Christine Darredeau

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.

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.

Cannabis use motives and personality risk factors

According to the model of substance abuse of Conrod, Pihl, Stewart, and Dongier (2000), four personality factors (i.e., anxiety sensitivity [AS], introversion/hopelessness [I/H], sensation seeking [SS], and impulsivity [IMP]) are associated with elevated risk for substance use/misuse, with each personality factor being related to preference for particular drugs of abuse (e.g., AS with anxiolytics). However, cannabis use has not been consistently linked to any one of these personality factors. This may be due to the heterogeneity in cannabis use motives. The present study explored the association between these four personality risk factors and different cannabis use motives. Cannabis users completed an interview about their motives for cannabis use as well as the self-report Substance Use Risk Profile Scale (SURPS; Woicik, Conrod, Stewart, & Pihl, 2009), which measures the four personality risk factors. Results showed that AS was associated with conformity motives and I/H was associated with coping motives for cannabis use. SS was positively associated with expansion motives and IMP was associated with drug availability motives. Thus, personality risk factors in the model of Conrod et al. (2000) are associated with distinct cannabis use motives in a pattern consistent with theory.

The acute effects of nicotine on the subjective and behavioural responses to denicotinized tobacco in dependent smokers.

Both nicotine and various non-nicotine smoking factors are believed to contribute to tobacco addiction but their relative roles remain incompletely understood. This study aimed to help clarify these roles by examining acute interactions between nicotine and denicotinized tobacco (DT). During two randomized blinded sessions, the effects of a quick-release 4 mg nicotine lozenge (NL) versus placebo lozenge (PL) on the subjective and behavioural responses to DT were examined in 27 (14 men) dependent, daily smokers. Participants were administered NL or PL for 30 min before receiving one initial DT cigarette. Participants could then earn additional DT cigarette puffs over the following 60 min. Subjective state was assessed using the Questionnaire of Smoking Urges-Brief and visual analogue scales at baseline, postlozenge and postinitial DT cigarette. Relative to PL, NL was associated with increased alertness as well as with reduced levels of DT self-administration (P<0.01). The administration of a single DT cigarette was followed by a reduction in craving under both lozenge conditions (P<0.001), an effect that was significantly greater in women (P<0.01). Moreover, DT administration was associated with increased ratings of ‘pleasant’, ‘satisfied’, ‘stimulated’ and ‘relaxed’, as well as with decreased ratings of ‘anxious’ (P’s<0.01), independent of lozenge condition. The findings suggest that both nicotine and non-nicotine smoking factors may make important contributions towards the addictive properties of tobacco.

The effects of nicotine content information on subjective and behavioural responses to nicotine-containing and denicotinized cigarettes.

The effects of nicotine content information on subjective and behavioural responses to nicotine-containing and denicotinized cigarettes were examined in 30 dependent and 30 nondependent 12-h abstinent smokers. Using the four conditions of a balanced placebo design, participants were given either nicotine-containing cigarettes or denicotinized cigarettes during two laboratory sessions but were told that they received nicotine-containing cigarettes in one session and nicotine-free cigarettes in the other. During each session, participants completed subjective assessments before and after sampling three puffs from the assigned cigarette and were then invited to earn additional cigarette puffs using a computerized progressive ratio task. Regardless of the actual nicotine content, participants self-administered more cigarette puffs when they were told the cigarettes contained nicotine than when told the cigarettes were nicotine-free and tended to show a decrease in craving associated with the intention to smoke after cigarette sampling when told the cigarettes were nicotine-free relative to when they were told the cigarettes contained nicotine. However, regardless of nicotine instructions, participants given nicotine-containing cigarettes showed greater postsampling increases in subjective ratings of ‘satisfied’ and ‘stimulated’ than did those given denicotinized cigarettes. The findings suggest that nicotine dose expectancy can affect both subjective and behavioural indices of smoking reinforcement but that the satisfying and stimulating aspects of smoking are related to actual nicotine administration.

