A behavioural economic analysis of alcohol, amphetamine, cocaine and ecstasy purchases by polysubstance misusers

Pathways to the persistence of drug use despite its adverse consequences

The persistence of drug taking despite its adverse consequences plays a central role in the presentation, diagnosis, and impacts of addiction. Eventual recognition and appraisal of these adverse consequences is central to decisions to reduce or cease use. However, the most appropriate ways of conceptualizing persistence in the face of adverse consequences remain unclear. Here we review evidence that there are at least three pathways to persistent use despite the negative consequences of that use. A cognitive pathway for recognition of adverse consequences, a motivational pathway for valuation of these consequences, and a behavioral pathway for responding to these adverse consequences. These pathways are dynamic, not linear, with multiple possible trajectories between them, and each is sufficient to produce persistence. We describe these pathways, their characteristics, brain cellular and circuit substrates, and we highlight their relevance to different pathways to self- and treatment-guided behavior change.

Anhedonia modulates benzodiazepine and opioid demand among persons in treatment for opioid use disorder

Background

Benzodiazepine (BZD) misuse is a significant public health problem, particularly in conjunction with opioid use, due to increased risks of overdose and death. One putative mechanism underlying BZD misuse is affective dysregulation, via exaggerated negative affect (e.g., anxiety, depression, stress-reactivity) and/or impaired positive affect (anhedonia). Similar to other misused substances, BZD consumption is sensitive to price and individual differences. Although purchase tasks and demand curve analysis can shed light on determinants of substance use, few studies have examined BZD demand, nor factors related to demand.

Methods

This ongoing study is examining simulated economic demand for alprazolam (among BZD lifetime misusers based on self-report and DSM-5 diagnosis; n = 23 total; 14 male, 9 female) and each participant's preferred-opioid/route using hypothetical purchase tasks among patients with opioid use disorder (n = 59 total; 38 male, 21 female) who are not clinically stable, i.e., defined as being early in treatment or in treatment longer but with recent substance use. Aims are to determine whether: (1) BZD misusers differ from never-misusers on preferred-opioid economic demand, affective dysregulation (using questionnaire and performance measures), insomnia/behavioral alertness, psychiatric diagnoses or medications, or urinalysis results; and (2) alprazolam demand among BZD misusers is related to affective dysregulation or other measures.

Results

Lifetime BZD misuse is significantly (p < 0.05) related to current major depressive disorder diagnosis, opioid-negative and methadone-negative urinalysis, higher trait anxiety, greater self-reported affective dysregulation, and younger age, but not preferred-opioid demand or insomnia/behavioral alertness. Alprazolam and opioid demand are each significantly positively related to higher anhedonia and, to a lesser extent, depression symptoms but no other measures of negative-affective dysregulation, psychiatric conditions or medications (including opioid agonist therapy or inpatient/outpatient treatment modality), or sleep-related problems.

Conclusion

Anhedonia (positive-affective deficit) robustly predicted increased BZD and opioid demand; these factors could modulate treatment response. Routine assessment and effective treatment of anhedonia in populations with concurrent opioid and sedative use disorder may improve treatment outcomes.

Clinical trial registration

https://clinicaltrials.gov/ct2/show/NCT03696017, identifier NCT03696017.

Examination of Individual Differences in Susceptibility to Food Addiction using Alcohol and Addiction Research Domain Criteria (AARDoC): Recent Findings and Directions for the Future

Purpose of Review

Alcohol and Addiction Research Domain Criteria (AARDoC) is a transdiagnostic, circuits-based framework for studying addictive behaviors. We examined parallels in individual differences that might increase susceptibility to FA and other addictive disorders using the following units of analysis in AARDoC domains: craving, relative reinforcing value of food and attention bias in the incentive salience domain; decisional impulsivity (delay discounting) and inhibitory control (Go-No-Go, Conner’s Continuous Performance Test, and the flanker task) in the executive function domain; and emotion dysregulation and negative urgency in the negative emotionality domain.

Recent Findings

There are a number of parallels between FA and other addictions in the incentive salience and negative emotionality domains, but somewhat divergent findings in the executive function domain. Trauma appears to be an important environmental stressor in maintenance of FA.

Summary

AARDoC may be a useful organizing framework for studying addictions, including FA. Future studies should incorporate other units of analysis to better characterize FA.

Exploring the use of cannabis as a substitute for prescription drugs in a convenience sample

BACKGROUND

The use of cannabis as medicine (CaM) both prescribed and non-prescribed has increased markedly in the last decade, mirrored in a global shift in cannabis policy towards a more permissive stance. There is some evidence that cannabis functions as a substitute for prescription drugs, particularly opioids; however, more knowledge is needed on the motives of substitution users, their patterns of use, and perceived effects of substitution use.

AIMS

To explore who substitutes prescription drugs with cannabis, the type of prescription drugs substituted and the type of cannabis used, and the impact that substitution with cannabis has on prescription drug use as well as the motives for substitution in terms of experienced effects and side effects.

METHODS

A self-selected convenience sample was recruited through social media, public media, and patient organizations to take part in an anonymous online survey. Inclusion criteria were 18 years or older and use of cannabis (prescribed or non-prescribed) with a medical purpose.

RESULTS

The final sample included 2.841 respondents of which the majority (91%) used non-prescribed cannabis, and more than half (54.6%) had used CaM with the purpose of replacing a prescribed drug. Compared to non-substitution users, substitution users were more likely to be women and to use CaM in the treatment of chronic pain and other somatic conditions. Pain medication (67.2%), antidepressants (24.5%), and arthritis medication (20.7%) were the most common types of drugs replaced with CaM. Among substitution users, 38.1% reported termination of prescription drug use, and 45.9% a substantial decrease in prescription drug use. The most frequent type of cannabis used as a substitute was CBD-oil (65.2%), followed by 'hash, pot or skunk' (36.6%). More than half (65.8%) found CaM much more effective compared to prescription drugs, and 85.5% that the side effects associated with prescription drug use were much worse compared to use of CaM.

CONCLUSION

CaM is frequently used as a substitute for prescription drugs, particularly opioids. More research is needed on the long-term consequences of use of CaM, including the impact from low and high THC cannabis products on specific somatic and mental health conditions.

