Decreased cerebral cortical serotonin transporter binding in ecstasy users: a positron emission tomography/[(11)C]DASB and structural brain imaging study

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.

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.

Serotonin Degeneration and Amyloid-β Deposition in Mild Cognitive Impairment: Relationship to Cognitive Deficits

BACKGROUND

Neuropathological and neuroimaging studies have demonstrated degeneration of the serotonin system in Alzheimer's disease (AD). Neuroimaging studies have extended these observations to the preclinical stages of AD, mild cognitive impairment (MCI). Serotonin degeneration has been observed also in transgenic amyloid mouse models, prior to widespread cortical distribution of amyloid-β (Aβ).

OBJECTIVE

The present study evaluated the regional distribution of the serotonin transporter (5-HTT) and of Aβ in individuals with MCI and healthy older controls, as well as the contribution of 5-HTT and Aβ to cognitive deficits.

METHODS

Forty-nine MCI participants and 45 healthy older controls underwent positron emission tomography (PET) imaging of 5-HTT and Aβ, structural magnetic resonance imaging and neuropsychological assessments.

RESULTS

Lower cortical, striatal, and limbic 5-HTT and higher cortical Aβ was observed in MCIs relative to healthy controls. Lower 5-HTT, mainly in limbic regions, was correlated with greater deficits in auditory-verbal and visual-spatial memory and semantic, not phonemic fluency. Higher cortical A β was associated with greater deficits in auditory-verbal and visual-spatial memory and in semantic, not phonemic fluency. When modeling the association between cognition, gray matter volumes and Aβ, inclusion of 5-HTT in limbic and in select cortical regions significantly improved model fit for auditory-verbal and visual-spatial memory and semantic, but not phonemic fluency.

CONCLUSIONS

These results support the role of serotonin degeneration in the memory and semantic fluency deficits observed in MCI.

Differential vulnerability of locus coeruleus and dorsal raphe neurons to chronic methamphetamine-induced degeneration

Methamphetamine (meth) increases monoamine oxidase (MAO)-dependent mitochondrial stress in axons of substantia nigra pars compacta (SNc), and ventral tegmental area (VTA) dopamine neurons. Chronic administration of meth results in SNc degeneration and MAO inhibition is neuroprotective, whereas, the VTA is resistant to degeneration. This differential vulnerability is attributed, at least in part, to the presence of L-type Ca²⁺ channel-dependent mitochondrial stress in SNc but not VTA dopamine neurons. MAO is also expressed in other monoaminergic neurons such as noradrenergic locus coeruleus (LC) and serotonergic dorsal raphe (DR) neurons. The impact of meth on mitochondrial stress in LC and DR neurons is unknown. In the current study we used a genetically encoded redox biosensor to investigate meth-induced MAO-dependent mitochondrial stress in LC and DR neurons. Similar to SNc and VTA neurons, meth increased MAO-dependent mitochondrial stress in axonal but not somatic compartments of LC norepinephrine and DR serotonin neurons. Chronic meth administration (5 mg/kg; 28-day) resulted in degeneration of LC neurons and MAO inhibition was neuroprotective whereas DR neurons were resistant to degeneration. Activating L-type Ca²⁺ channels increased mitochondrial stress in LC but not DR axons and inhibiting L-type Ca²⁺ channels in vivo with isradipine prevented meth-induced LC degeneration. These data suggest that similar to recent findings in SNc and VTA dopamine neurons, the differential vulnerability between LC and DR neurons can be attributed to the presence of L-type Ca²⁺ channel-dependent mitochondrial stress. Taken together, the present study demonstrates that both meth-induced MAO- and L-type Ca²⁺ channel-dependent mitochondrial stress are necessary for chronic meth-induced neurodegeneration.

Preliminary Results on the Long-Term Effects of Dextromethorphan on MDMA-Mediated Serotonergic Deficiency and Volumetric Changes in Primates Based on 4-[18F]-ADAM PET/MRI

Alterations to the serotonergic system due to 3,4-methylenedioxymethamphetamine (MDMA) (ecstasy) consumption have been extensively documented. However, knowledge of the reversibility of these neurotoxic effects based on in vivo evaluations of serotonin transport (SERT) availability remains limited. This study aimed to evaluate the long-term neurotoxicity of MDMA after 66 months abstinence and explored whether Dextromethorphan, a non-competitive N-methyl-D-aspartate (NMDA) receptor, could attenuate MDMA-induced neurotoxicity using 4-[18F]-ADAM, an imaging ligand that selectively targets SERT, with positron emission tomography technology (PET). Nine monkeys (Macaca cyclopis) were used in this study: control, MDMA, and DM + MDMA. Static 4-[18F]-ADAM PET was performed at 60 and 66 months after drug treatment. Serotonin transport (SERT) availability was presented as the specific uptake ratios (SURs) of 4-[18F]-ADAM in brain regions. Voxel-based region-specific SERT availability was calculated to generate 3D PET/MR images. Structural Magnetic Resonance Imaging (MRI) volumetric analysis was also conducted at 60 months. Significantly decreased 4-[18F]-ADAM SURs were observed in the striatum and thalamus of the MDMA group at 60 and 66 months compared to controls; the midbrain and frontal cortex SURs were similar at 60 and 66 months in the MDMA and control groups. All eleven brain regions showed significantly lower (∼13%) self-recovery rates over time; the occipital cortex and cingulate recovered to baseline by 66 months. DM attenuated MDMA-induced SERT deficiency on average, by ∼8 and ∼1% at 60 and 66 months, respectively; whereas significant differences were observed between the thalamus and amygdala of the MDMA and DM + MDMA groups at 66 months. Compared to controls, the MDMA group exhibited significantly increased (∼6.6%) gray matter volumes in the frontal cortex, occipital cortex, caudate nucleus, hippocampus, midbrain, and amygdala. Moreover, the gray matter volumes of the occipital cortex, hippocampus and amygdala correlated negatively with the 4-[18F]-ADAM SURs of the same regions. DM (n = 2) did not appear to affect MDMA-induced volumetric changes. The 4-[18F]-ADAM SURs, lower self-recovery rate and increased volumetric values indicate the occipital cortex, hippocampus and amygdala still exhibit MDMA-induced neurotoxicity after 66 months’ abstinence. Moreover, DM may prevent MDMA-induced serotonergic deficiency, as indicated by increased 4-[18F]-ADAM SURs and SERT availability, but not volumetric changes.

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.

