Dependent heroin use and associated risky behaviour: The role of rash impulsiveness and reward sensitivity

Impulsive temperament has long been considered as a risk factor for substance use disorders (SUD). Considering the heterogeneity of impulsivity, a biologically-based 2-factor model incorporating reward sensitivity and rash impulsiveness facets, has been proposed. Here we report how these two facets of impulsiveness could be associated with different aspects of dependent heroin use and associated risky behaviour. Two hundred and ninety three dependent heroin users and 232 non-users were assessed on reward sensitivity, rash impulsivity, and the related trait of punishment sensitivity. After adjusting for multiple comparisons, heroin users were found to be more rash-impulsive and reward-sensitive than non-users (p < 0.001). Within users, rash impulsivity was associated with high risk behaviour including escalating heroin consumption, injecting heroin use, hazardous drinking, low treatment-seeking and risky sexual behaviour. Reward sensitivity was uniquely associated with early onset of drug use. While greater impulsivity is a common trait in drug users compared with non-users, the use of a 2-factor model of impulsivity provides additional information regarding specific aspects of drug initiation and maintenance that can be targeted in the prevention and treatment of heroin dependence.     

Reward-related decision-making deficits and elevated impulsivity among MDMA and other drug users

BACKGROUND: The recreational drug, 3,4-methylenedioxymethamphetamine (MDMA; 'Ecstasy'), is a synthetic amphetamine derivative and a serotonin neurotoxin. MDMA use is associated with cognitive dysfunction and impulsivity, but since polydrug abuse is common among users it is difficult to attribute these problems specifically to MDMA. Moreover, few studies have examined reward-related cognitive processes. Our aim was to examine reward-related decision-making and impulsivity among MDMA users while controlling for polydrug use via appropriate comparison groups. METHODS: We examined decision-making [Iowa Gambling Task, IGT; Bechara, A., Damasio, A.R., Damasio, H., Anderson, S.W., 1994. Insensitivity to future consequences following damage to human prefrontal cortex. Cognition 50, 7-15], self-reported impulsivity (Multidimensional Personality Questionnaire-Brief Form [constraint subscale]; Barratt Impulsiveness Scale; Zuckerman Sensation Seeking Scale), and drug use among 22 abstinent MDMA users, 30 other drug users, and 29 healthy non-drug controls. RESULTS: MDMA and other drug users showed comparable patterns of decision-making and impulsivity. However, both drug groups demonstrated poorer IGT performance and elevated self-reported impulsivity relative to controls. Poorer decision-making was related to heavier drug use in the past year, heavier weekly alcohol use, and meeting lifetime substance use disorder (SUD) criteria for more drug classes. Elevated impulsivity was associated with heavier drug use, heavier weekly alcohol use, more lifetime SUDs, and higher self-reported depression levels. CONCLUSIONS: These findings contradict the idea that MDMA is specifically associated with deficient decision-making. Drug users, in general, may be at risk for decision-making deficits and elevated impulsivity. Such behaviors may represent trait factors that lead to the initiation of drug and alcohol use, and/or they may represent behavior patterns that are exacerbated by extensive use.     

Differences in impulsivity and sexual risk behavior among inner-city crack/cocaine users and heroin users

The current study utilized a sample of 123 inner-city drug users in residential treatment, comparing sexual risk behavior (SRB) across primary users of (a) heroin and not crack/cocaine, (b) crack/cocaine and not heroin, and (c) both heroin and crack/cocaine. Additional analyses also examined impulsivity as a mediator of drug choice and SRB. Results indicated that SRB was higher in primary crack/cocaine users than in primary heroin users, with those using both drugs evidencing intermediate levels of SRB. Beyond differences in SRB, a similar pattern across drugs was found for impulsivity. Finally, impulsivity mediated the relationship between drug choice and SRB. Although further research is necessary to establish causal relationships, these results support a relationship between SBR and crack/cocaine, and suggest that disinhibition processes including impulsivity may underlie this relationship.     

Differences in self-reported and behavioral measures of impulsivity in recreational and dependent cocaine users

Background

Dependent cocaine users consistently display increased trait impulsivity on self-report questionnaires and less consistently exhibit elevated motor impulsivity in some behavioral tasks. However, trait and behavioral impulsivity measures have rarely been investigated in recreational users. Therefore, we examined self-reported trait and motor impulsivities in recreational and dependent cocaine users to clarify the role of impulse control in cocaine addiction and non-dependent cocaine use.