The Clinical Significance of Food Addiction

OBJECTIVES

The construct of food addiction has received increased attention and has been proposed as a mental disorder. There is some evidence that supports the inclusion of food addiction in the psychiatric nosology; however, the construct has not been sufficiently validated for inclusion. This study used the addiction syndrome model as a guiding theoretical framework to understand food addiction. The addiction syndrome model emphasizes the shared antecedents and consequences of addictions even though specific manifestations may differ.

METHODS

Participants were adult community members with food addiction (n = 26) or healthy controls (n = 26) as classified by the Yale Food Addiction Scale. Participants completed a battery of self-report questionnaires assessing cognitive, emotional, and behavioral domains often associated with addiction.

RESULTS

Results revealed that individuals with food addiction demonstrated significantly higher scores than healthy controls on depressive symptoms, emotion dysregulation, emotional eating, demand characteristics, motives, impulsivity, and family history of mental health problems and addiction, providing support for the clinical significance of food addiction.

CONCLUSIONS

Overall, this study replicates and extends previous findings, particularly in regard to behavioral economics and demand for food, providing further support for the consideration of food addiction in the psychiatric nosology.

Purchase task sensitivity to drug and nondrug reinforcers in opioid-agonist treatment patients

The behavioral economics of substance abuse has been increasingly recognized as a method of determining the value of abused substances for individuals who use those substances. It has been hypothesized that such analyses could serve as a clinical tool and that demand functions can be targeted predictors for the level of intervention necessary. This study evaluated the sensitivity of a demand task in 2 patient groups in a medication assisted treatment program (methadone maintenance), those who had used opioids in the last 2 months and those who had not used opioids in at least 18 months. Demand for 7 drugs and a control was assessed using hypothetical purchase tasks. Participants maintaining long-term abstinence had significantly higher α (sensitivity to price) and lower Q₀ (intensity of demand) for heroin than participants who had recently used opioids. Further research is necessary to illustrate if treatment is responsible for this reduction in demand. If so, demand analyses may provide clinical utility as an aid for treatment planning or as a target for treatment.

One Is Not Enough: Understanding and Modeling Polysubstance Use

Substance use disorder (SUD) is a chronic, relapsing disease with a highly multifaceted pathology that includes (but is not limited to) sensitivity to drug-associated cues, negative affect, and motivation to maintain drug consumption. SUDs are highly prevalent, with 35 million people meeting criteria for SUD. While drug use and addiction are highly studied, most investigations of SUDs examine drug use in isolation, rather than in the more prevalent context of comorbid substance histories. Indeed, 11.3% of individuals diagnosed with a SUD have concurrent alcohol and illicit drug use disorders. Furthermore, having a SUD with one substance increases susceptibility to developing dependence on additional substances. For example, the increased risk of developing heroin dependence is twofold for alcohol misusers, threefold for cannabis users, 15-fold for cocaine users, and 40-fold for prescription misusers. Given the prevalence and risk associated with polysubstance use and current public health crises, examining these disorders through the lens of co-use is essential for translatability and improved treatment efficacy. The escalating economic and social costs and continued rise in drug use has spurred interest in developing preclinical models that effectively model this phenomenon. Here, we review the current state of the field in understanding the behavioral and neural circuitry in the context of co-use with common pairings of alcohol, nicotine, cannabis, and other addictive substances. Moreover, we outline key considerations when developing polysubstance models, including challenges to developing preclinical models to provide insights and improve treatment outcomes.

The drug purity discounting task: Ecstasy use likelihood is reduced by probabilistic impurity according to harmfulness of adulterants

BACKGROUND

Ecstasy typically contains adulterants in addition to, or in lieu of, MDMA which may pose a greater risk to users than MDMA itself. The current study aimed to evaluate the effectiveness of adulterant-related informational prompts in reducing Ecstasy use using a novel probability discounting task.

METHODS

An online sample of past-month Ecstasy users (N = 278) were randomized to one of four different framing prompt conditions: no prompt; a prompt describing MDMA's effects; a prompt describing adulterants as inert "filler"; or a prompt describing adulterants as pharmacologically-active, potentially-harmful compounds. Each prompt contained general, potential public-health information that was not specifically related to subsequent behavioral tasks. All participants then completed an identical Drug Purity Discounting Task, in which they indicated the likelihood of using a sample of Ecstasy across different probabilities of the sample being impure, and then completed a hypothetical Ecstasy purchasing task.

RESULTS

Likelihood of Ecstasy use decreased as impurity probability increased across conditions. Ecstasy use likelihood was highest in the "inert" prompt condition, whereas pharmacologically-active adulterant or adulterant-nonspecific prompts resulted in comparably low likelihood of use. Ecstasy-use likelihood did not differ among conditions when the likelihood of sample impurity was 0. Ecstasy purchasing did not differ among groups. Inelastic purchasing was associated with greater likelihood of using potentially-impure Ecstasy.

CONCLUSIONS

Altogether, these data highlight the necessity of education regarding pharmacologically-active, rather than inert, adulterants in Ecstasy, and suggest that increased access to drug checking kits and services may mitigate some of the harms associated with Ecstasy use.

Medical Marijuana and Marijuana Legalization

State-level marijuana liberalization policies have been evolving for the past five decades, and yet the overall scientific evidence of the impact of these policies is widely believed to be inconclusive. In this review we summarize some of the key limitations of the studies evaluating the effects of decriminalization and medical marijuana laws on marijuana use, highlighting their inconsistencies in terms of the heterogeneity of policies, the timing of the evaluations, and the measures of use being considered. We suggest that the heterogeneity in the responsiveness of different populations to particular laws is important for interpreting the mixed findings from the literature, and we highlight the limitations of the existing literature in providing clear insights into the probable effects of marijuana legalization.

