Neuroimaging of chronic MDMA (“ecstasy”) effects: A meta-analysis

Brain dysfunctions and neurotoxicity induced by psychostimulants in experimental models and humans: an overview of recent findings

Preclinical and clinical studies indicate that psychostimulants, in addition to having abuse potential, may elicit brain dysfunctions and/or neurotoxic effects. Central toxicity induced by psychostimulants may pose serious health risks since the recreational use of these substances is on the rise among young people and adults. The present review provides an overview of recent research, conducted between 2018 and 2023, focusing on brain dysfunctions and neurotoxic effects elicited in experimental models and humans by amphetamine, cocaine, methamphetamine, 3,4-methylenedioxymethamphetamine, methylphenidate, caffeine, and nicotine. Detailed elucidation of factors and mechanisms that underlie psychostimulant-induced brain dysfunction and neurotoxicity is crucial for understanding the acute and enduring noxious brain effects that may occur in individuals who use psychostimulants for recreational and/or therapeutic purposes.

The functional connectome of 3,4-methyldioxymethamphetamine-related declarative memory impairments

The chronic intake of 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") bears a strong risk for sustained declarative memory impairments. Although such memory deficits have been repeatedly reported, their neurofunctional origin remains elusive. Therefore, we here investigate the neuronal basis of altered declarative memory in recurrent MDMA users at the level of brain connectivity. We examined a group of 44 chronic MDMA users and 41 demographically matched controls. Declarative memory performance was assessed by the Rey Auditory Verbal Learning Test and a visual associative learning test. To uncover alterations in the whole brain connectome between groups, we employed a data-driven multi-voxel pattern analysis (MVPA) approach on participants' resting-state functional magnetic resonance imaging data. Recent MDMA use was confirmed by hair analyses. MDMA users showed lower performance in delayed recall across tasks compared to well-matched controls with moderate-to-strong effect sizes. MVPA revealed a large cluster located in the left postcentral gyrus of global connectivity differences between groups. Post hoc seed-based connectivity analyses with this cluster unraveled hypoconnectivity to temporal areas belonging to the auditory network and hyperconnectivity to dorsal parietal regions belonging to the dorsal attention network in MDMA users. Seed-based connectivity strength was associated with verbal memory performance in the whole sample as well as with MDMA intake patterns in the user group. Our findings suggest that functional underpinnings of MDMA-related memory impairments encompass altered patterns of multimodal sensory integration within auditory processing regions to a functional heteromodal connector hub, the left postcentral gyrus. In addition, hyperconnectivity in regions of a cognitive control network might indicate compensation for degraded sensory processing.

Cortical structural differences following repeated ayahuasca use hold molecular signatures

Introduction

Serotonergic psychedelics such as ayahuasca are reported to promote both structural and functional neural plasticity via partial 5-HT2A agonism. However, little is known about how these molecular mechanisms may extend to repeated psychedelic administration in humans, let alone neuroanatomy. While early evidence suggests localised changes to cortical thickness in long-term ayahuasca users, it is unknown how such findings may be reflected by large-scale anatomical brain networks comprising cytoarchitecturally complex regions.

Methods

Here, we examined the relationship between cortical gene expression markers of psychedelic action and brain morphometric change following repeated ayahuasca usage, using high-field 7 Tesla neuroimaging data derived from 24 members of an ayahuasca-using church (Santo Daime) and case-matched controls.

Results

Using a morphometric similarity network (MSN) analysis, repeated ayahuasca use was associated with a spatially distributed cortical patterning of both structural differentiation in sensorimotor areas and de-differentiation in transmodal areas. Cortical MSN remodelling was found to be spatially correlated with dysregulation of 5-HT2A gene expression as well as a broader set of genes encoding target receptors pertinent to ayahuasca's effects. Furthermore, these associations were similarly interrelated with altered gene expression of specific transcriptional factors and immediate early genes previously identified in preclinical assays as relevant to psychedelic-induced neuroplasticity.

Conclusion

Taken together, these findings provide preliminary evidence that the molecular mechanisms of psychedelic action may scale up to a macroscale level of brain organisation in vivo. Closer attention to the role of cortical transcriptomics in structural-functional coupling may help account for the behavioural differences observed in experienced psychedelic users.

Striatal Iron Deposition in Recreational MDMA (Ecstasy) Users

BACKGROUND

The common club drug MDMA (also known as ecstasy) enhances mood, sensory perception, energy, sociability, and euphoria. While MDMA has been shown to produce neurotoxicity in animal models, research on its potential neurotoxic effects in humans is inconclusive and has focused primarily on the serotonin system.

METHODS

We investigated 34 regular, largely pure MDMA users for signs of premature neurodegenerative processes in the form of increased iron load in comparison to a group of 36 age-, sex-, and education-matched MDMA-naïve control subjects. We used quantitative susceptibility mapping, a novel tool able to detect even small tissue (nonheme) iron accumulations. Cortical and relevant subcortical gray matter structures were grouped into 8 regions of interest and analyzed.

RESULTS

Significantly increased iron deposition in the striatum was evident in the MDMA user group. The effect survived correction for multiple comparisons and remained after controlling for relevant confounding factors, including age, smoking, and stimulant co-use. Although no significant linear relationship between measurements of the amounts of MDMA intake (hair analysis and self-reports) and quantitative susceptibility mapping values was observed, increased striatal iron deposition might nevertheless point to MDMA-induced neurotoxic processes. Additional factors (hyperthermia and simultaneous co-use of other substances) that possibly amplify neurotoxic effects of MDMA during the state of acute intoxication are discussed.

