Neurobiology, Clinical Presentation, and Treatment of Methamphetamine Use Disorder: A Review

Transcranial magnetic stimulation for methamphetamine use disorder: A scoping review within the neurocircuitry model of addiction

The use of methamphetamine in the United States is increasing, contributing now to the "fourth wave" in the national opioid epidemic crisis. People who suffer from methamphetamine use disorder (MUD) have a higher risk of death. No pharmacological interventions are approved by the FDA and psychosocial interventions are only moderately effective. Transcranial Magnetic Stimulation (TMS) is a relatively novel FDA-cleared intervention for the treatment of Major Depressive Disorder (MDD) and other neuropsychiatric conditions. Several lines of research suggest that TMS could be useful for the treatment of addictive disorders, including MUD. We will review those published clinical trials that show potential effects on craving reduction of TMS when applied over the dorsolateral prefrontal cortex (DLPFC) also highlighting some limitations that affect their generalizability and applicability. We propose the use of the Koob and Volkow's neurocircuitry model of addiction as a frame to explain the brain effects of TMS in patients with MUD. We will finally discuss new venues that could lead to a more individualized and effective treatment of this complex disorder including the use of neuroimaging, the exploration of different areas of the brain such as the frontopolar cortex or the salience network and the use of biomarkers.

[Stimulants : Current insights into the principles, diagnostics and treatment]

BACKGROUND

Consumption of stimulant drugs, a heterogeneous group of addictive substances, has significantly increased in recent years with rising numbers of stimulant-associated intoxication and deaths.

OBJECTIVE

To provide an overview of recent scientific evidence of the diagnosis and treatment of stimulant use disorders.

MATERIAL AND METHODS

A literature review of the neuropathology, clinical presentation, diagnostic criteria and evidence-based treatment for stimulant use disorders.

RESULTS

The chronic use of stimulant drugs is associated with significant physical (e.g., hypertension, tachycardia and dyspnoea) and psychological harm (e.g., dependence, psychotic disorders and affective disorders). Despite major advances in the research of the neuropathology of stimulant use disorder and the refinement of diagnostic criteria, the disorder still presents a challenge, not least because of the lack of effective treatments. There are currently no approved pharmacotherapeutic interventions for stimulant use disorder and meta-analyses show that the efficacy of behavioural interventions is low to moderate, similar to cognitive behavioural treatment.

CONCLUSION

Despite growing insights into the neuropathology associated with stimulant use disorder, treatment remains a challenge. The lack of effective interventions makes it difficult to give clear recommendations for the clinical practice. Further scientific research is thus warranted.

A narrative systematic review of associations and temporality between use of methamphetamine, ecstasy/MDMA, or cocaine with anxiety or depressive symptoms

OBJECTIVE

Anxiety and depression are prevalent mental health problems in people who use illicit stimulants. Improved understanding of the temporal relationship between methamphetamine, ecstasy/MDMA, or cocaine use with anxiety or depression informs public health interventions and treatment options for those experiencing this co-occurrence. This narrative systematic review sought to examine associations and temporality between the use of methamphetamine, ecstasy/MDMA, or cocaine, with anxiety or depressive symptoms. Method Systematic searches of 4 electronic databases were conducted up to August 2023. Study eligibility included the measurement of anxiety and/or depressive symptoms, and frequency of illicit stimulant use (methamphetamine, cocaine, or ecstasy/MDMA) at two separate time points, with data analysis of the association between these variables. The Joanna Briggs Critical Appraisal Checklist was utilised to assess quality. Data was extracted, and a narrative synthesis incorporating an eight-criteria framework to assess associations was conducted. Results 4432 studies were screened for eligibility; 11 studies (3 RCTs and 8 prospective cohort studies) were included. Evidence for an association between depressive symptoms and methamphetamine use was demonstrated in six studies, with temporal evidence in three studies supporting methamphetamine use preceding depressive symptoms. Three studies reported an association between cocaine use and depressive symptoms. Evidence for associations with any of the illicit stimulants and anxiety symptoms was lacking.

CONCLUSIONS

There was some evidence to support a case for temporality, particularly for methamphetamine use and depressive symptoms. Investing in longitudinal studies is pivotal to understanding the dynamic and reciprocal relationship between illicit stimulant use and anxiety or depressive symptoms. A limitation of the study was the variation in the measurement and analysis of outcomes.