Alterations in taste perception due to recreational drug use are due to smoking a substance rather than ingesting it

Two studies explored the differences in tastant (salt, sour, bitter, sweet and spicy) concentration preference between recreational drug users and abstainers. In study 1, 250 opportunistically recruited abstainers, cannabis only users and multiple-drug users completed psychometric questionnaires and a concentration preference tastant test. In study 2, 76 participants purposefully recruited abstainers, daily tobacco users, recreational cannabis users and daily cannabis users completed the same protocol as study 1. Study 1 demonstrated that both multiple drug users and cannabis users had a higher preference for salt and sour tastants than abstainers. Study 2 showed that daily cannabis and tobacco users had a higher preference for sweet and spicy tastants than recreational cannabis users and abstainers. As predicted, recreational drug users scored higher on both sensation-seeking and impulsivity compared to abstainers. Participants who habitually smoke tobacco or cannabis daily have different concentration preference for specific tastants. The aim of the current study was to provide an explanation for the inconsistency in published results on taste preferences in recreational drug users. The data offered in this paper indicate that variation in recruitment strategy, definition of 'drug users', and mode of drug delivery, as well as multiple drug use, may explain the preference for stronger tastants in habitual drug users. Future research exploring the psychobiological underpinnings of the impact of drug use on food preferences should carefully define recreational drug user groups.

Explaining trends in alcohol-related harms in Scotland 1991-2011 (II): policy, social norms, the alcohol market, clinical changes and a synthesis

OBJECTIVE

To provide a basis for evaluating post-2007 alcohol policy in Scotland, this paper tests the extent to which pre-2007 policy, the alcohol market, culture or clinical changes might explain differences in the magnitude and trends in alcohol-related mortality outcomes in Scotland compared to England & Wales (E&W).

STUDY DESIGN

Rapid literature reviews, descriptive analysis of routine data and narrative synthesis.

METHODS

We assessed the impact of pre-2007 Scottish policy and policy in the comparison areas in relation to the literature on effective alcohol policy. Rapid literature reviews were conducted to assess cultural changes and the potential role of substitution effects between alcohol and illicit drugs. The availability of alcohol was assessed by examining the trends in the number of alcohol outlets over time. The impact of clinical changes was assessed in consultation with key informants. The impact of all the identified factors were then summarised and synthesised narratively.

RESULTS

The companion paper showed that part of the rise and fall in alcohol-related mortality in Scotland, and part of the differing trend to E&W, were predicted by a model linking income trends and alcohol-related mortality. Lagged effects from historical deindustrialisation and socio-economic changes exposures also remain plausible from the available data. This paper shows that policy differences or changes prior to 2007 are unlikely to have been important in explaining the trends. There is some evidence that aspects of alcohol culture in Scotland may be different (more concentrated and home drinking) but it seems unlikely that this has been an important driver of the trends or the differences with E&W other than through interaction with changing incomes and lagged socio-economic effects. Substitution effects with illicit drugs and clinical changes are unlikely to have substantially changed alcohol-related harms: however, the increase in alcohol availability across the UK is likely to partly explain the rise in alcohol-related mortality during the 1990s.

CONCLUSIONS

Future policy should ensure that alcohol affordability and availability, as well as socio-economic inequality, are reduced, in order to maintain downward trends in alcohol-related mortality in Scotland.

The price elasticity of demand for heroin: Matched longitudinal and experimental evidence

This paper reports estimates of the price elasticity of demand for heroin based on a newly constructed dataset. The dataset has two matched components concerning the same sample of regular heroin users: longitudinal information about real-world heroin demand (actual price and actual quantity at daily intervals for each heroin user in the sample) and experimental information about laboratory heroin demand (elicited by presenting the same heroin users with scenarios in a laboratory setting). Two empirical strategies are used to estimate the price elasticity of demand for heroin. The first strategy exploits the idiosyncratic variation in the price experienced by a heroin user over time that occurs in markets for illegal drugs. The second strategy exploits the experimentally induced variation in price experienced by a heroin user across experimental scenarios. Both empirical strategies result in the estimate that the conditional price elasticity of demand for heroin is approximately -0.80.

High-frequency drug purity and price series as tools for explaining drug trends and harms in Victoria, Australia

AIMS

Methamphetamine-related harms in Victoria have increased recently in the context of stable or declining use prevalence. We determine how changes in price and purity of methamphetamine compared to other drugs such as heroin may, in part, explain these divergent patterns.

METHODS

Detailed methamphetamine and heroin purchase price data from 2152 participant interviews from the Melbourne Injecting Drug User cohort study were used to generate drug price series for the period January 2009-June 2013. Data on drug purity from 8818 seizures made within Victoria were used to generate drug purity series during the same period. Purity-adjusted price data for methamphetamine and heroin were obtained for the period 2009-13 by combining the two data sets.

RESULTS

While the average purity of heroin seizures remained consistent and low, the average purity of powder and of crystal methamphetamine seizures increased from 12% [95% confidence interval (CI) = 10-14%] to 37% (95% CI = 20-54%) and 21% (95% CI = 18-23%) to 64% (95% CI = 60-68%), respectively. Crystal methamphetamine purity was bimodal, with observations generally less than 20% or greater than 70%. The average unadjusted price per gram for heroin decreased from $374 (95% CI = $367-381) to $294 (95% CI = $280-308), powder methamphetamine did not change significantly from $252 (95% CI = $233-271), and crystal methamphetamine increased substantially from $464 (95% CI = $416-511) in 2009 to $795 (95% CI = $737-853) in 2011. This increase was offset by an even greater increase in purity, meaning the average purity-adjusted price per gram declined. Furthermore, pure prices of both methamphetamine forms were similar, whereas their unadjusted prices were not. The pure price of heroin fluctuated with no ongoing trends.

CONCLUSIONS

Decreases in methamphetamine purity-adjusted price along with the bimodality of crystal methamphetamine purity may account for some of the recent increase in methamphetamine-related harm. For a given amount spent, methamphetamine purchase power has increased and the presence of extreme purity variations may challenge individuals' control of consumption.

Can price get the monkey off our back? A meta-analysis of illicit drug demand

Because of the increased availability of price data over the past 15 years, several studies have estimated the demand for illicit drugs, providing 462 estimates of the price elasticity. Results from estimating several meta-regressions reveal that these price elasticity estimates are influenced by a number of study characteristics. For instance, the price elasticity differs across drugs, with its absolute value being smallest for marijuana, compared with cocaine and heroin. Furthermore, price elasticity estimates are sensitive to whether demand is modeled in the short-run or the long-run, measures of quantity and price, whether or not alcohol and other illicit drugs are included in the specification of demand, and the location of demand. However, a number of other factors, including the functional form of demand, several specification issues, the type of data and method used to estimate demand, and the quality of the publication outlet, have less influence on the price elasticity.