CONCLUSIONS

The demonstrated increased striatal iron accumulation may indicate that regular MDMA users have an increased risk potential for neurodegenerative diseases with progressing age.

Women and MDMA: particularities of gender and sex

This comprehensive review delves into the intricate interplay between gender/sex and MDMA use, drawing upon recent evidence. It explores how girls, as a means of coping with negative emotions, often resort to drug use, while boys primarily initiate drug use due to peer pressure or sensation-seeking tendencies. Women, frequently having endured traumatic life events, may turn to MDMA as a form of self-medication. Notably, women face an elevated risk of contracting sexually transmitted infections due to their altered mental states and diminished condom use during MDMA consumption. Additionally, females exhibit heightened sensitivity to the subjective effects of MDMA, consistently reporting heightened anxiety, adverse effects, and negative side effects. While women may have a higher susceptibility to hyponatremia, intriguingly, they appear to be less vulnerable to MDMA-induced hyperthermia. Although limited, available data suggest that prenatal MDMA exposure could lead to motor delays in infants, necessitating further research to unravel the potential cognitive effects. Furthermore, MDMA-assisted psychotherapy holds immense promise for addressing post-traumatic stress disorder (PTSD) among female subgroups. These pronounced gender and sex disparities in MDMA use and its effects underscore the pressing need for additional research to develop tailored, effective, and safe treatment approaches that account for these fundamental factors.

Understanding the Mechanisms of Action and Effects of Drugs of Abuse

AIM

Drug abuse and addiction are major public health concerns, with millions of people worldwide affected by the negative consequences of drug use. To better understand this complex issue, a review was conducted to examine the mechanisms of action and effects of drugs of abuse, including their acute and chronic effects, the symptoms of abstinence syndrome, as well as their cardiovascular impacts.

METHODS

The analyzed data were obtained after surveying an electronic database, namely PubMed, with no time limit, grey literature sources, and reference lists of relevant articles.

RESULTS

The review highlights the different categories of drugs of abuse, such as opioids, stimulants, depressants, hallucinogens, and cannabis, and discusses the specific ways that each drug affects the brain and body. Additionally, the review explores the short-term and long-term effects of drug abuse on the body and mind, including changes in brain structure and function, physical health problems, and mental health issues, such as depression and anxiety. In addition, the review explores the effects of drug abuse on cardiovascular health, focusing on electrocardiogram changes. Moreover, the analysis of relevant literature also highlighted possible genetic susceptibility in various addictions. Furthermore, the review delves into the withdrawal symptoms that occur when someone stops using drugs of abuse after a period of chronic use.

CONCLUSION

Overall, this review provides a comprehensive overview of the current state of knowledge on drug abuse and addiction. The findings of this review can inform the development of evidence-based prevention and intervention strategies to address this critical public health issue.

Chronic 3,4-Methylenedioxymethamphetamine (MDMA) Use Is Related to Glutamate and GABA Concentrations in the Striatum But Not the Anterior Cingulate Cortex

BACKGROUND

3,4-Methylenedioxymethamphetamine (MDMA) is a widely used recreational substance inducing acute release of serotonin. Previous studies in chronic MDMA users demonstrated selective adaptations in the serotonin system, which were assumed to be associated with cognitive deficits. However, serotonin functions are strongly entangled with glutamate as well as γ-aminobutyric acid (GABA) neurotransmission, and studies in MDMA-exposed rats show long-term adaptations in glutamatergic and GABAergic signaling.

METHODS

We used proton magnetic resonance spectroscopy (MRS) to measure the glutamate-glutamine complex (GLX) and GABA concentrations in the left striatum and medial anterior cingulate cortex (ACC) of 44 chronic but recently abstinent MDMA users and 42 MDMA-naïve healthy controls. While the Mescher-Garwood point-resolved-spectroscopy sequence (MEGA-PRESS) is best suited to quantify GABA, recent studies reported poor agreement between conventional short-echo-time PRESS and MEGA-PRESS for GLX measures. Here, we applied both sequences to assess their agreement and potential confounders underlying the diverging results.

RESULTS

Chronic MDMA users showed elevated GLX levels in the striatum but not the ACC. Regarding GABA, we found no group difference in either region, although a negative association with MDMA use frequency was observed in the striatum. Overall, GLX measures from MEGA-PRESS, with its longer echo time, appeared to be less confounded by macromolecule signal than the short-echo-time PRESS and thus provided more robust results.

CONCLUSION

Our findings suggest that MDMA use affects not only serotonin but also striatal GLX and GABA concentrations. These insights may offer new mechanistic explanations for cognitive deficits (e.g., impaired impulse control) observed in MDMA users.

