effects statistical modeling was used to describe wheel running behavior, time to event analysis was used to assess experimental exit, and a regressive partitioning algorithm was used to classify phenotypes. Results Objective criteria were identified for distinguishing novel phenotypes of activity-based anorexia, including a vulnerable phenotype that conferred maximal hyperactivity, minimal food intake, and the shortest time to experimental exit, and a resistant phenotype that conferred minimal activity and the longest time to experimental exit. Discussion The identification of objective criteria for defining vulnerable and resistant phenotypes of activity-based anorexia in adolescent female rats provides an important framework for studying the neural mechanisms that promote vulnerability to or protection against the development of self-starvation and hyperactivity during adolescence. Ultimately, future studies using these novel phenotypes may provide important translational insights into the mechanisms that promote these maladaptive behaviors characteristic of anorexia nervosa. © 2013 Wiley Periodicals, Inc. (Int J Eat Disord 2013; 46:737–746)

Despite the prevalent worldwide abuse of stimulants, such as amphetamines and cocaine, no medications are currently approved for treating this serious public health problem. Both preclinical and clinical studies suggest that the opioid antagonist naltrexone (NTX) is effective in reducing the abuse liability of amphetamine, raising the question of whether similar positive findings would be obtained for cocaine. The purpose of this study was to evaluate the ability of oral NTX to alter the cardiovascular and subjective effects of D-amphetamine (D-AMPH) and cocaine (COC). Non-treatment-seeking COC users (N=12) completed this 3-week inpatient, randomized, crossover study. Participants received 0, 12.5, or 50 mg oral NTX 60 min before active or placebo stimulant administration during 10 separate laboratory sessions. Oral AMPH (0, 10, and 20 mg; or all placebo) was administered in ascending order within a laboratory session using a 60-min interdose interval. Smoked COC (0, 12.5, 25, and 50 mg; or all placebo) was administered in ascending order within a laboratory session using a 14-min interdose interval. Active COC and AMPH produced dose-related increases in cardiovascular function that were of comparable magnitude. In contrast, COC, but not AMPH, produced dose-related increases in several subjective measures of positive drug effect (eg, high, liking, and willingness to pay for the drug). NTX did not alter the cardiovascular effects of AMPH or COC. NTX also did not alter positive subjective ratings after COC administration, but it did significantly reduce ratings of craving for COC and tobacco during COC sessions. These results show that (1) oral AMPH produces minimal abuse-related subjective responses in COC smokers, and (2) NTX reduces craving for COC and tobacco during COC sessions. Future studies should continue to evaluate NTX as a potential anti-craving medication for COC dependence.

Few individuals seeking treatment for marijuana use achieve sustained abstinence. The cannabinoid receptor agonist, Δ(9)-tetrahydrocannabinol (THC; dronabinol), decreases marijuana withdrawal symptoms, yet does not decrease marijuana use in the laboratory or clinic. Dronabinol has poor bioavailability, which may contribute to its poor efficacy. The FDA-approved synthetic analog of THC, nabilone, has higher bioavailability and clearer dose-linearity than dronabinol. This study tested whether nabilone administration would decrease marijuana withdrawal symptoms and a laboratory measure of marijuana relapse relative to placebo. Daily, nontreatment-seeking marijuana smokers (8 men and 3 women), who reported smoking 8.3±3.1 marijuana cigarettes/day completed this within-subject study comprising three, 8-day inpatient phases; each phase tested a different nabilone dose (0, 6, 8 mg/day, administered in counter-balanced order on days 2-8). On the first inpatient day, participants took placebo capsules and smoked active marijuana (5.6% THC) at six timepoints. For the next 3 days, they had the opportunity to self-administer placebo marijuana (0.0% THC; withdrawal), followed by 4 days in which active marijuana was available for self-administration (5.6% THC; relapse). Both nabilone dose conditions decreased marijuana relapse and reversed withdrawal-related irritability and disruptions in sleep and food intake (p