The behavioral economics of drug self-administration: a review and new analytical approach for within-session procedures

RATIONALE

Behavioral-economic demand curve analysis offers several useful measures of drug self-administration. Although generation of demand curves previously required multiple days, recent within-session procedures allow curve construction from a single 110-min cocaine self-administration session, making behavioral-economic analyses available to a broad range of self-administration experiments. However, a mathematical approach of curve fitting has not been reported for the within-session threshold procedure.

OBJECTIVES

We review demand curve analysis in drug self-administration experiments and provide a quantitative method for fitting curves to single-session data that incorporates relative stability of brain drug concentration.

METHODS

Sprague-Dawley rats were trained to self-administer cocaine, and then tested with the threshold procedure in which the cocaine dose was sequentially decreased on a fixed ratio-1 schedule. Price points (responses/mg cocaine) outside of relatively stable brain cocaine concentrations were removed before curves were fit. Curve-fit accuracy was determined by the degree of correlation between graphical and calculated parameters for cocaine consumption at low price (Q(0)) and the price at which maximal responding occurred (P(max)).

RESULTS

Removing price points that occurred at relatively unstable brain cocaine concentrations generated precise estimates of Q(0) and resulted in P (max) values with significantly closer agreement with graphical P(max) than conventional methods.

CONCLUSION

The exponential demand equation can be fit to single-session data using the threshold procedure for cocaine self-administration. Removing data points that occur during relatively unstable brain cocaine concentrations resulted in more accurate estimates of demand curve slope than graphical methods, permitting a more comprehensive analysis of drug self-administration via a behavioral-economic framework.

The role of alcohol price in young adult drinking cultures in Scotland

Minimum Unit Pricing (MUP) is one of the Scottish Government's key policy options to reduce alcohol consumption and related harm. Although strongly evidenced for efficacy in reducing headline population level consumption, efficacy in changing the role of alcohol in Scottish culture is unknown. Questions remain as to how MUP will play across population subgroups with different sensitivities to price. In this paper we explore the views of the young adult population and situate the influence of price paid for alcohol alongside broader cultural drivers of consumption. Qualitative data from two studies investigating the role of alcohol in the transition to adulthood from 130 participants (aged 16–30) are analysed to situate the influence of price paid in shaping drinking styles and practices. Findings highlight how considerations of price paid for alcohol compete with non-financial considerations associated with choosing to drink excessively, moderately or not at all. Two broad categories of response to potential price increases were anticipated by drinkers which indicate that young adults are not a homogenous group in relation to price sensitivity. These differences highlight the potential for variation in subgroup responses to a pricing policy conceived to be effective at a population level.

Poor impulse control predicts inelastic demand for nicotine but not alcohol in rats

Tobacco and alcohol dependence are characterized by continued use despite deleterious health, social and occupational consequences, implying that addicted individuals pay a high price for their use. In behavioral economic terms, such persistent consumption despite increased costs can be conceptualized as inelastic demand. Recent animal studies demonstrated that high-impulsive individuals are more willing to work for nicotine or cocaine infusions than their low-impulsive counterparts, indicating that this trait might be causally related to inelastic drug demand. By employing progressive ratio schedules of reinforcement combined with a behavioral economics approach of analysis, we determined whether trait impulsivity is associated with an insensitivity of nicotine or alcohol consumption to price increments. Rats were trained on a delayed discounting task, measuring impulsive choice. Hereafter, high- and low-impulsive rats were selected and trained to nose poke for intravenous nicotine or oral alcohol. Upon stable self-administration on a continuous reinforcement schedule, the price (i.e. response requirement) was increased. Demand curves, depicting the relationship between price and consumption, were produced using Hursh's exponential demand equation. Similar to human observations, nicotine and alcohol consumption in rats fitted this equation, thereby demonstrating the validity of our model. Moreover, high-impulsive rats displayed inelastic nicotine demand, as their nicotine consumption was less sensitive to price increments as compared with that in low-impulsive rats. Impulsive choice was not related to differences in alcohol demand elasticity. Our model seems well suited for studying nicotine and alcohol demand in rats and, as such, might contribute to our understanding of tobacco and alcohol dependence.

Questioning the method and utility of ranking drug harms in drug policy

In a 2010 Lancet paper Nutt et al. propose a model for evaluating and ranking drug harms, building on earlier work by incorporating multi criteria decision analysis. It is argued that problems arise in modelling drug harms using rankable single figure indices when determinants of harm reflect pharmacology translated through a complex prism of social and behavioural variables, in turn influenced by a range of policy environments. The delphic methodolgy used is highly vulnerable to subjective judgements and even the more robust measures, such as drug related death and dependence, can be understood as socially constructed. The failure of the model to dissaggregate drug use harms from those related to the policy environment is also highlighted. Beyond these methodological challenges the utility of single figure index harm rankings is questioned, specifically their role in increasingly redundant legal frameworks utilising a harm-based hierarchy of punitive sanctions. If analysis is to include the capacity to capture the complexity relating to drug using behaviours and environments; specific personal and social risks for particular using populations; and the broader socio-cultural context to contemporary intoxication, there will need to be acceptance that analysis of the various harm vectors must remain separate - the complexity of such analysis is not something that can or should be over generalised to suit political discourse or outdated legal frameworks.

Mexico's methamphetamine precursor chemical interventions: impacts on drug treatment admissions

AIMS

To help counter problems related to methamphetamine, Mexico has implemented interventions targeting pseudoephedrine and ephedrine, the precursor chemicals commonly used in the drug's synthesis. This study examines whether the interventions impacted methamphetamine treatment admissions-an indicator of methamphetamine consequences.

DESIGN

Quasi-experiment: autoregressive integrated moving average (ARIMA)-based intervention time-series analysis.

INTERVENTIONS

precursor chemical restrictions implemented beginning November 2005; major rogue precursor chemical company closed (including possibly the largest single drug-cash seizure in history) March 2007; precursor chemicals banned from Mexico (North America's first precursor ban) August 2008.