Experimental strategies to discover and develop the next generation of psychedelics and entactogens as medicines

Research on classical psychedelics (psilocybin, LSD and DMT) and entactogen, MDMA, has produced a renaissance in the search for more effective drugs to treat psychiatric, neurological and various peripheral disorders. Psychedelics and entactogens act though interaction with 5-HT_2A and other serotonergic receptors and/or monoamine reuptake transporters. 5-HT, which serves as a neurotransmitter and hormone, is ubiquitously distributed in the brain and peripheral organs, tissues and cells where it has vasoconstrictor, pro-inflammatory and pro-nociceptive actions. Serotonergic psychedelics and entactogens have known safety and toxicity risks. For these drugs, the risks been extensively researched and empirically assessed through human experience. However, novel drug-candidates require thorough non-clinical testing not only to predict clinical efficacy, but also to address the risks they pose during clinical development and later after approval as prescription medicines. We have defined the challenges researchers will encounter when developing novel serotonergic psychedelics and entactogens. We describe screening techniques to predict clinical efficacy and address the safety/toxicity risks emerging from our knowledge of the existing drugs: 1) An early-stage, non-clinical screening cascade to pharmacologically characterise novel drug-candidates. 2) Models to detect hallucinogenic activity. 3) Models to differentiate hallucinogens from entactogens. 4) Non-clinical preclinical lead optimisation technology (PLOT) screening to select drug-candidates. 5) Modified animal models to evaluate the abuse and dependence risks of novel psychedelics in Safety Pharmacology testing. Our intention has been to design non-clinical screening strategies that will reset the balance between benefits and harms to deliver more effective and safer novel psychedelics for clinical use. This article is part of the Special Issue on 'National Institutes of Health Psilocybin Research Speaker Series'.

Does chronic use of amphetamine-type stimulants impair interference control? - A meta-analysis

In substance use and addiction, inhibitory control is key to ignoring triggers, withstanding craving and maintaining abstinence. In amphetamine-type stimulant (ATS) users, most research focused on behavioral inhibition, but largely neglected the equally important subdomain of cognitive interference control. Given its crucial role in managing consumption, we investigated the relationship between interference control and chronic ATS use in adults. A database search (Pubmed & Web of Science) and relevant reviews were used to identify eligible studies. Effect sizes were estimated with random effects models. Subgroup, meta-regression, and sensitivity analyses explored heterogeneity in effect sizes. We identified 61 studies (53 datasets) assessing interference control in 1873 ATS users and 1905 controls. Findings revealed robust small effect sizes for ATS-related deficits in interference control, which were mainly seen in methamphetamine, as compared to MDMA users. The differential effects are likely due to tolerance-induced dopaminergic deficiencies (presumably most pronounced in methamphetamine users). Similarities between different ATS could be due to noradrenergic deficiencies; but elucidating their functional role in ATS users requires further/more research.

New and emerging approaches to treat psychiatric disorders

Psychiatric disorders are highly prevalent, often devastating diseases that negatively impact the lives of millions of people worldwide. Although their etiological and diagnostic heterogeneity has long challenged drug discovery, an emerging circuit-based understanding of psychiatric illness is offering an important alternative to the current reliance on trial and error, both in the development and in the clinical application of treatments. Here we review new and emerging treatment approaches, with a particular emphasis on the revolutionary potential of brain-circuit-based interventions for precision psychiatry. Limitations of circuit models, challenges of bringing precision therapeutics to market and the crucial advances needed to overcome these obstacles are presented.

Beyond monoamines: I. Novel targets and radiotracers for Positron emission tomography imaging in psychiatric disorders

With the emergence of positron emission tomography (PET) in the late 1970s, psychiatry had access to a tool capable of non-invasive assessment of human brain function. Early applications in psychiatry focused on identifying characteristic brain blood flow and metabolic derangements using radiotracers such as [¹⁵ O]H₂ O and [¹⁸ F]FDG. Despite the success of these techniques, it became apparent that more specific probes were needed to understand the neurochemical bases of psychiatric disorders. The first neurochemical PET imaging probes targeted sites of action of neuroleptic (dopamine D₂ receptors) and psychoactive (serotonin receptors) drugs. Based on the centrality of monoamine dysfunction in psychiatric disorders and the measured success of monoamine-enhancing drugs in treating them, the next 30 years witnessed the development of an armamentarium of PET radiopharmaceuticals and imaging methodologies for studying monoamines. Continued development of monoamine-enhancing drugs over this time however was less successful, realizing only modest gains in efficacy and tolerability. As patent protection for many widely prescribed and profitable psychiatric drugs lapsed, drug development pipelines shifted away from monoamines in search of novel targets with the promises of improved efficacy, or abandoned altogether. Over this period, PET radiopharmaceutical development activities closely paralleled drug development priorities resulting in the development of new PET imaging agents for non-monoamine targets. Part one of this review will briefly survey novel PET imaging targets with relevance to the field of psychiatry, which include the metabotropic glutamate receptor type 5 (mGluR5), purinergic P₂ X₇ receptor, type 1 cannabinoid receptor (CB₁ ), phosphodiesterase 10A (PDE10A), and describe radiotracers developed for these and other targets that have matured to human subject investigations. Current limitations of the targets and techniques will also be discussed.

White matter alterations in chronic MDMA use: Evidence from diffusion tensor imaging and neurofilament light chain blood levels

3,4-Methylenedioxymethamphetamine (MDMA, "Ecstasy") is a serotonin- and noradrenaline-releasing substance, currently among the most widely used illicit substances worldwide. In animal studies, repeated exposure to MDMA has been associated with dendritic but also axonal degeneration in the brain. However, translation of the axonal findings, specifically, to humans has been repeatedly questioned and the few existing studies investigating white matter alterations in human chronic MDMA users have yielded conflicting findings. In this study, we combined whole-brain diffusion tensor imaging and neurofilament light chain (NfL) analysis in blood to reveal potential MDMA-induced axonal neuropathology. To this end, we assessed 39 chronic MDMA users and 39 matched MDMA-naïve healthy controls. MDMA users showed increased fractional anisotropy in several white matter tracts, most prominently in the corpus callosum as well as corticospinal tracts, with these findings partly related to MDMA use intensity. However, the NfL levels of MDMA users were not significantly different from those of controls. We conclude that MDMA use is not associated with significant white matter lesions due to the absence of reduced fractional anisotropy and increased NfL levels commonly observed in conditions associated with white matter lesions, including stimulant and ketamine use disorders. Hence, the MDMA-induced axonal degradation demonstrated in animal models was not observed in this human study of chronic MDMA users.

