Sean P. Barrett

Effects of expectancy and abstinence on the neural response to smoking cues in cigarette smokers : An fMRI study

Cues associated with drug taking can trigger relapse, drug seeking, and craving in addicted individuals. Behavioral studies suggest that drug availability and withdrawal can affect the individual response to drug cues. Moreover, the importance of subjective craving in cue-induced relapse has been questioned and an alternative model put forward according to which drug cues trigger habitual drug-seeking behaviors independently of craving. We used functional magnetic resonance imaging to compare the brain response to smoking and control videotapes in 20 healthy smokers, while varying their expectancy to smoke and abstinence levels. The neural response to cigarette cues was strongly modulated by expectancy and, to a lesser extent, abstinence. In people expecting to smoke immediately after the scan, smoking cues activated brain areas implicated in arousal, attention, and cognitive control. However, when subjects knew they would not be allowed to smoke for 4 h, there was almost no brain activation in response to smoking cues, despite equivalent reported levels of craving. In the dorsolateral prefrontal cortex, the neural response was a function of both craving and expectancy. Thalamo-cingulate connectivity, thought to be an index of arousal, was greater during expectancy than nonexpectancy. Our findings confirm the importance of expectancy in the neural response to drug cues, and lend support to the theory that these cues act on brain areas involved in arousal and attention.

Characteristics of methylphenidate misuse in a university student sample.

Objective: Methylphenidate (MPH) is a prescription stimulant drug with known abuse potential; however, little is known about its patterns of misuse or the characteristics of its abusers. Methods: A sample of 50 university students reporting MPH misuse and 50 control subjects matched for age, sex, and ethnicity completed structured face-to-face interviews about their MPH and other drug use. For each substance ever used, they provided information regarding routes of administration and other substances ever coadministered, as well as details about the most recent administration. MPH users provided additional information about their reasons for use and, in 36 cases, about how they obtained the drug. Results: Relative to control subjects, those who misused MPH were more likely to have used various other prescription and nonprescription stimulant drugs over their lifetime, and most MPH users reported mixing the drug with other psychoactive substances. Of the MPH sample, 70% reported recreational use of the drug, while 30% reported that MPH was used exclusively for study purposes. Relative to those using it exclusively for study, recreational users were more likely to report using MPH intranasally, as well as coadministering MPH with other substances. Most of those who reported their source of MPH obtained it from an acquaintance with a prescription. Conclusions: Those who misuse MPH are more likely than their peers to misuse various other substances, and MPH misuse frequently occurs in the context of simultaneous polydrug use. Because the primary supply of inappropriately used MPH appears to be prescribed users, efforts should be directed toward preventing its diversion.

Patterns of Simultaneous Polysubstance Use in Canadian Rave Attendees

The aim of this study was to examine rave-related polydrug drug use and to determine if patterns of substance use were associated with previous rave attendance. One hundred and eighty-six rave attendees (50% female) representing a wide range of ages (16 to 47 years; mean = 23.5, sd = 5.15) and levels of rave attendance experience (1 to 400 events) completed structured interviews in Montreal, Canada between November 2002 and September 2003 about their rave attendance patterns and their use of various licit and illicit substances at the most recently attended event. On average, participants reported using 2.5 different psychoactive substances (excluding tobacco) at the most recent event attended. Cannabis, alcohol, MDMA (ecstasy), amphetamine, cocaine, ketamine, and GHB were the most frequently reported substances, and details about their orders of administration, dosages, and patterns of co-administration are presented and discussed. The total lifetime number of raves attended by participants varied considerably (mean = 48.6; sd = 69.7; median = 25), and there was a positive correlation between the number events attended and number of substances used at the most recent event attended (p < 0.001). Analyses revealed that individuals reporting the use of ketamine, GHB, and/or cocaine at the most recent event had attended significantly more events than nonusers even when controlling for various demographic variables. A subset of respondents (n = 27) completed a second interview to determine the reliability of their responses. Results indicated that respondents could reliably recall details about which drugs were used, the total doses administered, as well as order of drug administration.

