Association of a functional polymorphism in the serotonin transporter gene with abnormal emotional processing in ecstasy users

Pharmacogenomics of 3,4-Methylenedioxymethamphetamine (MDMA): A Narrative Review of the Literature

3,4-Methylenedioxymethamphetamine (MDMA) is a synthetic amphetamine derivative with notable psychoactive properties and emerging therapeutic potential, particularly for treating post-traumatic stress disorders (PTSD) and substance use disorders. However, its use remains controversial due to inter-individual variability influenced by both environmental and genetic factors. In this context, pharmacogenomics could play a crucial role in guiding MDMA treatment by identifying individuals with genetic predispositions affecting their response to MDMA. Tailoring treatment plans based on individual's genetic makeup may enhance therapeutic outcomes and minimize adverse effects, leading to safer and more effective use of MDMA in clinical settings. Literature analysis reveals that the influence of genetic variants within genes encoded for enzymes involved in MDMA metabolism and/or pharmacodynamics (PD) targets have been relatively under-investigated in humans. Some studies have pointed out associations between MDMA-induced effects and polymorphisms. For example, the catechol-O-methyltransferase (COMT) Val158Met polymorphism has been associated with cognitive and cardiovascular MDMA-induced effects. Similarly, polymorphisms in the serotonin-linked promoter region (5HTTLPR) have been associated with several MDMA-induced adverse effects including mood disorders. However, despite these findings, only a few associations have been highlighted. Furthermore, some genes encoded for MDMA targets have been only poorly investigated, representing a significant research gap. These observations underscore the need for large-scale, controlled pharmacogenomics studies focusing on a broad panel of genes involved into MDMA pharmacokinetics and PD. Such studies could provide critical insights for optimizing MDMA's therapeutic use and minimizing its risks.

Role of Serotonin Transporter and Receptor Gene Variations in the Acute Effects of MDMA in Healthy Subjects

Methylenedioxymethamphetamine (MDMA; ecstasy) is used recreationally and has been investigated as an adjunct to psychotherapy. Most acute effects of MDMA can be attributed to activation of the serotonin (5-hydroxytryptamine [5-HT]) system. Genetic variants, such as single-nucleotide polymorphisms (SNPs) and polymorphic regions in 5-HT system genes, may contribute to interindividual differences in the acute effects of MDMA. We characterized the effects of common genetic variants within selected genes that encode the 5-HT system (TPH1 [tryptophan 5-hydroxylase 1] rs1800532 and rs1799913, TPH2 [tryptophan 5-hydroxylase 2] rs7305115, HTR1A [5-HT_1A receptor] rs6295, HTR1B [5-HT_1B receptor] rs6296, HTR2A [5-HT_2A receptor] rs6313, and SLC6A4 [serotonin transporter] 5-HTTLPR and rs25531) on the physiological and subjective response to 125 mg of MDMA compared with placebo in 124 healthy subjects. Data were pooled from eight randomized, double-blind, placebo-controlled studies that were conducted in the same laboratory. TPH2 rs7305115, HTR2A rs6313, and SLC6A4 5-HTTLPR polymorphisms tended to moderately alter some effects of MDMA. However, after correcting for multiple comparisons, none of the tested genetic polymorphisms significantly influenced the response to MDMA. Variations in genes that encode key targets in the 5-HT system did not significantly influence the effects of MDMA in healthy subjects. Interindividual differences in the 5-HT system may thus play a marginal role when MDMA is used recreationally or therapeutically.

The serotonin transporter gene variants modulate acute stress-induced hippocampus and dorsomedial prefrontal cortex activity during memory retrieval

The short (s) allele of a polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) is related to reduced serotonin transporter efficiency and an increased vulnerability to stress and mental disorders. In the present study, we investigated how 5-HTTLPR impacts on memory retrieval under stress and related neural activity by reanalyzing a small genetic neuroimaging data set. Twenty-seven healthy male volunteers participated in both the Trier Social Stress Test (TSST) and a respective control procedure and then their brain activity was measured with functional MRI (fMRI) while they performed an emotional-face-recognition task. Sixteen participants were carriers of the short allele (ss/sl carriers) and 11 were homozygous for the long allele (ll carriers). Genotype groups were compared with respect to stress-related physiological changes, memory performance, and brain activity. No significant genotype-dependent effects on memory performance or cortisol levels were found. The ss/sl carriers showed significantly higher systolic and diastolic blood pressure than the ll carriers, independent of stress. The ss/sl carriers reported stronger stress-induced nervous mood than the ll carriers. Our fMRI data revealed that the ss/sl carriers showed significantly weaker left hippocampus activation and stronger dorsomedial prefrontal cortex (dmPFC) deactivation when retrieving memories under stress as compared with the ll carriers. Subsequent analyses revealed that the distinct hippocampal activation pattern in both genotypes was associated with stress-induced cortisol elevation, while the distinct dmPFC activation pattern in both genotypes was associated with stress-induced changes in reaction times. Our results thus add new evidence that serotonin signaling modulates neural activity in the hippocampus and dmPFC during memory retrieval under acute psychosocial stress.

A genetic deletion of the serotonin transporter differentially influences the behavioural effects of MDMA

BACKGROUND

While (±)-3,4-methylenedioxymethamphetamine (MDMA) primarily induces serotonin release, it also affects dopamine and noradrenaline transmission. It is, however, unclear what role each of these neurotransmitters play in the behavioural profile of MDMA.

METHODS

In this study we used the drug discrimination (DD) and the acoustic startle (ASR) paradigms to examine the behaviour of rats with and without a genetic deletion of the serotonin transporter SERT (SERT^-/- and SERT^+/+ rats). In DD, rats were trained to respond on different levers following an injection of 1.5 mg/kg MDMA, or saline. After acquisition, they were given a challenge dose of 0.5 mg/kg amphetamine (AMPH). In the ASR paradigm, SERT^+/+ and SERT^-/- rats were given 0, 5 or 10 mg/kg MDMA.

RESULTS

In DD, significantly fewer SERT^-/- rats acquired MDMA discrimination. When the acquirers were challenged with AMPH, SERT^+/+ showed partial, while SERT^-/- rats showed full generalisation to MDMA. In the ASR paradigm, MDMA significantly reduced prepulse inhibition and startle habituation in SERT^+/+ rats, while having no effect in SERT^-/- rats.

CONCLUSION

Together these data suggest that in wildtype rats the interoceptive cues of MDMA are primarily mediated by serotonin and to a lesser extent by dopamine and noradrenaline, while the effects in the startle paradigm are almost exclusively mediated via serotonin. Together, these data contribute to our understanding of the complex pharmacodynamics of MDMA.