Methods

We investigated relatively pure recreational (n = 68) and dependent (n = 30) cocaine users, as well as psychostimulant-naïve controls (n = 68), with self-report questionnaires (Barratt Impulsiveness Scale 11; Temperament and Character Inventory) and behavioral tasks (Rapid Visual Information Processing Task; Stop-Signal Task).

Results

Compared with controls, recreational and dependent cocaine users displayed higher trait impulsivity and novelty seeking scores on self-report questionnaires. Trait impulsivity scores were strongly associated with an increased number of symptoms of depression and attention deficit hyperactivity disorder and correlated significantly with long-term cocaine intake parameters. By contrast, none of the behavioral motor impulsivity measures showed significant group effects or correlated with cocaine use parameters. The correlations among the self-report measures were high, but self-reports were scarcely correlated with behavioral task measures.

Conclusions

These findings suggest that relatively pure cocaine users already display increased trait impulsivity at a recreational level of use. However, the results do not indicate any cocaine-related elevation of behavioral impulsivity in terms of motor or response inhibition. In summary, our data imply that elevated trait impulsivity is not a specific feature of dependent cocaine use.     

Differences in impulsivity and risk-taking propensity between primary users of crack cocaine and primary users of heroin in a residential substance-use program

Crack cocaine use is more associated with impulsivity and a propensity to take risks than heroin use, yet no studies have examined this relationship in the absence of acute drug effects. The current study examined impulsivity (using the Delay Discounting Task) and risk-taking propensity (using the Balloon Analogue Risk Task) across independent groups of primary crack cocaine users with minimal heroin use (n = 16) and primary heroin users with minimal crack cocaine use (n = 11) in residential treatment, with all participants drug abstinent during participation. Crack cocaine users evidenced greater levels of impulsivity and risk-taking propensity, with only the difference in impulsivity persisting after controlling for age and gender. These data hold potential theoretical importance in understanding differences between crack cocaine and heroin users, as the findings cannot be attributed solely to acute pharmacological drug effects.     

Mediational pathways among trait impulsivity,heroin-use consequences,and current mood state

Background: This study examined whether lifetime heroin-use consequences mediate the relationship between trait impulsivity and three current mood outcomes: depression symptoms, stress levels, and perception of life events.

Method: Regular heroin users (N?=?163) were assessed using the Barratt Impulsiveness Scale (BIS-11) to measure trait impulsivity; a standardized Drug History and Use Questionnaire to measure lifetime adverse consequences of heroin use; Beck Depression Inventory II to measure current depression symptoms; Stress subscale of the Depression Anxiety Stress scale; and Hassles and Uplifts scale to measure perception of life events.

Results: BIS-11 Attentional and Motor impulsivity were positively related to number of adverse heroin-use consequences, depression symptoms, and stress level, and negatively associated with positive perception of events. A greater number of heroin-use consequences was related to more depression symptoms, higher stress, more negative perception of events, injection heroin use, and earlier ages of first and regular heroin use. In six mediation models, lifetime heroin-use consequences partially mediated relationships between two trait impulsivity domains (Attentional, Motor) and current mood measures (depression symptoms, stress, perception of events).

Conclusions: The present findings suggest that current negative mood can be a response to the accumulated burden of heroin-use consequences, particularly in the presence of high trait impulsivity.     

Adversity among drug users: relationship to impulsivity

Illicit substance users experience adverse life events, but few studies have examined the role of impulsivity in these events. The present investigation sought to establish a link between negative life experiences and a trait measure of impulsivity and demonstrate that this association remains even accounting for potential confounds. Participants were 330 heroin and cocaine users recruited from the community for a health service research study. Participants completed a structured interview that assessed topics including drug and alcohol use, impulsivity, and negative life events. This group of drug users reported high rates of adverse life events in the 6 months prior to the assessment. No specific substance abuse/dependence diagnosis or combination of diagnoses was associated with adversity. Number of substance-related diagnoses was associated with adverse life events, but not when adjusting for impulsivity. Experience of these events was significantly associated with impulsivity (p<.001), above and beyond the shared relation with demographic variables, substance abuse and dependence, and number of substance-related diagnoses. These findings document the high frequencies of recent adverse life events among illicit drug users and indicate that trait impulsivity is associated with increased risk of these life events.     

