Biomedical subjects

Jörg Daumann

Publications and source records attributed to Jörg Daumann.

11 recordsLinked to original sources

PubMed2006

An fMRI approach to particularize the frontoparietal network for visuomotor action monitoring: Detection of incongruence between test subjects' actions and resulting perceptions.

Contemporary theories of motor control assume that motor actions underlie a supervisory control system which utilizes reafferent sensory feedbacks of actions for comparison with the original motor programs. The functional network of visuomotor action monitoring is considered to include inferior parietal, lateral and medial prefrontal cortices. To study both sustained monitoring for visuomotor incongruence and the actual detection of incongruence, we used a hybrid fMRI epoch-/event-related design. The basic experimental task was a continuous motor task, comprising a simple racing game. Within certain blocks of this task, incongruence was artificially generated by intermittent takeover of control over the car by the computer. Fifteen male subjects were instructed to monitor for incongruence between their own and the observed actions in order to abstain from their own action whenever the computer took over control. As a result of both sustained monitoring and actual detection of visuomotor incongruence, the rostral inferior parietal lobule displayed a BOLD signal increase. In contrast, the prefrontal cortex (PFC) exhibited two different activation patterns. Dorsolateral (BA 9/46) and medial/cingulate (BA 8, BA 32) areas of the PFC displayed a greater increase of activation in sustained monitoring, while ventrolateral PFC showed greater event-related activation for the actual detection of visuomotor incongruence. Our results suggest that the rostral inferior parietal lobule is specifically involved in the reafferent comparison of the test subjects' own actions and visually perceived actions. Different activation patterns of the PFC may reflect different frontoparietal networks for sustained action monitoring and actual detection of reafferent incongruence.

Adult↗

PubMed2006

Intensity dependence of auditory evoked dipole source activity in polydrug ecstasy users: evidence from an 18 months longitudinal study.

Numerous animal studies have been able to demonstrate neurotoxic damage to central serotonergic systems after exposure to 3,4-methylenedioxymethamphetamine (MDMA, ecstasy). It has been suggested that a high loudness dependence of auditory evoked potentials (LDAEP) and, particularly, of the tangential N1/P2 source activity is associated with a low functioning of serotonergic activity. Therefore, the LDAEP may be used as a non-invasive indicator for a possible neurotoxic damage caused by the long-term use of ecstasy in recreational users. We recorded auditory evoked potentials (AEP) with a passive listening paradigm in 18 polydrug ecstasy users at baseline (t1) and after 18 months (t2). Several aspects of ecstasy use, such as frequency of use, cumulative lifetime dose or period of abstinence were associated with the LDAEP for several tangential dipoles at both measuring times. However, we failed to demonstrate any significant relationship between drug use reported at follow-up and AEP changes from baseline to follow-up. Despite some incertitude these data suggest, yet do not unambiguously con.rm, the hypothesis that abstinent ecstasy users present with diminished central serotonergic activity. This feature of information processing is potentially related to the neurotoxic potential of ecstasy. However, alternative interpretations of these data refer to possible preexisting traits and the potential impact of other illicit drugs, particularly amphetamine, since ecstasy users typically exhibit polydrug use patterns. Thus, further research with larger sample sizes and prospective study designs are needed to definitively establish a causative link between ecstasy use and neurotoxicity-related dysfunctions in sensory processing.

Acoustic Stimulation↗

PubMed2006

The confounding problem of polydrug use in recreational ecstasy/MDMA users: a brief overview.

The popular dance drug ecstasy (3,4-methylenedioxymethamphetamine -- MDMA) is neurotoxic upon central serotonergic neurons in laboratory animals and possibly also in humans. In recent years, several studies reported alterations of serotonergic transmission and neuropsychiatric abnormalities in ecstasy users which might be related to MDMA-induced neurotoxic brain damage. To date, the most consistent findings associate subtle cognitive, particularly memory, deficits with heavy ecstasy use. However, most studies have important inherent methodological problems. One of the most serious confounds is the widespread pattern of polydrug use which makes it dif.cult to relate the findings in user populations to one specific drug. The present paper represents a brief overview on this issue. The most commonly co-used substances are alcohol, cannabis and stimulants (amphetamines and cocaine). Stimulants are also neurotoxic upon both serotonergic and dopaminergic neurons. Hence, they may act synergistically with MDMA and enhance its long-term adverse effects. The interactions between MDMA and cannabis use may be more complex: cannabis use is a well-recognized risk factor for neuropsychiatric disorders and it was shown to contribute to psychological problems and cognitive failures in ecstasy users. However, at the cellular level, cannabinoids have neuroprotective actions and they were shown to (partially) block MDMA-induced neurotoxicity in laboratory animals. In future, longitudinal and prospective research designs should hopefully lead to a better understanding of the relation between drug use and subclinical psychological symptoms or neurocognitive failures and, also, of questions around interactions between the various substances of abuse.