Ecstasy and drug consumption patterns: A canadian rave population study

Objective: This study investigates the drug consumption patterns of a sample of rave attendees in the city of Montreal, Quebec, and seeks to identify the prevalence of 3,4-methylendioxymethamphetamine (MDMA) and other drug use in this population. Method: We administered a self-report questionnaire to 210 respondents. For various licit and illicit substances, participants reported their age of first use, number of lifetime uses, and usage in the previous 30 days. Results: We found a significant rank order for the sequence of first use: 1) alcohol, 2) nicotine, 3) cannabis, 4) LSD, 5) psilocybin, 6) amphetamine, 7) cocaine, 8) MDMA, 9) gamma-hydroxybutyrate (GHB), 10) ephedrine, 11) ketamine. Alcohol and cannabis were the most commonly used substances, both in cumulative number of lifetime uses and in usage in the preceding 30 days. MDMA and amphetamine were also notable as the next 2 most popular drugs for use in the preceding 30 days and in terms of those who had tried the drugs at least once. We identified a progressive rank order of experimentation, with early alcohol or cannabis use (or both) associated with the early use of all other drugs tried by more than 25% of the sample. We found MDMA and amphetamine use to be prevalent, as was general experimentation with all drugs studied, other than heroin. Conclusion: Drug consumption levels were substantial in this “rave” population, particularly with respect to recent use of MDMA, amphetamine, cannabis, and alcohol. Results also indicate that the sequence of drug experimentation in this population follows an identifiable pattern.

Heightened Heart Rate Response to Alcohol Intoxication Is Associated With a Reward-Seeking Personality Profile

BACKGROUND The psychomotor stimulant theory of addiction posits that sensitivity to the positively rewarding properties of alcohol puts certain individuals at higher risk for alcohol abuse. A valid and reliable index of overactivation in the reward system has been a heightened baseline heart rate (HR) increase on the ascending limb of the blood alcohol curve. The main goal of this study was to investigate the relationship between this HR response and a questionnaire measuring sensitivity to reward and sensitivity to punishment. Additional goals included looking at (1). the association between a high HR response and various personality traits (hopelessness/introversion, anxiety sensitivity, impulsivity, and sensation-seeking) and (2). the relationship between these personality traits and stimulant use. METHODS A total of 18 low- and 19 high-HR responders completed the Sensitivity to Punishment and Sensitivity to Reward Questionnaire (SPSRQ), the Substance Use Risk Profile Scale (SURPS), and a modified version of the Addiction Severity Index. RESULTS High-HR responders obtained significantly higher scores than low-HR responders on the sensitivity to reward scale of the SPSRQ, as well as increased sensation-seeking scores on the SURPS. High-HR responders were not at significantly higher risk of having used stimulants, but stimulant use was associated with higher impulsivity scores on the SURPS. CONCLUSIONS Novelty/sensation-seeking is among the personality traits that have been linked to heavy alcohol use. This study suggests that reward sensitivity might mediate the relationship between this personality profile and drinking behavior.

Energy drink co-administration is associated with increased reported alcohol ingestion

INTRODUCTION AND AIMS While energy drinks (EDs) and alcohol have been reported to be frequently co-administered, little is known about the effect of this co-administration on alcohol drinking patterns. The purpose of the present research was to characterise patterns of ED and alcohol co-administration. DESIGN AND METHODS Seventy-two ED users were recruited from the Halifax university community. Participants provided information about their lifetime ED and other substance use, in addition to detailing instances of their ED and alcohol use during the previous week using a timeline follow-back interview. RESULTS Seventy-six per cent of participants reported ever deliberately mixing alcohol with EDs and 19% reported doing so during the previous week. Relative to alcohol drinking sessions in which EDs were not used, participants reported drinking significantly more alcohol when it was co-administered with EDs. DISCUSSION AND CONCLUSIONS Alcohol and ED co-administration is relatively common among ED users and seems to be associated with increased alcohol ingestion. It is recommended that this matter receive more clinical and research attention.