Effects of methamphetamine on actigraphy-based sleep parameters in female rhesus monkeys: Orexin receptor mechanisms

BACKGROUND

The orexin system has been implicated as a mechanism underlying insomnia and methamphetamine-induced sleep disruptions, with a potential role for OX2 receptors in the sleep-modulating effects of orexin. The aim of the present study was to investigate the extent to which orexin receptors mediate the effects of acute methamphetamine administration on actigraphy-based sleep in female rhesus monkeys.

METHODS

Actigraphy-based sleep measures were obtained in female rhesus monkeys (n=5) under baseline and acute test conditions. First, morning (10h) i.m. injections of methamphetamine (0.03 - 0.56mg/kg) were administered to determine the effects of methamphetamine alone. Then, saline or methamphetamine (0.3mg/kg) were administered at 10h, and evening (17h30) oral treatments with vehicle, the non-selective orexin receptor antagonist suvorexant (1 - 10mg/kg, p.o.), or the OX2-selective orexin receptor antagonist MK-1064 (1 - 10mg/kg, p.o.) were given. The ability of suvorexant and MK-1064 (10mg/kg, p.o.) to improve actigraphy-based sleep was also assessed in a group of female monkeys quantitatively identified with "short-duration sleep" (n=4).

RESULTS

Methamphetamine dose-dependently disrupted actigraphy-based sleep parameters. Treatment with either suvorexant or MK-1064 dose-dependently improved actigraphy-based sleep in monkeys treated with methamphetamine. Additionally, both suvorexant and MK-1064 promoted actigraphy-based sleep in a group of monkeys with baseline short actigraphy-based sleep.

CONCLUSIONS

These findings suggest that orexin-mediated mechanisms play a role in the effects of methamphetamine on actigraphy-based sleep in female monkeys. Targeting the orexin system, in particular OX2 receptors, could be an effective option for treating sleep disruptions observed in individuals with methamphetamine use disorder.

Decision-making task performance and patterns of methamphetamine use in people assigned male at birth who have sex with men

This study aims to determine whether performance on the Iowa Gambling Task (IGT), a simulation of risk-taking when faced with loss, is associated with greater frequency of methamphetamine (MA) use and challenges reducing or stopping MA use. The parent mSTUDY is a Los Angeles County-based longitudinal study of substance use and HIV risk in predominately Black/African American and Latinx people assigned male at birth who have sex with men. The IGT was offered for a limited timeframe to mSTUDY participants, of whom 192 consented to and completed this one-time task. Separate random intercept binary logistic regressions tested whether the IGT total score and subscore for Blocks 4 and 5 (last 40 card draws) were associated with the outcomes, testing positive for MA in urine and self-reported inability to control or cease MA use in the past 6 months. Separate random intercept ordered logistic regressions tested whether IGT total score and subscore were associated with self-reported frequency of MA use in past 6 months. Higher IGT subscores for Blocks 4 and 5 (lower risk-taking) were associated with lower odds of testing MA-positive (adjusted odds ratio, AOR = 0.97, 95% CI [0.95, 0.99], p = .025) and less frequent MA use in the past 6 months (AOR = 0.96, 95% CI [0.94, 0.99], p = .006). Higher IGT total scores (lower risk-taking) were also associated with less frequent MA use (AOR = 0.99, 95% CI [0.97, 0.99], p = .038). Findings from this analysis suggest that IGT performance may be a useful indicator of MA use severity in nontreatment-seeking people. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

"If You Plant That Seed, It Will Grow": A Qualitative Study to Improve Linkage to Care among Patients with Methamphetamine Use Disorder in Emergency Department Settings

OBJECTIVES

Methamphetamine addiction is a serious and difficult-to-treat disorder. Existing treatment options are limited, and patient perspectives on effective strategies are lacking. Emergency departments (EDs) may be a critical entry point for individuals with methamphetamine use disorder (MUD) to be identified and linked to treatment. We aimed to understand patients' perspectives regarding their methamphetamine use and related ED experiences and how to improve linkage to substance treatment.

METHODS

Between July and November 2022, semistructured qualitative interviews were conducted with adult patients with MUD in an urban safety-net healthcare setting in Denver, Colorado. Interviews were recorded, summarized, and analyzed using the Rapid Assessment Process.