Hard Boiled: Alcohol Use as a Risk Factor for MDMA-Induced Hyperthermia: a Systematic Review

Although MDMA (ecstasy) is a relatively safe recreational drug and is currently considered for therapeutic use for the treatment of posttraumatic stress disorder (PTSD) and alcohol use disorder (AUD), recreational MDMA use occasionally elicits hyperthermia and hyponatremia, sometimes with a fatal outcome. Specific risk factors for both adverse effects are profuse sweating while vigorously dancing under unfavorable conditions such as high ambient temperatures and insufficient fluid suppletion which result in dehydration. Concomitant use of MDMA and alcohol is highly prevalent, but adds to the existing risk, because alcohol facilitates the emergence of MDMA-induced adverse events, like hyperthermia, dehydration, and hyponatremia. Because of potential health-related consequences of concomitant use of MDMA and alcohol, it is important to identify the mechanisms of the interactions between alcohol and MDMA. This review summarizes the main drivers of MDMA-induced hyperthermia, dehydration, and hyponatremia and the role of concomitant alcohol use. It is shown that alcohol use has a profound negative impact by its interaction with most of these drivers, including poikilothermia, exposure to high ambient temperatures, heavy exercise (vigorous dancing), vasoconstriction, dehydration, and delayed initiation of sweating and diuresis. It is concluded that recreational and clinical MDMA-users should refrain from concomitant drinking of alcoholic beverages to reduce the risk for adverse health incidents when using MDMA.

Migraine prevalence in visual snow with prior illicit drug use (hallucinogen persisting perception disorder) versus without

BACKGROUND AND PURPOSE

This study was undertaken to investigate migraine prevalence in persons with hallucinogen persisting perception disorder (HPPD) presenting as visual snow syndrome (VSS).

METHODS

Persons with visual snow as a persisting symptom after illicit drug use (HPPD) were recruited via a Dutch consulting clinic for recreational drug use. A structured interview on (visual) perceptual symptomatology, details of drugs use, and medical and headache history was taken. As a control group, persons with visual snow who had never used illicit drugs prior to onset were included. The primary outcome was lifetime prevalence of migraine. Symptom severity was evaluated by the Visual Snow Handicap Inventory (VHI), a 25-item questionnaire.

RESULTS

None of the 24 HPPD participants had migraine, whereas 20 of 37 (54.1%) controls had migraine (p < 0.001). VHI scores did not differ significantly between the two groups; in both groups, the median score was 38 of 100. In most HPPD cases (17/24, 70.9%), visual snow had started after intake of ecstasy; other psychedelic drugs reported included cannabis, psilocybin mushrooms, amphetamine, 4-fluoroamphetamine, 3-methylmethcathinone, 4-Bromo-2,5-dimethoxypenethylamine, and nitrous oxide.

CONCLUSIONS

Whereas none of the HPPD participants had migraine, more than half of the visual snow controls without prior use of illicit drugs had migraine. This suggests that at least partly different pathophysiological factors play a role in these disorders. Users of ecstasy and other hallucinogens should be warned of the risk of visual snow. Further studies are needed to enhance understanding of the underlying neurobiology of HPPD and VSS to enable better management of these conditions.

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.

Targeting the 5-HT system: Potential side effects

Targeting the serotonin (5-HT) system is no simple task: there are at least 15 5-HT receptors, in addition to a number of transporters and metabolizing enzymes. Multiple 5-HT receptor variants exist due to genetic variations and/or post translational modifications, splice variants or editing variants. Some receptors may form homo and heteromers. The 5-HT system is targeted by multiple drugs to treat a variety of diseases. Given the homology amongst the 5-HT and neighbouring receptor classes, only few drugs are actually selective for a single target. In fact, many 5-HT drugs act on a combination of targets, i.e. several receptors and/or transporters or enzymes. For instance, a number of antidepressants or antipsychotics act on 5-HT and other transmitter systems. Recently developed drugs may show target selectivity by design, based on the current state of knowledge, whereas many older compounds hit multiple targets since they were developed using phenotypic screens, as was done well into the 1980's. Ergot analogues, antipsychotics or antidepressants, fall into this category. As our knowledge developed over the last 25-30 years, some targets have very well-defined liabilities: for instance, 5HT_2B or 5-HT_2A receptor agonists, will produce valvulopathies or hallucinations, respectively, whereas 5-HT₃ receptor antagonists, may lead to constipation. This short review will be limited in scope as there are multiple targets and even more compounds to discuss. This article is part of the special issue entitled 'Serotonin Research: Crossing Scales and Boundaries'.

Sex and the serotonergic underpinnings of depression and migraine

Most psychiatric disorders demonstrate sex differences in their prevalence and symptomatology, and in their response to treatment. These differences are particularly pronounced in mood disorders. Differences in sex hormone levels are among the most overt distinctions between males and females and are thus an intuitive underpinning for these clinical observations. In fact, treatment with estrogen and testosterone was shown to exert antidepressant effects, which underscores this link. Changes to monoaminergic signaling in general, and serotonergic transmission in particular, are understood as central components of depressive pathophysiology. Thus, modulation of the serotonin system may serve as a mechanism via which sex hormones exert their clinical effects in mental health disorders. Over the past 20 years, various experimental approaches have been applied to identify modes of influence of sex and sex hormones on the serotonin system. This chapter provides an overview of different molecular components of the serotonin system, followed by a review of studies performed in animals and in humans with the purpose of elucidating sex hormone effects. Particular emphasis will be placed on studies performed with positron emission tomography, a method that allows for human in vivo molecular imaging and, therefore, assessment of effects in a clinically representative context. The studies addressed in this chapter provide a wealth of information on the interaction between sex, sex hormones, and serotonin in the brain. In general, they offer evidence for the concept that the influence of sex hormones on various components of the serotonin system may serve as an underpinning for the clinical effects these hormones demonstrate.

Serotonin transporter protein in autopsied brain of chronic users of cocaine

RATIONALE

The long-held speculation that the brain serotonin system mediates some behavioral effects of the psychostimulant cocaine is supported in part by the high affinity of cocaine for the serotonin transporter (SERT) and by reports that the serotonin transporter (SERT), estimated by SERT binding, is increased in brain of human chronic cocaine users. Excessive SERT activity and consequent synaptic serotonin deficiency might cause a behavioral (e.g., mood) abnormality in chronic users of the drug.

OBJECTIVE AND METHODS

Previous studies focused on changes in SERT binding, which might not necessarily reflect changes in SERT protein. Therefore, we compared levels of SERT protein, using a quantitative Western blot procedure, in autopsied brain (striatum, cerebral cortices) of chronic human cocaine users (n = 9), who all tested positive for the drug/metabolite in brain, to those in control subjects (n = 15) and, as a separate drug of abuse group, in chronic heroin users (n = 11).

RESULTS

We found no significant difference in protein levels of SERT or the serotonin synthesizing enzyme tryptophan hydroxylase-2 among the control and drug abuse groups. In the cocaine users, no significant correlations were observed between SERT and brain levels of cocaine plus metabolites, or with levels of serotonin or its metabolite 5-hydroxyindoleacetic acid.

CONCLUSION

Our postmortem data suggest that a robust increase in striatal/cerebral cortical SERT protein is not a common characteristic of chronic, human cocaine users.

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.

The Correlation Between Mid-Brain Serotonin Transporter Availability and Intelligence Quotient in Healthy Volunteers

Purpose:

This study was performed to investigate the association between the mid-brain serotonin transporter (SERT) availability and intelligence quotient (IQ).