Amphetamine-Related Disorders↗

PubMed2005

Memory-related hippocampal dysfunction in poly-drug ecstasy (3,4-methylenedioxymethamphetamine) users.

RATIONALE: 3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) is neurotoxic in animal studies and its use has been associated with cognitive impairments in humans. OBJECTIVE: To study hippocampal activation during the retrieval from episodic memory in polyvalent users of ecstasy. METHODS: Twelve polyvalent ecstasy users and twelve matched controls were examined by means of functional magnetic resonance imaging (fMRI) while they retrieved face-profession associations from episodic memory. RESULTS: Ecstasy users had a normal structural MRI scan without focal brain lesions or anatomical abnormalities. They exhibited equal retrieval accuracy during memory retrieval to that of the matched controls. Yet, their retrieval-related activity was lower and more spatially restricted in the left anterior hippocampus than that of the controls. CONCLUSIONS: These results provide evidence for abnormal hippocampal functioning in MDMA users even at the presence of normal memory performance. This finding may be linked to MDMA-induced neurotoxicity and suggests that diminished hippocampal activation during memory retrieval might be a more sensitive or earlier index of MDMA-related neurotoxicity than neuropsychological performance.

Adult↗

PubMed2004

Neural mechanisms of working memory in ecstasy (MDMA) users who continue or discontinue ecstasy and amphetamine use: evidence from an 18-month longitudinal functional magnetic resonance imaging study.

BACKGROUND: Working memory processing in ecstasy (3,4-methylenedioxymethamphetamine) users is associated with neural alterations as measured by functional magnetic resonance imaging. Here, we examined whether cortical activation patterns change after prolonged periods of continued use or abstinence from ecstasy and amphetamine. METHODS: We used an n-back task and functional magnetic resonance imaging in 17 ecstasy users at baseline (t(1)) and after 18 months (t(2)). Based on the reported drug use at t(2) we separated subjects with continued ecstasy and amphetamine use from subjects reporting abstinence during the follow-up period (n = 9 and n = 8, respectively). RESULTS: At baseline both groups had similar task performance and similar cortical activation patterns. Task performance remained unchanged in both groups. Furthermore, there were no detectable functional magnetic resonance imaging signal changes from t(1) to t(2) in the follow-up abstinent group. However, the continuing users showed a dose-dependent increased parietal activation for the 2-back task after the follow-up period. CONCLUSIONS: Our data suggest that ecstasy use, particularly in high doses, is associated with greater parietal activation during working memory performance. An altered activation pattern might appear before changes in cognitive performance become apparent and, hence, may reflect an early stage of neuronal injury from the neurotoxic drug ecstasy.

Adult↗

PubMed2004

Proton magnetic resonance spectroscopy in ecstasy (MDMA) users.

The popular recreational drug 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) has well-recognized neurotoxic effects upon central serotonergic systems in animal studies. In humans, the use of MDMA has been linked to cognitive problems, particularly to deficits in long-term memory and learning. Recent studies with proton magnetic resonance spectroscopy (1H MRS) have reported relatively low levels of the neuronal marker N-acetylaspartate (NAA) in MDMA users, however, these results have been ambiguous. Moreover, the only available 1H MRS study of the hippocampus reported normal findings in a small sample of five MDMA users. In the present study, we compared 13 polyvalent ecstasy users with 13 matched controls. We found no differences between the NAA/creatine/phosphocreatine (Cr) ratios of users and controls in neocortical regions, and only a tendency towards lower NAA/Cr ratios in the left hippocampus of MDMA users. Thus, compared with cognitive deficits, 1H MRS appears to be a less sensitive marker of potential neurotoxic damage in ecstasy users.

Adult↗

PubMed2004

Self-reported psychopathological symptoms in recreational ecstasy (MDMA) users are mainly associated with regular cannabis use: further evidence from a combined cross-sectional/longitudinal investigation.

RATIONALE: 3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) has become a widely used recreational drug among young people. This is of great concern, since MDMA is neurotoxic in animal studies and its use has been associated with psychological distress and a variety of self-reported psychiatric symptoms. However, exploring the origins of psychopathology in ecstasy users is hampered by the frequent polydrug use and by the cross-sectional design of all investigations, so far. OBJECTIVES: The present study combines a cross-sectional with a longitudinal approach to further clarify the impact of the use of other illicit drugs on psychopathological symptoms reported by ecstasy users. METHODS: At baseline, we administered self-rating scales for impulsivity, sensation seeking and general psychological complaints to 60 recreational ecstasy users and 30 matched controls. From the initial sample of ecstasy users, 38 subjects were re-examined 18 months later. RESULTS. At baseline, ecstasy users reported significantly more psychological complaints than controls. However, self-reported psychopathology was mainly associated with regular cannabis use. At follow-up, subjects who had abstained from ecstasy use during the follow-up period did not differ from those reporting continued consumption. In contrast, subjects with regular concomitant cannabis use during the follow-up period reported more anxiety, interpersonal sensitivity and obsessive-compulsive behaviour than cannabis-abstinent users. Finally, higher levels of obsessive-compulsive behaviour, interpersonal sensitivity, depression, anxiety, phobic anxiety and paranoid ideation were significantly correlated with the duration of regular interim cannabis use. CONCLUSIONS: The present findings suggest that self-reported psychopathology in ecstasy users is predominantly attributable to concomitant use of cannabis. Abstinence from cannabis and not ecstasy seems to be a reliable predictor for remission of psychological complaints in ecstasy users.

