Social context and perceived effects of drugs on sexual behavior among individuals who use both heroin and cocaine

Researchers have identified the association between the use of cocaine and sexual behavior as an important risk factor for HIV infection and have attempted to elucidate the nature of this association. Several lines of research have suggested that facilitation of sexual behavior during intoxication with cocaine may be because of the direct pharmacological effects of the drug (e.g., increase in sexual desire), whereas others have pointed to the importance of factors related to the context of drug use (e.g., opportunities for sexual behavior, expectations about the effects of the drug, social norms). The present study explored the perceived effects of cocaine and heroin on sexual behavior, as well as the social context of drug use as a function of drug type (cocaine vs. heroin), among 46 inner-city drug users who reported a history of regular use of both crack cocaine and heroin. Results indicated that compared to heroin, cocaine had deleterious effects on participants' perceived sexual desire and performance. Despite such deleterious effects on sexual behavior, cocaine was more frequently used with an intimate partner than heroin. Furthermore, participants did not differ in the extent to which they used the two drugs in other social contexts (e.g., with friends, family, or neighbors). These preliminary results suggest that the relationship between cocaine and sexual behavior, especially among long-term cocaine users, may be facilitated by opportunities for sex that exist in the context of cocaine use, rather than by the pharmacological effects of the drug.

Obesity, overweight and liver disease in the Midspan prospective cohort studies

OBJECTIVES

To analyse the relationship between body mass index (BMI) and liver disease in men and women.

DESIGN

The Midspan prospective cohort studies.

PARTICIPANTS

The three studies were: Main study, screened in 1965-1968, workplaces across Scotland, the general population of the island of Tiree and mainland relatives; Collaborative study, conducted from 1970 to 1973, 27 workplaces in Glasgow, Clydebank and Grangemouth; Renfrew/Paisley general population study, screened in 1972-1976. After exclusions there were 16 522 men and 10 216 women, grouped by BMI into under/normal weight (< 25 kg m(-2)), overweight (25 to < 30 kg m(-2)) and obese (>or=30 kg m(-2)).

MEASUREMENTS

Relative rates (RRs) of liver disease mortality, subdivided into liver cancer and all other liver disease, by BMI category and per s.d. increase in BMI, followed-up to end 2007. RRs of liver disease from any diagnosis on the death certificate, hospital discharge records or cancer registrations (Collaborative and Renfrew/Paisley studies only 13 027 men and 9328 women). Analyses adjusted for age and study, then other confounders.

RESULTS

In total, 146 men (0.9%) and 61 women (0.6%) died of liver disease as main cause. There were strong associations of BMI with liver disease mortality in men (RR per s.d. increase in BMI=1.41 (95% confidence interval 1.21-1.65)). Obese men had more than three times the rate of liver disease mortality than under/normal weight men. Adjustment for other risk factors had very little effect. No substantial or robust associations were observed in women. In all, 325 men (2.5%) and 155 women (1.7%) had liver disease established from any source. Similar positive associations were observed for men, and there was evidence of a relationship in women.

CONCLUSIONS

BMI is related to liver disease, although not to liver disease mortality in women. The current rise in overweight and obesity may lead to a continuing epidemic of liver disease.

Modafinil does not serve as a reinforcer in cocaine abusers

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.

Regulation of craving by cognitive strategies in cigarette smokers

Cigarette craving is an important contributor to cigarette smoking, and clinical approaches that focus on regulation of craving are effective in reducing rates of relapse. However, a laboratory model that targets the use of cognitive strategies to regulate craving is lacking. To develop such a model, twenty heavy cigarette smokers (>12/day), twenty-two tobacco "chippers" (<6/day), and twenty non-smoking controls completed this outpatient study, during which they were presented with photographs of cigarettes and foods that have been previously shown to induce craving. During each trial, participants were instructed to think of the stimulus in one of two ways: by focusing either on the short-term consequences associated with consuming the item (e.g., it will taste good) or on the long-term consequences associated with regular consumption (e.g., I may get lung cancer). Participants reported significantly reduced food cravings when focusing on the long-term consequences associated with eating. For cigarette-smoking participants, cigarette craving was significantly reduced when focusing on the long-term consequences associated with smoking. This latter finding confirms clinical data and extends it by highlighting the importance of cognition in the modulation of craving. Future studies using this laboratory model could test the efficacy of different cognitive strategies and develop targeted interventions for smoking cessation based on the regulation of craving.