Heterosexual relationships among heroin users in Italy

This study investigated how many stable partners of drug users (DUs) had a history of drug use or were current DUs. Of 589 DUs interviewed, 41% reported that they had a partner with current or previous experience of drug addiction. A strong gender difference emerged: 77% of female DUs reported a stable relationship with partners with a history of addiction, versus only 30% for male DUs. Partners with a history of drug dependence are more likely to be: male, older, with a lower educational level and a lower rate of stable employment than partners without a history of drug addiction. Logistic regression analysis indicated that the characteristics of heroin users who have current partners with histories of drug use include: female gender, older age, living with a partner, lengthy duration of the relationship and HIV positive status. Fewer subjects are married if the partner has a history of addiction, and there is an association between lengthy drug use and partner without drug addiction history. The high percentage (59%) of subjects who were in stable relationships with partners without histories of heroin addiction and the relatively long duration of these relationships, raises the issue of possible transmission of blood-borne viruses from the DUs to their sexual partners. The study does suggest the need for consideration of sexual partnerships and gender differences in providing drug abuse treatment for heroin users.     

Unidirectional relationship between heroin self-administration and impulsive decision-making in rats

Rationale  

There is growing clinical evidence for a strong relationship between drug addiction and impulsivity. However, it is not fully clear whether impulsivity is a pre-existing trait or a consequence of drug abuse. Recent observations in the animal models show that pre-existing levels of impulsivity predict cocaine and nicotine seeking. Whether such relationships also exist with respect to non-stimulant drugs is largely unknown.     

Changes in the initiation of heroin use after a reduction in heroin supply

Increasing heroin use in Australia over the past 30 years has been associated with a decline in the age of initiation to heroin use. The 2001 Australian heroin shortage was used to assess the effects of a reduction in heroin supply on age of initiation into heroin injecting. Data collected from regular injecting drug users (IDU) over the period 1996 - 2004 as part of the Australian Illicit Drug Reporting System were examined for changes in self-reported age of first heroin use after the onset of the heroin shortage. Estimates were also made of the number of young people who may not have commenced injecting heroin during the heroin shortage. The proportion of IDU interviewed in the IDRS who were aged ≤24 years decreased from 46% in 1996 to 12% in 2004, with the most marked drop in 2001, the year in which there was an abrupt and marked reduction in heroin availability. Of those who reported first injecting between 1993 and 2000, similar proportions reported heroin and amphetamine as the first drug injected. After 2000, methamphetamine was the drug most often reported as being the first injected. Estimates suggested that between 2745 and 10 560 young people may not have begun to inject heroin in 2001 as a result of reduced heroin supply. If around one in four of these young users had progressed to regular or dependent heroin use, then there may have been a reduction of between 700 and 2500 dependent heroin users. There was an increase in amphetamine injecting but it is unclear to what extent any reduction in heroin injecting has been offset by increased amphetamine injecting. Reduced heroin availability probably resulted in a reduction in the number of new heroin injectors in Australia. Efforts need to be made to reduce the chances that young people who have initiated methamphetamine injecting do not move to heroin injecting when the heroin supply returns. [Day C, Degenhardt L, Hall W. Changes in the initiation of heroin use after a reduction in heroin supply. Drug Alcohol Rev 2006;25:307 - 313]     

Comparing primary heroin and primary amphetamine users' knowledge of withdrawal and treatment options in inner metropolitan Brisbane, Australia

The present study compared knowledge of withdrawal and treatment services among twelve primary heroin injectors (PHIs) and fourteen primary amphetamine injectors (PAIs). Assessment of knowledge about withdrawal and treatment was made using the Withdrawal Knowledge Questionnaire (WKQ). Results showed that, on average, knowledge about withdrawal differed depending on the drug used. Specifically, regular amphetamine users knew less about withdrawal from amphetamine, than regular heroin users knew about withdrawal from heroin. In addition, amphetamine users appeared to underestimate the likely length of amphetamine withdrawal. There was no difference between regular amphetamine and regular heroin users' knowledge of available treatment services, such that both groups knew where to seek assistance for detoxification and rehabilitation. However, both user groups shared some important misconceptions about withdrawal. This suggests a clear need for improved dissemination of educational resources, emphasizing the length and severity of amphetamine withdrawal and the risks associated with excessive self-medication of withdrawal symptoms.     

A comparison of the harms associated with the injection of heroin and amphetamines

An investigation into whether or not the level of harm associated with injecting drug use varies depending on the drug that is injected was conducted among 151 primary heroin injectors and 145 primary amphetamine injectors. Compared to primary amphetamine injectors, primary heroin injectors were more dependent on their primary drug, had poorer social functioning, and had recently exhibited a higher degree of criminal behaviour. There were no differences between the two groups in terms of the prevalence of needle sharing, their health, or their psychological functioning, despite the amphetamine users being significantly younger and having used less frequently. It is concluded that while there are some harms that are attributable to injecting per se, the type of drug that is injected does play a mediating role in the relationship between injecting drug use and its associated harm.     