MDMA related neuro-inflammation and adenosine receptors

3,4-methylenedioxymethamphetamine (MDMA) is a world-wide abused psychostimulant, which has the neurotoxic effects on dopaminergic and serotonergic neurons in both rodents and non-human primates. Adenosine acts as a neurotransmitter in the brain through the activation of four specific G-protein-coupled receptors and it acts as a neuromodulator of dopamine neurotransmission. Recent studies suggest that stimulation of adenosine receptors oppose many behavioral effects of methamphetamines. This review summarizes the specific cellular mechanisms involved in MDMA neuroinflammatory effects, along with the protective effects of adenosine receptors.

Serotonin transporter availability, neurocognitive function and their correlation in abstinent 3,4-methylenedioxymethamphetamine users

RATIONALE

MDMA or Ecstasy has made a resurgence in popularity and the majority of users consist of teenagers and adolescents. Therefore, it is important to determine whether MDMA causes long-term damage and what this damage entails. There is an ongoing debate about possible neurocognitive changes in 3,4-methylenedioxymethamphetamine (MDMA) users related to MDMA's neurotoxic potential. Multiple neuroimaging studies have shown that Ecstasy use leads to lower serotonin transporter (SERT) availability in multiple brain regions. This may express itself in a loss of cognitive functions like memory, attention and executive function. However, there is increasing evidence reporting that MDMA's induced serotonergic adaptations are reversible over time. The question we thus address is whether the recovery of SERT function predicts a recovery of cognitive function.

OBJECTIVES

This review aims to investigate MDMA's long-term effects on SERT availability and cognitive functioning.

METHODS

A literature search was performed in PubMed. Studies that investigated the effects of MDMA on both SERT availability and cognitive performance were eligible for inclusion.

RESULTS

SERT availability positively correlated with time of abstinence, whereas memory performance did not show this correlation, but remained impaired in MDMA users. No significant correlation between SERT availability and memory function was found (r = 0.232, p = 0.581; r = 0.176, p = 0.677).

CONCLUSIONS

The main findings of this review are that MDMA-use leads to an acute decrease in SERT availability and causes an impairment in cognitive functions, mostly memory. However, SERT availability recovers with sustained abstinence while memory function does not. This suggests that SERT availability is not a biomarker for MDMA-induced cognitive impairment and likely also not for MDMA-induced neurotoxicity.

3,4-Methylenedioxy methamphetamine, synthetic cathinones and psychedelics: From recreational to novel psychotherapeutic drugs

The utility of classical drugs used to treat psychiatric disorders (e.g., antidepressants, anxiolytics) is often limited by issues of lack of efficacy, delayed onset of action or side effects. Psychoactive substances have a long history of being used as tools to alter consciousness and as a gateway to approach the unknown and the divinities. These substances were initially obtained from plants and animals and more recently by chemical synthesis, and its consumption evolved toward a more recreational use, leading to drug abuse-related disorders, trafficking, and subsequent banning by the authorities. However, these substances, by modulation of certain neurochemical pathways, have been proven to have a beneficial effect on some psychiatric disorders. This evidence obtained under medically controlled conditions and often associated with psychotherapy, makes these substances an alternative to conventional medicines, to which in many cases the patient does not respond properly. Such disorders include post-traumatic stress disease and treatment-resistant depression, for which classical drugs such as MDMA, ketamine, psilocybin and LSD, among others, have already been clinically tested, reporting successful outcomes. The irruption of new psychoactive substances (NPS), especially during the last decade and despite their recreational and illicit uses, has enlarged the library of substances with potential utility on these disorders. In fact, many of them were synthetized with therapeutic purposes and were withdrawn for concrete reasons (e.g., adverse effects, improper pharmacological profile). In this review we focus on the basis, existing evidence and possible use of synthetic cathinones and psychedelics (specially tryptamines) for the treatment of mental illnesses and the properties that should be found in NPS to obtain new therapeutic compounds.

Neurotoxicity of MDMA: Main effects and mechanisms

Preclinical and clinical studies indicate that 3,4-methylenedioxymethamphetamine (MDMA; 'ecstasy'), in addition to having abuse potential, may elicit acute and persistent abnormalities of varying severity at the central level. Importantly, neurotoxic effects of MDMA have been demonstrated in experimental animals. Accordingly, central toxicity induced by MDMA may pose a serious harm for health, since MDMA is among the substances that are used for recreational purposes by young and adult people. This review provides a concise overview of recent findings from preclinical and clinical studies that evaluated the central effects of MDMA, and the mechanisms involved in the neurotoxicity induced by this amphetamine-related drug.