RESULTS

During the interviews, 18 patients shared their experiences. Participants described feeling stigmatized and experiencing a lack of communication from ED staff during their visit. Additionally, participants shared the perception that ED staff often did not take their health concerns seriously once substance use was identified. Participants were uncertain about overdose risk and felt that their psychiatric symptoms complicated treatment. Referrals to treatment were lacking, and participants supported a care navigation intervention that incorporates elements of contingency management. Participants also shared the importance of ED staff recognizing their social needs and being empathetic, trauma-informed, and flexible to meet patients where they are regardless of their readiness to seek treatment.

CONCLUSIONS

Treatment options and entry points for individuals with MUD are currently limited. The patient perspectives described here are helpful in developing services to support, engage, and link individuals to MUD services after discharge from ED services.

Individuals with Methamphetamine Use Disorder Show Reduced Directed Exploration and Learning Rates Independent of an Aversive Interoceptive State Induction

Methamphetamine Use Disorder (MUD) is associated with substantially reduced quality of life. Yet, decisions to use persist, due in part to avoidance of anticipated withdrawal states. However, the specific cognitive mechanisms underlying this decision process, and possible modulatory effects of aversive states, remain unclear. Here, 56 individuals with MUD and 58 healthy comparisons (HCs) performed a decision task, both with and without an aversive interoceptive state induction. Computational modeling measured the tendency to test beliefs about uncertain outcomes (directed exploration) and the ability to update beliefs in response to outcomes (learning rates). Compared to HCs, those with MUD exhibited less directed exploration and slower learning rates, but these differences were not affected by aversive state induction. These results suggest novel, state-independent computational mechanisms whereby individuals with MUD may have difficulties in testing beliefs about the tolerability of abstinence and in adjusting behavior in response to consequences of continued use.

Effects of exercise interventions on negative emotions, cognitive performance and drug craving in methamphetamine addiction

Introduction

Methamphetamine is currently one of the most commonly used addictive substances with strong addiction and a high relapse rate. This systematic review aims to examine the effectiveness of physical activity in improving negative emotions, cognitive impairment, and drug craving in people with methamphetamine use disorder (MUD).

Methods

A total of 17 studies out of 133 found from Embase and PubMed were identified, reporting results from 1836 participants from MUD populations. Original research using clearly described physical activity as interventions and reporting quantifiable outcomes of negative mood, cognitive function and drug craving level in people with MUD were eligible for inclusion. We included prospective studies, randomized controlled trials, or intervention studies, focusing on the neurological effects of physical activity on MUD.

Results

Taken together, the available clinical evidence showed that physical activity-based interventions may be effective in managing MUD-related withdrawal symptoms.

Discussion

Physical exercise may improve drug rehabilitation efficiency by improving negative emotions, cognitive behaviors, and drug cravings.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42024530359.

Methamphetamine Use Disorder and Inflammation: A Case-Control Study

OBJECTIVE

Methamphetamine use disorder (MUD) is a global health condition that impairs a person's health which may result in morbidity and mortality. Inflammation is a crucial process playing a vital role in MUD. For this reason, it is necessary to examine biochemical parameters for follow-up and treatment alternatives.

METHODS

We aimed to reveal the relationship between inflammatory response and MUD by evaluating peripheral hemogram parameters, leukocyte count, subtypes, and their ratios to each other, systemic immune inflammation index (SII), monocyte/high-density lipoprotein (HDL) ratio, and human C-reactive protein (CRP) in adult men with MUD. We included 76 adult male participants in the patient group and 70 adult male participants in the control group. We calculated the neutrophil/lymphocyte rate (NLR), monocyte/lymphocyte rate (MLR), platelet/lymphocyte rate (PLR), and basophil/lymphocyte rate (BLR). In addition, we obtained the SII and the monocyte/HDL rate.

RESULTS

The patients' leukocyte (p<0.001), platelet (p<0.001), plateletcrit (PCT) (p=0.002), neutrophil (p<0.001), monocyte (p=0.002), CRP (p<0.001), NLR (p=0.001), PLR (p=0.004), MLR (p=0.009), SII (p<0.001) and monocyte/HDL ratio (p<0.001) were higher than the control group. We observed a significant and positive relationship between the daily methamphetamine intake, and methamphetamine use duration (p=0.002), PCT (p=0.044), neutrophil (p=0.021), NLR (p=0.001), PLR (p=0.004), MLR (p=0.029), and SII (p<0.001). Daily methamphetamine intake had a significant and positive effect on SII. A one-unit increase in daily methamphetamine intake elevated SII by 165.53 units.