Methods:

One hundred and thirteen healthy participants, including 52 male and 61 female subjects, were recruited. We used SPECT with [123I]ADAM images to determine the SERT availability in the mid-brain, and measured the subjects’ IQ using the WAIS-R.

Results:

We found a significant positive correlation between the mid-brain SERT availability and the IQ of the participants. Even when controlling for age and sex, the significant association still existed.

Conclusion:

This result implied that the higher the SERT binding in the mid-brain, the better the IQ in healthy participants.

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.

Psychostimulant use and the brain

Psychostimulant users are typically young adults. We have conducted a narrative review of neuropsychiatric harms associated with the psychostimulants methamphetamine/amphetamine, cocaine and 3,4-methylenedioxymethamphetamine (MDMA), focusing on epidemiological factors, common clinical presentations, underlying causal mechanisms and treatment options. The major neuropsychiatric harms of psychostimulant use are stroke, neurocognitive impairment, Parkinson's disease, seizures and psychotic illness. These arise through a combination of acute monoamine release, longer-term neurotransmitter effects and indirect effects. These effects are moderated by factors in the individual and in the pattern of substance use. Neuropsychiatric harms associated with psychostimulant use can thus lead to severe long-term impairment.

Illegal drug use and prospective memory: A systematic review

Illegal drug use is proposed to interfere with neurobiological functioning by damaging the neurotransmitter communication systems that are believed to be responsible for cognitive abilities, including perception, attention, and memory. This review specifically examined effects of illegal drug use on prospective memory (PM) - memory for future actions. Twenty- seven studies spanning 14 years were included in this review which were divided into two broad categories based on testing methods used: self-report and lab-based testing methods. The quality of the included studies was assessed across five categories: sample type, sample size, abstinence period, testing methods and control for confounding factors. The overall quality of evidence was good for six studies and moderate for sixteen studies and low for five studies. The results from the studies employing self-report were inconsistent as illegal drug users exhibited PM deficits in some studies, but not in others. However, the studies with lab-based testing methods demonstrated more consistent findings with illegal drug users scoring worse than non-users on various PM tests. There were also consistent findings on the link between the dosage of drug taken and level of PM deficit. Based on the literature, there is moderate evidence that illegal drug use impairs PM ability. We recommend that further lab-based studies be conducted to assess dose-response effects on drug-specificity.

In vivo long-lasting alterations of central serotonin transporter activity and associated dopamine synthesis after acute repeated administration of methamphetamine

Background

Methamphetamine (METH)-associated alterations in the striatal dopamine (DA) system or dopamine transport (DAT) have been identified in clinical and preclinical studies with positron emission tomography (PET) imaging but have not been well correlated with in vivo serotonin transporter (SERT) availability due to the lack of appropriate imaging agents to assess SERTs. N,N-dimethyl-2-(2-amino-4-[¹⁸F]-fluorophenylthio) benzylamine (4-[¹⁸F]-ADAM) has been developed by our group and validated for its high affinity and selectivity for SERTs, allowing the in vivo examination of SERT density, location, and binding function. The aims of this study were to investigate the potential of SERT imaging using 4-[¹⁸F]-ADAM PET to estimate the long-lasting effects of METH-induced serotonergic neurotoxicity, and further determine whether a correlative relationship exists between SERT availability/activity and tyrosine hydroxylase (TH) activity in various brain regions due to the long-lasting consequences of METH treatment.

Results

Male rats received four administrations of METH (5 or 10 mg/kg, s.c.) or saline (1 ml/kg, s.c.) at 1-h intervals. At 30 days post-administration, in vivo SERT availability and activity were measured by 4-[¹⁸F]ADAM PET imaging. In contrast to the controls, the uptake of 4-[¹⁸F]ADAM in METH-treated mice was significantly reduced in a dose-dependent manner in the midbrain, followed by the hypothalamus, thalamus, striatum, hippocampus, and frontal cortex. The regional effects of METH on TH activity were assessed by quantitative immunohistochemistry and presented as integrated optical density (IOD). A significant decrease in TH immunostaining and IOD ratios was seen in the caudate, putamen, nucleus accumbens, substantia nigra pars compacta, and substantia nigra pars reticulata in the METH-treated rats compared to controls.

Conclusion

The present results suggested that the long-lasting response to METH decreased the uptake of 4-[¹⁸F]-ADAM and varied regionally along with TH immunoreactivity. In addition, 4-[¹⁸F]ADAM PET could be used to detect serotonergic neuron loss and to evaluate the severity of serotonergic neurotoxicity of METH.

Neuroimaging of reward mechanisms in Gambling disorder: an integrative review

Gambling disorder (GD) was reclassified as a behavioral addiction in the DSM-5 and shares clinical and behavioral features with substance use disorders (SUDs). Neuroimaging studies of GD hold promise in isolating core features of the addiction syndrome, avoiding confounding effects of drug neurotoxicity. At the same time, a neurobiologically-grounded theory of how behaviors like gambling can become addictive remains lacking, posing a significant hurdle for ongoing decisions in addiction nosology. This article integrates research on reward-related brain activity (functional MRI) and neurotransmitter function (PET) in GD, alongside the consideration of structural MRI data as to whether these signals more likely reflect pre-existing vulnerability or neuroadaptive change. Where possible, we point to qualitative similarities and differences with established markers for SUDs. Structural MRI studies indicate modest changes in regional gray matter volume and diffuse reductions in white matter integrity in GD, contrasting with clear structural deterioration in SUDs. Functional MRI studies consistently identify dysregulation in reward-related circuitry (primarily ventral striatum and medial prefrontal cortex), but evidence is mixed as to the direction of these effects. The need for further parsing of reward sub-processes is emphasized, including anticipation vs outcome, gains vs. losses, and disorder-relevant cues vs natural rewards. Neurotransmitter PET studies indicate amplified dopamine (DA) release in GD, in the context of minimal differences in baseline DA D2 receptor binding, highlighting a distinct profile from SUDs. Preliminary work has investigated further contributions of opioids, GABA and serotonin. Neuroimaging data increasingly highlight divergent profiles in GD vs. SUDs. The ability of gambling to perpetually activate DA (via maximal uncertainty) may contribute to neuroimaging similarities between GD and SUDs, whereas the supra-physiological DA effects of drugs may partly explain differences in the neuroimaging profile of the two syndromes. Coupled with consistent observations of correlations with gambling severity and related clinical variables within GD samples, the overall pattern of effects is interpreted as a likely combination of shared vulnerability markers across GD and SUDs, but with further experience-dependent neuroadaptive processes in GD.