Depressive mood ratings are reduced by MDMA in female polydrug ecstasy users homozygous for the l-allele of the serotonin transporter

MDMA exerts its main effects via the serotonergic system and the serotonin transporter. The gene coding for this transporter determines the expression rate of the transporter. Previously it was shown that healthy individuals with the short allelic variant ('s-group') of the 5-HTTLPR-polymorphism displayed more anxiety and negative mood, and had a lower transcriptional efficiency compared to individuals who are homozygous for the l-allele ('l-group'). The present study aimed to investigate the role of the 5-HTTLPR polymorphism in MDMA-induced mood effects. Four placebo-controlled, within-subject studies were pooled, including in total 63 polydrug ecstasy users (N_s-group = 48; N_l-group = 15) receiving MDMA 75 mg and placebo on two test days, separated by minimally 7 days. Mood was assessed by means of the Profile of Mood States. Findings showed that MDMA induced -independent of sex- a positive mood state, and as a side effect also increased two negative affect states, anxiety and confusion. Anxiety ratings were higher in the l-group and independent of treatment or sex. Depression ratings were lowered by MDMA in the female l-group. Findings indicate that the MDMA-induced reduction in self-rated depressive feelings is sex- and genotype-dependent, with females homozygous for the l-allele showing this beneficial effect.

Gene polymorphisms associated with temperament

When individuals are exposed to stressful environmental challenges, the response varies widely in one or more of three components: psychology, behavior and physiology. This variability among individuals can be defined as temperament. In recent years, an increasing large body of evidence suggests that the dimensions of temperament, as well as personality, psychological disorders and behavioral traits, are influenced by genetic factors, and much of the variation appears to involve variation in genes or gene polymorphisms in the hypothalamic-pituitary-adrenocortical (HPA) axis and the behavior-controlling neurotransmitter networks. Here, we review our current understanding of the probabilistic impact of a number of candidate gene polymorphisms that control temperament, psychological disorders and behavioral traits in animals and human, including the gene polymorphisms related to corticotrophin-releasing hormone (CRH) production and adrenal cortisol production involved in the HPA axis, and a large number of gene polymorphisms in the dopaminergic and serotonergic neurotransmitter networks. It will very likely to assist in diagnosis and treatment of human relevant disorders, and provide useful contributions to our understanding of evolution, welfare and conservation, for animals in the wild and in production systems. Additionally, investigations of gene-gene and gene-environment complex interactions in humans and animals need further clear illustration.

Changes in serotonin transporter (5-HTT) gene expression in peripheral blood cells after MDMA intake

RATIONALE

3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) is an amphetamine derivative abused worldwide. Although data report that relatively high doses of MDMA deplete serotonin (5-HT) content and decrease the availability of serotonin transporters (5-HTT), there is no available evidence as to the adaptive mechanisms taking place in 5-HTT gene expression following MDMA intake in humans.

OBJECTIVE

To evaluate the pharmacological effects of MDMA on 5-HTT gene expression, using peripheral mononuclear cells as a biomarker of the central nervous system, and study whether an association exists between 5-HTT gene expression and psychobiological scores.

METHODS

A randomized, double-blind, controlled trial was conducted in 18 (nine women) healthy recreational MDMA users. Subjects were genotyped for 5-HTT linked polymorphism region (5-HTTLPR). MDMA 75 mg or placebo was administered; Profile of Mood States (POMS) and 5-HTT gene expression measures were performed at baseline, 90, and 165 min post administration. POMS scores were correlated with changes in gene expression.

RESULTS

The administration of 75 mg MDMA induced a significant twofold increase in 5-HTT gene expression after 165 min of drug administration. Significant associations were found between gene expression and POMS scores after MDMA administration. Results for each gender and 5-HTTLPR genotype are also reported.

CONCLUSIONS

Preliminary results show that MDMA causes substantial regulatory changes in the expression of serotonergic markers, likely being modulated by the 5-HTTLPR polymorphism. Changes in 5-HTT gene expression may play an important role in the regulation of mood state.

COMT val158met and 5-HTTLPR genetic polymorphisms moderate executive control in cannabis users

The adverse effects of cannabis use on executive functions are still controversial, fostering the need for novel biomarkers able to unveil individual differences in the cognitive impact of cannabis consumption. Two common genetic polymorphisms have been linked to the neuroadaptive impact of Δ9-tetrahydrocannabinol (THC) exposure and to executive functions in animals: the catechol-O-methyltransferase (COMT) gene val158met polymorphism and the SLC6A4 gene 5-HTTLPR polymorphism. We aimed to test if these polymorphisms moderate the harmful effects of cannabis use on executive function in young cannabis users. We recruited 144 participants: 86 cannabis users and 58 non-drug user controls. Both groups were genotyped and matched for genetic makeup, sex, age, education, and IQ. We used a computerized neuropsychological battery to assess different aspects of executive functions: sustained attention (CANTAB Rapid Visual Information Processing Test, RVIP), working memory (N-back), monitoring/shifting (CANTAB ID/ED set shifting), planning (CANTAB Stockings of Cambridge, SOC), and decision-making (Iowa Gambling Task, IGT). We used general linear model-based analyses to test performance differences between cannabis users and controls as a function of genotypes. We found that: (i) daily cannabis use is not associated with executive function deficits; and (ii) COMT val158met and 5-HTTLPR polymorphisms moderate the link between cannabis use and executive performance. Cannabis users carrying the COMT val/val genotype exhibited lower accuracy of sustained attention, associated with a more strict response bias, than val/val non-users. Cannabis users carrying the COMT val allele also committed more monitoring/shifting errors than cannabis users carrying the met/met genotype. Finally, cannabis users carrying the 5-HTTLPR s/s genotype had worse IGT performance than s/s non-users. COMT and SLC6A4 genes moderate the impact of cannabis use on executive functions.

MDMA, serotonergic neurotoxicity, and the diverse functional deficits of recreational 'Ecstasy' users

Serotonergic neurotoxicity following MDMA is well-established in laboratory animals, and neuroimaging studies have found lower serotonin transporter (SERT) binding in abstinent Ecstasy/MDMA users. Serotonin is a modulator for many different psychobiological functions, and this review will summarize the evidence for equivalent functional deficits in recreational users. Declarative memory, prospective memory, and higher cognitive skills are often impaired. Neurocognitive deficits are associated with reduced SERT in the hippocampus, parietal cortex, and prefrontal cortex. EEG and ERP studies have shown localised reductions in brain activity during neurocognitive performance. Deficits in sleep, mood, vision, pain, psychomotor skill, tremor, neurohormonal activity, and psychiatric status, have also been demonstrated. The children of mothers who take Ecstasy/MDMA during pregnancy have developmental problems. These psychobiological deficits are wide-ranging, and occur in functions known to be modulated by serotonin. They are often related to lifetime dosage, with light users showing slight changes, and heavy users displaying more pronounced problems. In summary, abstinent Ecstasy/MDMA users can show deficits in a wide range of biobehavioral functions with a serotonergic component.

5-HTTLPR and early childhood adversities moderate cognitive and emotional processing in adolescence

BACKGROUND

Polymorphisms in the promoter region of the serotonin transporter gene (5-HTTLPR) and exposure to early childhood adversities (CA) are independently associated with individual differences in cognitive and emotional processing. Whether these two factors interact to influence cognitive and emotional processing is not known.

METHODOLOGY AND PRINCIPAL FINDINGS

We used a sample of 238 adolescents from a community study characterised by the presence of the short allele of 5-HTTLPR (LL, LS, SS) and the presence or absence of exposure to CA before 6 years of age. We measured cognitive and emotional processing using a set of neuropsychological tasks selected predominantly from the CANTAB® battery. We found that adolescents homozygous for the short allele (SS) of 5-HTTLPR and exposed to CA were worse at classifying negative and neutral stimuli and made more errors in response to ambiguous negative feedback. In addition, cognitive and emotional processing deficits were associated with diagnoses of anxiety and/or depressions.