Induced fit, ensemble binding space docking and Monte Carlo simulations of MDMA 'ecstasy' and 3D pharmacophore design of MDMA derivatives on the human serotonin transporter (hSERT)

The popular recreational drug MDMA (3,4-methylenedioxy-methamphetamine) has a documented potential as a psychopharmacological clinical and research tool. This is due to its unique ability to promote reprocessing of traumatic memories, empathetic and pro-social states. Although it is established that MDMA exerts its behavioural effects via the serotonin transporter (SERT), the ligand-protein molecular interplay remains elusive. In order to shed light on the binding of MDMA and its primary congeneric entactogens (MDA, MBDB and MDAI), we first combined induced fit with Monte Carlo simulations. The computed interaction energies of the models correlated well with experimental activities (_adjR² = 0.78). Then we carried out 'ensemble binding space docking' on trajectories generated by interpolation of experimentally derived structures of the hSERT from the outward-open, and the occluded, to the inward-open states. This approach revealed low-energy alternative binding modes, suggesting high occupancy of the central site, yet considerable MDMA mobility within it, favouring the paroxetine-like orientation. Finally, we designed a pharmacophore that may be used to recognise hSERT-mediated serotonin releasers and uptake inhibitors of diverse chemical structure, identifying their active conformations and interacting residues. We conclude that the conserved amine-Asp98 ionic and edge-to-face π-π interactions are crucial to the mode of action of MDMA on the hSERT, underscoring the contributions of Tyr95 and gating residues Phe341, Tyr176 and Phe335. Amenable to experimental testing, our modelling may aid the rational design of novel entactogenic compounds and contribute to the understanding of an action mechanism, common and typical of psychotropic agents.

Pharmacologic Similarities and Differences Among Hallucinogens

Hallucinogens constitute a unique class of substances that cause changes in the user's thoughts, perceptions, and mood through various mechanisms of action. Although the serotonergic hallucinogens such as lysergic acid diethylamide, psilocybin, and N,N-dimethyltryptamine have been termed the classical hallucinogens, many hallucinogens elicit their actions through other mechanisms such as N-methyl-D-aspartate receptor antagonism, opioid receptor agonism, or inhibition of the reuptake of monoamines including serotonin, norepinephrine, and dopamine. The aim of this article is to compare the pharmacologic similarities and differences among substances within the hallucinogen class and their impact on physical and psychiatric effects. Potential toxicities, including life-threatening and long-term effects, will be reviewed.

Beyond ecstasy: Alternative entactogens to 3,4-methylenedioxymethamphetamine with potential applications in psychotherapy

The last two decades have seen a revival of interest in the entactogen 3,4-methylenedioxy-N-methylamphetamine (MDMA) as an adjunct to psychotherapy, particularly for the treatment of post-traumatic stress disorder. While clinical results are highly promising, and MDMA is expected to be approved as a treatment in the near future, it is currently the only compound in its class of action that is being actively investigated as a medicine. This lack of alternatives to MDMA may prove detrimental to patients who do not respond well to the particular mechanism of action of MDMA or whose treatment calls for a modification of MDMA's effects. For instance, patients with existing cardiovascular conditions or with a prolonged history of stimulant drug use may not fit into the current model of MDMA-assisted psychotherapy, and could benefit from alternative drugs. This review examines the existing literature on a host of entactogenic drugs, which may prove to be useful alternatives in the future, paying particularly close attention to any neurotoxic risks, neuropharmacological mechanism of action and entactogenic commonalities with MDMA. The substances examined derive from the 1,3-benzodioxole, cathinone, benzofuran, aminoindane, indole and amphetamine classes. Several compounds from these classes are identified as potential alternatives to MDMA.

Illicit Drug Use and Associated Problems in the Nightlife Scene: A Potential Setting for Prevention

Illicit drug use is prevalent in the nightlife scene, especially at electronic dance music (EDM) events. The aim of the present study was to investigate illicit drug use patterns and consequences of drug use among frequent visitors of EDM events. Young adults (18-34 years old) who had visited at least six EDM events in Sweden during the past year participated in a web-based survey on drug use patterns and its consequences. Fifty-nine percent of participants had used illicit drugs during the past year, most often cannabis followed by ecstasy, cocaine, and amphetamine. Nightlife venues were identified as the main setting for the use of central stimulants, while cannabis was mostly used at home. Frequent alcohol and tobacco use was associated with illicit drug use. The most prevalent negative consequences of drug use were related to mental health, such as impairments in mood, sleep, and memory problems, but physical manifestations were also reported, such as palpitations and collapsing. These findings confirm that drug use is prevalent and associated with negative health effects among EDM nightlife attendees. The nightlife scene is a setting with promising potential to reach a high-risk target group with illicit drug use prevention interventions.

Use and abuse of dissociative and psychedelic drugs in adolescence

Adolescence is a period of profound developmental changes, which run the gamut from behavioral and neural to physiological and hormonal. It is also a time at which there is an increased propensity to engage in risk-taking and impulsive behaviors like drug use. This review examines the human and preclinical literature on adolescent drug use and its consequences, with a focus on dissociatives (PCP, ketamine, DXM), classic psychedelics (LSD, psilocybin), and MDMA. It is the case for all the substances reviewed here that very little is known about their effects in adolescent populations. An emerging aspect of the literature is that dissociatives and MDMA produce mixed reinforcing and aversive effects and that the balance between reinforcement and aversion may differ between adolescents and adults, with consequences for drug use and addiction. However, many studies have failed to directly compare adults and adolescents, which precludes definitive conclusions about these consequences. Other important areas that are largely unexplored are sex differences during adolescence and the long-term consequences of adolescent use of these substances. We provide suggestions for future work to address the gaps we identified in the literature. Given the widespread use of these drugs among adolescent users, and the potential for therapeutic use, this work will be crucial to understanding abuse potential and consequences of use in this developmental stage.