SETTINGS

Mexico and Texas (1996-2008).

MEASUREMENTS

Monthly treatment admissions for methamphetamine (intervention series) and cocaine, heroin and alcohol (quasi-control series).

FINDINGS

The precursor restriction was associated with temporary methamphetamine admissions decreases of 12% in Mexico and 11% in Texas. The company closure was associated with decreases of 56% in Mexico and 48% in Texas; these decreases generally remained to the end of the study period. Neither intervention was associated with significant changes in the Mexico or Texas quasi-control series. The analysis of Mexico's ban was indeterminate due largely to a short post-ban series.

CONCLUSIONS

This study, one of the first quasi-experimental analyses of an illicit-drug policy in Mexico, indicates that the country's precursor interventions were associated with positive impacts domestically and in one of the Unites States' most populous states--Texas. These interventions, coupled with previous US and Canadian interventions, amount to a new, relatively cohesive level of methamphetamine precursor control across North America's largest nations, raising the possibility that the impacts found here could continue for an extended period.

Substitution and complementarity in the face of alcohol-specific policy interventions

AIM

Policy responses to the growing burden of alcohol-related disease fail to consider the interrelated nature of substance misuse and the potential for complex interactions in response to alcohol-specific interventions. This paper considers possible aggregate level responses to the alcohol policy and whether alcohol policy can be expected to reduce overall harm.

METHODS

A review and discussion of the relevant literature was conducted.

RESULTS

Evidence indicates that those at greatest risk consume stronger alcoholic beverages more frequently, that they are likely to complement their consumption with a range of intoxicants and that they are more likely to substitute alcohol with other substances.

CONCLUSIONS

Policies aimed at reducing alcohol consumption can be successful. However, evidence suggests a significant minority of consumers are likely to substitute or complement consumption with a range of intoxicants suggesting that policy is unlikely to reduce all-cause mortality and morbidity. Further research into the nature of substitution and complementarity is required.

Effects of alcohol preload on attentional bias towards cocaine-related cues

BACKGROUND

Drug and alcohol users have an 'attentional bias' for substance-related cues, which is likely to reflect the incentive-motivational properties of those cues. Furthermore, administration of an alcohol preload increases attentional bias for alcohol and tobacco-related cues in heavy drinkers and tobacco smokers, respectively. The present study investigated attentional bias for cocaine cues in cocaine users and non-users following administration of either alcohol or placebo.

METHOD

Thirty-two regular cocaine users and 40 non-users took part. Participants were administered alcohol or placebo, and administration was double blind. After drink administration, a Visual Probe task and Modified Stroop task were used to assess attentional bias. Subjective craving and alcohol outcome expectancies were also measured.

RESULTS

There was a significant interaction between group and drink type on the visual probe task indicating that cocaine users who had received alcohol had increased attentional bias for cocaine pictures compared to non-users and cocaine users who received placebo. The cocaine Stroop revealed no differences between cocaine users and non-users, and no effects of alcohol in either group.

CONCLUSIONS

Alcohol preload in regular cocaine users increases attentional bias for cocaine cues. However, cocaine users who received placebo did not show attentional bias for cocaine stimuli. Future research should investigate the effects of alcohol preload on attentional bias in cocaine-dependent individuals.

The behavioral economics of drug dependence: towards the consilience of economics and behavioral neuroscience

In this chapter, we review the research in this growing field by first discussing the concepts related to price and consumption (demand), its applications to the study of drug consumption and drug seeking, and the impact of other commodities on drug consumption. We then review the discounting of future commodities and events among the addicted, review the most recent research examining the neural correlates of discounting, and describe and review the new theory of addiction that results from that research. We conclude by addressing the next research steps that these advances engender.

Cannabis as a substitute for alcohol and other drugs

Background

Substitution can be operationalized as the conscious choice to use one drug (legal or illicit) instead of, or in conjunction with, another due to issues such as: perceived safety; level of addiction potential; effectiveness in relieving symptoms; access and level of acceptance. This practice of substitution has been observed among individuals using cannabis for medical purposes. This study examined drug and alcohol use, and the occurrence of substitution among medical cannabis patients.

Methods

Anonymous survey data were collected at the Berkeley Patient's Group (BPG), a medical cannabis dispensary in Berkeley, CA. (N = 350) The sample was 68% male, 54% single, 66% White, mean age was 39; 74% have health insurance (including MediCal), 41% work full time, 81% have completed at least some college, 55% make less than $40,000 a year. Seventy one percent report having a chronic medical condition, 52% use cannabis for a pain related condition, 75% use cannabis for a mental health issue.

Results

Fifty three percent of the sample currently drinks alcohol, 2.6 was the average number of drinking days per week, 2.9 was the average number of drinks on a drinking occasion. One quarter currently uses tobacco, 9.5 is the average number of cigarettes smoked daily. Eleven percent have used a non-prescribed, non OTC drug in the past 30 days with cocaine, MDMA and Vicodin reported most frequently. Twenty five percent reported growing up in an abusive or addictive household. Sixteen percent reported previous alcohol and/or drug treatment, and 2% are currently in a 12-step or other recovery program. Forty percent have used cannabis as a substitute for alcohol, 26% as a substitute for illicit drugs and 66% as a substitute for prescription drugs. The most common reasons given for substituting were: less adverse side effects (65%), better symptom management (57%), and less withdrawal potential (34%) with cannabis.

Conclusion

The substitution of one psychoactive substance for another with the goal of reducing negative outcomes can be included within the framework of harm reduction. Medical cannabis patients have been engaging in substitution by using cannabis as an alternative to alcohol, prescription and illicit drugs.

Measuring principal substance of abuse in comorbid patients for clinical research

Few individuals with substance use disorders limit their intake to one substance of abuse; however, many studies focus on a single substance. Unfortunately, the optimal method to determine the principal substance is unclear. In particular, this issue is problematic in patients with co-occurring psychiatric illness, who commonly use multiple substances. Hence we compared three methods for assessing the principal substance of abuse in 150 subjects with bipolar disorder and substance dependence: 1) the Addiction Severity Index interview, 2) a self-administered questionnaire, and 3) the most frequently used substance. While most subjects were concordant on the interview and the other two methods, we found substantial disagreement (9.3% between the interview and the questionnaire, and 12.7% between the interview and the most frequently used substance) and partial agreement (14.0%). These findings from a comorbid population demonstrate that different methods to assess principal substance of abuse could lead to different conclusions about treatment outcomes. Hence studies of comorbid patients may benefit from 1) using more than one method to assess principal substance and 2) reporting use of all substances as well as a targeted substance.