What constitutes prescription drug misuse? Problems and pitfalls of current conceptualizations

Many medications with sedative, anxiolytic, analgesic, or stimulant properties have the potential to be inappropriately used. However, because these substances have beneficial effects, many issues pertinent to understanding prescription drug misuse may differ from those associated with other misused substances. There is currently a lack of consensus about what constitutes prescription misuse and a wide range of operational criteria have been proposed. Inappropriate medication use is frequently defined on the basis of user characteristics (i.e. any non-prescribed use), the reason for use (i.e. use for recreational purposes), the presence of clinically significant symptoms (i.e. meeting diagnostic criteria for abuse and dependence) or on the presence of any of these factors. In cases where multiple criteria are used to define misuse there is often a lack of differentiation among them, while studies that use more specific criteria tend to exclude certain types of misuse from consideration altogether. In addition, in some cases there are a number of potential ways that a single operational criterion can be met and many of these may be associated with substantially different risks, harms, and predictors. Due to considerable variability in the classification of medication misuse both within and between studies, it is currently difficult to interpret the clinical significance of existing findings or to determine the true magnitude of problems associated with any particular form of misuse. In the present review many of the problems and challenges for adequately defining prescription drug misuse will be overviewed and recommendations will be made on how to better characterize this phenomenon.

The comorbidity of tobacco smoking and gambling: A review of the literature

ISSUES Evidence suggests that tobacco smoking and gambling frequently co-occur. Although high rates of comorbid smoking and gambling have been documented in studies with clinical populations of pathological gamblers in treatment, in studies using samples drawn from the community, and in large-epidemiological surveys, little empirical attention has been directed towards investigating the exact nature of this relationship. APPROACH In this review, we stress the literature that has examined the epidemiology, aetiology and environmental factors implicated in comorbid smoking and gambling. Publications included in the review were identified through PsycInfo, PubMed and Medline searches. KEY FINDINGS Although conclusive evidence is lacking, a growing body of literature suggests that smoking and gambling might share similar neurobiological, genetic and/or common environmental influences. IMPLICATIONS Comorbid tobacco smoking and gambling are highly prevalent at the event and syndrome levels. However, research investigating how smoking might affect gambling or vice versa is currently lacking. CONCLUSION More studies that examine the impact of this comorbidity on rates of tobacco dependence and problem gambling, as well as implications for treatment outcomes, are needed.

The role of dopamine in alcohol self-administration in humans: Individual differences

OBJECTIVE To clarify dopamines role in alcohol self-administration in a heterogeneous sample of drinkers using acute phenylalanine/tyrosine depletion (APTD). METHODS Sixteen men with variable drinking histories were characterized on their ethanol-induced cardiac response, a marker previously proposed to index dopamine system reactivity and vulnerability to alcohol abuse. During separate sessions participants were administered (i) a nutritionally balanced (BAL) amino acid (AA) mixture, (ii) a mixture lacking the dopamine precursors, phenylalanine and tyrosine, and (iii) APTD followed by the dopamine precursor, L-DOPA. Five hours after AA administration, participants could earn units of alcohol using a progressive ratio breakpoint task. RESULTS Alcohol self-administration was reduced in the APTD and APTD+L-DOPA conditions relative to the BAL condition. In both cases the changes were predicted by ethanol-induced cardiac change. CONCLUSIONS The motivation to drink is likely regulated by more than one neurobiological mechanism. Individual differences in cardiac responsivity to ethanol might provide a peripheral marker of responsiveness to pharmacological manipulations of dopamine.

Self-generated motives for gambling in two population-based samples of gamblers

In the present study, self-generated responses to a question regarding reasons for gambling from two epidemiological surveys were combined and placed into another earlier motivational model for alcohol use, adapted for gambling. Of the 3601 reasons, 954 could be categorised into the models categories: (a) coping motives (internal, negative reinforcement); (b) enhancement motives (internal, positive reinforcement); and (c) social motives (external, positive reinforcement). Results indicate that coping gamblers experienced greater gambling severity and psychopathology, enhancement gamblers were most likely to gamble while intoxicated and social gamblers were more likely to choose socially-related gambling. An examination of remaining motives suggests additional categories may be warranted – specifically financial and charitable reasons. These findings offer some support for the model; however, it may need to be expanded to account for other motives. The study highlights the advantages and limitations of using self-generated reasons to study gambling motivation.