CONCLUSION AND SIGNIFICANCE

Cognitive and emotional processing deficits may act as a transdiagnostic intermediate marker for anxiety and depressive disorders in genetically susceptible individuals exposed to CA.

Pharmacokinetics and pharmacodynamics of 3,4-methylenedioxymethamphetamine (MDMA): interindividual differences due to polymorphisms and drug-drug interactions

Clinical outcome following 3,4-methylenedioxymethamphetamine (MDMA) intake ranges from mild entactogenic effects to a life-threatening intoxication. Despite ongoing research, the clinically most relevant mechanisms causing acute MDMA-induced adverse effects remain largely unclear. This complicates the triage and treatment of MDMA users needing medical care. The user's genetic profile and interactions resulting from polydrug use are key factors that modulate the individual response to MDMA and influence MDMA pharmacokinetics and dynamics, and thus clinical outcome. Polymorphisms in CYP2D6, resulting in poor metabolism status, as well as co-exposure of MDMA with specific substances (e.g. selective serotonin reuptake inhibitors (SSRIs)) can increase MDMA plasma levels, but can also decrease the formation of toxic metabolites and subsequent cellular damage. While pre-exposure to e.g. SSRIs can increase MDMA plasma levels, clinical effects (e.g. blood pressure, heart rate, body temperature) can be reduced, possibly due to a pharmacodynamic interaction at the serotonin reuptake transporter (SERT). Pretreatment with inhibitors of the dopamine or norepinephrine reuptake transporter (DAT or NET), 5-HT(2A) or α-β adrenergic receptor antagonists or antipsychotics prior to MDMA exposure can also decrease one or more MDMA-induced physiological and/or subjective effects. Carvedilol, ketanserin and haloperidol can reduce multiple MDMA-induced clinical and neurotoxic effects. Thus besides supportive care, i.e. sedation using benzodiazepines, intravenous hydration, aggressive cooling and correction of electrolytes, it is worthwhile to investigate the usefulness of carvedilol, ketanserin and haloperidol in the treatment of MDMA-intoxicated patients.

Toxicity of amphetamines: an update

Amphetamines represent a class of psychotropic compounds, widely abused for their stimulant, euphoric, anorectic, and, in some cases, emphathogenic, entactogenic, and hallucinogenic properties. These compounds derive from the β-phenylethylamine core structure and are kinetically and dynamically characterized by easily crossing the blood-brain barrier, to resist brain biotransformation and to release monoamine neurotransmitters from nerve endings. Although amphetamines are widely acknowledged as synthetic drugs, of which amphetamine, methamphetamine, and 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) are well-known examples, humans have used natural amphetamines for several millenniums, through the consumption of amphetamines produced in plants, namely cathinone (khat), obtained from the plant Catha edulis and ephedrine, obtained from various plants in the genus Ephedra. More recently, a wave of new amphetamines has emerged in the market, mainly constituted of cathinone derivatives, including mephedrone, methylone, methedrone, and buthylone, among others. Although intoxications by amphetamines continue to be common causes of emergency department and hospital admissions, it is frequent to find the sophism that amphetamine derivatives, namely those appearing more recently, are relatively safe. However, human intoxications by these drugs are increasingly being reported, with similar patterns compared to those previously seen with classical amphetamines. That is not surprising, considering the similar structures and mechanisms of action among the different amphetamines, conferring similar toxicokinetic and toxicological profiles to these compounds. The aim of the present review is to give an insight into the pharmacokinetics, general mechanisms of biological and toxicological actions, and the main target organs for the toxicity of amphetamines. Although there is still scarce knowledge from novel amphetamines to draw mechanistic insights, the long-studied classical amphetamines-amphetamine itself, as well as methamphetamine and MDMA, provide plenty of data that may be useful to predict toxicological outcome to improvident abusers and are for that reason the main focus of this review.

Cognitive mechanisms of treatment in depression

Cognitive abnormalities are a core feature of depression, and biases toward negatively toned emotional information are common, but are they a cause or a consequence of depressive symptoms? Here, we propose a 'cognitive neuropsychological' model of depression, suggesting that negative information processing biases have a central causal role in the development of symptoms of depression, and that treatments exert their beneficial effects by abolishing these biases. We review the evidence pertaining to this model: briefly with respect to currently depressed patients, and in more detail with respect to individuals at risk for depression and the effects of antidepressant treatments. As well as being present in currently depressed individuals, negative biases are detectable in those vulnerable for depression due to neuroticism, genetic risk, or previous depressive illness. Recent evidence provides strong support for the notion that both antidepressant drugs and psychological therapies modify negative biases, providing a common mechanism for understanding treatments for depression. Intriguingly, it may even be possible to predict which patients will benefit most from which treatments on the basis of neural responses to negative stimuli. However, further research is required to ascertain whether negative processing biases will be useful in predicting, detecting, and treating depression, and hence in preventing a chronic, relapsing course of illness.

Serotonin transporter genotype modulates subgenual response to fearful faces using an incidental task

This study assessed the impact of serotonin transporter genotype (5-HTTLPR) on regional responses to emotional faces in the amygdala and subgenual cingulate cortex (sgACC), while subjects performed a gender discrimination task. Although we found no evidence for greater amygdala reactivity or reduced amygdala-sgACC coupling in short variant 5-HTTLPR homozygotes (s/s), we observed an interaction between genotype and emotion in sgACC. Only long variant homozygotes (la/la) exhibited subgenual deactivation to fearful versus neutral faces, whereas the effect in s/s subjects was in the other direction. This absence of subgenual deactivation in s/s subjects parallels a recent finding in depressed subjects [Grimm, S., Boesiger, P., Beck, J., Schuepbach, D., Bermpohl, F., Walter, M., et al. Altered negative BOLD responses in the default-mode network during emotion processing in depressed subjects. Neuropsychopharmacology, 34, 932-943, 2009]. Taken together, the findings suggest that subgenual cingulate activity may play an important role in regulating the impact of aversive stimuli, potentially conferring greater resilience to the effects of aversive stimuli in la/la subjects. Using dynamic causal modeling of functional magnetic resonance imaging data, we explored the effects of genotype on effective connectivity and emotion-specific changes in coupling across a network of regions implicated in social processing. Viewing fearful faces enhanced bidirectional excitatory coupling between the amygdala and the fusiform gyrus, and increased the inhibitory influence of the amygdala over the sgACC, although this modulation of coupling did not differ between the genotype groups. The findings are discussed in relation to the role of sgACC and serotonin in moderating responses to aversive stimuli [Dayan, P., & Huys, Q. J., Serotonin, inhibition, and negative mood. PLoS Comput Biol, 4, e4, 2008; Mayberg, H. S., Liotti, M., Brannan, S. K., McGinnis, S., Mahurin, R. K., Jerabek, P. A., et al. Reciprocal limbic-cortical function and negative mood: Converging PET findings in depression and normal sadness. Am J Psychiatry, 156, 675-682, 1999].