Psychedelics in Psychiatry: Neuroplastic, Immunomodulatory, and Neurotransmitter Mechanisms

Mounting evidence suggests safety and efficacy of psychedelic compounds as potential novel therapeutics in psychiatry. Ketamine has been approved by the Food and Drug Administration in a new class of antidepressants, and 3,4-methylenedioxymethamphetamine (MDMA) is undergoing phase III clinical trials for post-traumatic stress disorder. Psilocybin and lysergic acid diethylamide (LSD) are being investigated in several phase II and phase I clinical trials. Hence, the concept of psychedelics as therapeutics may be incorporated into modern society. Here, we discuss the main known neurobiological therapeutic mechanisms of psychedelics, which are thought to be mediated by the effects of these compounds on the serotonergic (via 5-HT_2A and 5-HT_1A receptors) and glutamatergic [via N-methyl-d-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors] systems. We focus on 1) neuroplasticity mediated by the modulation of mammalian target of rapamycin-, brain-derived neurotrophic factor-, and early growth response-related pathways; 2) immunomodulation via effects on the hypothalamic-pituitary-adrenal axis, nuclear factor ĸB, and cytokines such as tumor necrosis factor-α and interleukin 1, 6, and 10 production and release; and 3) modulation of serotonergic, dopaminergic, glutamatergic, GABAergic, and norepinephrinergic receptors, transporters, and turnover systems. We discuss arising concerns and ways to assess potential neurobiological changes, dependence, and immunosuppression. Although larger cohorts are required to corroborate preliminary findings, the results obtained so far are promising and represent a critical opportunity for improvement of pharmacotherapies in psychiatry, an area that has seen limited therapeutic advancement in the last 20 years. Studies are underway that are trying to decouple the psychedelic effects from the therapeutic effects of these compounds. SIGNIFICANCE STATEMENT: Psychedelic compounds are emerging as potential novel therapeutics in psychiatry. However, understanding of molecular mechanisms mediating improvement remains limited. This paper reviews the available evidence concerning the effects of psychedelic compounds on pathways that modulate neuroplasticity, immunity, and neurotransmitter systems. This work aims to be a reference for psychiatrists who may soon be faced with the possibility of prescribing psychedelic compounds as medications, helping them assess which compound(s) and regimen could be most useful for decreasing specific psychiatric symptoms.

Breathing new life into neurotoxic-based monkey models of Parkinson's disease to study the complex biological interplay between serotonin and dopamine

Numerous clinical studies have shown that the serotonergic system also degenerates in patients with Parkinson's disease. The causal role of this impairment in Parkinson's symptomatology and the response to treatment remains to be refined, in particular thanks to approaches allowing the two components DA and 5-HT to be isolated if possible. We have developed a macaque monkey model of Parkinson's disease exhibiting a double lesion (dopaminergic and serotonergic) thanks to the sequential use of MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) and MDMA (3,4-methylenedioxy-N-methamphetamine) (or MDMA prior MPTP). We characterized this monkey model by multimodal imaging (PET, positron emission tomography with several radiotracers; DTI, diffusion tensor imaging), behavioral assessments (parkinsonism, dyskinesia, neuropsychiatric-like behavior) and post-mortem analysis (with DA and 5-HT markers). When administrated after MPTP, MDMA damaged the 5-HT presynaptic system without affecting the remaining DA neurons. The lesion of 5-HT fibers induced by MDMA altered rigidity and prevented dyskinesia and neuropsychiatric-like symptoms induced by levodopa therapy in MPTP-treated animals. Interestingly also, prior MDMA administration aggravates the parkinsonian deficits and associated DA injury. Dystonic postures, action tremor and global spontaneous activities were significantly affected. All together, these data clearly indicate that late or early lesions of the 5-HT system have a differential impact on parkinsonian symptoms in the macaque model of Parkinson's disease. Whether MDMA has an impact on neuropsychiatric-like symptoms such as apathy, anxiety, depression remains to be addressed. Despite its limitations, this toxin-based double-lesioned monkey model takes on its full meaning and provides material for the experimental study of the heterogeneity of patients.

Imaging of dopamine transporters in Parkinson disease: a meta-analysis of 18 F/123 I-FP-CIT studies

OBJECTIVE

¹⁸ F-FP-CIT and ¹²³ I-FP-CIT are widely used radiotracers in molecular imaging for Parkinson's disease (PD) diagnosis. Compared with ¹²³ I-FP-CIT, ¹⁸ F-FP-CIT has superior tracer kinetics. We aimed to conduct a meta-analysis to assess the efficacy of using ¹⁸ F-FP-CIT positron emission tomography (PET) and ¹²³ I-FP-CIT single-photon emission computed tomography (SPECT) of dopamine transporters in patients with PD in order to provide evidence for clinical decision-making.

METHODS

We searched the PubMed, Embase, Wanfang Data, and China National Knowledge Infrastructure databases to identify the relevant studies from the time of inception of the databases to 30 April 2020. We identified six PET studies, including 779 patients with PD and 124 healthy controls, which met the inclusion criteria. Twenty-seven SPECT studies with 1244 PD patients and 859 controls were also included in this meta-analysis.

