Vincent M. Hendriks

Initial validation of two opiate craving questionnaires: The Obsessive Compulsive Drug Use Scale and the Desires for Drug Questionnaire

In the present study, the factor structure, internal consistency, and the concurrent validity of two heroin craving questionnaires are examined. The Desires for Drug Questionnaire (DDQ) measures three factors: desire and intention, negative reinforcement, and control. The Obsessive Compulsive Drug Use Scale (OCDUS) also measures three factors: thoughts about heroin and interference, desire and control, and resistance to thoughts and intention. Subjects were 102 Dutch patients who were currently in treatment for drug dependency. All proposed scales have good reliability and concurrent validity. Implementation of these instruments in both clinical and research field is advocated.

Neurophysiological evidence for abnormal cognitive processing of drug cues in heroin dependence

RationaleRecent studies provide evidence for specific aspects of cue processing in addictive disorders.ObjectiveThe present study employs event related potentials (ERPs) to investigate heroin related visual information processingMethodsNeutral and heroin related pictures were presented to 19 male abstinent heroin dependent patients and 14 male healthy controls.ResultsPatients exhibited larger slow positive wave (SPW) components of the ERP on heroin related pictures than on neutral pictures. Within healthy control subjects there was no difference on the SPW between neutral and heroin pictures. Within heroin dependent patients, mean SPW response to heroin pictures was correlated with post-experiment craving.ConclusionThis study provides neurophysiological evidence that information processing of drug-related information is abnormal in heroin dependent patients. The results provide further evidence for the cognitive and neurobiological accounts of substance dependence such as the incentive-sensitization theory.

Influence of individual differences in craving and obsessive cocaine thoughts on attentional processes in cocaine abuse patients

In the present pilot-study, the relation between craving, obsessive thoughts about cocaine, experienced control, and attentional bias for cocaine related words is investigated. Sixteen cocaine abuse patients participated in a reaction time (RT) experiment which was employed to measure the ability of subjects to shift their attention away from cocaine related words. Postexperiment craving was found to be positively correlated with reaction times on drug related cues, in contrast to RT on neutral cues. Furthermore, obsessive thoughts about cocaine use and the experienced cocaine use control, in the week before the experiment, were correlated in a higher degree with RTs on drug cues than postexperiment craving. Attentional bias for drug cues was evidenced in patients with higher scores on obsessive cocaine thoughts and higher craving scores. This study shows that individual differences on information processing, within a cocaine abuse patient population, are present.

A role for dopamine in the processing of drug cues in heroin dependent patients

Drug and alcohol dependence are associated with enhanced attention for drug-related stimuli. This cognitive processing bias has been suggested to be related to craving and to represent one of the core mechanisms of addition. The present study tests the hypothesis that enhanced attention for heroin cues is mediated by the dopaminergic system using haloperidol as dopamine antagonist. In a double blind, randomized crossover design, 17 detoxified heroin dependent patients received a single oral dose of haloperidol 2 mg and placebo. Patients performed an Emotional Stroop Task to assess the cognitive processing of drug cues under both conditions. In addition, self-reported craving was assessed. In the haloperidol condition, patients performed better on the Emotional Stroop Task than in the placebo condition. However, no effect of haloperidol on subjective craving was found. These findings provide preliminary indications that attentional bias in heroin dependent humans is mediated by dopaminergic mechanisms.

Cue Reactivity and Effects of Cue Exposure in Abstinent Posttreatment Drug Users

After 12 months of inpatient treatment, 16 opiate-addicted patients were exposed to drug-related stimuli. The results of this study indicate that cue reactivity in opiate-addicted subjects is still present after 12 months of intensive inpatient treatment. After exposing subjects to drug-related stimuli, there is an increase in craving, feelings of depression, and anger. Because posttreatment subjects are likely to be confronted with these stimuli following discharge, a reduction of this reactivity is desirable. In the present study, cue reactivity (feelings of depression, anger, tension, craving, and physical symptoms) reduced after protocolized cue exposure treatment. This effect maintained for at least 6 weeks after the last cue exposure session.

Event-related potentials indicate motivational relevance of cocaine cues in abstinent cocaine addicts

RationaleMotivational drive and its underlying affect-related states are the core mechanisms that precede the seeking and taking of drugs in substance dependence.ObjectiveThe present study aimed to investigate the motivational relevance of cocaine cues and whether or not an appetitive emotional system is involved employing event-related potential (ERP) measurements.MethodsCocaine-addicted subjects and healthy controls were exposed to neutral and cocaine-related pictures whilst ERPs were recorded simultaneously over frontal, parietal and midline sites.ResultsPatients exhibited ERP amplitude discrepancies between neutral and cocaine-related pictures for N300, late slow positive wave (LSPW) and sustained slow positive wave (SSPW), whilst this effect was absent in control subjects. Differences in neutral and cocaine cue-evoked ERP waves were also found at left frontal sites for LSPW and SSPW in the patient group only. No group-specific cue-evoked ERP amplitudes were observed at parietal and midline sites.ConclusionThe findings confirm the assumption that cocaine cues induce motivational relevance in cocaine-dependent individuals. It is possible that exposure to cocaine cues triggers an appetitive emotional system since left frontal sites are assumed to be involved in processing positive emotional-laden stimuli. The present study provides evidence that the sensitivity of ERP correlates for cocaine cues may be an indicator of motivational and emotional processes in drug-dependent individuals.