Autophagy inhibition plays a protective role against 3, 4-methylenedioxymethamphetamine (MDMA)-induced loss of serotonin transporters and depressive-like behaviors in rats

The 3,4-methylenedioxymethamphetamine (MDMA) is a popular recreational drug, which ultimately leads to serotonergic (5-HT) neurotoxicity and psychiatric disorders. Previous in vitro studies have consistently demonstrated that MDMA provokes autophagic activation, as well as damage of 5-HT axons and nerve fibers. So far, whether autophagy, a well-conserved cellular process that is critical for cell fate, also participates in MDMA-induced neurotoxicity in vivo remains elusive. Here, we first examined time-course of autophagy-related changes during repeated administration of MDMA (10 mg/kg s.c. twice daily for 4 consecutive days) using immunofluorescent staining for tryptophan hydroxylase and microtubule-associated protein 1 light chain 3 beta in rats. We also evaluated the protective effects of 3-methyadanine (3-MA, an autophagy inhibitor, 15 mg/kg i.p.) against MDMA-induced acute and long-term reductions in serotonin transporters (SERT) density in various brain regions using immunohistochemical staining and positron emission tomography (PET) imaging respectively. Plasma corticosterone measurements and forced swim tests were performed to evaluate the depressive performance. The staining results showed that repeated administration of MDMA increased expression of autophagosome and caused reduction in SERT densities of striatum and frontal cortex, which was ameliorated in the presence of 3-MA. PET imaging data also revealed that 3-MA could ameliorate MDMA-induced long-term decreased SERT availability in various brain regions of rats. Furthermore, immobility time of forced swim tests and plasma corticosterone levels were less in the group of MDMA co-injected with 3-MA compared with that of MDMA group. Together, these findings suggest that autophagy inhibition may confer protection against neurobiological and behavioral changes induced by MDMA.

Are ecstasy induced serotonergic alterations overestimated for the majority of users?

BACKGROUND

Neuroimaging studies imply that the regular use of ±3,4-methylenedioxymethamphetamine (MDMA), the major constituent of ecstasy pills, alters the brain's serotonergic system in a dose-dependent manner. However, the relevance of these findings remains unclear due to limited knowledge about the ecstasy/MDMA use pattern of real-life users.

AIMS

We examined the representativeness of ecstasy users enrolled in neuroimaging studies by comparing their ecstasy use habits with the use patterns of a large, international sample.

METHODS

A systematic literature search revealed 10 imaging studies that compare serotonin transporter levels in recreational ecstasy users to matched controls. To characterize the ecstasy use patterns we relied on the Global Drug Survey, the world's largest self-report database on drug use. The basis of the dose comparison were the Usual Amount (pills/session), Use Frequency (sessions/month) and Dose Intensity (pills/year) variables.

RESULTS

Both the average Usual Amount (pills/session) and Use Frequency (sessions/month) of neuroimaging study participants corresponded to the top 5-10% of the Global Drug Survey sample and imaging participants, on average, consumed 720% more pills over a year than the Global Drug Survey participants.

CONCLUSIONS

Our findings suggest that the serotonin brain imaging literature has focused on unusually heavy ecstasy use and therefore the conclusions from these studies are likely to overestimate the extent of serotonergic alterations experienced by the majority of people who use ecstays.

Social Cognition and Interaction in Chronic Users of 3,4-Methylenedioxymethamphetamine (MDMA, "Ecstasy")

BACKGROUND

The empathogen 3,4-methylenedioxymethamphetamine (MDMA) is the prototypical prosocial club drug inducing emotional openness to others. It has recently been shown that acutely applied 3,4-MDMA in fact enhances emotional empathy and prosocial behavior, while it simultaneously decreases cognitive empathy. However, the long-term effects of 3,4-MDMA use on socio-cognitive functions and social interactions have not been investigated yet. Therefore, we examined emotional and cognitive empathy, social decision-making, and oxytocin plasma levels in chronic 3,4-MDMA users.

METHODS

We tested 38 regular but recently abstinent 3,4-MDMA users and 56 3,4-MDMA-naïve controls with the Movie for the Assessment of Social Cognition, the Multifaceted Empathy Test, and the Distribution Game and the Dictator Game. Drug use was objectively quantified by 6-month hair analyses. Furthermore, oxytocin plasma levels were determined in smaller subgroups (24 3,4-MDMA users, 9 controls).

RESULTS

3,4-MDMA users showed superior cognitive empathy compared with controls in the Multifaceted Empathy Test (Cohen's d=.39) and in the Movie for the Assessment of Social Cognition (d=.50), but they did not differ from controls in emotional empathy. Moreover, 3,4-MDMA users acted less self-serving in the Distribution Game. However, within 3,4-MDMA users, multiple regression analyses showed that higher 3,4-MDMA concentrations in hair were associated with lower cognitive empathy (βMDMA=-.34, t=-2.12, P<.05). Oxytocin plasma concentrations did not significantly differ between both groups.

CONCLUSIONS

We conclude that people with high cognitive empathy abilities and pronounced social motivations might be more prone to 3,4-MDMA consumption. In contrast, long-term 3,4-MDMA use might nevertheless have a detrimental effect on cognitive empathy capacity.

Differential effects of MDMA and cocaine on inhibitory avoidance and object recognition tests in rodents

INTRODUCTION

Drug addiction continues being a major public problem faced by modern societies with different social, health and legal consequences for the consumers. Consumption of psychostimulants, like cocaine or MDMA (known as ecstasy) are highly prevalent and cognitive and memory impairments have been related with the abuse of these drugs.

AIM

The aim of this work was to review the most important data of the literature in the last 10 years about the effects of cocaine and MDMA on inhibitory avoidance and object recognition tests in rodents.

DEVELOPMENT

The object recognition and the inhibitory avoidance tests are popular procedures used to assess different types of memory. We compare the effects of cocaine and MDMA administration in these tests, taking in consideration different factors such as the period of life development of the animals (prenatal, adolescence and adult age), the presence of polydrug consumption or the role of environmental variables. Brain structures involved in the effects of cocaine and MDMA on memory are also described.

CONCLUSIONS

Cocaine and MDMA induced similar impairing effects on the object recognition test during critical periods of lifetime or after abstinence of prolonged consumption in adulthood. Deficits of inhibitory avoidance memory are observed only in adult rodents exposed to MDMA. Psychostimulant abuse is a potential factor to induce memory impairments and could facilitate the development of future neurodegenerative disorders.

Recreational 3,4-methylenedioxymethamphetamine or 'ecstasy': Current perspective and future research prospects

AIMS

The purpose of this article is to debate current understandings about the psychobiological effects of recreational 3,4-methylenedioxymethamphetamine (MDMA or 'ecstasy'), and recommend theoretically-driven topics for future research.

METHODS

Recent empirical findings, especially those from novel topic areas were reviewed. Potential causes for the high variance often found in group findings were also examined.

RESULTS AND CONCLUSIONS

The first empirical reports into psychobiological and psychiatric aspects from the early 1990s concluded that regular users demonstrated some selective psychobiological deficits, for instance worse declarative memory, or heightened depression. More recent research has covered a far wider range of psychobiological functions, and deficits have emerged in aspects of vision, higher cognitive skill, neurohormonal functioning, and foetal developmental outcomes. However, variance levels are often high, indicating that while some recreational users develop problems, others are less affected. Potential reasons for this high variance are debated. An explanatory model based on multi-factorial causation is then proposed.