RESULTS

Overall effect-size analysis indicated that patients with PD showed significantly reduced ¹⁸ F-FP-CIT uptake in three brain regions [caudate nucleus: standardized mean difference (SMD) = -1.71, Z = -3.31, P = 0.0009; anterior putamen: SMD = -3.71, Z = -6.26, P < 0.0001; and posterior putamen: SMD = -5.49, Z = -5.97, P < 0.0001]. Significant decreases of ¹²³ I-FP-CIT uptake were also observed in the caudate (SMD = -2.31, Z = -11.49, P < 0.0001) and putamen (SMD = -3.25, Z = -14.79, P < 0.0001).

INTERPRETATION

In conclusion, our findings indicate that both ¹⁸ F-FP-CIT PET and ¹²³ I-FP-CIT SPECT imaging of dopamine transporters can provide viable biomarkers for early PD diagnosis.

The Efficacy of Nerve Growth Factor Antibody for the Treatment of Osteoarthritis Pain and Chronic Low-Back Pain: A Meta-Analysis

BACKGROUND

Nerve growth factor (NGF) plays a crucial role in pain modulation and is being considered as a new therapeutic target for pain therapy. The purpose of this meta-analysis was to study the efficacy of anti-NGF antibodies for the treatment of osteoarthritis pain and chronic low-back pain, and to provide evidence and direction for further research and practice.

METHODS

PubMed, Embase, Wanfang Data, and China National Knowledge Infrastructure (CNKI) were searched from inception to November 30, 2019. Eligible studies should include randomized clinical trial-based investigations of anti-NGF antibody treatment for osteoarthritis pain and chronic low-back pain. Pooled overall mean changes from baseline to check point in the Western Ontario and McMaster Universities Arthritis Index (WOMAC) measures of pain, physical function, and Patient's Global Assessment (PGA) were calculated with either a fixed-effects model or a random-effects model, depending on the tests for heterogeneity. Sensitivity analysis and bias of publication were assessed.

RESULTS

A total of seven studies (3890 patients) were included in this meta-analysis. The pooled analysis showed a statistically significant reduction in the WOMAC pain (standardized mean difference (SMD) = -2.22, 95% confidence interval (CI) = -3.44 to -0.99, Z = -3.55, P = 0.0004; I2 = 99%), the WOMAC Physical Function (SMD = -2.76, 95% CI = -4.22 to -1.30, Z = -3.71, P = 0.0002; I2 = 99%), and the PGA Index (SMD = -2.76, 95% CI = -4.42 to -1.09, Z = -3.24, P = 0.0012; I2 = 99%). Pooled differences of adverse events rates in experimental and control groups was 0.11 (95% CI = 0.02 to 0.20, Z = 2.41, P = 0.016; I2 = 83%).

CONCLUSION

Our meta-analysis data indicate that anti-NGF antibodies can relieve pain and improve function in patients with osteoarthritis pain and chronic low-back pain.

γ-aminobutyric acid and glutamate/glutamine alterations of the left prefrontal cortex in individuals with methamphetamine use disorder: a combined transcranial magnetic stimulation-magnetic resonance spectroscopy study

Background

GABAergic and glutamatergic neurotransmitter systems are critical in the pathophysiology of addiction and represent potential targets for repetitive transcranial magnetic stimulation (rTMS). This study aims to investigate changes in γ-aminobutyric acid (GABA) levels, the combined resonance of glutamate and glutamine (Glx) in the left dorsolateral prefrontal cortex (DLPFC), and cognitive function of patients with methamphetamine dependence following rTMS intervention, using proton magnetic resonance spectroscopy (¹H MRS).

Methods

Fifty methamphetamine-dependent patients were randomized to a 4-week course of active or sham rTMS, with ¹H MRS measurement of DLPFC GABA and Glx levels relative to n-acetyl-aspartate (NAA) and craving and cognitive function measured at baseline and post-intervention.

Results

We observed significant reductions of GABA/NAA concentration in the active group and Glx/NAA concentration in the group receiving sham rTMS. There was a significant association between changes in GABA concentration and problem solving/error monitoring.

Conclusions

The effect of rTMS on cognitive function in individuals with methamphetamine dependence may be related to changes in GABA levels in the prefrontal cortex, and warrants further investigation.

Mephedrone and MDMA: A comparative review

Mephedrone and MDMA are both constituents of party drugs, with mephedrone being relatively new compared to MDMA. This review compares current knowledge regarding the patterns of usage and neuropsychobiological effects of both mephedrone and MDMA. Both drugs share common psychoactive effects, the duration of which is significantly shorter with mephedrone use, attributing towards a pattern of binge use among users. Both drugs have also been associated with adverse health, psychiatric, and neurocognitive problems. Whilst there is extensive research into the psychobiological problems induced by MDMA, the evidence for mephedrone is comparatively limited. The adverse effect profile of mephedrone appears to be less severe than that of MDMA. Users often believe it to be safer, although both drugs have been associated with overdoses. The neurotoxic potential of mephedrone appears to be low, whereas MDMA can cause long-term damage to the serotonergic system, although this needs further investigation. The abuse liability of mephedrone is significantly greater than that of MDMA, raising concerns regarding the impact of lifetime usage on users. Given that mephedrone is relatively new, the effects of long-term exposure are yet to be documented. Future research focused on lifetime users may highlight more severe neuropsychobiological effects from the drug.