Attentional Bias Towards Cocaine-Related Stimuli: Relationship to Treatment-Seeking for Cocaine Dependence

BACKGROUND

Cocaine-dependent individuals demonstrate attentional bias when measured by Stroop color-naming tasks that have been modified to include cocaine-related words. However, the relationship between attentional bias and the treatment-seeking status of cocaine-dependent individuals has never been explored. The purpose of this study was to compare attentional bias towards cocaine-related verbal stimuli between treatment-seeking and nontreatment-seeking cocaine abusers.

METHODS

We examined performance on a Stroop task modified to include drug-related words in 17 cocaine-dependent treatment-seeking male participants and 20 cocaine-dependent nontreatment-seeking male participants.

RESULTS

Although treatment seekers reported less experience with cocaine than nontreatment seekers, they exhibited increased response latency and made more errors when identifying the colors of cocaine-related words, relative to neutral words (p<.05), whereas nontreatment seekers did not.

CONCLUSIONS

Factors other than a high frequency of cocaine use may contribute to the difference in attentional bias towards cocaine cues between these subgroups of cocaine users.

Cognitive Performance by Humans During a Smoked Cocaine Binge-Abstinence Cycle

Five cocaine-dependent individuals completed a 22-day inpatient study of sleep and cognition. Following 3 days of drug-free baseline, participants underwent 3 days of twice-daily smoked cocaine base self-administration (6 50-mg doses, 14 minutes apart), followed by 15 days of abstinence. Each morning and afternoon, the CDR repeatable, multiple-version, computerized cognitive battery (whose stability following practice has been documented) was administered. During abstinence, performance deteriorated on vigilance tasks (especially reaction time) as well as on immediate and delayed verbal recognition tasks but not on working memory tasks. Declines were most evident in the afternoon. Data suggest that abstinence can unmask cognitive deficits induced by chronic cocaine use and circadian factors may mediate their severity.

Effects of research setting on observed depressive symptoms in marijuana users

A post hoc analysis examined depressive symptoms in regular marijuana smokers interested in nontreatment, laboratory studies, and marijuana-dependent treatment-seekers considering clinical trial participation. Among marijuana-dependent treatment-seeking patients screened for a clinical trial, the mean Beck Depression Inventory Score (BDI) was significantly higher than for marijuana-using volunteers screened for nontreatment laboratory studies. Mean self-reported baseline marijuana use was not significantly different between groups, and BDI score was not correlated with use. Although the methods by which the two groups were selected influenced their characteristics (i.e., treatment-seekers are more likely to be experiencing some degree of clinical distress), it is notable that treatment-seeking, and not marijuana use per se, is associated with significantly higher rates of depression.

Methamphetamine self-administration by humans subjected to abrupt shift and sleep schedule changes

RATIONALE

Methamphetamine attenuates disruptions that occur after changes in work shifts. The reinforcing effects of the drug during shift work have yet to be characterized.

OBJECTIVES

This study examined methamphetamine-related mood, performance, and reinforcing effects during simulated shift work.

MATERIALS AND METHODS

Ten volunteers (four women and six men) completed this 19-day study. Participants were given an opportunity to self-administer oral methamphetamine (10 mg) or receive a $1 voucher before and after an 8-h work period for four consecutive days under two shift conditions: (1) "day shift" in which they went to bed at 2400 hours and woke up at 0800 hours and (2) "night shift" when they went to bed at 1600 hours and woke up at 2400 hours. Thus, participants completed task batteries either from 0815 to 1715 hours or from 0015 to 0915 hours. Shift conditions alternated three times during the study and were separated by an "off" day.