FUTURE DIRECTIONS

A number of theoretically driven research topics are suggested, in order to empirically investigate the potential causes for these diverse psychobiological deficits. Future neuroimaging studies should study the practical implications of any serotonergic and/or neurohormonal changes, using a wide range of functional measures.

Serotonergic Approaches in Parkinson's Disease: Translational Perspectives, an Update

Parkinson's disease (PD) has long been seen as a disorder caused by degeneration of the dopaminergic system, leading to the classic motor manifestations of the disease. However, there is now overwhelming evidence that PD is more than a disease merely caused by dopamine depletion. It is well-known that a myriad of other neurotransmitters are affected by the disease process. One such neurotransmitter is serotonin (5-HT). 5-HT has been shown to play a role in several motor and nonmotor manifestations of PD, including tremor, cognition, depression and psychosis. 5-HT also seems to play a critical role in L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia. A breadth of preclinical studies and clinical trials have been conducted that aimed at modulating the 5-HT system in order to alleviate depression, cognitive deficits, psychosis, and dyskinesia. In this Review, we summarize recent advances in the 5-HT field in PD, but with a translational emphasis. We start by presenting a novel nonhuman primate model of PD that presents with dual dopamine and 5-HT lesions. We then present preclinical and clinical data that introduce new concepts, such as the use of biased and partial agonists, as well as molecules recently introduced to the field of PD, such as eltoprazine, pimavanserin, nelotanserin, and SYN-120, to enhance therapeutic benefit while minimizing adverse events, notably on parkinsonian disability.

Recreational stimulants, herbal, and spice cannabis: The core psychobiological processes that underlie their damaging effects

AIMS

Recreational drugs are taken for their positive mood effects, yet their regular usage damages well-being. The psychobiological mechanisms underlying these damaging effects will be debated.

METHODS

The empirical literature on recreational cannabinoids and stimulant drugs is reviewed. A theoretical explanation for how they cause similar types of damage is outlined.

RESULTS

All psychoactive drugs cause moods and psychological states to fluctuate. The acute mood gains underlie their recreational usage, while the mood deficits on withdrawal explain their addictiveness. Cyclical mood changes are found with every central nervous system stimulant and also occur with cannabis. These mood state changes provide a surface index for more profound psychobiological fluctuations. Homeostatic balance is altered, with repetitive disturbances of the hypothalamic-pituitary-adrenal axis, and disrupted cortisol-neurohormonal secretions. Hence, these drugs cause increased stress, disturbed sleep, neurocognitive impairments, altered brain activity, and psychiatric vulnerability. Equivalent deficits occur with novel psychoactive stimulants such as mephedrone and artificial "spice" cannabinoids. These psychobiological fluctuations underlie drug dependency and make cessation difficult. Psychobiological stability and homeostatic balance are optimally restored by quitting psychoactive drugs.

CONCLUSIONS

Recreational stimulants such as cocaine or MDMA (3.4-methylenedioxymethamphetamine) and sedative drugs such as cannabis damage human homeostasis and well-being through similar core psychobiological mechanisms.

Mephedrone and 3,4-methylenedioxy-methamphetamine: Comparative psychobiological effects as reported by recreational polydrug users

AIMS

The purpose of this study was to compare the effects of mephedrone and 3,4-methylenedioxy-methamphetamine (MDMA), as reported by young recreational polydrug users.

METHODS

152 MDMA users and 81 mephedrone users were recruited through snowballing on social network sites. They completed a standard online questionnaire for either mephedrone or MDMA. The questions covered the average amount taken per session, the longest duration of usage in the last 12-months, subjective effects while on-drug, and recovery effects in the days afterwards.

RESULTS

Mephedrone users reported a significantly longer maximum session of use than MDMA users. Mephedrone users also reported a significantly greater average amount used per session. The majority of on-drug subjective ratings did not differ between drugs, with similar increases in entactogenic effects. Although mephedrone users did report significantly more frequent issues with sleeping, anger and anxiety. In relation to recovery, mephedrone users reported more frequent craving, nasal irritation, paranoia, and relationship difficulties. Mephedrone users also rated general recovery effects as more severe over the seven-day period following use, taking more days to feel normal.

CONCLUSIONS

The acute effects of MDMA and mephedrone were broadly similar. However, the recovery period for mephedrone was more enduring, possibly due to the longer duration of acute session usage.

Serotonergic neurotransmission in emotional processing: New evidence from long-term recreational poly-drug ecstasy use

The brain's serotonergic system plays a crucial role in the processing of emotional stimuli, and several studies have shown that a reduced serotonergic neurotransmission is associated with an increase in amygdala activity during emotional face processing. Prolonged recreational use of ecstasy (3,4-methylene-dioxymethamphetamine [MDMA]) induces alterations in serotonergic neurotransmission that are comparable to those observed in a depleted state. In this functional magnetic resonance imaging (fMRI) study, we investigated the responsiveness of the amygdala to emotional face stimuli in recreational ecstasy users as a model of long-term serotonin depletion. Fourteen ecstasy users and 12 non-using controls underwent fMRI to measure the regional neural activity elicited in the amygdala by male or female faces expressing anger, disgust, fear, sadness, or no emotion. During fMRI, participants made a sex judgement on each face stimulus. Positron emission tomography with ¹¹C-DASB was additionally performed to assess serotonin transporter (SERT) binding in the brain. In the ecstasy users, SERT binding correlated negatively with amygdala activity, and accumulated lifetime intake of ecstasy tablets was associated with an increase in amygdala activity during angry face processing. Conversely, time since the last ecstasy intake was associated with a trend toward a decrease in amygdala activity during angry and sad face processing. These results indicate that the effects of long-term serotonin depletion resulting from ecstasy use are dose-dependent, affecting the functional neural basis of emotional face processing.

Decision-making in chronic ecstasy users: a systematic review

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

MDMA decreases glutamic acid decarboxylase (GAD) 67-immunoreactive neurons in the hippocampus and increases seizure susceptibility: Role for glutamate

3,4-Methylenedioxy-methamphetamine (MDMA) is a unique psychostimulant that continues to be a popular drug of abuse. It has been well documented that MDMA reduces markers of 5-HT axon terminals in rodents, as well as humans. A loss of parvalbumin-immunoreactive (IR) interneurons in the hippocampus following MDMA treatment has only been documented recently. In the present study, we tested the hypothesis that MDMA reduces glutamic acid decarboxylase (GAD) 67-IR, another biochemical marker of GABA neurons, in the hippocampus and that this reduction in GAD67-IR neurons and an accompanying increase in seizure susceptibility involve glutamate receptor activation. Repeated exposure to MDMA (3×10mg/kg, ip) resulted in a reduction of 37-58% of GAD67-IR cells in the dentate gyrus (DG), CA1, and CA3 regions, as well as an increased susceptibility to kainic acid-induced seizures, both of which persisted for at least 30days following MDMA treatment. Administration of the NMDA antagonist MK-801 or the glutamate transporter type 1 (GLT-1) inducer ceftriaxone prevented both the MDMA-induced loss of GAD67-IR neurons and the increased vulnerability to kainic acid-induced seizures. The MDMA-induced increase in the extracellular concentration of glutamate in the hippocampus was significantly diminished in rats treated with ceftriaxone, thereby implicating a glutamatergic mechanism in the neuroprotective effects of ceftriaxone. In summary, the present findings support a role for increased extracellular glutamate and NMDA receptor activation in the MDMA-induced loss of hippocampal GAD67-IR neurons and the subsequent increased susceptibility to evoked seizures.