CONCLUSION

The results confirm the presence of peripheral subclinical inflammation and systemic immune inflammation in adult men with MUD.

Vesicular monoamine transporter-2 inhibitor JPC-141 prevents methamphetamine-induced dopamine toxicity and blocks methamphetamine self-administration in rats

Previous research has demonstrated therapeutic potential for VMAT2 inhibitors in rat models of methamphetamine use disorder. Here, we report on the neurochemical and behavioral effects of 1-(2-methoxyphenethyl)-4-phenethypiperazine (JPC-141), a novel analog of lobelane. JPC-141 potently inhibited (Ki = 52 nM) [3H]dopamine uptake by VMAT2 in striatal vesicles with 50 to 250-fold greater selectivity for VMAT2 over dopamine, norepinephrine and serotonin plasmalemma transporters. Also, JPC-141 was 57-fold more selective for inhibiting VMAT2 over [3H]dofetilide binding to hERG channels expressed by HEK293, suggesting relatively low potential for cardiotoxicity. When administered in vivo to rats, JPC-141 prevented the METH-induced reduction in striatal dopamine content when given either prior to or after a high dose of METH, suggesting a reduction in METH-induced dopaminergic neurotoxicity. In behavioral assays, JPC-141 decreased METH-stimulated locomotor activity in METH-sensitized rats at doses of JPC-141 which did not alter locomotor activity in the saline control group. Moreover, JPC-141 specifically decreased iv METH self-administration at doses that had no effect on food-maintained responding. These findings support the further development of VMAT2 inhibitors as pharmacotherapies for individuals with methamphetamine use disorder.

Hereditary and cortical morphological biomarker of sensitivity to reward in short-term withdrawal methamphetamine abusers

Higher sensitivity to reward (SR) and weaker sensitivity to punishment (SP) construct the fundamental craving characteristics of methamphetamine abuse. However, few studies have appraised relationships between SR/SP (SR or SP) and cortical morphological alterations in methamphetamine abusers and whether hereditary factors take effects on SR/SP is unclear. Based on surface-based morphometric analysis, cortical discrepancy was investigated between 38 methamphetamine abusers and 37 healthy controls. Within methamphetamine abusers, correlation profiling was performed to discover associations among aberrant neuroimaging substrates, SR, SP, and craving. According to nine single nucleotide polymorphism sites of dopamine-related genes, we conducted univariate general linear model to find different effects of genotypes on cortical alterations and SR/SP/craving (SR, SP, or craving). Ultimately, mediation analyses were conducted among single nucleotide polymorphism sites, SR/SP/craving, and cortical morphological alterations to discover their association pathways. Compared to healthy controls, thinner cortices in inferior temporal gyrus, lateral orbitofrontal cortex, medial orbitofrontal cortex, inferior parietal lobule, and lateral occipital cortex in the left hemisphere were found in methamphetamine abusers (P < 0.05, family-wise error corrected). Cortical thickness in the inferior temporal gyrus was negatively correlated with SR scores. We found that rs1800497 A-containing genotypes had lower cortical thickness in the left inferior parietal lobule than the GG genotype. The rs5751876 had effects on SR scores. This study would provide convincing biomarkers for SR in methamphetamine abusers and offer potential genetic targets for personalizing relapse prevention.

The Effectiveness of Mindfulness in the Treatment of Methamphetamine Addiction Symptoms: Does Neuroplasticity Play a Role?

INTRODUCTION

Methamphetamine is a highly stimulating psychoactive drug that causes life-threatening addictions and affects millions of people around the world. Its effects on the brain are complex and include disturbances in the neurotransmitter systems and neurotoxicity. There are several known treatment methods, but their effectiveness is moderate. It must be emphasised that no drugs have been approved for treatment. For this reason, there is an urgent need to develop new, effective, and safe treatments for methamphetamine. One of the potential treatments is mindfulness meditation. In recent years, this technique has been researched extensively in the context of many neurological and psychiatric disorders.

METHODS

This review explores the use of mindfulness in the treatment of methamphetamine addiction. Searches were conducted in the PubMed/Medline, Research Gate, and Cochrane databases.