Impact of US and Canadian precursor regulation on methamphetamine purity in the United States

AIMS

Reducing drug purity is a major, but largely unstudied, goal of drug suppression. This study examines whether US methamphetamine purity was impacted by the suppression policy of US and Canadian precursor chemical regulation.

DESIGN

Autoregressive integrated moving average (ARIMA)-intervention time-series analysis.

SETTING

Continental United States and Hawaii (1985-May 2005). Interventions US federal regulations targeting precursors, ephedrine and pseudoephedrine, in forms used by large-scale producers were implemented in November 1989, August 1995 and October 1997. US regulations targeting precursors in forms used by small-scale producers (e.g. over-the-counter medications) were implemented in October 1996 and October 2001. Canada implemented federal precursor regulations in January 2003 and July 2003 and an essential chemical (e.g. acetone) regulation in January 2004.

MEASUREMENTS

Monthly median methamphetamine purity series.

FINDINGS

US regulations targeting large-scale producers were associated with purity declines of 16-67 points; those targeting small-scale producers had little or no impact. Canada's precursor regulations were associated with purity increases of 13-15 points, while its essential chemical regulation was associated with a 13-point decrease. Hawaii's purity was consistently high, and appeared to vary little with the 1990s/2000s regulations.

CONCLUSIONS

US precursor regulations targeting large-scale producers were associated with substantial decreases in continental US methamphetamine purity, while regulations targeting over-the-counter medications had little or no impact. Canada's essential chemical regulation was also associated with a decrease in continental US purity. However, Canada's precursor regulations were associated with purity increases: these regulations may have impacted primarily producers of lower-quality methamphetamine, leaving higher-purity methamphetamine on the market by default. Hawaii's well-known preference for 'ice' (high-purity methamphetamine) may have helped to constrain purity there to a high, attenuated range, possibly limiting its sensitivity to precursor regulation.

Careers in ecstasy use: do ecstasy users cease of their own accord? Implications for intervention development

Background

Ecstasy (MDMA, 3, 4-methylenodioxymethamphetamine) use is widespread in the Netherlands, with a lifetime prevalence of 4.3%, and two-thirds of dance party visitors being ecstasy users. However, research into Dutch ecstasy use patterns is lacking. In addition, recent studies suggest that ecstasy users cease their use automatically, which implies that interventions would do better to better focus on the promotion of harm reduction strategies than on inducing cessation. The current study addresses this process of ecstasy cessation.

Methods

32 participants from the Dutch dance scene were interviewed, and the results were systematically analysed using NVivo.

Results

Most ecstasy users had started to use out of curiosity. During use, users applied a host of harm reduction strategies, albeit inconsistently and sometimes incorrectly. Most users appeared to cease ecstasy use automatically because of loss of interest or changing life circumstances (e.g. a new job or relationship).

Conclusion

It appears that cessation of ecstasy use is largely determined by environmental variables and not by health concerns. This supports the idea that health promotion resources are better spent in trying to promote consistent and correct application of harm reduction practices than in trying to induce cessation.

Ecstasy use and higher-level cognitive functions: weak effects of ecstasy after control for potential confounds

BACKGROUND

Although there have been several reports linking ecstasy use with lowered cognitive function, much previous research suffers from substantial methodological limitations. The present study aimed to examine associations between ecstasy use and higher-level cognitive functions, using a larger sample size than most previous research and better controlling for a range of potential confounds.

METHOD

A cross-sectional cohort design assessed 45 currently abstinent ecstasy polydrug users (EP), 48 cannabis polydrug users (CP) and 40 legal drug users (LD). Standardized neuropsychological tests were used to measure attention, verbal, visual and working memory and executive function. Prospective memory function was also assessed.

RESULTS

It was not possible to discriminate between groups on the basis of the cognitive functions assessed. Regression analyses showed an inverse association between lifetime dose of ecstasy and verbal memory performance. A combination of drug-use variables, including measures of ecstasy use, contributed to prediction of attention/working memory. However, individual associations were small, explaining 1-6% of variance in cognitive scores.

CONCLUSIONS

Although the results suggest that heavy use of ecstasy is associated with some lowering of higher-level cognitive functions, they do not indicate a clinical picture of substantial cognitive dysfunction.

Dissociation of alcohol-seeking and consumption under a chained schedule of oral alcohol reinforcement in baboons

BACKGROUND

Initiation and maintenance of compulsive alcohol drinking involves a sequence of behaviors which occur in the presence of environmental cues. Animal models using chained schedules of alcohol reinforcement may be useful for examining the complex interactions between cues and alcohol-seeking and -consumption.

METHODS

Four baboons self-administered alcohol under a 3-component chained schedule of reinforcement; distinct cues were presented in the context of different behavioral contingencies associated with gaining access to 4% w/v alcohol (alcohol-seeking) and concluding with alcohol self-administration. First, the response strength of alcohol-related seeking responses was evaluated using a between-sessions progressive ratio (PR) procedure in which the response requirement to initiate the final contingency and gain access to the daily supply of alcohol was increased each session. The highest response requirement completed that resulted in alcohol access was defined as the breaking point (BP). Second, water was substituted for alcohol and PR procedures were repeated. The effects of increasing the "seeking" response requirement on subsequent alcohol or water consumption were also determined.

RESULTS

When alcohol was available, operant responses to gain access to and self-administer alcohol were maintained. When water was substituted for alcohol, alcohol-related cues continued to maintain alcohol-seeking responses. However, higher BPs, higher rates of self-administration and higher volumes of intake occurred when alcohol was available compared with water. Increasing the response requirement to gain access to alcohol did not reduce alcohol consumption (total alcohol intake).

CONCLUSIONS

These results show that alcohol-related cues maintained alcohol-seeking even after a prolonged period of only water availability. Cue-maintained alcohol-seeking behavior can be dissociated from subsequent alcohol consumption.