The ugly side of amphetamines: short- and long-term toxicity of 3,4-methylenedioxymethamphetamine (MDMA, 'Ecstasy'), methamphetamine and D-amphetamine

Amphetamine ('Speed'), methamphetamine ('Ice') and its congener 3,4-methylenedioxymethamphetamine (MDMA; 'Ecstasy') are illicit drugs abused worldwide for their euphoric and stimulant effects. Despite compelling evidence for chronic MDMA neurotoxicity in animal models, the physiological consequences of such toxicity in humans remain unclear. In addition, distinct differences in the metabolism and pharmacokinetics of MDMA between species and different strains of animals prevent the rationalisation of realistic human dose paradigms in animal studies. Here, we attempt to review amphetamine toxicity and in particular MDMA toxicity in the pathogenesis of exemplary human pathologies, independently of confounding environmental factors such as poly-drug use and drug purity.

Are ecstasy users biased toward endorsing somatic mental health symptoms? Results from a general community sample

RATIONALE

Whether the reported poorer mental health of ecstasy users is due to a bias in endorsement of somatic symptoms has been postulated, but rarely examined.

OBJECTIVES

The purpose of this study is to investigate whether levels of ecstasy use were associated with differential probabilities of endorsing somatic mental health symptoms.

METHODS

Current ecstasy users aged 24-30 years (n = 316) were identified from a population-based Australian study. Measures included frequency of ecstasy, meth/amphetamine, and cannabis use and the Goldberg anxiety/depression symptom scales.

RESULTS

Multiple indicator, multiple cause models demonstrated no bias towards endorsing somatic symptoms with higher ecstasy use, both with and without adjustment for gender, cannabis, and meth/amphetamine use.

CONCLUSIONS

Other studies using alternate measures of mental health should adopt this approach to determine if there is a bias in the endorsement of somatic symptoms among ecstasy users.

Neuroethical issues in cognitive enhancement

Neuroethics is a developing field, concerned with addressing present and future applied ethical issues brought about directly and indirectly by neuroscience advancements. One domain where neuroscience has begun to have far-reaching ethical implications is in the research and development of pharmaceutical cognitive enhancers. Though such drugs are typically developed to treat cognitive disabilities and improve the quality of life for patients with neuropsychiatric disorders and brain injury, research has found that such drugs can improve performance on cognitive tasks in healthy individuals. In line with such findings is the growing use of these drugs by students and others for cognitive-enhancing purposes. The present paper reviews some of the evidence in both neuropsychiatric and healthy individuals and discusses the implications such research can have for society.

Comorbid psychiatric diagnoses among individuals presenting to an addiction treatment program for alcohol dependence

A retrospective patient record review was conducted to examine comorbid psychiatric diagnoses, and comorbid substance use, among 465 patients below 45 years of age, presenting to a national alcohol addiction treatment unit in Dublin, between 1995 and 2006. Rates were high for depressive disorder (25.3%) particularly among females (35.4%). Lifetime reported use of substances other than alcohol was 39.2%, and further analysis showed significantly higher rates of deliberate self-harm among this group. Lifetime reported use of ecstasy was also significantly associated with depression in this alcohol-dependent population using logistic regression analysis. Implications and limitations of the findings are discussed.

The influence of 5-HTT and COMT genotypes on verbal fluency in ecstasy users

Deficits in verbal fluency associated with ecstasy use have been well established; however, the mechanisms underlying this impairment have yet to be elucidated. In this study we investigated for the first time whether there was a disproportionate impairment in two cognitive subcomponents of verbal fluency: clustering (ability to generate words within the same subcategory) and switching (ability to change the subcategory). We also investigated a possible association between ecstasy use and verbal fluency in subjects genotyped for 5-HTT (5-HTTLPR and 5-HTTVNTR) and COMT (val(108/158)met, rs165599 and rs2097603) polymorphisms, in order to find a potential implication of genetic factors. Ecstasy polydrug users (n = 30) and non-ecstasy users (n = 41) were evaluated in both semantic and phonemic fluency. Results showed that ecstasy users had poorer semantic (but not phonemic) fluency performance than controls. Detailed analysis of clustering and switching performance revealed that this impairment was associated with poorer clustering mechanisms. Clustering was also modulated by the COMT rs165599 polymorphism independently of the group. A specific effect of the 5-HTTLPR polymorphism on switching performance was also found, with ss carriers performing significantly worse than ls and ll carriers, suggesting a serotonin modulation of frontal-executive flexibility. Based on the impaired clustering and switching strategies observed in ecstasy users, it might be proposed that both semantic knowledge and retrieval are impaired in this population. The verbal fluency deficit in ecstasy users may be attributable to a disruption of frontal-striatal circuits directly related with the serotonin function as well as a depletion of lexical-semantic stores mediated by temporal structures.

Serotonin transporter polymorphisms (SLC6A4 insertion/deletion and rs25531) do not affect the availability of 5-HTT to [11C] DASB binding in the living human brain

Studies in vitro suggest that the expression of the serotonin transporter (5-HTT) is regulated by polymorphic variation in the promoter region of the 5-HTT gene (5-HTTLPR); however, results from human brain imaging studies examining the relation between 5-HTT genotype and 5-HTT radioligand binding in vivo have been inconsistent. This inconsistency could reflect small participant numbers or the use of sub-optimal radiotracer for measuring the 5-HTT. We used positron emission tomography in conjunction with the selective 5-HTT ligand [(11)C] DASB to examine the availability of the 5-HTT in seven brain regions in 63 healthy European caucasian volunteers who were genotyped for short (S) and long (L) variants (SLC6A4 and rs25531) of the 5-HTTLPR. [(11)C] DASB binding potential was not influenced by the allelic status of participants whether classified on a biallelic or triallelic basis in any of the regions studied. Our PET findings, in a relatively large sample with a near optimal radiotracer, suggest that 5-HTTLPR polymorphic variation does not affect the availability of 5-HTT to [(11)C] DASB binding in adult human brain. The reported impact of 5-HTTLPR polymorphic variation on emotional processing and vulnerability to depression are more likely therefore to be expressed through effects exerted during neurodevelopment.

Depressive and anxiety symptomatology in ecstasy users: the relative contribution of genes, trauma, life stress and drug use

RATIONALE

Previous research has identified elevated rates of depressive and anxiety symptoms amongst ecstasy users; however, few studies have examined which factors increase the likelihood of experiencing such symptoms.

OBJECTIVES

The current study aimed to determine the relationship between ecstasy use and depressive/anxiety symptomatology after controlling for known environmental and genetic (polymorphism of the serotonin transporter gene) risk factors for depression and anxiety disorders.

METHODS

Participants consisted of a community sample of 184 18-35-year olds who had taken ecstasy at least once in the past 12 months. Participants completed an interview and questionnaires and provided a saliva sample. Mood symptoms were assessed using the Mood and Anxiety Symptom Questionnaire. Timeline methods were used to collect information on lifetime and recent ecstasy use, as well as recent other drug use and life stress. Trauma exposure was measured using the Composite International Diagnostic Interview--Trauma List. Genomic DNA was extracted from participant saliva samples.

RESULTS

Neither lifetime nor recent ecstasy use was associated with the severity of current mood symptoms, either alone or in combination with genetic risk factors. Rather, lifetime trauma, recent stressful life events, the frequency of tobacco use and recent polydrug use significantly predicted the severity of depressive and anxiety symptoms.