RESULTS

Night-shift work disrupted psychomotor task performance and some ratings of mood, especially on the first night. Consistent with this, participants chose to take methamphetamine significantly more often on the first night-shift night compared with the first day-shift day. Regardless of shift condition, however, participants selected markedly more methamphetamine doses before the work period than after it (73% versus 34%).

CONCLUSIONS

These data show that methamphetamine self-administration occurred more often before work rather than after work, suggesting that the use of stimulants by shift workers may be one strategy employed to meet behavioral demands especially under conditions engendering poor performance, fatigue, and/or sleep disruptions.

Modafinil decreases food intake in humans subjected to simulated shift work

In a limited number of studies modafinil has been shown to decrease food intake by laboratory animals and humans. The present study represents a secondary data analysis, in which the effects of modafinil on several measures of food intake were determined in humans living in a residential laboratory during simulated shift work. During this 23-day study, a wide selection of food items and beverages were freely available. During this double-blind, within-participant study, volunteers (N = 11) received oral modafinil dose (0, 200, or 400 mg) 1 h 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. Modafinil (200, 400 mg) dose-dependently decreased total caloric intake by approximately 18% and approximately 38%, respectively, regardless of shift condition, without selectively altering the proportion of total calories derived from carbohydrate, fat and protein. Ratings of "Hungry" were also significantly decreased by both active doses, but only immediately before the lunch break period. In addition, tolerance to the anorexic effects of modafinil was not apparent, as these effects remained stable across the three days of modafinil dosing. These findings show that modafinil produced clear reductions in food intake and suggest that future prospective studies should examine the drug in obese participants.

Tolerability and effects of oral Delta9-tetrahydrocannabinol in older adolescents with marijuana use disorders

OBJECTIVE

The tolerability and effects of oral Delta9-tetrahydrocannabinol (THC) have been previously investigated in adult marijuana abusers. However, no studies have included adolescent participants. This double-blind laboratory study investigated the tolerability and effects of oral THC in a group of older adolescents with marijuana use disorders.

METHODS

Eight participants (ages 16-21 years), smoking an average of 5.2 days/week and 2.5 "joints"/day, completed this four-session study, during which they received one of four oral THC doses (0, 2.5, 5, 10 mg) each session. Administration of oral THC doses was counterbalanced across participants. During each session, participants completed the Digit-Symbol Substitution Task (DSST) and subjective-effect ratings at baseline and 1, 2, and 3 h after oral THC administration.

RESULTS

Oral THC (5 mg and 10 mg) increased several "positive" subjective-effect ratings (e.g., "Good Drug Effect"), while producing no significant effects on cardiovascular measures, DSST performance, or "negative" subjective-effect ratings.

CONCLUSIONS

These results indicate that oral THC was well tolerated and suggest further study of this medication in adolescent marijuana abusers.

Acute physiological and behavioral effects of intranasal methamphetamine in humans

Intranasal methamphetamine abuse has increased dramatically in the past decade, yet only one published study has investigated its acute effects under controlled laboratory conditions. Thus, the current study examined the effects of single-dose intranasal methamphetamine administration on a broad range of behavioral and physiological measures. Eleven nontreatment-seeking methamphetamine abusers (two females, nine males) completed this four-session, in-patient, within-participant, double-blind study. During each session, one of four intranasal methamphetamine doses (0, 12, 25, and 50 mg/70 kg) was administered and methamphetamine plasma concentrations, cardiovascular, subjective, and psychomotor/cognitive performance effects were assessed before drug administration and repeatedly thereafter. Following drug administration, methamphetamine plasma concentrations systematically increased for 4 h postdrug administration then declined. Methamphetamine dose dependently increased cardiovascular measures and 'positive' subjective effects, with peaks occurring approximately 5-15 min after drug administration, when plasma levels were still ascending. In addition, cognitive performance on less complicated tasks was improved by all active methamphetamine doses, whereas performance on more complicated tasks was improved only by the intermediate doses (12 and 25 mg). These results show that intranasal methamphetamine produced predictable effects on multiple behavioral and physiological measures before peak plasma levels were observed. Of interest is the dissociation between methamphetamine plasma concentrations with cardiovascular measures and positive subjective effects, which might have important implications for potential toxicity after repeated doses.