Adult↗

PubMed2004

Plasticity of the acoustic startle reflex in currently abstinent ecstasy (MDMA) users.

RATIONALE: 3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) is neurotoxic upon central serotonin systems in experimental animals and probably also in humans. Serotonin is involved in the habituation, sensitization and prepulse inhibition (PPI) of the startle reflex. OBJECTIVES: To study the plasticity of startle reflex in currently abstinent MDMA users. METHODS: Electromyographic responses to acoustic startle stimuli (pulse alone and prepulse-pulse trials) were recorded in 23 currently abstinent ecstasy users and 20 matched control subjects. Depending on the extent of their previous drug use ecstasy users were divided into two groups [life-time dose <90 (n=11) and > or =90 pills (n=12), respectively]. RESULTS: There were no significant differences in habituation, sensitization or PPI of the startle reflex between the entire group of ecstasy users and controls. However, sensitization of the startle reflex was stronger in the > or =90 compared with either the <90 MDMA pills or the control group. Correlations between patterns of drug use and startle parameters did not reach the level of significance, although users with a younger age at the onset of MDMA (and other drug) use tended to present with higher sensitization of the startle reflex. CONCLUSIONS: Heavy users of MDMA (and other recreational drugs) present with strong sensitization of the startle reflex. Nevertheless, it is unclear whether this finding is secondary to the use of MDMA and its well-recognized neurotoxic potential. Alternatively, strong sensitization might reflect a pre-existing trait predisposing to drug use. A clearer picture of the impact of ecstasy on startle plasticity may be obtained from longitudinal investigations.

Adult↗

PubMed2003

Neural correlates of working memory in pure and polyvalent ecstasy (MDMA) users.

Poor cognitive performance in ecstasy (3,4-methylenedioxymethamphetamine; MDMA) users has been related to the well-recognized neurotoxic effects of the drug upon central serotonergic and possibly also dopaminergic systems. However, concomitant use of other drugs has been a critical confound in most investigations. In this study we used an n-back task and fMRI to investigate working memory performance and related cerebral activation in eight, currently abstinent pure MDMA users and two matched groups of polyvalent MDMA users and non-users. Pure MDMA users presented lower activations than controls and/or polyvalent users, most notably in inferior temporal regions, the angular gyrus and the striate cortex, whereas polyvalent users did not differ from controls. Our results suggest that altered brain activation patterns during cognitive processing in ecstasy users may be mainly associated with prior MDMA use. Concomitant use of other drugs may modify this effect.

Adult↗

PubMed2003

Cerebral activation in abstinent ecstasy (MDMA) users during a working memory task: a functional magnetic resonance imaging (fMRI) study.

The popular recreational drug ecstasy (3,4-methylenedioxymethamphetamine=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 long-term learning and memory problems in ecstasy users. In our study we used functional magnetic resonance imaging (fMRI) and a working memory task to investigate cerebral activation in eleven heavy, but currently abstinent MDMA users and two equally sized groups of moderate users and non-users. There were no significant group differences in working memory performance and no differences in cortical activation patterns for a conservative level of significance. However, for a more liberal statistical criterion, both user groups showed stronger activations than controls in right parietal cortex. Furthermore, heavy users had a weaker blood oxygenation level-dependent (BOLD) response than moderate users and controls in frontal and temporal areas. Our results may indicate subtle altered brain functioning associated with prior MDMA use, although alternative interpretations of these group differences must be considered.

Adult↗

PubMed2002

Neuroendocrine abnormalities in recreational ecstasy (MDMA) users: is it ecstasy or cannabis?

BACKGROUND: The purpose of this study was to investigate neuroendocrine function in ecstasy (3,4-methylenedioxymethamphetamine = MDMA) users and controls. METHODS: Prolactin response to d-fenfluramine was assessed in abstinent ecstasy users with concomitant use of cannabis only (n = 24, male/female 13/11) and in two control groups: healthy nonusers (n = 13, female) and exclusive cannabis users (n = 7, male). RESULTS: Prolactin response to d-fenfluramine was slightly blunted in female ecstasy users. Both male user samples exhibited a weak prolactin response to d-fenfluramine, but this was weaker in the group of cannabis users. Baseline prolactin and prolactin response to d-fenfluramine were associated with the extent of previous cannabis use. CONCLUSIONS: Endocrinological abnormalities of ecstasy users may be closely related to their coincident cannabis use. Cannabis use may be an important confound in endocrinological studies of ecstasy users and should be looked for more systematically in future studies.

Adrenergic Uptake Inhibitors↗