CONCLUSIONS

These results highlight the need to consider the role of environmental factors when examining the relationship between ecstasy use and mood symptoms. Whether ecstasy exacerbates such symptoms in vulnerable individuals requires further investigation using prospective designs.

5-HTTLPR polymorphism, mood disorders and MDMA use in a 3-year follow-up study

A 3-year longitudinal prospective study was conducted to compare the incidence of substance use disorders (SUD) and non-substance use disorders (NSUD) among ecstasy users and two control groups: one of cannabis users and the other of non-drug users. The 5-HTTLPR polymorphism related to NSUD was also studied. A total of 94 subjects were included: 37 ecstasy users, 23 cannabis users and 34 non-drug users. SUD and NSUD disorders were diagnosed according to the fourth edition of the Diagnostic and Statistical Manual of Mental Health Disorders criteria using the Psychiatric Research Interview for Substance and Mental Disorders. Incidence Rates (IR) are presented. The 5-HTTLPR polymorphism was analyzed. Hardy-Weinberg equilibrium was studied. The results of the study showed that the highest IR of SUD was cannabis abuse/dependence in both the ecstasy (IR: 48.6/100 person-year) and cannabis (IR: 2.5/100 person-year) groups. There were no new cases of SUD in non-drug users at follow-up. The highest IR of NSUD was primary mood disorder in both the ecstasy (IR: 4.2/100 person-year) and in the non-drug (IR: 1.3/100 person-year) groups (P < 0.282). There were no new cases of NSUD in the cannabis group at follow-up. 5-HTTLPR polymorphism was associated with lifetime of primary mood disorders in ecstasy group (P = 0.018). Ecstasy use was associated with a higher rate of cannabis abuse/dependence disorders and mood disorders than cannabis use. In the ecstasy users, 5-HTTLPR polymorphism may result in a high vulnerability to primary mood disorders.

The genetics of bipolar disorder

Bipolar disorder is a mood disorder characterized by impairing episodes of mania and depression. Twin studies have established that bipolar disorder is among the most heritable of medical disorders and efforts to identify specific susceptibility genes have intensified over the past two decades. The search for genes influencing bipolar disorder has been complicated by a paucity of animal models, limited understanding of pathogenesis, and the genetic and phenotypic complexity of the syndrome. Linkage studies have implicated several chromosomal regions as harboring relevant genes, but results have been inconsistent. It is now widely accepted that the genetic liability to bipolar disorder reflects the action of many genes of individually small effect, a scenario for which linkage studies are poorly suited. Thus, association studies, which are more powerful for the detection of modest effect loci, have become the focus of gene-finding research. A large number of candidate genes, including biological candidates derived from hypotheses about the pathogenesis of the disorder and positional candidates derived from linkage and cytogenetic studies, have been evaluated. Several of these genes have been associated with the disorder in independent studies (including BDNF, DAOA, DISC1, GRIK4, SLC6A4, and TPH2), but none has been established. The clinical heterogeneity of bipolar disorder and its phenotypic and genetic overlap with other disorders (especially schizophrenia, schizoaffective disorder, and major depressive disorder) have raised questions about the optimal phenotype definition for genetic studies. Nevertheless, genomewide association analysis, which has successfully identified susceptibility genes for a variety of complex disorders, has begun to implicate specific genes for bipolar disorder (DGKH, CACNA1C, ANK3). The polygenicity of the disorder means that very large samples will be needed to detect the modest effect loci that likely contribute to bipolar disorder. Detailed genetic dissection of the disorder may provide novel targets (both pharmacologic and psychosocial) for intervention.

Neurotoxicity of drugs of abuse--the case of methylenedioxyamphetamines (MDMA, ecstasy), and amphetamines

Ecstasy (MDMA, 3,4-methylendioxymethamphetamine) and the stimulants methamphetamine (METH, speed) and amphetamine are popular drugs among young people, particularly in the dance scene. When given in high doses both MDMA and the stimulant amphetamines are clearly neurotoxic in laboratory animals. MDMA causes selective and persistent lesions of central serotonergic nerve terminals, whereas amphetamines damage both the serotonergic and dopaminergic systems. In recent years, the question of ecstasy-induced neurotoxicity and possible functional sequelae has been addressed in several studies in drug users. Despite large methodological problems, the bulk of evidence suggests residual alterations of serotonergic transmission in MDMA users, although at least partial recovery may occur after long-term abstinence. However, functional sequelae may persist even after longer periods of abstinence. To date, the most consistent findings associate subtle cognitive impairments with ecstasy use, particularly with memory. In contrast, studies on possible long-term neurotoxic effects of stimulant use have been relatively scarce. Preliminary evidence suggests that alterations of the dopaminergic system may persist even after years of abstinence from METH, and may be associated with deficits in motor and cognitive performance. In this paper, we will review the literature focusing on human studies.

Association of the serotonin transporter gene promoter region (5-HTTLPR) polymorphism with biased attention for emotional stimuli

A deletion polymorphism in the serotonin transporter-linked polymorphic region (5-HTTLPR) has been associated with vulnerability to affective disorders, yet the mechanism by which this gene confers vulnerability remains unclear. Two studies examined associations between the 5-HTTLPR polymorphism and attentional bias for emotional stimuli among nondepressed adults. Biased attention, attention engagement, and difficulty with attention disengagement were assessed with a spatial cuing task using emotional stimuli. Results from Study 1 (N = 38) indicated that short 5-HTTLPR allele carriers experienced greater difficulty disengaging their attention from sad and happy stimuli compared with long allele homozygotes. Study 2 participants (N = 144) were genotyped for the 5-HTTLPR polymorphism, including single nucleotide polymorphism rs25531 in the long allele of the 5-HTTLPR. Consistent with Study 1, individuals homozygous for the low-expressing 5-HTTLPR alleles (i.e., S and LG) experienced greater difficulty disengaging attention from sad, happy, and fear stimuli than high-expressing 5-HTTLPR homozygotes. Because this association exists in healthy adults, it may represent a susceptibility factor for affective disorders that becomes problematic during stressful life experiences.

Differential effects of 5-HTTLPR genotypes on mood, memory, and attention bias following acute tryptophan depletion and stress exposure

RATIONALE

Polymorphisms of the serotonin transporter gene (5-HTTLPR) may be associated with increased vulnerability to acute tryptophan depletion (ATD) and depression vulnerability especially following stressful life events.

OBJECTIVE

The aim of the present study was to investigate the effects of ATD in subjects with different 5-HTTLPR profiles before and after stress exposure on affective and cognitive-attentional changes.

MATERIALS AND METHODS

Eighteen subjects with homozygotic short alleles (S'/S') and 17 subjects with homozygotic long alleles (L'/L') of the 5-HTTLPR participated in a double-blind, placebo-controlled, crossover design to measure the effects of ATD on mood, memory, and attention before and after acute stress exposure.

RESULTS

ATD lowered mood in all subjects independent of genotype. In S'/S' genotypes, mild acute stress increased depressive mood and in L'/L' genotypes increased feelings of vigor. Furthermore, S'/S' genotypes differed from L'/L' genotypes on measures of attention independent of treatment and memory following ATD.

CONCLUSIONS

Polymorphisms of the 5-HTTLPR differentially affect responses to mild stress and ATD, suggesting greater vulnerability of S'/S' carriers to serotonergic manipulations and supporting increased depression vulnerability.