Residual effects of intranasal methamphetamine on sleep, mood, and performance

Although intranasal methamphetamine abuse has increased, there are no published data investigating the residual effects of the drug under controlled conditions. Thus, the current study examined the residual effects of single-dose intranasal methamphetamine administration on a broad range of behavioral and physiological measures. Non-treatment seeking methamphetamine abusers (n=11) completed this two-week, in patient, within-participant, double-blind study. The study consisted of four two-day blocks of sessions; each block was separated by at least 48 h. At approximately 10:00 h, on the first day of each block, participants received one of four intranasal methamphetamine doses (0, 12, 25, 50mg/70 kg). Lights were turned out at 23:00 h that evening and sleep measures were assessed. On the morning of the second day of each block, methamphetamine plasma levels, cardiovascular measures, mood, subjective reports of the previous evening's sleep, and psychomotor performance were assessed to determine residual drug effects. The larger methamphetamine doses (25 and 50 mg) markedly disrupted subjective measures of that night's sleep and some indices of next-day mood, but only the largest dose (50 mg) dose decreased objective measures of that night's sleep and increased next-day physiological measures. Methamphetamine did not produce any negative residual effects on early next-day performance. Future studies should assess methamphetamine-related residual effects following repeated doses administered over consecutive days.

Smoked cocaine self-administration is decreased by modafinil

Modafinil has been reported to reduce cocaine use in a clinical sample of infrequent users (2 days/week), but the effects of modafinil on cocaine self-administration in the laboratory have not been studied. The present study investigated the effects of modafinil maintenance on cocaine self-administration by frequent users (4 days/week) under controlled laboratory conditions. During this 48-day double-blind, crossover design study, the effects of modafinil maintenance (0, 200, and 400 mg/day) on response to smoked cocaine (0, 12, 25, and 50 mg) were examined in nontreatment-seeking cocaine-dependent individuals (n=8). Cocaine significantly increased self-administration, subjective-effect ratings, and cardiovascular measures; modafinil at both doses (200 and 400 mg/day) markedly attenuated these effects. These findings agree with data from previous human laboratory and clinical investigations of modafinil as a potential cocaine abuse treatment medication. Thus, our data support the potential of modafinil as a pharmacotherapy for cocaine dependence.

Effects of intranasal methamphetamine on metacognition of agency

BACKGROUND

Although methamphetamine abuse has been associated with cognitive deficits, few studies have investigated the acute effects of the drug on complex cognitive performance. This study evaluated the acute effects of intranasal methamphetamine on a computerized task measuring metacognition of agency.

PROCEDURE

Ten nontreatment seeking methamphetamine abusers (2F, 8M) completed this four-session, within-participant, double-blind laboratory study; during each session, participants received one of four doses (0, 12, 25, or 50 mg/70 kg) and completed the metacognition of agency task. In this task, participants were instructed to "catch" falling targets with a mouse and then provide metacognitive judgments about their feelings of control.

RESULTS

Following placebo, judgments of agency were greater under optimal task conditions compared with less than optimal task conditions. Relative to placebo, the 12-mg dose improved task performance, increased judgments of agency under the optimal condition, and decreased judgments of agency under the less than optimal condition. By contrast, the larger doses (25 and 50 mg) increased judgments of agency only under the optimal condition but disrupted performance under the less than optimal condition.

CONCLUSION

These data show that a low intranasal methamphetamine dose enhanced judgments of agency and performance, while larger doses produced limited effects.

Effects of THC and lofexidine in a human laboratory model of marijuana withdrawal and relapse

INTRODUCTION

Individuals seeking treatment for their marijuana use rarely achieve sustained abstinence.