RESULTS

Ten studies were identified that used mindfulness-based interventions in the treatment of methamphetamine addiction. The results show that mindfulness is an effective form of reducing hunger, risk of relapses, stress indicators, depression, and aggression, alone or in combination with transcranial direct current stimulation (tDCS). Mindfulness also improved the cognitive function in addicts. The included studies used only behavioural measures. The potential mechanisms of mindfulness in addiction were explained, and it was proposed that it can induce neuroplasticity, alleviating the symptoms of addiction.

CONCLUSIONS

Evidence from the studies suggest that mindfulness may be an effective treatment option for methamphetamine addiction, used alone or in combination with tDCS. However, further high-quality research is required to establish the role of this treatment option in this field. The use of neuroimaging and neurophysiological measures is fundamental to understand the mechanisms of mindfulness.

Unlocking the Potential of High-Quality Dopamine Transporter Pharmacological Data: Advancing Robust Machine Learning-Based QSAR Modeling

The dopamine transporter (DAT) plays a critical role in the central nervous system and has been implicated in numerous psychiatric disorders. The ligand-based approaches are instrumental to decipher the structure-activity relationship (SAR) of DAT ligands, especially the quantitative SAR (QSAR) modeling. By gathering and analyzing data from literature and databases, we systematically assemble a diverse range of ligands binding to DAT, aiming to discern the general features of DAT ligands and uncover the chemical space for potential novel DAT ligand scaffolds. The aggregation of DAT pharmacological activity data, particularly from databases like ChEMBL, provides a foundation for constructing robust QSAR models. The compilation and meticulous filtering of these data, establishing high-quality training datasets with specific divisions of pharmacological assays and data types, along with the application of QSAR modeling, prove to be a promising strategy for navigating the pertinent chemical space. Through a systematic comparison of DAT QSAR models using training datasets from various ChEMBL releases, we underscore the positive impact of enhanced data set quality and increased data set size on the predictive power of DAT QSAR models.

Cognitive functioning of adolescents using Methamphetamine: The impact of inflammatory and oxidative processes

BACKGROUND

Methamphetamine is a substance that causes neurotoxicity and its use is increasing in recent years. Literature highlights cognitive impairment resulting from Methamphetamine use. The aim of the present study is to evaluate the relationship between cognitive impairment and inflammatory processes in adolescents with Methamphetamine use disorder.

METHODS

The study included 69 adolescents aged 15-19 years, comprising 37 participants with Methamphetamine Use Disorder and 32 healthy controls. Central Nervous System Vital Signs was used to detect cognitive impairment. Childhood Trauma Questionnaire-33 and The Children's Depression Inventory scales were used. In addition, venous blood was collected from the volunteers. Biochemical parameters (IL-1beta, IL-6, TNF-a, BDNF, FAM19A5, TAS, TOS) were analyzed.

RESULTS

Our study showed that (I) IL-6 and TNF-a levels of Methamphetamine users were lower than the healthy group; (II) BDNF levels of Methamphetamine users were higher than the healthy group; (III) mean Neurocognitive Index in cognitive tests of Methamphetamine using adolescents was negatively correlated with duration of Methamphetamine use and BDNF levels.

CONCLUSIONS

Our study suggests that Methamphetamine use may have a negative effect on cognitive functions.

Methamphetamine use shortens telomere length in male adults and rats

BACKGROUND

Methamphetamine (MA) use increases the risk of age-related diseases. However, it remains uncertain whether MA use exhibits accelerated biological aging, as indicated by telomere length (TL), a proposed marker of aging. Here we conducted studies in both humans and rats to investigate the association between MA use and TL.

METHODS

We recruited 125 male MA users and 66 healthy controls, aged 30-40 years. MA users were diagnosed using DSM-5 criteria and categorized into two groups: non-severe (n = 78) and severe (n = 47) MA use disorder (MUD). MA-treated conditioned place preference (CPP) rats were utilized to validate our clinical investigations. TL was assessed using real-time polymerase chain reaction.

RESULTS

At clinical levels, MA users exhibited significantly shorter leukocyte TL compared to healthy controls. Among MA users, individuals with severe MUD had significantly shorter leukocyte TL than those with non-severe MUD. Importantly, both univariate and multivariate linear regression analyses demonstrated a negative association between the severity of MA use and leukocyte TL. In a rat model of MA-induced CPP, leukocyte TL was also significantly shortened after MA administration, especially in rats with higher CPP expression or reinstatement scores.

CONCLUSION

MA use shortened TL, and the severity of MA use was negatively correlated with TL. These findings provide new insights into the pathophysiology of accelerated aging caused by MA use and may have implications for identifying biomarkers and developing novel treatment strategies for MUD.

