Wim van den Brink

Long-term effects of frequent cannabis use on working memory and attention: an fMRI study

RationaleExcessive use of cannabis may have long-term effects on cognitive abilities. Mild impairments have been found in several cognitive domains, particularly in memory and attention. It is not clear, however, whether these effects also occur with moderate, recreational use of cannabis. Furthermore, little is known about underlying brain correlates.ObjectivesThe aim of this study is to assess brain function in frequent but relatively moderate cannabis users in the domains of working memory and selective attention.MethodsFunctional magnetic resonance imaging was used to examine verbal working memory and visuo-auditory selective attention in ten frequent cannabis users (after 1xa0week of abstinence) and ten non-using healthy controls. Groups were similar in age, gender and estimated IQ.ResultsCannabis users and controls performed equally well during the working memory task and the selective attention task. Furthermore, cannabis users did not differ from controls in terms of overall patterns of brain activity in the regions involved in these cognitive functions. However, for working memory, a more specific region-of-interest analysis showed that, in comparison to the controls, cannabis users displayed a significant alteration in brain activity in the left superior parietal cortex.ConclusionNo evidence was found for long-term deficits in working memory and selective attention in frequent cannabis users after 1xa0week of abstinence. Nonetheless, frequent cannabis use may affect brain function, as indicated by altered neurophysiological dynamics in the left superior parietal cortex during working memory processing.

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.

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.

Middelengebruik en crimineel gedrag

In het eerste deel van dit hoofdstuk wordt uiteengezet dat er de laatste tweehonderd jaar grote veranderingen zijn geweest in ons denken over het gebruik van middelen en over het begrip verslaving. Daarmee zijn ook de behandeling en bejegening van verslaafden veranderd. De laatste decennia worden daarbij gekenmerkt door een toenemende belangstelling voor het model waarbij verslaving wordt gezien als hersenziekte. In het tweede deel van dit hoofdstuk wordt dit model nader toegelicht en wordt tevens aandacht besteed aan de relatie tussen verslavingsgedrag en enkele van de mogelijke voorlopers van crimineel gedrag. In het derde deel van dit hoofdstuk wordt ingegaan op de complexe relatie tussen middelengebruik en criminaliteit. Uit dit overzicht komt naar voren dat de sterkte en de aard van deze relatie afhangt van de kenmerken van de gebruiker van het middel, de kenmerken van de omgeving, de aard van het gebruikte middel en de aard van het criminele gedrag.