The effect of Ecstasy on memory is moderated by a functional polymorphism in the cathechol-O-methyltransferase (COMT) gene

There is ample evidence for decreased verbal memory in heavy Ecstasy users. However, findings on the presence of a dose-response relation are inconsistent, possibly due to individual differences in genetic vulnerability. Catechol-O-methyltransferase (COMT) is involved in the catabolism of Ecstasy. Therefore, COMT gene polymorphisms may moderate this vulnerability. We prospectively assessed verbal memory in subjects with a high risk for future Ecstasy use, and compared 59 subjects after first Ecstasy use with 60 subjects that remained Ecstasy-naive. In addition, we tested the interaction effect of Ecstasy and the functional val (158)met polymorphism on verbal memory. Met-allele carriers were somewhat more sensitive to the effects of Ecstasy on verbal learning than homozygous val-subjects. After correction for the use of other substances this effect was no longer statistically significant. The findings suggest that the COMT gene moderates the negative effect of Ecstasy on memory, but also other drug use seems to play a role.

Impulsivity as a vulnerability marker for substance-use disorders: review of findings from high-risk research, problem gamblers and genetic association studies

There is a longstanding association between substance-use disorders (SUDs) and the psychological construct of impulsivity. In the first section of this review, personality and neurocognitive data pertaining to impulsivity will be summarised in regular users of four classes of substance: stimulants, opiates, alcohol and 3,4-methylenedioxymethamphetamine (MDMA). Impulsivity in these groups may arise via two alternative mechanisms, which are not mutually exclusive. By one account, impulsivity may occur as a consequence of chronic exposure to substances causing harmful effects on the brain. By the alternative account, impulsivity pre-dates SUDs and is associated with the vulnerability to addiction. We will review the evidence that impulsivity is associated with addiction vulnerability by considering three lines of evidence: (i) studies of groups at high-risk for development of SUDs; (ii) studies of pathological gamblers, where the harmful consequences of the addiction on brain structure are minimised, and (iii) genetic association studies linking impulsivity to genetic risk factors for addiction. Within each of these three lines of enquiry, there is accumulating evidence that impulsivity is a pre-existing vulnerability marker for SUDs.

The effects of acute tryptophan depletion and serotonin transporter polymorphism on emotional processing in memory and attention

Polymorphism at the serotonin transporter linked polymorphic region (5-HTTLPR) has been associated with neuroticism, increased risk for affective disorders and greater vulnerability to mood change following serotonin (5-HT) depletion. The aim of the present study was to investigate whether the cognitive effects of 5-HT depletion were differentially affected by genotype at the 5-HTTLPR polymorphism, using neuropsychological measures of memory and attention. We utilized the acute tryptophan depletion (ATD) technique to temporarily reduce 5-HT synthesis in two groups of healthy volunteers pre-selected on the basis of 5-HTTLPR genotype, 15 of the ll genotype and 15 of the ss genotype, in a double-blind, placebo-controlled crossover design. As expected, ATD resulted in a robust reduction in plasma tryptophan concentration in both genotype groups. However, the genotype groups differed in terms of the effect of ATD on cognitive performance. The ss genotype group showed impaired verbal recall following depletion, while episodic memory was unimpaired by ATD in the ll genotype group. Averaging across depletion condition, the ss genotype group outperformed the ll genotype group on tests of episodic memory and attention. Neither group was significantly affected by ATD on measures of emotional state. These data confirm previous reports that ss individuals are particularly vulnerable to 5-HT depletion, but extend these findings to the cognitive domain. The unexpected finding that ss volunteers showed improved memory and attention relative to ll volunteers suggests a possible evolutionary advantage to possession of the s allele, which may offset the disadvantage of vulnerability to depression following stressful life events.

Review: Serotonin by stress interaction: a susceptibility factor for the development of depression?

A genetic predisposition to depression may be a potential risk factor in the development of depression. Although the neurobiological equivalent of the predisposition remains unclear, it seems as though the brain serotonin (5-HT) system plays an important mediating role. Therefore, individuals with a family history of depression (FH+) may be more likely to develop depression due to an innate vulnerability related to altered serotonergic neurotransmission in the brain. A major problem, however, is that the role of brain 5-HT in depression is complex and this serotonin-related innate vulnerability, by itself, is not sufficient enough to cause a depressive episode. In the search for additional factors, stress has received particular attention. Stressful life events influence and precede the onset of depression. Furthermore, depression is associated with stress hormone dysregulation and bidirectional interactions are thought to occur between stress-related changes in the neuroendocrine stress system and the 5-HT system. In the current review, we argue that healthy individuals with a positive family history of depression are more prone to develop depression due to a genetic 5-HT susceptibility, which deteriorates stress coping mechanisms and increases stress vulnerability.

Serotonergic vulnerability and depression: assumptions, experimental evidence and implications

In recent years, the term serotonergic vulnerability (SV) has been used in scientific literature, but so far it has not been explicitly defined. This review article attempts to elucidate the SV concept. SV can be defined as increased sensitivity to natural or experimental alterations of the serotonergic (5-HTergic) system. Several factors that may disrupt the 5-HTergic system and hence contribute to SV are discussed, including genetic factors, female gender, personality characteristics, several types of stress and drug use. It is explained that SV can be demonstrated by means of manipulations of the 5-HTergic system, such as 5-HT challenges or acute tryptophan depletion (ATD). Results of 5-HT challenge studies and ATD studies are discussed in terms of their implications for the concept of SV. A model is proposed in which a combination of various factors that may compromise 5-HT functioning in one person can result in depression or other 5-HT-related pathology. By manipulating 5-HT levels, in particular with ATD, vulnerable subjects may be identified before pathology initiates, providing the opportunity to take preventive action. Although it is not likely that this model applies to all cases of depression, or is able to identify all vulnerable subjects, the strength of the model is that it may enable identification of vulnerable subjects before the 5-HT related pathology occurs.

Anxiety, depression, and behavioral symptoms of executive dysfunction in ecstasy users: contributions of polydrug use

BACKGROUND

Given ecstasy's (MDMA) potential serotonergic neurotoxicity, it is plausible that regular ecstasy users would have an elevated prevalence of behavioral executive dysfunction or mood symptoms. However, recent studies have found that the relationship between ecstasy use and psychological symptoms was no longer significant after controlling for marijuana use (e.g., Morgan et al., 2002). The goal of the present study was to examine the relationship between ecstasy exposure and self-reported executive functioning and psychological symptoms after controlling for gender, ethnicity, and other drug use.

METHODS

Data were collected from 65 men and women with a wide range of ecstasy use (including 17 marijuana-using controls). Participants were administered the Frontal Systems Behavioral Scale, State-Trait Anxiety Inventory for adults, and the Beck Depression Inventory-2nd edition.

RESULTS

Although 19-63% of the ecstasy users demonstrated clinically elevated psychological symptoms, frequency of ecstasy use did not predict the psychological symptoms. No gender differences or interactions were observed.

CONCLUSIONS

These results revealed that, although ecstasy users demonstrate elevated levels of psychological symptoms and executive dysfunction, these symptoms are not statistically associated with their ecstasy consumption. Instead, other drug use (alcohol, marijuana, opioids, and inhalants) significantly predict psychological symptoms in this sample of polydrug users.