Structural indices of brain aging in methamphetamine use disorder

BACKGROUND

Methamphetamine use is surging globally. It has been linked to premature stroke, Parkinsonism, and dementia, suggesting that it may accelerate brain aging.

METHODS

We performed a retrospective study to determine if structural indices of brain aging were more prevalent prior to old age (26 - 54 years) in individuals with Methamphetamine Use Disorder (MUD), who were in early abstinence (M ± SD = 22.1 ± 25.6 days) than in healthy control (HC) participants. We compared T1-weighted MRI brain scans in age- and sex-matched groups (n = 89/group) on three structural features of brain aging: the brain volume/cerebrospinal fluid (BV/CSF) index, volume of white matter hypointensities/lesions, and choroid plexus volume.

RESULTS

The MUD group had a lower mean BV/CSF index and larger volumes of white matter hypointensities and choroid plexus (p-values < 0.01). Regression analyses showed significant age-by-group effects, indicating different age trajectories of the BV/CSF index and choroid plexus volume, consistent with abnormal global brain atrophy and choroid plexus pathology in the MUD group. Significant age and group main effects reflected a larger volume of white matter hypointensities for older participants across groups and for the MUD group irrespective of age. None of the three measures of brain aging correlated significantly with recent use or duration of recent abstinence from methamphetamine.

CONCLUSIONS

Premature brain pathology, which may reflect cerebrovascular damage and dysfunction of the choroid plexus, occurs in people with MUD. Such pathology may affect cognition and thereby efficacy of behavioral treatments for MUD.

Applications of TMS in individuals with methamphetamine use disorder: A review

Methamphetamine abuse results in a host of social and medical issues. Methamphetamine use disorder (MUD) can hinder the brain and impair cognitive functions and mental health. Transcranial magnetic stimulation (TMS) is a non-invasive approach in the treatment of MUD. Recent studies have demonstrated encouraging and positive effects of TMS on the craving, affective symptoms, sleep quality, and cognitive functions in individuals with MUD. The regulation of specific brain activities through TMS has also been found to be a contributing factor to these positive outcomes. It is essential to employ more techniques, participants, and stimulation parameters and targets in the future.

Robust identification of a neuromarker of methamphetamine craving

In the January issue of Cell Reports Medicine, Tian et al.1 apply high-density 128-channel resting-state electroencephalography (EEG) to examine the neurophysiological connectomes in individuals with methamphetamine use disorder (MUD). They identify neurobiological connectome biomarkers for craving prediction in MUD.

Conflict monitoring and emotional processing in 3,4-methylenedioxymethamphetamine (MDMA) and methamphetamine users - A comparative neurophysiological study

In stimulant use and addiction, conflict control processes are crucial for regulating substance use and sustaining abstinence, which can be particularly challenging in social-affective situations. Users of methamphetamine (METH, "Ice") and 3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy") both experience impulse control deficits, but display different social-affective and addictive profiles. We thus aimed to compare the effects of chronic use of the substituted amphetamines METH and MDMA on conflict control processes in different social-affective contexts (i.e., anger and happiness) and investigate their underlying neurophysiological mechanisms. For this purpose, chronic but recently abstinent users of METH (n = 38) and MDMA (n = 42), as well as amphetamine-naïve healthy controls (n = 83) performed an emotional face-word Stroop paradigm, while event-related potentials (ERPs) were recorded. Instead of substance-specific differences, both MDMA and METH users showed smaller behavioral effects of cognitive-emotional conflict processing (independently of emotional valence) and selective deficits in emotional processing of anger content. Both effects were underpinned by stronger P3 ERP modulations suggesting that users of substituted amphetamines employ altered stimulus-response mapping and decision-making. Given that these processes are modulated by noradrenaline and that both MDMA and METH use may be associated with noradrenergic dysfunctions, the noradrenaline system may underlie the observed substance-related similarities. Better understanding the functional relevance of this currently still under-researched neurotransmitter and its functional changes in chronic users of substituted amphetamines is thus an important avenue for future research.

Psychosocial interventions for stimulant use disorder

BACKGROUND

Stimulant use disorder is a continuously growing medical and social burden without approved medications available for its treatment. Psychosocial interventions could be a valid approach to help people reduce or cease stimulant consumption. This is an update of a Cochrane review first published in 2016.