Of mice and men on MDMA: A translational comparison of the neuropsychobiological effects of 3,4-methylenedioxymethamphetamine ('Ecstasy')

MDMA (3,4-methylendioxymethamphetamine), also known as Ecstasy, is a stimulant drug recreationally used by young adults usually in dance clubs and raves. Acute MDMA administration increases serotonin, dopamine and noradrenaline by reversing the action of the monoamine transporters. In this work, we review the studies carried out over the last 30 years on the neuropsychobiological effects of MDMA in humans and mice and summarise the current knowledge. The two species differ with respect to the neurochemical consequences of chronic MDMA, since it preferentially induces serotonergic dysfunction in humans and dopaminergic neurotoxicity in mice. However, MDMA alters brain structure and function and induces hormonal, psychomotor, neurocognitive, psychosocial and psychiatric outcomes in both species, as well as physically damaging and teratogen effects. Pharmacological and genetic studies in mice have increased our knowledge of the neurochemical substrate of the multiple effects of MDMA. Future work in this area may contribute to developing pharmacological treatments for MDMA-related disorders.

Neuronal and peripheral damages induced by synthetic psychoactive substances: an update of recent findings from human and animal studies

Preclinical and clinical studies indicate that synthetic psychoactive substances, in addition to having abuse potential, may elicit toxic effects of varying severity at the peripheral and central levels. Nowadays, toxicity induced by synthetic psychoactive substances poses a serious harm for health, since recreational use of these substances is on the rise among young and adult people. The present review summarizes recent findings on the peripheral and central toxicity elicited by “old” and “new” synthetic psychoactive substances in humans and experimental animals, focusing on amphetamine derivatives, hallucinogen and dissociative drugs and synthetic cannabinoids.

Minocycline attenuates 3,4-methylenedioxymethamphetamine-induced hyperthermia in the rat brain

Hyperthermia is most dangerous clinical symptom of acute MDMA administration, and a key factor related to potentially life-threatening MDMA-induced complications. MDMA induces a consistently faster onset of brain hyperthermia when compared to a delayed and moderate hyperthermia in the body, and the most harmful effects of MDMA are related to its modulation of neural functions. The primary focus of this study was to investigate the effects of minocycline, a centrally acting tetracycline derivative on MDMA-induced brain hyperthermia at high ambient temperature. However, we also simultaneously recorded body temperature, heart rate, and locomotor activity changes, allowing us to gain a better understanding of the mechanisms underlying the MDMA-induced hyperthermic response. We also investigated the effects of MDMA at normal ambient temperature to provide further evidence as to the importance of environmental factors on the intensity of MDMA's temperature effects. At normal ambient temperature, MDMA (10 mg/kg, i.p.) induced a significant brain and body hypothermia for the first 90 min following drug administration, and significantly increased heart rate and locomotor activity compared to saline controls. At high ambient temperature however, MDMA (10 mg/kg, i.p.) induced a robust and extended brain and body hyperthermia, as well as significantly increased heart rate and locomotor activity. A 3-day minocycline (50 mg/kg, i.p.) pre-treatment significantly attenuated MDMA-induced increases in brain temperature, body temperature, heart rate, and locomotor activity. Our findings indicate that minocycline is more effective in attenuating the exacerbated MDMA-induced hyperthermic response in the brain compared to the body at high ambient temperature.

Receptor-Enriched Analysis of functional connectivity by targets (REACT): A novel, multimodal analytical approach informed by PET to study the pharmacodynamic response of the brain under MDMA

One of the main limitations of pharmacological fMRI is its inability to provide a molecular insight into the main effect of compounds, leaving an open question about the relationship between drug effects and haemodynamic response. The aim of this study is to investigate the acute effects of 3,4-methylenedioxymethamphetamine (MDMA) on functional connectivity (FC) using a novel multimodal method (Receptor-Enriched Analysis of functional Connectivity by Targets - REACT). This approach enriches the resting state (rs-)fMRI analysis with the molecular information about the distribution density of serotonin receptors in the brain, given the serotonergic action of MDMA.

Twenty healthy subjects participated in this double-blind, placebo-controlled, crossover study. A high-resolution in vivo atlas of four serotonin receptors (5-HT_1A, 5-HT_1B, 5-HT_2A, and 5-HT₄) and its transporter (5-HTT) was used as a template in a two-step multivariate regression analysis to estimate the spatial maps reflecting the whole-brain connectivity behaviour related to each target under placebo and MDMA.

Results showed that the networks exhibiting significant changes after MDMA administration are the ones informed by the 5-HTT and 5-HT_1A distribution density maps, which are the main targets of this compound. Changes in the 5-HT_1A-enriched functional maps were also associated with the pharmacokinetic levels of MDMA and MDMA-induced FC changes in the 5-HT_2A-enriched maps correlated with the spiritual experience subscale of the Altered States of Consciousness Questionnaire.

By enriching the rs-fMRI analysis with molecular data of voxel-wise distribution of the serotonin receptors across the brain, we showed that MDMA effects on FC can be understood through the distribution of its main targets. This result supports the ability of this method to characterise the specificity of the functional response of the brain to MDMA binding to serotonergic receptors, paving the way to the definition of a new fingerprint in the characterization of new compounds and potentially to a further understanding to the response to treatment.

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MDMA connectivity effects understood through the distribution of 5-HT_1A and 5-HTT.

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Direct link between PK levels of MDMA and 5-HT_1A-enriched functional connectivity maps.

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Ability to link receptor targets to functional mechanisms underlying behaviour.

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Mapping pharmacodynamic effects onto the drug's molecular targets.