The effects of perceived quality on the behavioural economics of alcohol, amphetamine, cannabis, cocaine, and ecstasy purchases

Previous research has indicated that non-dependent polydrug users are willing to pay more money to buy good quality drugs as their income increased. This study sought to examine whether altering the perceived quality of controlled drugs would affect drug purchases if the monetary price remained fixed. A random sample of 80 polydrug users were recruited. All participants were administered an anonymous questionnaire consisting of the Drug Abuse Screening Test for Adolescents (DAST-A), the Severity of Dependence Scale for cannabis (SDS), the Alcohol Use Disorders Identification Test (AUDIT), the Hospital Anxiety and Depression Scale (HADS), and questions about their drug use. Participants then completed a simulation of controlled drug purchases where the price of alcohol, amphetamine, cannabis, cocaine, and ecstasy remained the same but their perceived quality changed (i.e. unit price increased as the perceived quality decreased). The demand for alcohol was quality inelastic and alcohol quality had no effects on the purchase of any other controlled drug. Demand for cannabis was quality elastic and alcohol substituted for cannabis as its unit price increased. Demand for cocaine was quality elastic and alcohol, cannabis, and ecstasy substituted for cocaine as its unit price increased. Demand for ecstasy was quality elastic and alcohol and cocaine both substituted for ecstasy as its unit price increased. These results suggest that perceived quality influences the demand for controlled drugs and that monitoring the perceived quality of controlled drugs may provide a warning of potential public health problems in the near future.

Cocaine/crack cocaine consumption, treatment demand, seizures, related offences, prices, average purity levels and deaths in the UK (1990 - 2004)

A recent trend of escalating use of cocaine/crack cocaine was observed in the UK. The number of mentions on death certificates; last year use of cocaine; treatment demand, number of drug offenders, seizures, prices and average purity levels were the indicators used for this descriptive and correlational study. Figures (1990-2004) were taken from official UK sources. A total of 1022 cocaine/crack cocaine death mentions (i.e. deaths from any cause where the presence of cocaine/crack cocaine was also detected) were identified, with cocaine/crack cocaine being the sole drug mentioned in 36% of cases. The number of cocaine/crack cocaine death mentions showed a year-on-year increase and correlated positively with the following cocaine (powder) figures: last year use (p < 0.001); number of offenders (p < 0.001) and number of seizures (p < 0.001), but correlated negatively with price (p < 0.001). Furthermore, the number of cocaine/crack cocaine death mentions correlated positively with the number of crack offenders (p < 0.001) and seizures (p < 0.001), but correlated negatively with both crack purity ( p < 0.001) and price (p < 0.05). With conditions of increasing drug availability having been met in the UK, decrease in cocaine prices were associated with higher consumption levels and this, in turn, contributed to the increase in number of cocaine-related fatalities. There are limitations with the information collected, since no distinction is usually made on medical death certificates between cocaine and crack cocaine. The present study being an ecological one, it proved difficult to address the role of confounding variables that may well explain some of the associations observed.

An investigation of the subjective experiences of sex after alcohol or drug intoxication

Despite long-standing concern over the sexual health of the population there has been little work undertaken in the UK investigating sexual risk taking and sexual behaviours in the context of substance use. To investigate this further, 270 non-drug treatment seeking members of the public aged between 18 and 66 were administered a questionnaire containing the Alcohol Use Disorders Identification Test (AUDIT), the Drug Abuse Screening Test (DAST), the Severity of Dependence Scale (SDS), the Sexual Risks Scale and Attitudes toward condom use (SRSA), the Sexual Sensation Seeking Scale (SSSS); the Hospital Anxiety and Depression Scale (HADS), and questions pertaining to sexual episodes proximal to substance use. The population reported a varied history of substances and despite there not being self-awareness of problematic drug use, 39.4% reported above the cut-off mark of six on the DAST. An even greater percentage (57.8%) reported a score above eight on the AUDIT indicating hazardous or harmful drinking behaviour. The substance most often associated with sexual episodes was alcohol, followed by cannabis and ecstasy, and all were most frequently consumed in private houses. Sexual activity after drug use was most frequently circumstantial (i.e. the individual hadn't taken the substance for the specific purposes of sex), and was significantly associated with use of cannabis and ecstasy. The second most frequently reported association between drug use and sex was facilitation of a sexual encounter (i.e. to lower sexual inhibitions, increase self esteem and confidence), which was associated with use of alcohol, cannabis, cocaine and ecstasy. Although it was not possible to identify differences in subjective sexual changes after use of particular drugs, subjects reported that compared to sex after alcohol, sex on other drugs was more pleasurable and satisfying, with a greater perception of interpersonal contact with the partner and a greater willingness to sexually experiment. However, this latter change was not associated with changes in the type of sexual activity engaged in. Regression analysis revealed that the greatest subjective changes in sexual experiences were reported by younger participants who had ingested either ecstasy or cannabis prior to the sexual episode. These results are discussed in the context of sexual risk taking and suggest areas of intervention focus which may address substance use and sexual risk taking together.

The effects of stereotype threat on cognitive function in ecstasy users

Stereotype threat occurs when individuals, believed to be intellectually inferior, perform badly on cognitive tests they perceive to confirm stereotypes about them. Due to the wide media coverage of studies purporting to show cognitive deficits in ecstasy users it is possible that they experience stereotype threat. This study tested ecstasy and non-ecstasy using polysubstance misusers on a variety of cognitive tests after they had been exposed to stereotype threat. This priming consisted of exposing them to information about the long-term effects of ecstasy which either stated that ecstasy caused memory loss or that it did not. Ecstasy users that had been primed that ecstasy did not cause cognitive deficits performed better than the other three groups on the delayed portion of the prose recall task from the Rivermead Behavioural Memory Test battery. There were no other statistically significant differences between any of the groups on any of the other cognitive tests used. This suggests that stereotype threat exists in ecstasy users and may be influencing their performance in experiments designed to identify cognitive deficits. In order to prevent this occurring in future studies, experimenters must be careful how they conduct their experiments and discuss their results with the media.