Impaired recognition of fear facial expressions in 5-HTTLPR S-polymorphism carriers following tryptophan depletion

RATIONALE

Genotype at the 5' promoter region (5-HTTLPR) of the serotonin transporter has been implicated in moderating the effects of acute tryptophan depletion on neurocognitive functioning. Acute tryptophan depletion has been associated with the processing of fear-relevant cues, such as emotional expressions, but the effect of genotype at the 5-HTTLPR has not been assessed.

OBJECTIVE

The present study investigated the effects of acute tryptophan depletion on the recognition of standardized facial expressions of emotions in healthy volunteers classified as ll homozygotes or s carriers.

MATERIALS AND METHODS

A double-blind between-groups design was used with volunteers randomly selected to ingest capsules containing an amino acid mixture specifically lacking tryptophan, or placebo capsules containing lactose. 5 h after capsule ingestion, subjects were required to identify anger, disgust, fear, happiness, sadness, and surprise expressions that progressed from neutral to each full emotional expression in 5% steps.

RESULTS

Tryptophan depletion significantly impaired the recognition of fearful facial expressions in s carriers but not ll homozygotes. This impairment was specific to fear expressions. No significant differences in the recognition of other expressions were found. Free tryptophan levels were correlated with fear recognition in s carriers but not ll homozygotes.

CONCLUSIONS

The effects of acute tryptophan depletion on the processing of emotional expressions varies as a function of genotype at the 5-HTTLPR. Depletion impairs the recognition of fear in s carriers but not ll homozygotes. This finding reinforces the importance of considering genotype when assessing the behavioral effects of pharmacologic modulation.

Serotonin transporter polymorphism mediates vulnerability to loss of incentive motivation following acute tryptophan depletion

The serotonin (5-HT) system is implicated in incentive motivational processes. The present study utilized the acute tryptophan depletion (ATD) procedure to investigate the effect of temporarily lowering 5-HT synthesis on motivation in healthy volunteers, stratifying the results by allelic variation at the serotonin transporter gene (5-HTTLPR). ATD resulted in a robust reduction in plasma tryptophan concentration. Consistent with a previous study, ATD attenuated motivationally speeded action on the Cued-Reinforcement Reaction Time task. The present investigation revealed that this effect was restricted to volunteers of the ss genotype, whereas ll volunteers exhibited intact motivationally speeded action following ATD (treatment x reinforcement probability x genotype interaction: F1,26=5.8, p=0.024). Furthermore, tryptophan availability to the brain was correlated positively with motivationally speeded action following ATD in the ss genotype group (rho13=0.71, p=0.006), whereas this correlation was negative in the ll genotype group (rho14=-0.60, p=0.023). This is the first study to suggest that allelic variation at the 5-HTTLPR mediates motivational responses to ATD in healthy volunteers. These data indicate that the s allele at the 5-HTTLPR may confer risk for depression via its effect on incentive motivational processing, and highlight the importance of genetic variation in determining individual responses to pharmacological treatments.

The effect of polymorphism at the serotonin transporter gene on decision-making, memory and executive function in ecstasy users and controls

RATIONALE

3, 4-Methylenedioxymethamphetamine (MDMA or "ecstasy") is a popular drug of abuse known to result in depletions of the serotonin (5-HT) system. A number of studies have reported that ecstasy users differ from controls on a variety of measures of cognitive function. However, the literature is not consistent and many negative findings were also reported. One reason for such inconsistency might be interindividual variance in vulnerability to the deleterious effects of ecstasy due to a number of factors, both genetic and environmental.

OBJECTIVES

To investigate the hypothesis that carriers of the s allele at the 5-HT transporter gene-linked polymorphic region (5-HTTLPR), which was associated with reduced serotonergic neurotransmission relative to the l allele, would be most vulnerable to the effects of ecstasy on cognitive function.

METHODS

We assessed memory, decision-making, and executive function in ecstasy users and controls, stratifying by genotype at the 5-HTTLPR.

RESULTS

We observed that the 5-HTTLPR genotype groups differed on a number of measures in both the ecstasy users and the controls. While performing a risky decision-making task, ss and ls controls attended to differences in the probability of winning chosen gambles to a greater extent than the ll controls. However, this difference was dramatically attenuated in the ss ecstasy users. Furthermore, independent of ecstasy use, volunteers of the ss genotype outperformed the ll genotype on a visual planning task.

CONCLUSIONS

The results are consistent with the hypothesis that cognitive impairment in ecstasy users may depend on genetic variation at the 5-HTTLPR.

Neurobiology of multiple insults: HIV-1-associated brain disorders in those who use illicit drugs

Despite two decades of research, certain aspects of HIV-related central nervous system (CNS) disease remain poorly understood. HIV targets microglia and macrophages within the CNS and enters the brain compartment early. However, HIV is there held in check apparently until the onset of significant immune compromise, when viral replication, microglial activation, neuronal damage, and cognitive impairment are likely to ensue. Illicit drug abuse continues to be a significant risk factor for HIV transmission worldwide. Whether HIV-related CNS disease is more prevalent or more severe in this risk group has long been debated. Drugs of abuse can of themselves cause immune suppression, blood-brain barrier breakdown, microglial activation, and neuronal injury. This review presents evidence that HIV associated CNS disorders are indeed accentuated in drug abusers. However, the advent of effective therapy has added a new dimension, which must be taken into consideration. Treated individuals are surviving much longer and HIV encephalitis and HIV-associated dementia have become much less common. However, more subtle forms of CNS damage are emerging. Examination of the brains of individuals who have been treated long term with highly active antiretroviral therapy (HAART) reveals a surprising degree of microglial activation, comparable at times to that seen formerly in milder cases of HIV encephalitis. In addition, these individuals show evidence of increased deposition of neurodegenerative proteins, particularly hyperphosphorylated tau. Similar observations have been made in young opiate abusers who are HIV negative. Taken together, these results suggest that neuroinflammation and neurodegeneration, which are clinically silent at present, may cause problems in the future in HAART-treated subjects.

Memory function and serotonin transporter promoter gene polymorphism in ecstasy (MDMA) users

Although 3,4-methylenedioxymethamphetamine (MDMA or ecstasy) has been shown to damage brain serotonin (5-HT) neurons in animals and possibly humans, little is known about the long-term consequences of MDMA-induced 5-HT neurotoxic lesions on functions in which 5-HT is involved, such as cognitive function. Because 5-HT transporters play a key element in the regulation of synaptic 5-HT transmission it may be important to control for the potential covariance effect of a polymorphism in the 5-HT transporter promoter gene region (5-HTTLPR) when studying the effects of MDMA as well as cognitive functioning. The aim of the study was to investigate the effects of moderate and heavy MDMA use on cognitive function, as well as the effects of long-term abstention from MDMA, in subjects genotyped for 5-HTTLPR. A second aim of the study was to determine whether these effects differ for females and males. Fifteen moderate MDMA users (<55 lifetime tablets), 22 heavy MDMA+ users (>55 lifetime tablets), 16 ex-MDMA+ users (last tablet > 1 year ago) and 13 controls were compared on a battery of neuropsychological tests. DNA from peripheral nuclear blood cells was genotyped for 5-HTTLPR using standard polymerase chain reaction methods.A significant group effect was observed only on memory function tasks (p = 0.04) but not on reaction times (p = 0.61) or attention/executive functioning (p = 0.59). Heavy and ex-MDMA+ users performed significantly poorer on memory tasks than controls. In contrast, no evidence of memory impairment was observed in moderate MDMA users. No significant effect of 5-HTTLPR or gender was observed. While the use of MDMA in quantities that may be considered "moderate" is not associated with impaired memory functioning, heavy use of MDMA use may lead to long lasting memory impairments. No effect of 5-HTTLPR or gender on memory function or MDMA use was observed.