OBJECTIVES

The objectives of the study are to determine if THC, a cannabinoid agonist, and lofexidine, an alpha(2)-adrenergic receptor agonist, given alone and in combination, decreased symptoms of marijuana withdrawal and relapse, defined as a return to marijuana use after a period of abstinence.

MATERIALS AND METHODS

Nontreatment-seeking, male volunteers (n = 8), averaging 12 marijuana cigarettes/day, were maintained on each of four medication conditions for 7 days: placebo, tetrahydrocannabinol (THC) (60 mg/day), lofexidine (2.4 mg/day), and THC (60 mg/day) combined with lofexidine (2.4 mg/day); each inpatient phase was separated by an outpatient washout phase. During the first three inpatient days, placebo marijuana was available for self-administration (withdrawal). For the next 4 days, active marijuana was available for self-administration (relapse). Participants paid for self-administered marijuana using study earnings. Self-administration, mood, task performance, food intake, and sleep were measured.

RESULTS

THC reversed the anorexia and weight loss associated with marijuana withdrawal, and decreased a subset of withdrawal symptoms, but increased sleep onset latency, and did not decrease marijuana relapse. Lofexidine was sedating, worsened abstinence-related anorexia, and did not robustly attenuate withdrawal, but improved sleep and decreased marijuana relapse. The combination of lofexidine and THC produced the most robust improvements in sleep and decreased marijuana withdrawal, craving, and relapse in daily marijuana smokers relative to either medication alone.

CONCLUSIONS

These data suggest the combination of lofexidine and THC warrant further testing as a potential treatment for marijuana dependence.

Dronabinol and Marijuana in HIV-Positive Marijuana Smokers

OBJECTIVES

Individuals with HIV constitute the largest group using cannabinoids for medicinal reasons; yet, no studies have directly compared the tolerability and efficacy of smoked marijuana and oral dronabinol maintenance in HIV-positive marijuana smokers. This placebo-controlled within-subjects study evaluated marijuana and dronabinol across a range of behaviors: eating topography, mood, cognitive performance, physiologic measures, and sleep.

METHODS

HIV-positive marijuana smokers (n = 10) completed 2 16-day inpatient phases. Each dronabinol (5 and 10 mg) and marijuana (2.0% and 3.9% Delta9-tetrahydrocannabinol [THC]) dose was administered 4 times daily for 4 days, but only 1 drug was active per day, thereby maintaining double-blind dosing. Four days of placebo washout separated each active cannabinoid condition.

RESULTS

As compared with placebo, marijuana and dronabinol dose dependently increased daily caloric intake and body weight in HIV-positive marijuana smokers. All cannabinoid conditions produced significant intoxication, except for low-dose dronabinol (5 mg); the intoxication was rated positively (eg, "good drug effect") with little evidence of discomfort and no impairment of cognitive performance. Effects of marijuana and dronabinol were comparable, except that only marijuana (3.9% THC) improved ratings of sleep.

CONCLUSIONS

These data suggest that for HIV-positive marijuana smokers, both dronabinol (at doses 8 times current recommendations) and marijuana were well tolerated and produced substantial and comparable increases in food intake.

Acute effects of smoked marijuana on decision making, as assessed by a modified gambling task, in experienced marijuana users

The impact of regular marijuana use on executive cognitive abilities, including decision making, is not well understood. While cross-sectional studies have suggested that substance abusers exhibit impaired decision making, as assessed by the Iowa Gambling Task, the direct role of marijuana use in the Gambling Task performance of marijuana smokers has not been well defined. In this report, we present data on performance on a modified Gambling Task in experienced marijuana users after they had smoked marijuana under controlled laboratory conditions. A total of 36 marijuana users, who reported smoking approximately 24 marijuana cigarettes per week, completed this 3-session outpatient study. During each session, these volunteers completed the Gambling Task once at baseline and 3 times after smoking a single marijuana cigarette (0.0, 1.8, or 3.9% Delta9-THC). Marijuana cigarettes were administered in a double-blind fashion, and the sequence of Delta9-THC concentration was balanced across volunteers. Marijuana increased the time required to complete the task. However, advantageous card selection and money earned on the task were not disrupted by marijuana. These data are consistent with previous findings that indicated that speed of performance on tests of executive function, but not accuracy, is disrupted in experienced marijuana users during marijuana intoxication.