OBJECTIVES

To assess the efficacy and safety of psychosocial interventions for stimulant use disorder in adults.

SEARCH METHODS

We searched the Cochrane Drugs and Alcohol Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, three other databases, and two trials registers in September 2023. All searches included non-English language literature. We handsearched the references of topic-related systematic reviews and the included studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing any psychosocial intervention with no intervention, treatment as usual (TAU), or a different intervention in adults with stimulant use disorder.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included a total of 64 RCTs (8241 participants). Seventy-three percent of studies included participants with cocaine or crack cocaine use disorder; 3.1% included participants with amphetamine use disorder; 10.9% included participants with methamphetamine use disorder; and 12.5% included participants with any stimulant use disorder. In 18 studies, all participants were in methadone maintenance treatment. In our primary comparison of any psychosocial treatment to no intervention, we included studies which compared a psychosocial intervention plus TAU to TAU alone. In this comparison, 12 studies evaluated cognitive behavioural therapy (CBT), 27 contingency management, three motivational interviewing, one study looked at psychodynamic therapy, and one study evaluated CBT plus contingency management. We also compared any psychosocial intervention to TAU. In this comparison, seven studies evaluated CBT, two contingency management, two motivational interviewing, and one evaluated a combination of CBT plus motivational interviewing. Seven studies compared contingency management reinforcement related to abstinence versus contingency management not related to abstinence. Finally, seven studies compared two different psychosocial approaches. We judged 65.6% of the studies to be at low risk of bias for random sequence generation and 19% at low risk for allocation concealment. Blinding of personnel and participants was not possible for the type of intervention, so we judged all the studies to be at high risk of performance bias for subjective outcomes but at low risk for objective outcomes. We judged 22% of the studies to be at low risk of detection bias for subjective outcomes. We judged most of the studies (69%) to be at low risk of attrition bias. When compared to no intervention, we found that psychosocial treatments: reduce the dropout rate (risk ratio (RR) 0.82, 95% confidence interval (CI) 0.74 to 0.91; 30 studies, 4078 participants; high-certainty evidence); make little to no difference to point abstinence at the end of treatment (RR 1.15, 95% CI 0.94 to 1.41; 12 studies, 1293 participants; high-certainty evidence); make little to no difference to point abstinence at the longest follow-up (RR 1.22, 95% CI 0.91 to 1.62; 9 studies, 1187 participants; high-certainty evidence); probably increase continuous abstinence at the end of treatment (RR 1.89, 95% CI 1.20 to 2.97; 12 studies, 1770 participants; moderate-certainty evidence); may make little to no difference in continuous abstinence at the longest follow-up (RR 1.14, 95% CI 0.89 to 1.46; 4 studies, 295 participants; low-certainty evidence); reduce the frequency of drug intake at the end of treatment (standardised mean difference (SMD) -0.35, 95% CI -0.50 to -0.19; 10 studies, 1215 participants; high-certainty evidence); and increase the longest period of abstinence (SMD 0.54, 95% CI 0.41 to 0.68; 17 studies, 2118 participants; high-certainty evidence). When compared to TAU, we found that psychosocial treatments reduce the dropout rate (RR 0.79, 95% CI 0.65 to 0.97; 9 studies, 735 participants; high-certainty evidence) and may make little to no difference in point abstinence at the end of treatment (RR 1.67, 95% CI 0.64 to 4.31; 1 study, 128 participants; low-certainty evidence). We are uncertain whether they make any difference in point abstinence at the longest follow-up (RR 1.31, 95% CI 0.86 to 1.99; 2 studies, 124 participants; very low-certainty evidence). Compared to TAU, psychosocial treatments may make little to no difference in continuous abstinence at the end of treatment (RR 1.18, 95% CI 0.92 to 1.53; 1 study, 128 participants; low-certainty evidence); probably make little to no difference in the frequency of drug intake at the end of treatment (SMD -1.17, 95% CI -2.81 to 0.47, 4 studies, 479 participants, moderate-certainty evidence); and may make little to no difference in the longest period of abstinence (SMD -0.16, 95% CI -0.54 to 0.21; 1 study, 110 participants; low-certainty evidence). None of the studies for this comparison assessed continuous abstinence at the longest follow-up. Only five studies reported harms related to psychosocial interventions; four of them stated that no adverse events occurred.