Background Few marijuana smokers in treatment achieve sustained abstinence, yet factors contributing to high relapse rates are unknown. Methods Study 1: data from five inpatient laboratory studies assessing marijuana intoxication, withdrawal, and relapse were combined to assess factors predicting the likelihood and severity of relapse. Daily, nontreatment-seeking marijuana smokers ( n = 51; 10 ± 5 marijuana cigarettes/day) were enrolled. Study 2: to isolate the effects of cigarette smoking, marijuana intoxication, withdrawal, and relapse were assessed in daily marijuana and cigarette smokers ( n = 15) under two within-subject, counter-balanced conditions: while smoking tobacco cigarettes as usual (SAU), and after at least 5 days without cigarettes (Quit). Results Study 1: 49% of participants relapsed the first day active marijuana became available. Tobacco cigarette smokers (75%), who were not abstaining from cigarettes, were far more likely to relapse than non-cigarette smokers (odds ratio: 19, p .01). Individuals experiencing more positive subjective effects (i.e., feeling "high") after marijuana administration and those with more negative affect and sleep disruption during marijuana withdrawal were more likely to have severe relapse episodes ( p 87%) relapsed to marijuana whether in the SAU or Quit phase. Tobacco cigarette smoking did not significantly influence relapse, nor did it affect marijuana intoxication or most symptoms of withdrawal relative to tobacco cessation. Conclusions Daily marijuana smokers who also smoke cigarettes have high rates of marijuana relapse, and cigarette smoking versus recent abstinence does not directly influence this association. These data indicate that current cigarette smoking is a clinically important marker for increased risk of marijuana relapse.

Epidemiological findings suggest that men and women vary in their pattern of cocaine use resulting in differences in cocaine dependence and relapse rates. Preclinical laboratory studies have demonstrated that female rodents are indeed more sensitive to cocaine's reinforcing effects than males, with estrous cycle stage as a key determinant of this effect. The current study sought to extend these findings to normally cycling female rhesus macaques, a species that shares a nearly identical menstrual cycle to humans. Dose-dependent intravenous cocaine self-administration (0.0125, 0.0250, and 0.0500 mg/kg/infusion) using a progressive-ratio schedule of reinforcement was determined across the menstrual cycle. The menstrual cycle was divided into 5 discrete phases – menses, follicular, periovulatory, luteal, and late luteal phases – verified by the onset of menses and plasma levels of estradiol and progesterone. Dependent variables including number of infusions self-administered per session, progressive ratio breakpoint, and cocaine intake were analyzed according to cocaine dose and menstrual cycle phase. Analysis of plasma hormone levels verified phase-dependent fluctuations of estradiol and progesterone, with estrogen levels peaking during the periovulatory phase, and progesterone peaking during the luteal phase. Progressive ratio breakpoint, infusions self-administered, and cocaine intake did not consistently vary based on menstrual cycle phase. These findings demonstrate that under the current experimental parameters, the reinforcing effects of cocaine did not vary across the menstrual cycle in a systematic fashion in normally cycling rhesus macaques.

The purpose of the current study was to examine the relative reinforcing effect of exercise compared to a non-monetary alternative reinforcer (leisure activity), and to money, before and after weight restoration in an inpatient population with anorexia nervosa (AN). Sixty-two inpatients with AN completed a progressive ratio (PR) task to earn exercise, leisure activities, or cash at low weight and after weight restoration. Measures of pathology and motivation to exercise were completed and post-treatment discharge weights were collected. Patients worked harder for exercise at low weight than after weight restoration (df = 46, t = 5.50, p