Meta-analysis of executive functioning in ecstasy/polydrug users

Ecstasy/3,4-methylenedioxymethamphetamine (MDMA) use is proposed to cause damage to serotonergic (5-HT) axons in humans. Therefore, users should show deficits in cognitive processes that rely on serotonin-rich, prefrontal areas of the brain. However, there is inconsistency in findings to support this hypothesis. The aim of the current study was to examine deficits in executive functioning in ecstasy users compared with controls using meta-analysis. We identified k = 39 studies, contributing 89 effect sizes, investigating executive functioning in ecstasy users and polydrug-using controls. We compared function-specific task performance in 1221 current ecstasy users and 1242 drug-using controls, from tasks tapping the executive functions - updating, switching, inhibition and access to long-term memory. The significant main effect demonstrated overall executive dysfunction in ecstasy users [standardized mean difference (SMD) = -0.18, 95% confidence interval (CI) -0.26 to -0.11, Z = 5.05, p < 0.001, I 2 = 82%], with a significant subgroup effect (χ 2 = 22.06, degrees of freedom = 3, p < 0.001, I 2 = 86.4%) demonstrating differential effects across executive functions. Ecstasy users showed significant performance deficits in access (SMD = -0.33, 95% CI -0.46 to -0.19, Z = 4.72, p < 0.001, I 2 = 74%), switching (SMD = -0.19, 95% CI -0.36 to -0.02, Z = 2.16, p < 0.05, I 2 = 85%) and updating (SMD = -0.26, 95% CI -0.37 to -0.15, Z = 4.49, p < 0.001, I 2 = 82%). No differences were observed in inhibitory control. We conclude that this is the most comprehensive analysis of executive function in ecstasy users to date and provides a behavioural correlate of potential serotonergic neurotoxicity.

The effects of ecstasy on neurotransmitter systems: a review on the findings of molecular imaging studies

RATIONALE

Ecstasy is a commonly used psychoactive drug with 3,4-methylenedioxymethamphetamine (MDMA) as the main content. Importantly, it has been suggested that use of MDMA may be neurotoxic particularly for serotonergic (5-hydroxytryptamine (5-HT)) neurons. In the past decades, several molecular imaging studies examined directly in vivo the effects of ecstasy/MDMA on neurotransmitter systems.

OBJECTIVES

The objective of the present study is to review the effects of ecstasy/MDMA on neurotransmitter systems as assessed by molecular imaging studies in small animals, non-human primates and humans.

METHODS

A search in PubMed was performed. Eighty-eight articles were found on which inclusion and exclusion criteria were applied.

RESULTS

Thirty-three studies met the inclusion criteria; all were focused on the 5-HT or dopamine (DA) system. Importantly, 9 out of 11 of the animal studies that examined the effects of MDMA on 5-HT transporter (SERT) availability showed a significant loss of binding potential. In human studies, this was the case for 14 out of 16 studies, particularly in heavy users. In abstinent users, significant recovery of SERT binding was found over time. Most imaging studies in humans that focused on the DA system did not find any significant effect of ecstasy/MDMA use.

CONCLUSIONS

Preclinical and clinical molecular imaging studies on the effects of ecstasy/MDMA use/administration on neurotransmitter systems show quite consistent alterations of the 5-HT system. Particularly, in human studies, loss of SERT binding was observed in heavy ecstasy users, which might reflect 5-HT neurotoxicity, although alternative explanations (e.g. down-regulation of the SERT) cannot be excluded.

Evaluation of brain SERT occupancy by resveratrol against MDMA-induced neurobiological and behavioral changes in rats: A 4-[¹⁸F]-ADAM/small-animal PET study

The misuse of 3,4-methylenedioxymethamphetamine (MDMA) has drawn a growing concern worldwide for its psychophysiological impacts on humans. MDMA abusers are often accompanied by long-term serotonergic neurotoxicity, which is associated with reduced density of cerebral serotonin transporters (SERT) and depressive disorders. Resveratrol (RSV) is a natural polyphenolic phytoalexin that has been known for its antidepressant and neuroprotective effects. However, biological targets of RSV as well as its neuroprotective effects against MDMA remained largely unknown. In this study, we examined binding potency of RSV and MDMA to SERT using small-animal positron emission tomography (PET) with the SERT radioligand, N,N-dimethyl-2-(2-amino-4-[(18)F]fluorophenylthio)benzylamine (4-[(18)F]-ADAM) and investigated the protection of RSV against the acute and long-term adverse effects of MDMA. We found that RSV exhibit binding potentials to SERT in vivo in a dose-dependent manner with variation among brain regions. When the MDMA-treated rats (10mg/kg, s.c.) were co-injected with RSV (20mg/kg, i.p.) twice daily for 4 consecutive days, MDMA-induced acute elevation in plasma corticosterone was significantly reduced. Further, 4-[(18)F]-ADAM PET imaging revealed that RSV protected against the MDMA-induced decrease in SERT availability in the midbrain and the thalamus 2 weeks following the co-treatment. The PET data were comparable to the observation from the forced swim test that RSV sufficiently ameliorated the depressive-like behaviors of the MDMA-treated rats. Together, these findings suggest that RSV is a potential antidepressant and may confer protection against neurobiological and behavioral changes induced by MDMA.

Learning, Memory, and Executive Function in New MDMA Users: A 2-Year Follow-Up Study

3,4-Methylenedioxymethamphetamine (MDMA) is associated with changes in neurocognitive performance. Recent studies in laboratory animals have provided additional support for the neurodegeneration hypothesis. However, results from animal research need to be applied to humans with caution. Moreover, several of the studies that examine MDMA users suffer from methodological shortcomings. Therefore, a prospective cohort study was designed in order to overcome these previous methodological shortcomings and to assess the relationship between the continuing use of MDMA and cognitive performance in incipient MDMA users. It was hypothesized that, depending on the amount of MDMA taken, the continued use of MDMA over a 2-year period would lead to further decreases in cognitive performance, especially in visual paired association learning tasks. Ninety-six subjects were assessed, at the second follow-up assessment: 31 of these were non-users, 55 moderate-users, and 10 heavy-users. Separate repeated measures analyses of variance were conducted for each cognitive domain, including attention and information processing speed, episodic memory, and executive functioning. Furthermore, possible confounders including age, general intelligence, cannabis use, alcohol use, use of other concomitant substances, recent medical treatment, participation in sports, level of nutrition, sleep patterns, and subjective well-being were assessed. The Repeated measures analysis of variance (rANOVA) revealed that a marginally significant change in immediate and delayed recall test performances of visual paired associates learning had taken place within the follow-up period of 2 years. No further deterioration in continuing MDMA-users was observed in the second follow-up period. No significant differences with the other neuropsychological tests were noted. It seems that MDMA use can impair visual paired associates learning in new users. However, the groups differed in their use of concomitant use of illicit drugs. Therefore, performance differences between the groups cannot completely ascribed to the use of MDMA.

