Biomedical subjects

Joerg Daumann

Publications and source records attributed to Joerg Daumann.

4 recordsLinked to original sources

PubMed2006

Inhibition of return in the human 5HT2A agonist and NMDA antagonist model of psychosis.

Patients with schizophrenia exhibit disturbances of orienting of attention. However, findings have been inconsistent. Pharmacologic challenges with hallucinogens have been used as models for psychosis. The NMDA antagonist state (PCP, ketamine) resembles undifferentiated psychoses with positive and negative symptoms, while the 5-HT(2A) agonist state (LSD, dimethyltryptamine (DMT)) is thought to be an appropriate model for psychoses with prominent positive symptoms. The aim of this study was to investigate orienting of attention in the human NMDA antagonist and 5-HT(2A) agonist models of psychosis. A total of 15 healthy volunteers participated in a randomized, double-blind, crossover study with a low and a high dose of DMT and S-ketamine, which elicited subtle 'prepsychotic' or full-blown psychotic symptoms (low and high dose, respectively). Nine subjects completed both experimental days with the two doses of both drugs. Overall, both hallucinogens slowed down reaction times dose dependently (DMT >S-ketamine) and DMT diminished the general response facilitating (alerting) effect of spatially neutral cues. Inhibition of Return (IOR), that is, the normal reaction time disadvantage for validly cued trials with exogenous cues and long cue target intervals, was blunted after both doses of DMT and the low dose of S-ketamine. IOR reflects an automatic, inhibitory mechanism of attention, which is thought to protect the organism from redundant, distracting sensory information. In conclusion, our data suggest a deficit of IOR in both hallucinogen models of psychosis, with the effect being clearer in the serotonin model. Blunted IOR may underlie or predispose to different psychotic manifestations, but particularly to those with prominent positive symptoms.

Adult↗

PubMed2005

Memory performance in polyvalent MDMA (ecstasy) users who continue or discontinue MDMA use.

BACKGROUND: The popular dance drug ecstasy (3,4-methylenedioxymethamphetamine=MDMA) is a serotonergic neurotoxin in animal studies. Several cross-sectional investigations reported low memory and learning performance in ecstasy users, particularly in those reporting heavy patterns of drug use. Since, serotonin has a recognized role in memory processes, these findings were mostly interpreted as evidence for ecstasy-related neurotoxicity in humans. However, studies with user populations and controls suffer from many inherent methodological problems. Moreover, longitudinal data on memory performance after continued or discontinued ecstasy use are scarce. METHODS: In the present longitudinal study, we examined memory performance in 38 MDMA users over the course of 18 months. RESULTS: Subjects who stopped MDMA use after the baseline examination (n=17) did not improve, and subjects who continued MDMA use (n=21) did not deteriorate in terms of test performance. CONCLUSIONS: Our data do not support, but they also do not rule out memory decline following use of the serotonergic neurotoxin MDMA. In light of the popularity of ecstasy among young people, further investigations are needed. In our view, research strategies should now move to prospective designs in order to shed more light on the course of possible adverse cognitive effects of ecstasy use.

Adult↗

PubMed2003

Memory impairment suggests hippocampal dysfunction in abstinent ecstasy users.

Previous studies have consistently shown impairments of memory and learning in regular users of the neurotoxic drug ecstasy (3,4-methylenedioxymethamphetamine [MDMA]). In addition, deficits in working memory, planning ability and central executive control, as well as high cognitive impulsivity, were also reported in some studies. Hence, the memory decrements may be secondary due to other cognitive failures. The purpose of this study was to analyze the nature of the cognitive deficits of ecstasy users. Tests of memory, working memory, central executive function and cognitive impulsivity were administered to 60 currently abstinent ecstasy users and to 30 nonusers. Heavy ecstasy users (n=30, lifetime dose > or =80 ecstasy tablets) had lower memory performance than both nonusers and moderate users (n=30, lifetime dose <80 ecstasy tablets). In contrast, we found no group differences in central executive function, working memory, planning ability and cognitive impulsivity between ecstasy users and controls. Poorer memory and working memory performance was associated with a heavier pattern of ecstasy use. Low working memory, planning ability and central executive control and high cognitive impulsivity did not predict poor memory performance. Our results indicate primary memory dysfunction in heavy ecstasy users, which may be related to a particularly high vulnerability of the hippocampus to the neurotoxic effects of MDMA. Hippocampal dysfunction after ecstasy use may be a risk factor for earlier onset and/or more severe age-related memory decline in later years.

Adult↗

PubMed2001

Psychological profile of abstinent recreational Ecstasy (MDMA) users and significance of concomitant cannabis use.

The popular recreational drug Ecstasy (3,4-methylenedioxymethamphetamine, or MDMA, and related congeners) is neurotoxic upon central serotonergic systems in animal studies. So far, the most convincing evidence for neurotoxicity-related functional deficits in humans derives from neurocognitive studies demonstrating dose-related memory problems in Ecstasy users. The aim of the current investigation was to study the relationship between the psychological profile of recreational Ecstasy users and the patterns of their drug use. Twenty-eight abstinent recreational Ecstasy users with concomitant use of cannabis only and two equally sized, matched groups of cannabis users and non-users were administered standardized self-rating scales for the assessment of psychological problems which are thought to be related to central serotonergic function. Ecstasy users had elevated scores on subscales measuring impulsiveness, anxiety, sensation seeking, somatic complaints, obsessive-compulsive behavior and psychoticism. Higher scores were associated with both heavier Ecstasy and heavier cannabis use. After controlling for cannabis use, most group differences in psychometric scores no longer achieved statistical significance. The present data are in line with other reports demonstrating a broad range of psychological problems in Ecstasy users. However, the concomitant use of other drugs, specifically cannabis, seems to be crucial in this respect. Therefore, compared with cognitive deficits, psychological problems appear to be less suitable functional indices of Ecstasy-related neurotoxic damage of central serotonergic systems in humans. Copyright 2001 John Wiley & Sons, Ltd.

Journal Article↗