Immunopharmacotherapy offers an approach for treating cocaine abuse by specifically targeting the cocaine molecule and preventing its access to the CNS. dAd5GNE is a novel cocaine vaccine that attenuates the stimulant and the reinforcing effects of cocaine in rats. The goal of this study was to extend and validate dAd5GNE vaccine efficacy in non-human primates. Six experimentally naive adult female rhesus monkeys (Macaca mulatta) were trained to self-administer 0.1mg/kg/injection intravenous (i.v.) cocaine or receive candy; then 4 monkeys were administered the vaccine and 2 monkeys were administered vehicle intramuscularly, with additional vaccine boosts throughout the study. The reinforcing effects of cocaine were measured during self-administration, extinction, and reacquisition (relapse) phases. Serum antibody titers in the vaccinated monkeys remained high throughout the study. There was no change in the preference for cocaine over candy over a 20-week period in 5 of the 6 monkeys; only one of the 4 (25%) vaccinated monkeys showed a decrease in cocaine choice. All 6 monkeys extinguished responding for cocaine during saline extinction testing; vaccinated monkeys tended to take longer to extinguish responding than control monkeys (17.5 vs. 7.0 sessions). Vaccination substantially retarded reacquisition of cocaine self-administration; control monkeys resumed cocaine self-administration within 6-41 sessions and 1 vaccinated monkey resumed cocaine self-administration in 19 sessions. The other 3 vaccinated monkeys required between 57 and 94 sessions to resume cocaine self-administration even in the context of employing several manipulations to encourage cocaine reacquisition. These data suggest that the dAdGNE vaccine may have therapeutic potential for humans who achieve cocaine abstinence as part of a relapse prevention strategy.

In addition to difficulties in daily social functioning, regular cocaine users have decrements in social processing (the cognitive and affective processes underlying social behavior) relative to non-users. Little is known, however, about the effects of clinically-relevant pharmacological agents, such as cocaine and potential treatment medications, on social processing in cocaine users. Such drug effects could potentially alleviate or compound baseline social processing decrements in cocaine abusers. Here, we assessed the individual and combined effects of smoked cocaine and a potential treatment medication, levodopa-carbidopa-entacapone (LCE), on facial emotion recognition in cocaine smokers. Healthy non-treatment-seeking cocaine smokers ( N = 14; two female) completed this 11-day inpatient within-subjects study. Participants received LCE (titrated to 400mg/100mg/200mg b.i.d.) for five days with the remaining time on placebo. The order of medication administration was counterbalanced. Facial emotion recognition was measured twice during target LCE dosing and twice on placebo: once without cocaine and once after repeated cocaine doses. LCE increased the response threshold for identification of facial fear, biasing responses away from fear identification. Cocaine had no effect on facial emotion recognition. Results highlight the possibility for candidate pharmacotherapies to have unintended impacts on social processing in cocaine users, potentially exacerbating already existing difficulties in this population.

Marijuana withdrawal contributes to the high relapse rates in individuals seeking treatment for marijuana-use disorders. Quetiapine, an atypical antipsychotic, reduces characteristic symptoms of marijuana withdrawal in a variety of psychiatric conditions, including mood lability, sleep disruption and anorexia. This human laboratory study investigated the effectiveness of quetiapine to decrease marijuana withdrawal and relapse to marijuana use in non-treatment-seeking marijuana smokers. Volunteers were maintained on placebo or quetiapine (200 mg/day) in this double-blind, counter-balanced, within-subject study consisting of two 15-day medication phases, the last 8 days of which were in-patient. On the first in-patient day, active marijuana [6.2% delta (9)-tetrahydrocannabinol (THC)] was repeatedly smoked under controlled conditions. For the next 3 days, inactive marijuana (0.0% THC) was available for self-administration (withdrawal). On the subsequent 4 days, active marijuana (6.2% THC) was available for self-administration (relapse). Volunteers (n = 14) who smoked an average of 10 marijuana cigarettes/day, 7 days/week, completed the study. Under placebo, withdrawal was marked by increased subjective ratings of negative mood, decreased sleep quality, and decreased caloric intake and weight loss. Compared with placebo, quetiapine improved sleep quality, increased caloric intake and decreased weight loss. However, quetiapine increased marijuana craving and marijuana self-administration during the relapse phase. These data do not suggest that quetiapine shows promise as a potential treatment for marijuana dependence.

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.