Ecstasy use and self-reported depression, impulsivity, and sensation seeking: a prospective cohort study

Although there are indications that ecstasy users have higher levels of depression, impulsivity, and sensation seeking, it is unknown whether these are consequences of ecstasy use or predisposing factors for starting ecstasy use. We prospectively assessed the predictive value of depression, impulsivity, and sensation seeking on future first time ecstasy use. We also assessed whether depression, impulsivity, and sensation seeking had changed after first ecstasy use. Depression, impulsivity, and sensation seeking were assessed using self-report questionnaires in 188 ecstasy-naive volunteers with high probability for future ecstasy use. After a mean follow-up of 17 months, measurements were repeated in 59 incident ecstasy users (mean 6.0 tablets) and 61 matched persistent ecstasy-naive volunteers. Only experience seeking (subscale of the sensation seeking scale) predicted future ecstasy use (OR -- 1.05, 95% CI 1.00 to 1.10), but after adjustment for potential confounders this was not significant anymore. At follow-up, significant effects of ecstasy use on the general and the disinhibition subscale of the sensation seeking scale were observed (after adjustment for potential confounders: regression coefficient B 0.51, 95% CI 0.20 to 0.83 and B -- 3.25, 95% CI 1.74 to 4.76, respectively). These data indicate that depression, impulsivity, and sensation seeking do not predict first time ecstasy use in a population of young adults with the intention to start using ecstasy and that low level ecstasy use does not seem to cause depression or impulsivity. However, low level ecstasy use may increase (certain aspects of) sensation seeking.

MDMA in humans: factors which affect the neuropsychobiological profiles of recreational ecstasy users, the integrative role of bioenergetic stress

Many recreational ecstasy/MDMA users display neuropsychobiological deficits, whereas others remain problem free. This review will investigate some of the drug and non-drug factors which influence the occurrence of these deficits. Acute and chronic MDMA usage are both important. Intensive use within a session is often associated with more problems. In term of lifetime usage, novice users generally remain unimpaired, whereas most heavy users report memory or other psychobiological problems which they attribute to ecstasy. These complaints are confirmed by objective deficits in working memory, attention, frontal-executive, and episodic memory tasks. Psychobiological deficits include disturbed sleep, sexual dysfunction, reduced immuno-competence, and increased oxidative stress. Further MDMA-related factors which may contribute to these changes, include acute and chronic tolerance, and drug dependence. Around 90ñ95% of ecstasy/MDMA users also take cannabis, and this can independently contribute to the adverse neuropsychobiological pro.les; although in some situations the acute co-use of these two drugs may be interactive rather than additive, since cannabis has relaxant and hypothermic properties. Alcohol, nicotine, amphetamine, and other drugs, can also affect the psychobiological pro.les of ecstasy polydrug users in complex ways. Pure MDMA users are rare but they have been shown to display significant neurocognitive deficits. Psychiatric aspects are debated in the context of the diathesis-stress model. Here the stressor of ecstasy polydrug drug use, interacts with various predisposition factors (genetic, neurochemical, personality), to determine the psychiatric outcome. Recreational MDMA is typically taken in hot and crowded dances/raves. Prolonged dancing, feeling hot, and raised body temperature, can also be associated with more psychobiological problems. This is consistent with the animal literature, where high ambient temperature and other metabolic stimulants boost the acute effects of MDMA, and cause greater serotonergic neurotoxicity. In conclusion, the neuropsychobiological effects of MDMA are modulated by a wide range of drug and non-drug factors. These multiple influences are integrated within a bioenergetic stress model, where factors which heighten acute metabolic distress lead to more neuropsychobiological problems.

Neuroimaging findings with MDMA/ecstasy: technical aspects, conceptual issues and future prospects

Users of ecstasy (3,4-methylenedioxymethamphetamine; MDMA) may be at risk of developing MDMA-induced injury to the serotonin (5-HT) system. Previously, there were no methods available for directly evaluating the neurotoxic effects of MDMA in the living human brain. However, development of in vivoneuroimaging tools have begun to provide insights into the effects of ecstasy on the human brain. Single photon emission computed tomography (SPECT), positron emission computed tomography (PET) and proton magnetic resonance spectroscopy (1H-MRS) studies which have evaluated ecstasy's neurotoxic potential will be reviewed and discussed in terms of technical aspects, conceptual issues and future prospects. Although PET and SPECT may be limited by several factors such as the low cortical uptake and the use of a non-optimal reference region (cerebellum) the few studies conducted so far provide suggestive evidence that people who heavily use ecstasy are at risk of developing subcortical, and probably also cortical reductions in serotonin transporter (SERT) densities, a marker of 5-HT neurotoxicity. There seem to be dose-dependent and transient reductions in SERT for which females may be more vulnerable than males. 1H-MRS appears to be a less sensitive technique for studying ecstasy's neurotoxic potential. Whether individuals with a relatively low ecstasy exposure also demonstrate loss of SERT needs to be determined. Because most studies have had a retrospective design, in which evidence is indirect and differs in the degree to which any causal links can be implied, longitudinal studies in human ecstasy users are needed to draw definite conclusions.

Neurotoxicity of methylenedioxyamphetamines (MDMA; ecstasy) in humans: how strong is the evidence for persistent brain damage?

BACKGROUND

The popular dance drug ecstasy (3,4-methylenedioxymethamphetamine: MDMA and some analogues) causes selective and persistent neurotoxic damage of central serotonergic neurones in laboratory animals. Serotonin plays a role in numerous functional systems in the central nervous system (CNS). Consequently, various abnormalities including psychiatric, vegetative, neuroendocrine and cognitive disorders could be expected in humans following MDMA-induced neurotoxic brain damage.

AIMS

In recent years, the question of ecstasy-induced neurotoxicity and possible functional sequelae has been addressed in several studies with drug users. The aim of this paper was to review this literature and weigh the strength of the evidence for persistent brain damage in ecstasy users.

METHODS

We used Medline to view all available publications on 'ecstasy' or 'MDMA'. All available studies dealing with ecstasy users entered this analysis.

FINDINGS AND CONCLUSIONS

Despite large methodological problems the bulk of evidence suggests residual alterations of serotonergic transmission in MDMA users, although at least partial restitution may occur after long-term abstinence. However, functional sequelae may persist even after longer periods of abstinence. To date, the most consistent findings associate subtle cognitive, particularly memory, impairments with heavy ecstasy use. However, the evidence cannot be considered definite and the issues of possible pre-existing traits or the effects of polydrug use are not resolved.

RECOMMENDATIONS

Questions about the neurotoxic effects of ecstasy on the brain remain highly topical in light of its popularity among young people. More longitudinal and prospective studies are clearly needed in order to obtain a better understanding of the possible long-term sequelae of ecstasy use in humans.