Sustained incentive value of heroin-related cues in short- and long-term abstinent heroin users

Models of addiction and addiction memory propose that drug-associated cues elicit incentive effects in drug users, which play an important role in maintenance of drug use and relapse. Incentive effects have been demonstrated for smoking and alcohol-related cues but evidence for heroin-related cues has been inconclusive. Furthermore, it is unknown whether appetitive effects of heroin-related cues persist after prolonged abstinence, although heroin addiction is known to have high relapse rates. Therefore, we investigated implicit and explicit valence of heroin-related cues in dependent users at different stages of abstinence using affective startle modulation. In Study I, 15 current heroin users were measured before and after detoxification. Correspondingly, 15 healthy control participants were tested twice at an interval of 14 days. In Study II, 14 long-term abstinent heroin users were additionally measured in a single session. Implicit processing of drug-related stimuli was assessed using affective startle modulation by pictures of heroin and smoking scenes. Explicit reactions were measured using ratings of valence and craving. In contrast to controls, heroin-dependent participants showed a clear reduction of startle response during heroin-related pictures (p<0.05). Detoxification did not significantly change their startle responses to heroin-cues. No difference between non-detoxified current and long-term abstinent heroin users was found in implicit reactions to heroin-cues, whereas explicit measures differed between both groups (all p<0.05). After detoxification and even after prolonged abstinence, heroin cues still exert implicit appetitive effects in heroin users. This implies that drug-induced adaptations of reward circuits are long-lasting, resulting in a highly stable addiction memory.     

药物滥用者人格特质之研究

目的：探讨药物滥用者之人格特质,以及何种人格特质者较易发生药物滥用之行为。方法：以2010年12月在台湾澎湖烟毒犯专业监狱的男性受刑人为抽样对象,采随机抽样方式合计发放800份问卷,回收742份有效问卷,其有效回收率为93.4%,抽样误差为1.17%。结果：药物滥用者以 B 型人格特质者占多数,具此人格特质者通常性格外向又好动、社会适应不良、情绪不稳定;年纪愈轻者有较高的中枢神经兴奋剂（古柯碱、安非他命、摇头丸、MDMA 类）使用现象;六成以上的受测者有双重或多重用药的情形,又以混合使用海洛因及安非他命此二种药物者为最多,在多重用药方面则是混合使用海洛因、安非他命及大麻。结论：整体而言,药物使用者大都具有外向性格、情绪不稳定及心理不健康等心理特质。     

Punishment induces risky decision-making in methadone-maintained opiate users but not in heroin users or healthy volunteers.

Reinforcing properties of psychoactive substances are considered to be critically involved in the development and maintenance of substance dependence. While accumulating evidence suggests that the sensitivity to reinforcement values may generally be altered in chronic substance users, relatively little is known about the influence reinforcing feedback exerts on ongoing decision-making in these individuals. Decision-making was investigated using the Cambridge Risk Task, in which there is a conflict between an unlikely large reward option and a likely small reward option. Responses on a given trial were analyzed with respect to the outcome on the previous trial, providing a measure of the impact of prior feedback in modulating behavior. Five different groups were compared: (i) chronic amphetamine users, (ii) chronic opiate users in methadone maintenance treatment (MMT), (iii) chronic users of illicit heroin, (iv) ex-drug users who had been long-term amphetamine / opiate users but were abstinent from all drugs of abuse for at least 1 year and (v) matched controls without a history of illicit substance use. Contrary to our predictions, choice preference was modified in response to feedback only in opiate users enrolled in MMT. Following a loss, the MMT opiate group chose the likely small reward option significantly less frequently than controls and heroin users. Our results suggest that different opiates are associated with distinctive behavioral responses to feedback. These findings are discussed with respect to the different mechanisms of action of heroin and methadone.Neuropsychopharmacology (2005) 30, 2115-2124. doi:10.1038/sj.npp.1300812; published online 6 July 2005.     