Aims Research on drug dependence often involves the administration of drugs of abuse to experienced drug users under controlled laboratory conditions. The primary objective of this study was to assess whether participation in such research alters the frequency of heroin use by non-treatment-seeking opioid-dependent volunteers after study completion. Design Data were examined from four in-patient studies involving controlled opioid administration. Setting Substance Use Research Center at Columbia University, New York State Psychiatric Institute. Participants Sixty-nine heroin-dependent volunteers. Measurements Participants' self-reported heroin use prior to and 1 month after study participation was compared using a Wilcoxon test. Because a number of participants reported that they had stopped using heroin, a logistic regression was used to identify correlates of heroin cessation 1 month after study completion. Findings One hundred and one participants entered laboratory studies and 69 completed them. Self-reported heroin use significantly decreased 1 month after study participation [1.7 (±2.0) bags per day] compared to baseline [6.8 (±4.2) bags per day], P

Anorexia nervosa is a severe psychiatric disorder characterized by unrelenting self-starvation and life-threatening weight loss. The relentlessness with which individuals with anorexia nervosa pursue starvation and in some cases exercise despite the negative physical, emotional, and social consequences parallels features of addictive disorders. From a clinical perspective, individuals with anorexia nervosa behave similarly to individuals with substance abuse by narrowing their behavioral repertoire so that weight loss, restricting food intake, and excessive exercise interfere with other activities in much the same way that substance abuse does. However, fundamental differences exist between anorexia nervosa and substance abuse that suggest anorexia nervosa is not an addiction in and of itself.

Although methamphetamine and alcohol are commonly used together in a binge-like pattern, there is a dearth of empirical data investigating the repeated effects of this drug combination. The current study examined acute and residual mood, performance, and physiological effects of methamphetamine alone, alcohol alone, and the combination. Nine adult male volunteers completed this 20-day within-participant, residential laboratory study. During four 5-day blocks of sessions, participants were administered oral methamphetamine (0, 10 mg) combined with alcohol (0, 0.375, 0.75 g/kg) three times (day 2: AM, day 2: PM, and day 3: PM). Breath alcohol concentrations, cardiovascular, subjective, and cognitive/psychomotor performance effects were assessed before drug administration and repeatedly thereafter. Subjective and objective sleep measures were also assessed; residual effects were assessed on days 3–5 of each block. Following the first drug administration, the methamphetamine–alcohol combination produced greater elevations of heart rate and ratings of “good drug effect” compared to either drug alone. Methamphetamine attenuated alcohol-related performance decrements and feelings of intoxication, whereas alcohol attenuated methamphetamine-related sleep disruptions. By the third administration, many of these effects were significantly diminished, suggesting that participants developed tolerance. Few residual effects were observed. These data show that methamphetamine combined with alcohol produced a profile of effects that was different from the effects of either drug alone. The largely positive effects of the drug combination (i.e., greater euphoria, and fewer performance and sleep disruptions) might explain why these drugs are often used in combination.

We examined the effects of periodic access to a palatable, high sugar content food (candy) in 8 male baboons on the anorectic response to d -amphetamine, which increases dopamine, and dexfenfluramine, which increases serotonin. During candy access, up to 200 candies containing 75% of energy as sugar were available during the morning on Mondays, Wednesdays and Fridays; food pellets (19% of energy as sugar) were available in the afternoon and throughout the remaining days of the week. During candy access, baboons consumed a mean of 177 pieces of candy containing 696 kcal (2.91 MJ) in the morning compared to 44 food pellets and 150 kcal (0.63 MJ) in the morning on non-candy days. Food pellet intake was lower during candy access. Complete dose–response functions for the effects of the drugs on food pellet intake on days that candy was not available were determined before, during, and after the period of access to candy. Dexfenfluramine and amphetamine produced dose-dependent decreases in food pellet intake and increases in latency to eat food pellets before, during, and after candy access. During access to candy, the dose–response function for dexfenfluramine was shifted to the right indicating the development of tolerance, while that for amphetamine was shifted to the left indicating sensitization. Only the dose–response function for dexfenfluramine returned to baseline after candy access suggesting that the difference was specific to concurrent palatable food consumption. We hypothesize that tolerance to the effects of dexfenfluramine reflects a decrease in the satiating effect of serotonin release due to repeatedly eating large amounts of palatable food.