Delay discounting and the behavioural economics of cigarette purchases in smokers: the effects of nicotine deprivation

RATIONALE

In smokers, nicotine deprivation may increase impulsive decision-making and the demand for cigarettes.

OBJECTIVES

To investigate the effects of acute nicotine deprivation on (a) the delay discounting of monetary and cigarette rewards, and (b) the behavioural economics of hypothetical cigarette purchases.

MATERIALS AND METHODS

A repeated measures design was employed, with participants (daily cigarette smokers, N=30) repeating experimental tasks in two different sessions, once after at least 13 h of abstinence from smoking and once after ad lib smoking. Participants completed measures of cigarette craving, impulsivity, delay discounting and a behavioural economic simulation in which participants made hypothetical purchases of cigarettes and other commodities as the price of cigarettes was systematically varied.

RESULTS

Participants showed more pronounced delay discounting of both cigarette and monetary rewards after abstinence compared to after ad lib smoking. In the behavioural economic simulation, nicotine deprivation had no influence on hypothetical cigarette purchases. However, spending on some commodities (alcohol, clothing, household goods, leisure activities and long-distance travel) was reduced as the price of cigarettes increased in order to fund increased spending on cigarettes, although the number of packs of cigarettes purchased actually decreased.

CONCLUSIONS

Nicotine deprivation increases impulsive choices for both cigarette and monetary rewards in a delay-discounting task. Results from a behavioural economic simulation suggest that increases in the price of cigarettes may increase smokers' spending on cigarettes, while also reducing the number of cigarettes purchased.

Ecstasy (MDMA, MDA, MDEA, MBDB) consumption, seizures, related offences, prices, dosage levels and deaths in the UK (1994-2003)

In the last decade, a global trend of escalating ecstasy (MDMA, MDA, MDEA, MBDB) use was observed. Mentions on medical death certificates, last year's ecstasy use, number of drug offenders, seizures, prices and dosage levels figures were used for this descriptive and correlational study. Figures (1994-2003) were taken from the UK General Mortality Registers, from the Home Office Statistical Bulletins, from the British Crime Survey and from those reported to both the National Crime Intelligence and Forensic Science Services. A total of 394 ecstasy deaths mentions were here identified from the UK; in 42% of cases ecstasy was the sole drug mentioned. Overall, number of fatalities showed a year-per-year increase and positively correlated with: prevalence of last year's use (p < 0.01); number of offenders (p < 0.01) and number of seizures (p < 0.01) but negatively correlated with ecstasy price (p < 0.05). Price negatively correlated with: prevalence of last year's use (p < 0.001) and number of seizures (p < 0.01); but positively correlated with average MDMA dosage per tablet (p < 0.01). MDA, MDEA and MBDB accounted for a significant proportion of tablets only up to 1997, but not afterwards. Increasing production with a concomitant decrease in ecstasy price may have facilitated an increase in consumption levels and this, in turn, may have determined an increase in number of ecstasy deaths mentions. Only medical death certificates and not coroners' reports at the end of their inquests were here analysed; no data were available in respect of other drugs use and toxicology results.

The impact of a reduction in drug supply on demand for and compliance with treatment for drug dependence

BACKGROUND

In early 2001, Australia experienced a sudden, dramatic and sustained decrease in heroin availability that was accompanied by sharp increases in price and decreases in street level purity--the so-called "heroin shortage". These unprecedented changes occurred in a context of widespread treatment availability, which made it possible for the first time to examine the impact of a sharp reduction in heroin supply in New South Wales (NSW) on entry to and adherence with treatment for heroin dependence. Given the evidence of drug substitution by some users, the current paper also examines the effects of the shortage on entry to treatment for other forms of drug dependence.

METHODS

Interrupted time-series analysis of the number of persons entering opioid pharmacotherapy and other treatment modalities in NSW for heroin dependence and for the treatment for other types of drug dependence.

FINDINGS

The heroin shortage was associated with a reduction in the number of younger persons entering opioid pharmacotherapy. There was a dramatic decrease in the number of persons entering heroin withdrawal or "assessment only" treatment episodes. There appear to have been small improvements in adherence to and retention in heroin treatment after the reduction in heroin supply. Relatively small increases were observed in numbers being treated for cocaine dependence.

CONCLUSIONS

In the context of good treatment provision, a reduction in heroin supply appeared to produce modest improvements in intermediate outcomes. Supply and demand reduction measures, when both are implemented successfully, may be complementary.

Ecstasy and cocaine: patterns of use among prime age individuals in Amsterdam

This paper uses information about prime age individuals living in Amsterdam to study the patterns of use of ecstasy and cocaine. The information was collected in surveys in 1994, 1997 and 2001. The analysis shows that the use of ecstasy and cocaine is mainly influenced by calendar year, family situation, and parental cannabis use. Individuals that are more likely to use cocaine are also more likely to use ecstasy. The entrance of ecstasy in the Amsterdam drugs market in the course of the 1990s did not reduce the use of cocaine.

Self-reported depressive symptomatology in community samples of polysubstance misusers who report Ecstasy use: a meta-analysis

National drugs information strategies convey the message that use of Ecstasy is associated with an increase in both the incidence and severity of major depressive disorder. However, very little primary research supports this. Unlike apparent deficits in higher cognitive functions, most published studies have found no difference in self-reported depressive symptomatology between Ecstasy users and controls. To investigate this further, we conducted a meta-analysis of studies investigating depressive symptomatology in recreational users of Ecstasy. According to selection criteria, we identified 25 relevant studies. A statistically significant effect size (ES) of 0.31 (95% confidence interval 0.17-0.37, p < 0.001) was calculated. Significance remained after examining the small number of studies that controlled for cannabis use (n = 9, p < 0.001) but, in general, drug histories were poorly reported. There was an association between ES and lifetime Ecstasy exposure (p < 0.001), but not for other use parameters or abstention (p > 0.05). These data indicate that there is an association between Ecstasy use and depressive symptomatology, but this is small and unlikely to be clinically relevant. In addition, the self-report scales used may be heavily confounded by the somatic effects of substance misuse. Public health strategies derived from psychopharmacological investigations should acknowledge the potential negative effects of substance misuse but qualify the difficulties in interpreting research studies.