Reward sensitivity and outcome expectancies as predictors of ecstasy use in young adults

'Higher education' - substance use among Berlin college students

Berlin is internationally known for its intense nightlife associated with high rates of psychoactive substance use. Previous studies conducted in other cities indicated college students as a group at high risk for substance (mis-)use that was associated with individual psychological and cognitive impairments as well as lower academic performance. The aim of this study was to provide detailed data about the substance use patterns of Berlin college students. In addition, major protective and risk factors were analysed. An online questionnaire assessing sociodemographic data and various relevant aspects of both legal and illegal substance use such as consumption pattern and frequency as well as risk-taking behaviour was developed and distributed among colleges in Berlin. A sample of 9351 participants from 17 different colleges in Berlin completed the questionnaire. The study revealed high lifetime (69.3%), past year (45.9%) and past month (28.3%) prevalence of illicit substance use in the sample. Daily tobacco-smoking, a mental disorder diagnosis, a positive screening for problematic consumption (Cage-AID), bisexual orientation and living in open relationship were main factors positively associated with the prevalence and the extent of illicit substance use. Students in Berlin appear to show higher rates of illicit substance use than was previously reported for age-matched individuals in the general German population and college students in other cities. Thus, they are a relevant target group for early prevention and intervention concerning substance use and abuse.

Neurochemical substrates of the rewarding effects of MDMA: implications for the development of pharmacotherapies to MDMA dependence

In recent years, studies with animal models of reward, such as the intracranial self-stimulation, self-administration, and conditioned place preference paradigms, have increased our knowledge on the neurochemical substrates of the rewarding effects of 3,4-methylenedioxymetamphetamine (MDMA) in rodents. However, pharmacological and neuroimaging studies with human participants are scarce. Serotonin [5-hydroxytryptamine (5-HT)], dopamine (DA), endocannabinoids, and endogenous opiates are the main neurotransmitter systems involved in the rewarding effects of MDMA in rodents, but other neurotransmitters such as glutamate, acetylcholine, adenosine, and neurotensin are also involved. The most important finding of recent research is the demonstration of differential involvement of specific neurotransmitter receptor subtypes (5-HT2, 5-HT3, DA D1, DA D2, CB1, μ and δ opioid, etc.) and extracellular proteins (DA and 5-HT transporters) in the acquisition, expression, extinction, and reinstatement of MDMA self-administration and conditioned place preference. It is important to extend the research on the effects of different compounds acting on these receptors/transporters in animal models of reward, especially in priming-induced, cue-induced, and stress-induced reinstatement. Increase in knowledge of the neurochemical substrates of the rewarding effects of MDMA may contribute to the design of new pharmacological treatments for individuals who develop MDMA dependence.

Decision-making in chronic ecstasy users: a systematic review

Different cognitive impairments have been reported as a result of long-term MDMA/ecstasy use. Increased impulsivity and altered decision-making have been shown to be associated with the development and maintenance of addictive disorders pointing toward the necessity to understand a potential impairment of decision-making due to MDMA use. Thus, assessing the long-term effects of MDMA is crucial in order to evaluate its controversially discussed therapeutic use. The aim of this systematic review was to summarize the scientific literature on potential effects of chronic MDMA use on higher order decision-making processes in humans. Therefore, a systematic search for controlled trials relevant to the topic has been performed. Only studies using specific tasks on decision-making were included that involved subjects in the drug-free interval with drug-naïve, and/or polydrug control groups. A total of 12 studies could be identified that met the inclusion criteria, all of which were cross-sectional studies. The findings on decision-making disturbances in MDMA users were heterogeneous. Seven studies reported increased risky decisions, whereas five studies did not find MDMA-specific influences on decision-making. Increased impulsivity was observed both in MDMA groups and in (poly)drug control groups in almost all studies. Thus, the current state of research does not allow for the conclusion that long-term use of MDMA affects decision-making behavior in general. More detailed specifications as well as further investigations of the relevant processes are needed. Significant tendencies toward risky decision-making among long-term MDMA use have been observed, but need to be confirmed by studies using a longitudinal design.

Impulsivity: four ways five factors are not basic to addiction

Several impulsivity-related models have been applied to understanding the vulnerability to addiction. While there is a growing consensus that impulsivity is multifaceted, debate continues as to the precise number of facets and, more critically, which are most relevant to explaining the addiction-risk profile. In many ways, the current debate mirrors that which took place in the personality literature in the early 1990s (e.g., Eysenck's 'Big Three' versus Costa and McCrae's 'Big Five'). Indeed, many elements of this debate are relevant to the current discussion of the role of impulsivity in addictive behavior. Specifically, 1) the use of factor analysis as an atheoretical 'truth-grinding machine'; 2) whether additional facets add explanatory power over fewer; 3) the delineation of specific neurocognitive pathways from each facet to addictive behaviors, and; 4) the relative merit of 'top-down' versus 'bottom-up' approaches to the understanding of impulsivity. Ultimately, the utility of any model of impulsivity and addiction lies in its heuristic value and ability to integrate evidence from different levels of analysis. Here, we make the case that theoretically-driven, bottom-up models proposing two factors deliver the optimal balance of explanatory power, parsimony, and integration of evidence.

Decision-making in polydrug amphetamine-type stimulant users: an fMRI study

Qualitative poor decision-making and associated altered neuronal activation patterns have been described for the users of several drugs, amongst others for stimulants like amphetamine and MDMA. Deficits in decision-making might be caused by an augmented attraction to short-term rewarding properties despite negative long-term consequences, leading to rigid stimulus-response patterns. In the present imaging study, we investigated decision-making and associated neuronal activation in three groups differing in their exposure to amphetamine and MDMA. An established paradigm on risky choices was used to evaluate decision-making performance and corresponding functional magnet resonance imaging (fMRI) activation. Subjects could choose between a low-risk control gamble and an experimental gamble, which always differed in the probability of winning or losing, as well as the magnitudes of monetary gain or loss. Experienced users (EU), users with low exposure to stimulants and drug-naive controls, did not differ from each other in behavioral performance. In accordance with our hypotheses, the anticipation of reward led to an activation of primarily the frontal cortex and the striatum in low-exposure users and drug-naive controls. In contrast, frontal and parietal activation was observed in all groups when the actual outcome of an experimental gamble was presented. EU displayed more activation compared to both control groups when there was a high probability of winning. The study at hand supports the hypothesis that neuronal activation patterns might even differ between drug users and healthy controls when no behavioral deficits are apparent. In EU, the probability of the occurrence of an event has more influence on neuronal activation than on the actual magnitude of reinforcing properties of this event.