Despite their chemical similarities, methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA) produce differing neurochemical and behavioral responses in animals. In humans, individual studies of methamphetamine and MDMA indicate that the drugs engender overlapping and divergent effects; there are only limited data comparing the two drugs in the same individuals.This study examined the effects of methamphetamine and MDMA using a within-subject design.Eleven adult volunteers completed this 13-day residential laboratory study, which consisted of four 3-day blocks of sessions. On the first day of each block, participants received oral methamphetamine (20, 40 mg), MDMA (100 mg), or placebo. Drug plasma concentrations, cardiovascular, subjective, and cognitive/psychomotor performance effects were assessed before drug administration and after. Food intake and sleep were also assessed. On subsequent days of each block, placebo was administered and residual effects were assessed.Acutely, both drugs increased cardiovascular measures and "positive" subjective effects and decreased food intake. In addition, when asked to identify each drug, participants had difficulty distinguishing between the amphetamines. The drugs also produced divergent effects: methamphetamine improved performance and disrupted sleep, while MDMA increased "negative" subjective-effect ratings. Few residual drug effects were noted for either drug.It is possible that the differences observed could explain the differential public perception and abuse potential associated with these amphetamines. Alternatively, the route of administration by which the drugs are used recreationally might account for the many of the effects attributed to these drugs (i.e., MDMA is primarily used orally, whereas methamphetamine is used by routes associated with higher abuse potential).

This pilot study compared basic neurocognitive functioning among older and younger cocaine abusers and control participants, as a preliminary assessment of whether specific cognitive deficits exist in an aged cocaine-abusing population. We hypothesized an interaction between aging and cocaine abuse, such that older cocaine abusers would exhibit decreased neuropsychological test performance relative to both younger cocaine abusers and older control participants. Four groups (n = 20 each) were examined: older cocaine abusers (ages 51-70), younger cocaine abusers (ages 21-39), and two non-illicit substance-using control groups. Basic neuropsychological and psychiatric measures were administered to all participants. Older participants performed more poorly than younger participants on the Mini-Mental State Examination (MMSE, p .05). Older cocaine abusers performed more poorly than older control participants and younger cocaine abusers on the Digit Span Forward (p < .0125). Older cocaine abusers also performed more poorly than younger cocaine abusers on TMT A (p < .0125). This study provides preliminary evidence that older cocaine abusers use a significant amount of cocaine and that there is an interaction between aging and cocaine abuse on psychomotor speed, attention, and short-term memory. Future examination of neurocognitive function in older cocaine abusers is clearly warranted.

Partial dopamine receptor agonists have been proposed as candidate pharmacotherapies for cocaine dependence.This 42-day, within-subject, human laboratory study assessed how maintenance on aripiprazole, a partial D(2) receptor agonist, influenced smoked cocaine self-administration, cardiovascular measures, subjective effects, and cocaine craving in nontreatment-seeking, cocaine-dependent volunteers.In order to achieve steady-state concentrations, participants (n = 8 men) were administered placebo and aripiprazole (15 mg/day) capsules in counter-balanced order for 21 days. A smoked cocaine dose-response curve (0, 12, 25, 50 mg) was determined twice under placebo and aripiprazole maintenance. Sessions comprised a "sample" trial, when participants smoked the cocaine dose available that session, and five choice trials, when they responded on a progressive-ratio schedule of reinforcement to receive the cocaine dose or receive $5.00.Cocaine's reinforcing, subjective, and cardiovascular effects were dose-dependent. Aripiprazole significantly increased cocaine (12, 25 mg) self-administration. Following a single administration of cocaine (25 mg), aripiprazole decreased ratings of how much participants would pay for that dose. Following repeated cocaine (50 mg) self-administration, aripiprazole decreased ratings of cocaine quality, craving, and good drug effect as compared to placebo.These data suggest that aripiprazole may have increased self-administration to compensate for a blunted subjective cocaine effect. Overall, the findings do not suggest aripiprazole would be useful for treating cocaine dependence.