The Effects of Alcohol on Responses to Nicotine-Containing and Denicotinized Cigarettes in Dependent and Nondaily Smokers

BACKGROUND Alcohol consumption has been linked to increased tobacco use and craving in both dependent and nondaily smokers, yet the extent to which these relationships depend on interactions involving nicotine remains unclear. This study examined the acute effects of alcohol on the subjective and behavioral responses to nicotine-containing tobacco and denicotinized tobacco in 17 (10 male) dependent daily smokers (DDS) and 23 (11 male) nondependent nondaily smokers (NNS). METHODS During 4 randomized double-blind sessions, participants assessed the effects of nicotine-containing tobacco or denicotinized tobacco following the administration of a moderately intoxicating dose of alcohol (mean blood alcohol concentration = 0.076 g/dl) or a placebo beverage. They could then self-administer additional puffs of the same type of cigarette sampled over a 60-minute period using a progressive ratio task. RESULTS In NNS, alcohol significantly increased the self-administration of both nicotine-containing and denicotinized cigarettes, and no differences in self-administration were observed between the 2 types of tobacco within either beverage condition. In contrast, in DDS, alcohol was associated with decreased denicotinized tobacco self-administration relative to the placebo beverage condition as well as with increased self-administration of nicotine-containing tobacco relative to denicotinized tobacco. DDS also exhibited relatively elevated craving following the administration of a nicotine-containing cigarette in the alcohol beverage condition. CONCLUSIONS Findings suggest that nicotine may be critical to the drinking-smoking relationship in DDS, but that nonnicotine smoking factors may be more important in NNS.

A comparative approach to cue competition with one and two strong predictors.

The relative validity effect (Wagner, Logan, Haberlandt, & Price, 1968) demonstrated that a strong cue or cause reduces responding to, or judgments of, a weaker cue or cause. We report two experiments with human subjects using relative validity preparations in which we investigate one- and two-cue competition effects. Previously, we investigated the effect using instrumental and Pavlovian conditioning preparations with rats. In the first experiment, we used a procedure analogous to the animal preparations. In the second experiment, we used a different probabilistic procedure. The results with humans and rats are very similar. In each species we find similar interference with processing the moderate predictor with one or with two strong competitors.

Competition between multiple causes of a single outcome in causal reasoning

A strong positive predictor of an outcome modulates the causal judgments of a moderate predictor. To study the empirical basis of this modulation, we compared treatments with one and with two strong competing (i.e., modulating) causes. This allowed us to vary the frequency of outcome occurrences or effects paired with the predictors. We investigated causal competition between positive predictors (those signaling the occurrence of the outcome), between negative predictors (those signaling the absence of the outcome) and between predictors of opposite polarity (positive and negative). The results are consistent with a contrast rather than a reduced associative strength or conditional contingency account, because a strong predictor of opposite polarity enhances rather than reduces causal estimates of moderate predictors. In addition, we found competition effects when the strong predictor predicted fewer outcome occurrences than the moderate predictor, thus implying that cue competition is, at least sometimes, a consequence of contingency rather than total cue-outcome pairings.

Patterns and Effects of Alcohol and Psychostimulant Co-administration: a Brief Review of Pharmacological Considerations and Subjective Responses

Alcohol is commonly used with various illicit and prescription drugs that have psychostimulant properties, but the reasons for this remain incompletely understood. Evidence from community samples of drug users suggest that when alcohol is co-administered with many psychostimulant drugs, its initial use typically precedes the onset of psychostimulant use and that co-administration is often associated with increased alcohol consumption. There is growing experimental evidence that alcohol and psychostimulant co-administration can result in significant pharmacological interactions as well as in the production of positive subjective effects but that the specific nature of the interactions may depend on factors such as the orders, routes, and doses of the substances administered. In this paper, we aim to review similarities and differences in the effects of alcohol co-administration with the psychostimulants cocaine, amphetamine, methylphenidate, and 3,4-methylenedioxymethamphetamine (MDMA) and to link these to their patterns of use by drug users in the natural environment.

Substance use patterns associated with injection drug use initiation in a low-threshold methadone-maintained sample

Abstract Substance use patterns associated with the initiation of injection drug use were examined in a sample of low-threshold methadone-maintained injection drug users. Injection initiation tended to coincide with concurrent heavy alcohol and cannabis use, increasing use of stimulants such as cocaine, and the onset of prescription opioid and sedative misuse. Nearly half of the sample reported simultaneously using at least one other drug (excluding tobacco) during the first-ever injection drug use session, with alcohol being the most commonly co-administered substance. Findings suggest that specific patterns of multiple substance use may be appropriate targets for prevention of injection drug use.