Substance use and psychosocial outcomes following participation in residential laboratory studies of marijuana, methamphetamine and zolpidem

RATIONALE

Non-therapeutic research with drugs of abuse in humans is important for a more comprehensive understanding of substance abuse and for the development of more effective treatments. However, the administration of substances from drug classes with abuse potential to human volunteers raises ethical questions regarding potential risk to study volunteers.

OBJECTIVE

The purpose of this study was to assess the psychosocial functioning and reported drug-taking behavior of volunteers before and after participating in a residential laboratory study, during which either marijuana, methamphetamine or zolpidem was administered.

METHODS

Twenty-two volunteers were administered Addiction Severity Index (ASI) interviews at intake and approximately six months following their study participation.

RESULTS

No significant differences between intake and follow-up assessments were found on any ASI composite or drug/alcohol-taking variable.

CONCLUSION

These preliminary data suggest that participation in residential laboratory studies involving the administration of drugs from classes with abuse potential does not alter subsequent psychosocial functioning or reported drug use.

Gabapentin does not reduce smoked cocaine self-administration: employment of a novel self-administration procedure

Previously, we reported that gabapentin, a nonselective gamma-aminobutyric acid agonist, reduced 'positive' subjective effects of cocaine without reducing cocaine self-administration. We speculated that the self-administration procedure used in that study was not sensitive to subtle shifts in the reinforcing effects of cocaine. Thus, this study examined the effects of gabapentin maintenance on cocaine self-administration using a purchase-cocaine choice procedure. During this 48-day inpatient/outpatient study, nontreatment-seeking cocaine abusers (n = 12) were maintained on gabapentin (0, 600, 1200 mg/day); four doses of cocaine (0, 12, 25, 50 mg) were each tested twice under each gabapentin condition. All cocaine testing was conducted while participants were inpatients. Before the start of each session, participants were provided with 25 dollars (five 5 dollar bills, one for each choice opportunity) and smoked the 'sample' cocaine dose once. Subsequently, participants were given five opportunities to purchase the sampled dose of cocaine (at 5 dollars per dose) or to keep 5 dollars for that choice trial. Choice to self-administer cocaine increased significantly with escalating cocaine doses; gabapentin maintenance did not alter choice to self-administer cocaine. These results concur with findings from our previous investigations of gabapentin and with those from a clinical trial examining the effects of larger gabapentin doses on cocaine use by treatment-seeking cocaine-dependent individuals. Together, the data indicate that gabapentin does not show promise as a treatment medication for cocaine dependence.

Smoked cocaine self-administration by humans is not reduced by large gabapentin maintenance doses

Previously, we reported that gabapentin, a lambda-aminobutyric acid (GABA) agonist, significantly reduced "positive" subjective effects of cocaine without reducing cocaine self-administration. We speculated that the gabapentin doses used in that study were too low to detect subtle shifts in the reinforcing effects of cocaine. Thus, the present study examined the effects of larger gabapentin maintenance doses on cocaine-related effects, including self-administration. During this 48-day double-blind, crossover design study, the effects of gabapentin maintenance (0, 2400, 3200 mg/day) on response to cocaine (0, 12, 25, 50 mg) were investigated in six cocaine-dependent individuals not seeking treatment for their cocaine use. Active cocaine significantly increased choice to self-administer cocaine, subjective-effect ratings (e.g., "Good Drug Effect"), blood pressure, and heart rate. Gabapentin did not decrease cocaine self-administration, cardiovascular measures, or most subjective effects of cocaine. These data agree with findings from a clinical trial examining the effects of similar gabapentin doses on cocaine use by treatment-seeking cocaine-dependent individuals and suggest that gabapentin does not show promise as a treatment medication for cocaine dependence.