Zolpidem attenuates shift-change-related sleep and performance disruptions. It is unknown whether these benefits alter the reinforcing effects of the drug during shift work. This study examined zolpidem-related reinforcing effects during simulated shift work. Eleven volunteers (3F, 8M) completed this 16-day within-participant, residential laboratory study. Each day participants were given an opportunity to self-administer oral zolpidem (10 mg) or receive a $1 voucher immediately following a 9-h work period and immediately before going to bed. Participants worked under two shift conditions: (1) during the night shift, participants completed computerized task batteries from 00:30 to 09:30 h and went to bed at 16:00 h and (2) during the day shift, participants completed task batteries from 08:30 to 17:30 h and went to bed at 24:00 h. Shift conditions alternated three times during the study. Despite the fact that sleep, psychomotor performance, and some ratings of mood were disrupted during night-shift work, there was no significant effect of shift on choice to take zolpidem. Overall, participants selected markedly fewer zolpidem doses than monetary vouchers (17% versus 83%). Thus, zolpidem did not serve as a reinforcer even when sleep was disrupted. These data are consistent with previous reports indicating that sedatives produce limited reinforcing effects in individuals without a history of drug abuse.

Rationale Previously, we reported that acute marijuana intoxication minimally affected complex cognitive performance of daily marijuana smokers. It is possible that the cognitive tests used were insensitive to marijuana-related cognitive effects. Objectives In the current study, electroencephalographic (EEG) signals were recorded as daily marijuana users performed additional tests of immediate working memory and delayed episodic memory, before and after smoking marijuana. Methods Research volunteers (N = 24), who reported smoking ∼ 24 marijuana cigarettes/week, completed this study. Participants completed baseline computerized cognitive tasks, smoked a single marijuana cigarette (0%, 1.8%, or 3.9% ∆ 9 -THC w/w), and completed additional cognitive tasks; sessions were separated by at least 72-hours. Cardiovascular and subjective effects were also assessed throughout sessions. Results Overall performance accuracy was not significantly altered by marijuana, although the drug increased response times during task performance and induced a response bias towards labeling “new” words as having been previously seen in the verbal episodic memory task. Marijuana reduced slow wave evoked potential amplitude in the episodic memory task and decreased P300 amplitude and EEG power in the alpha band in the spatial working memory task. Heart rate and “positive” subjective-effect ratings were increased in a ∆ 9 -THC concentration-dependent manner. Conclusions Relative to previous findings with infrequent marijuana users, the frequent users in the current study exhibited similar neurophysiological effects but more subtle performance effects. These data emphasize the importance of taking into account the drug-use histories of research participants and examining multiple measures when investigating marijuana-related effects on cognitive functioning.

The purpose of this double-blind, randomized, outpatient study was to evaluate the reinforcing and subjective effects of modafinil (200, 400, or 600 mg) in cocaine abusers. Twelve participants (2 female, 10 male) completed this study, consisting of 3 blocks of 7 sessions; each block tested a difference dose of modafinil. During the first 2 sessions of each block, participants "sampled" 1 of the doses of modafinil, and placebo. These doses of modafinil and placebo were available for the subsequent five choice sessions of the block. In each choice session, participants had an opportunity to administer active or placebo capsules. Modafinil administration did not differ from placebo administration, and subjective-effects ratings were not systematically altered as a function of modafinil dose. Results suggest that modafinil does not have abuse liability in cocaine abusers.