Screening and Diagnosis of Anxiety and Mood Disorders in Substance Abuse Patients

The aims of this study are (1) to study the prevalence of anxiety and mood disorders in a clinical substance abuse population, (2) to asses the pre- and post-detoxification change in SCL-90 score in this population for subjects with psychopathology compared to subjects without psychopathology, and (3) to asses the value of the SCL-90 and the Addiction Severity Index-psychiatric problems scale as clinical diagnostic screening instrument for psychopathology. The design was a longitudinal prospective cohort study with pre-detoxification ASI and SCL-90 data and post-detoxification CIDI and SCL-90 data on a clinical sample of 116 substance abuse patients. The present results indicate that the ASI-Psychiatric problems score is a limited indicator of psychiatric comorbidity. When a pre-detoxification screening for psychopathology is warranted, the present results show that the use of the SCL-90 is preferable above the ASI-PSY scale. Of the screening scores under study, the post-detoxification SCL-90 score is found to be the most valid screening instrument for diagnosis of anxiety and mood disorders in a clinical substance abuse population. Although the post-detoxification SCL-90 score holds moderate specificity combined with high sensitivity, applying this instrument in clinical substance abuse practice will result in a substantial reduction of patients unnecessarily referred for further psychiatric diagnostic evaluation. Further studies aimed at improvement of screening instruments in this population are needed.

Medical Co-Prescription of Heroin to Chronic, Treatment-Resistant Methadone Patients in the Netherlands

This paper begins with a brief description of the epidemiology of heroin addiction in the Netherlands and an overview of the current treatment system, with special emphasis on oral methadone maintenance. It is followed by a short history of the debate over the prescription of heroin to addicted patients. This history reveals that alternatives to methadone have been viewed as essential in the Netherlands since the early 1980s. Earlier experiments with intravenous morphine, intravenous methadone and oral dextromoramide (PalfiumR) were not as successful as had been hoped and precluded their introduction in daily practice. Finally, recent experiences in Switzerland with the medical prescription of heroin facilitated the decision to initiate a scientific study of the medical co-prescription of heroin in the Netherlands. The paper provides a detailed description of the randomized clinical trial regarding the effectiveness of co-prescribed heroin that is now underway in the Netherlands. It concludes with a brief discussion of the likely consequences for future treatment options of different study outcomes.

Cue Exposure Therapy for the Treatment of Opiate Addiction: Results of a Randomized Controlled Clinical Trial

Background: Persistent cue reactivity to drug-related stimuli is a well-known phenomenon among abstinent drug users and has been found to be a predictor of relapse. Cue exposure therapy (CET) aims to reduce this cue reactivity by exposing abstinent drug users to conditioned drug-related stimuli while preventing their habitual response, i.e. drug use. Methods: 127 abstinent heroin-dependent Dutch inpatients were randomized to CET (n = 65; 55 completers) and placebo psychotherapy treatment (PPT) (n = 62; 59 completers). It was examined whether CET would lead to a decrease in drug-related cue reactivity (using mixed-design ANOVA) and subsequently to lower dropout and relapse rates (using logistic regression) compared to PPT. Results: Both groups responded with a similar decrease in self-reported cue reactivity (craving, mood). The CET group did show a significant decrease in physiological reactivity (skin conductance) compared to PPT. However, dropout and relapse rates were, contrary to our expectations, significantly higher in the CET group. Conclusions: This is the first randomized controlled trial showing that CET, compared to a non-specific psychotherapy, might increase dropout and relapse rates among abstinent heroin-dependent clients in a drug-free setting. Caution is warranted when applying CET in this specific context.

Two new neurophysiological indices of cocaine craving: evoked brain potentials and cue modulated startle reflex.

Craving for cocaine is one of the hallmarks of cocaine dependence. One of the problems with craving is its measurement. Traditional psychophysiological indices such as skin conductance and heart rate have yielded contradictory results. These measures of craving were found to correlate only moderately with self-reported craving. In the present study, event-related brain potentials (ERPs) and the cue modulated startle response (CMSR) are evaluated as indices for cocaine craving. Twenty-one abstinent cocaine-dependent subjects were divided into high and low cravers group based on the median split of self-reported craving scores. ERPs and CMSR were measured when subjects watched neutral, pleasant, unpleasant and cocaine-related pictures. Overall, it was found that cocaine-dependent subjects showed augmented slow-positive waves (SPWs) of the ERP on the cocaine pictures compared to neutral pictures. Only high cravers showed larger SPWs on the cocaine cues, suggesting an association between cue-elicited SPWs and self-reported cocaine craving. By contrast to the ERP measures, CMSR did not differentiate between cocaine pictures and neutral pictures. In addition, no differences between the low- and high cravers on the CMSR measure were found. The present results show that the evoked-potentials paradigm provides promising results to index cue-elicited craving. The use of startle modulation deserves further investigation.