Cognitive impulsivity in cocaine and heroin polysubstance abusers

RATIONALE: Chronic abuse of psychoactive substances produces significant deficits in executive control functions (ECF). These deficits are prominent in different domains associated with cognitive impulsivity, including response inhibition and decision-making. The extent and nature of these deficits may depend on the principal substance of abuse. OBJECTIVES: To analyse response inhibition and decision-making performance in abstinent polysubstance abusers (PSA) of cocaine and heroin, and healthy participants. METHODS: We used univariate and multivariate analyses of variance to compare the performances of cocaine and heroin PSA and healthy controls on several well-validated measures of response inhibition (Stroop, 5-Digit Test and Go/No Go Task) and decision-making (Iowa Gambling Task). Post-hoc exploratory analyses of the results from the Go/No Go task were conducted to examine specific effects of task switching on the pattern of omission/commission errors in the PSA groups. RESULTS: Cocaine but not heroin PSA showed significant deficits on several measures of response inhibition, when compared to controls. Reversal of task contingencies in the Go/No Go task primarily altered the commission error rate in cocaine PSA, and the omission error rate in heroin PSA. In contrast, both cocaine and heroin PSA showed poorer performance on decision-making compared to controls. CONCLUSIONS: Assuming the relevance of polysubstance involvement, cocaine abuse seems to differentially correlate with motor impulsivity skills, while both substances seem to be equally linked to the inability to decide advantageously in complex decision-making tasks. Possible discrepancies in the neurological and psychological effects of these drugs are discussed.     

Heroin and cocaine dependence and the risk of accidental non-fatal drug overdose

The relation between illicit drug dependence and the likelihood of drug overdose is unclear. We recruited 1,066 habitual drug users for this analysis through street-based outreach in New York City. In this sample, 99.3% of respondents used heroin in the past year and 87.1% of respondents used cocaine; 819 (77.5%) heroin users and 735 (79.2%) cocaine users were severely dependent on either drug respectively. In multivariable models, among heroin users, persons who were severely heroin dependent were less likely (OR = 0.6; 95% CI = 0.4-0.9) to have overdosed on any drug in the past year; among cocaine users, those who were severely cocaine dependent were more likely (OR = 1.6; 95% CI = 1.0-2.6) to have overdosed in the past year. The relation between illicit drug dependence and risk of overdose may vary for different patterns of drug dependence. These observations suggest that overdose prevention interventions, perhaps even those specifically targeting opiate overdose, may be more efficiently directed at individuals exhibiting cocaine dependence.     

Prescribing drug of choice to opiate dependent drug users: a comparison of clients receiving heroin with those receiving injectable methadone at a West London drug clinic

Fifty-eight long-term treatment resistant opiate-dependent drug users were offered the choice of receiving injectable heroin or injectable methadone at a West London drug clinic. Drugs were dispensed on-site at the clinic with weekend take-home. There was no routine ongoing supervised injecting. A ceiling dose of 200 mg/day of heroin or methadone was set. One-third chose injectable methadone. Compared to those choosing heroin, these drug users were less likely to have used heroin or crack/cocaine before entering treatment, and were more likely to have previously received treatment with injectable methadone. Drug users reported choosing methadone because it was their primary drug of addiction, and compared with heroin has a longer duration of action and increased strength. Problems with each drug were reported: those choosing heroin complained that the upper dose limit was too low to maintain them adequately, and some receiving methadone complained of discomfort while injecting intravenously. While those choosing each drug had different baseline characteristics, both groups were well retained in treatment and at 3 months made significant reductions in drug use and crime, which were sustained over the 12-month follow-up period. There was no significant difference between treatment outcome between each group. There is an urgent need to conduct randomized controlled trials to establish the effectiveness of prescribing injectable methadone and heroin to inform policy and practice.     

Reductions in heroin use are not associated with increases in other drug use: 2-year findings from the Australian Treatment Outcome Study

AIMS: To determine whether reductions in frequency of heroin use were associated with reductions in the use of other drugs over a 24-month period. DESIGN: Longitudinal cohort, with follow-up at 3, 12 and 24 months. PARTICIPANTS: Six hundred and fifteen heroin users recruited for the Australian Treatment Outcome Study. SETTING: New South Wales, Australia. FINDINGS: The proportion reporting weekly heroin use declined significantly at 3, 12 and 24 months. Reductions in heroin use were associated with longer periods in both residential rehabilitation (RR) and maintenance treatment (MT). Less frequent use of other opioids, cocaine, amphetamine, cannabis and benzodiazepines were noted over follow-up, with alcohol use remaining stable. Across follow-up, lower frequency heroin use was associated with reduced likelihood of frequent use of other opioids, cocaine, amphetamine and benzodiazepines. Alcohol and cannabis use were unrelated to heroin use. Longer periods spent in RR were associated with declines in the use of all other drug classes, with MT associated with declines in other opioid and alcohol use. CONCLUSIONS: There was no evidence for drug substitution in the face of reduced heroin use in this cohort of treatment seekers. The fear that a successful reduction in heroin use amongst treatment seekers will precipitate an increase in the use of other drugs appears ill-founded.