Objective—To use a Progressive Ratio (PR) computerized “work” paradigm to measure course and correlates of exercise motivation in inpatients with Anorexia Nervosa (AN). Method—Sixteen inpatients with AN participated in a PR task assessing the relative reinforcing effect of 2 different increments of cash versus the opportunity to exercise for up to 30 minutes, twice; at low weight, and, for n=10 participants, after weight restoration. Results—There was a trend toward a higher work for exercise with $2 versus $5 increments of cash as the alternative reinforcer. Exercise breakpoint did not differ between low and normalweight states. Exercise breakpoint at each time point was correlated with pre-hospitalization exercise “commitment” (Commitment to Exercise Scale, r=0.613, p=0.012 at T1; r=0.634, p=0.049 at T2). Discussion—Patients with AN will work at a PR task for access to even a small amount of exercise. Exercise motivation during hospitalization is correlated with pre-hospital exercise commitment, and does not appear to change consistently with weight restoration.

The Iowa Gambling task, which typically incorporates hypothetical monetary earnings and losses for performance, has been widely used to measure decision-making in substance abusers. We examined the effects of a cash monetary contingency on Gambling task performance in cocaine abusers and control participants.Twenty-two long-term cocaine smokers who met DSM-IV criteria for cocaine dependence and 24 non-cocaine-using control participants completed this study. Both groups were similar in terms of age, executive function, and self-reported alcohol and marijuana use. All participants performed the Gambling task under two counterbalanced conditions: under one condition, earnings and losses were hypothetical, and under the other condition, earnings and losses were in cash.Condition x group interactions on card selection and task completion time were noted (p0.05). Under the hypothetical payment condition, cocaine abusers selected a greater proportion of cards from disadvantageous decks than advantageous decks (p0.05), but took a similar amount of time to complete the task, relative to control participants. However, under the cash payment condition, no group differences were seen for card selection and cocaine abusers took more time than controls to complete the task (p0.05).The application of tangible consequences improved the decision-making and effort of cocaine abusers on the Gambling task, relative to control participants. These findings underscore the importance of considering population-specific factors (e.g., sensitivity to instructional vs. consequential control) when conducting neuropsychological research in substance abusers.

Objective The goal of this study was to determine D1 receptor availability in human cocaine dependent (CD) subjects and matched healthy controls (HC). In addition, the cocaine dependent subjects performed cocaine self-administration sessions in order to explore the association between D1 receptor availability and cocaine seeking behavior. Methods 25 cocaine dependent subjects (40 ±4 yrs, 19M/6 F) and 23 matched healthy controls (38 ±4 yrs, 19M/4F) were scanned with PET and the radiotracer [11C]NNC 112. During the cocaine self-administration sessions, cocaine dependent volunteers were given the choice to self-administer cocaine (0, 6, and 12 mg) or to receive a monetary voucher worth $5. D1 receptor availability was measured in the limbic, associative and sensori-motor striatum in addition to cortical brain regions. Results No difference in D1 receptor availability was seen between the two groups. A negative association was seen between D1 receptor BPND in the limbic striatum and the choice for the 6 mg dose of cocaine (r = - 0.47, p = 0.02, corrected for age). Conclusions These results do not support the hypothesis that cocaine dependence is associated with a reduction in D1 receptor availability in the striatum. However, within the cocaine-dependent subjects, low D1 receptor availability in the ventral striatum was associated with the choice to self-administer cocaine, suggesting that low D1 receptor availability may be associated with an increased risk of relapse in cocaine dependence.

Excessive consumption of highly palatable foods may contribute to the development of weight gain. Therefore medications that selectively suppress eating of such foods would be useful in clinical practice. We compared the effects of the glutamatergic antagonists memantine and MTEP to dexfenfluramine in baboons given periodic access to highly palatable food and ad libitum access to a standard chow diet. Three days a week baboons received a sugar-coated candy during the first meal and standard standard-diet chow pellets were available in subsequent meals. All baboons derived a greater amount of energy from the single single-candy meal than from the standard diet across an entire day. Pre-treatment with dexfenfluramine, memantine, and MTEP produced decreases in candy consumption without altering candy-seeking behaviour. At the same time, dexfenfluramine and memantine, but not MTEP, produced a decrease in seeking and consumption of standard chow pellets. Both memantine and MTEP are promising agents for the treatment of obesity.