Cortical oxygenation suggests increased effort during cognitive inhibition in ecstasy polydrug users

BACKGROUND

It is understood that 3,4-methylenedioxymethamphetamine (ecstasy) causes serotonin dysfunction and deficits in executive functioning. When investigating executive function, functional neuroimaging allows the physiological changes underlying these deficits to be investigated. The present study investigated behavioural and brain indices of inhibition in ecstasy-polydrug users.

METHODS

Twenty ecstasy-polydrug users and 20 drug-naïve participants completed an inhibitory control task (Random Letter Generation (RLG)) while prefrontal haemodynamic response was assessed using functional near infrared spectroscopy (fNIRS).

RESULTS

There were no group differences on background measures including sleep quality and mood state. There were also no behavioural differences between the two groups. However, ecstasy-polydrug users displayed significant increases in oxygenated haemoglobin (oxy-Hb) from baseline compared to controls at several voxels relating to areas of the inferior right medial prefrontal cortex, as well the right and left dorsolateral prefrontal cortex. Regression analysis revealed that recency of ecstasy use was a significant predictor of oxy-Hb increase at two voxels over the right hemisphere after controlling for alcohol and cannabis use indices.

CONCLUSION

Ecstasy-polydrug users show increased neuronal activation in the prefrontal cortex compared to non-users. This is taken to be compensatory activation/recruitment of additional resources to attain similar performance levels on the task, which may be reversible with prolonged abstinence.

Amphetamine-related drugs neurotoxicity in humans and in experimental animals: Main mechanisms

Amphetamine-related drugs, such as 3,4-methylenedioxymethamphetamine (MDMA) and methamphetamine (METH), are popular recreational psychostimulants. Several preclinical studies have demonstrated that, besides having the potential for abuse, amphetamine-related drugs may also elicit neurotoxic and neuroinflammatory effects. The neurotoxic potentials of MDMA and METH to dopaminergic and serotonergic neurons have been clearly demonstrated in both rodents and non-human primates. This review summarizes the species-specific cellular and molecular mechanisms involved in MDMA and METH-mediated neurotoxic and neuroinflammatory effects, along with the most important behavioral changes elicited by these substances in experimental animals and humans. Emphasis is placed on the neuropsychological and neurological consequences associated with the neuronal damage. Moreover, we point out the gap in our knowledge and the need for developing appropriate therapeutic strategies to manage the neurological problems associated with amphetamine-related drug abuse.

Personality disorder symptomatology is associated with anomalies in striatal and prefrontal morphology

Personality disorder symptomatology (PD-Sx) can result in personal distress and impaired interpersonal functioning, even in the absence of a clinical diagnosis, and is frequently comorbid with psychiatric disorders such as substance use, mood, and anxiety disorders; however, they often remain untreated, and are not taken into account in clinical studies. To investigate brain morphological correlates of PD-Sx, we measured subcortical volume and shape, and cortical thickness/surface area, based on structural magnetic resonance images. We investigated 37 subjects who reported PD-Sx exceeding DSM-IV Axis-II screening thresholds, and 35 age, sex, and smoking status-matched control subjects. Subjects reporting PD-Sx were then grouped into symptom-based clusters: N = 20 into Cluster B (reporting Antisocial, Borderline, Histrionic, or Narcissistic PD-Sx) and N = 28 into Cluster C (reporting Obsessive–Compulsive, Avoidant, or Dependent PD-Sx); N = 11 subjects reported PD-Sx from both clusters, and none reported Cluster A (Paranoid, Schizoid, or Schizotypal) PD-Sx. Compared to control, Cluster C PD-Sx was associated with greater striatal surface area localized to the caudate tail, smaller ventral striatum volumes, and greater cortical thickness in right prefrontal cortex. Both Cluster B and C PD-Sx groups also showed trends toward greater posterior caudate volumes and orbitofrontal surface area anomalies, but these findings did not survive correction for multiple comparisons. The results point to morphological abnormalities that could contribute to Cluster C PD-Sx. In addition, the observations parallel those in substance use disorders, pointing to the importance of considering PD-Sx when interpreting findings in often-comorbid psychiatric disorders.

5-HTTLPR Genotype Moderates the Effects of Past Ecstasy Use on Verbal Memory Performance in Adolescent and Emerging Adults: A Pilot Study

OBJECTIVE

Ecstasy use is associated with memory deficits. Serotonin transporter gene (5-HTTLPR) polymorphisms have been linked with memory function in healthy samples. The present pilot study investigated the influence of 5-HTTLPR polymorphisms on memory performance in ecstasy users, marijuana-using controls, and non-drug-using controls, after a minimum of 7 days of abstinence.

METHOD

Data were collected from 116 young adults (18-25 years-old), including 45 controls, 42 marijuana users, and 29 ecstasy users, and were balanced for 5-HTTLPR genotype. Participants were abstinent seven days prior to completing memory testing. Three MANCOVAs and one ANCOVA were run to examine whether drug group, 5-HTTLPR genotype, and their interactions predicted verbal and visual memory after controlling for gender, past year alcohol use, other drug use, and nicotine cotinine levels.

RESULTS

MANCOVA and ANCOVA analysis revealed a significant interaction between drug group and genotype (p = .03) such that ecstasy users with the L/L genotype performed significantly worse on CVLT-2 total recall (p = .05), short (p = .008) and long delay free recall (p = .01), and recognition (p = .006), with the reverse pattern found in controls. Ecstasy did not significantly predict visual memory. 5-HTTLPR genotype significantly predicted memory for faces (p = .02); short allele carriers performed better than those with L/L genotype.

CONCLUSIONS

5-HTTLPR genotype moderated the effects of ecstasy on verbal memory, with L/L carriers performing worse compared to controls. Future research should continue to examine individual differences in ecstasy's impact on neurocognitive performance as well as relationships with neuronal structure. Additional screening and prevention efforts focused on adolescents and emerging adults are necessary to prevent ecstasy consumption.

Why all stimulant drugs are damaging to recreational users: an empirical overview and psychobiological explanation

AIMS

Stimulant drugs such as nicotine and Ecstasy/3, 4-methylenedioxymethamphetamine (MDMA) are taken for positive reasons, yet their regular use leads to deficits rather than gains. This article outlines the psychobiological rationale for this paradox.

METHODS

The empirical literature on nicotine, cocaine, amphetamine, Ecstasy/MDMA, and mephedrone are reviewed. A theoretical explanation for why they are problematic to humans is then described.

RESULTS

The acute effects of central nervous system (CNS) stimulants are typically positive, with greater alertness and emotional intensity. However, in the post-drug recovery period, the opposite feelings develop, with lethargy and low moods. All recreational stimulants cause mood fluctuation, although it is most pronounced in drugs with rapid onset and comedown (e.g. nicotine and cocaine), explaining why they are the most addictive. Parallel fluctuations occur across many psychological and neurocognitive functions, with users suffering various off-drug deficits. CNS stimulants also affect the hypothalamic-pituitary-adrenal axis, impairing sleep, disrupting homeostasis, and exacerbating psychiatric distress. Neuroimaging studies reveal altered brain activity patterns in regular users. These problems are related to lifetime usage but commence in novice users.

CONCLUSIONS

Repetitive CNS stimulation is potentially damaging to the organism, both acutely and chronically. The review describes the various psychobiological systems through which recreational stimulant drugs impair human well-being.

Developmental outcomes of 3,4-methylenedioxymethamphetamine (ecstasy)-exposed infants in the UK

OBJECTIVE

This paper aims to review findings from a longitudinal study of prenatal methylenedioxymethamphetamine (MDMA, "ecstasy") on infant development.

METHODS

In a prospective, longitudinal cohort design, we followed 28 MDMA-exposed and 68 non-MDMA-exposed infants from birth to 2 years of age. Women recruited voluntarily into a study of recreational drug use during pregnancy were interviewed to obtain type, frequency, and amount of recreational drug use. Their children were followed for a 2-year period after birth. A large number of drug and environmental covariates were controlled. Infants were seen at 1, 4, 12, 18, and 24 months using standardized normative tests of mental and motor development.

RESULTS

There were no differences between MDMA-exposed and non-MDMA-exposed infants at birth except that MDMA-exposed infants were more likely to be male. Motor delays were evident in MDMA infants at each age and amount of MDMA exposure predicted motor deficits at 12 months in a dose-dependent fashion.

CONCLUSIONS

Prenatal MDMA exposure is related to fine and gross motor delays in the first 2 years of life. Follow-up studies are needed to determine long-term effects.

MDMA for the treatment of mood disorder: all talk no substance?

BACKGROUND

Unipolar depression is the third highest contributor to the global burden of disease, yet current pharmacotherapies typically take about 6 weeks to have an effect. A rapid-onset agent is an attractive prospect, not only to alleviate symptoms before first-line antidepressants display therapeutic action, but as a further treatment option in nonresponsive cases. It has been suggested that 3,4-methylene-dioxymethamphetamine (MDMA) could play a part in the treatment of depression, either as a rapid-onset pharmacological agent or as an adjunct to psychotherapy. Whilst these hypotheses are in keeping with the monoamine theory of depression and the principles surrounding psychotherapy, explicit experimental evidence of an antidepressant effect of MDMA has rarely been established.

AIMS

To address the hypothesis surrounding MDMA as a rapid-onset antidepressant by examining pharmacological, psychological and behavioural studies. We consider whether this therapy could be safe by looking at the translation of neurotoxicity data from animals to humans.

METHOD

A literature review of the evidence supporting this hypothesis was performed.

CONCLUSIONS

The pharmacology of MDMA offers a promising target as a rapid-onset agent and MDMA is currently being investigated for use in psychotherapy in anxiety disorders; translation from these studies for use in depression may be possible. However, experimental evidence and safety analysis are insufficient to confirm or reject this theory at present.

MDMA 'ecstasy' increases cerebral cortical perfusion determined by bolus-tracking arterial spin labelling (btASL) MRI

BACKGROUND AND PURPOSE

The purpose of this study was to assess cerebral perfusion changes following systemic administration of the recreational drug 3,4-methylendioxymethamphetamine (MDMA 'ecstasy') to rats.

EXPERIMENTAL APPROACH

Cerebral perfusion was quantified using bolus-tracking arterial spin labelling (btASL) MRI. Rats received MDMA (20 mg·kg(-1); i.p.) and were assessed 1, 3 or 24 h later. Rats received MDMA (5 or 20 mg·kg(-1); i.p.) and were assessed 3 h later. In addition, rats received MDMA (5 or 10 mg·kg(-1); i.p.) or saline four times daily over 2 consecutive days and were assessed 8 weeks later. Perfusion-weighted images were generated in a 7 tesla (7T) MRI scanner and experimental data was fitted to a quantitative model of cerebral perfusion to generate mean transit time (MTT), capillary transit time (CTT) and signal amplitude.

KEY RESULTS

MDMA reduces MTT and CTT and increases amplitude in somatosensory and motor cortex 1 and 3 h following administration, indicative of an increase in perfusion. Prior exposure to MDMA provoked a long-term reduction in cortical 5-HT concentration, but did not produce a sustained effect on cerebral cortical perfusion. The response to acute MDMA challenge (20 mg·kg(-1); i.p.) was attenuated in these animals indicating adaptation in response to prior MDMA exposure.

CONCLUSIONS AND IMPLICATIONS

MDMA provokes changes in cortical perfusion, which are quantifiable by btASL MRI, a neuroimaging tool with translational potential. Future studies are directed towards elucidation of the mechanisms involved and correlating changes in cerebrovascular function with potential behavioural deficits associated with drug use.

Differences in prefrontal blood oxygenation during an acute multitasking stressor in ecstasy polydrug users

BACKGROUND

Cognitive deficits are well documented in ecstasy (3,4-methylenedioxymethamphetamine; MDMA) users, with such deficits being taken as evidence of dysregulation of the serotonin (5-hydroxytryptamine; 5-HT) system. More recently neuroimaging has been used to corroborate these deficits. The present study aimed to assess multitasking performance in ecstasy polydrug users, polydrug users and drug-naive individuals. It was predicted that ecstasy polydrug users would perform worse than non-users on the behavioural measure and this would be supported by differences in cortical blood oxygenation.

METHOD

In the study, 20 ecstasy-polydrug users, 17 polydrug users and 19 drug-naive individuals took part. On day 1, drug use history was taken and questionnaire measures were completed. On day 2, participants completed a 20-min multitasking stressor while brain blood oxygenation was measured using functional near infrared spectroscopy (fNIRS).

RESULTS

There were no significant differences between the three groups on the subscales of the multitasking stressor. In addition, there were no significant differences on self-report measures of perceived workload (NASA Task Load Index). In terms of mood, ecstasy users were significantly less calm and less relaxed compared with drug-naive controls. There were also significant differences at three voxels on the fNIRS, indicating decreased blood oxygenation in ecstasy users compared with drug-naive controls at voxel 2 (left dorsolateral prefrontal cortex), voxel 14 and voxel 16 (right dorsolateral prefrontal cortex), and compared with polydrug controls at V14.

CONCLUSIONS

The results of the present study provide support for changes in brain activation during performance of demanding tasks in ecstasy polydrug users, which could be related to cerebral vasoconstriction.