AUTHORS' CONCLUSIONS

This review's findings indicate that psychosocial treatments can help people with stimulant use disorder by reducing dropout rates. This conclusion is based on high-certainty evidence from comparisons of psychosocial interventions with both no treatment and TAU. This is an important finding because many people with stimulant use disorders leave treatment prematurely. Stimulant use disorders are chronic, lifelong, relapsing mental disorders, which require substantial therapeutic efforts to achieve abstinence. For those who are not yet able to achieve complete abstinence, retention in treatment may help to reduce the risks associated with stimulant use. In addition, psychosocial interventions reduce stimulant use compared to no treatment, but they may make little to no difference to stimulant use when compared to TAU. The most studied and promising psychosocial approach is contingency management. Relatively few studies explored the other approaches, so we cannot rule out the possibility that the results were imprecise due to small sample sizes.

Understanding Regional Patterns of Overdose Deaths Related to Opioids and Psychostimulants

BACKGROUND

As overdose rates increase for multiple substances, policymakers need to identify geographic patterns of substance-specific deaths. In this study, we describe county-level opioid and psychostimulant overdose patterns and how they correlate with county-level social vulnerability measures.

METHODS

A cross-sectional observational study, we used nationwide 2016-2018 restricted access Centers for Disease Prevention and Control county-level mortality files for 1,024 counties. We estimated quartiles of opioid and psychostimulant overdose mortality and provided estimates of their association with county-level Social Vulnerability Index (SVI) percentile.

RESULTS

There was high opioid and psychostimulant overdose mortality in the Middle Atlantic, South Atlantic, East North Central, and Mountain regions. The Central US had the lowest opioid and psychostimulant overdose mortality rates. Counties with higher SVI scores (i.e. higher social vulnerability) were significantly more likely to experience high opioid and high psychostimulant overdose (high-high) mortality. A 10-percentile increase in SVI score was associated with a 3.1 percentage point increase in the likelihood of being a high-high county (p < 0.001) in unadjusted models and a 1.5 percentage point increase (p < 0.05) in models adjusting for region.

CONCLUSION

Our results illustrated the heterogenous geographic distribution of the growing concurrent opioid and psychostimulant overdose crisis. The substantial regional variation we identified highlights the need for local data to guide policymaking and treatment planning. The association of opioid-psychostimulant overdose mortality with social vulnerability demonstrates the critical need in impacted counties for tailored treatment that addresses the complex medical and social needs of people who use both opioids and psychostimulants.

Association of current substance use treatment with future reduced methamphetamine use in an observational cohort of men who have sex with men in Los Angeles

INTRODUCTION

Methamphetamine use is highly prevalent among men who have sex with men (MSM), but knowledge of the long-term dynamics, and how they are affected by substance use treatment, is limited. This study aimed to describe trajectories of methamphetamine use among MSM, and to evaluate the impact of treatment for any kind of substance use on frequency of methamphetamine use.

METHODS

This analysis used data from a cohort of MSM in Los Angeles, CA, who participated in semi-annual study visits from 2014 to 2022. The study characterized trajectories of methamphetamine use using a continuous time multistate Markov model with three states. States were defined using self-reported frequency of methamphetamine use in the past six months: frequent (daily), occasional (weekly or less), and never. The model estimated the association between receiving treatment for any kind of substance use and changes in state of frequency of methamphetamine use.

RESULTS

This analysis included 2348 study visits among 285 individuals who were followed-up for an average of 4.4 years. Among participants who were in the frequent use state, 65 % (n = 26) of those who were receiving any kind of substance use treatment at a study visit had reduced their methamphetamine use at their next visit, compared to 33 % (n = 95) of those who were not receiving treatment. Controlling for age, race/ethnicity, and HIV-status, those who reported receiving current treatment for substance use were more likely to transition from occasional to no use (HR: 1.63, 95 % CI: 1.10-2.42) and frequent to occasional use (HR: 4.25, 95 % CI: 2.11-8.59) in comparison to those who did not report receiving current treatment for substance use.

CONCLUSIONS

Findings from this dynamic modeling study provide a new method for assessing longitudinal methamphetamine use outcomes and add important evidence outside of clinical trials that substance use treatment may reduce methamphetamine use.

Prescription psychostimulants for the treatment of amphetamine-type stimulant use disorder: A systematic review and meta-analysis of randomized placebo-controlled trials

BACKGROUND AND AIMS

There is currently no standard of care for pharmacological treatment of amphetamine-type stimulant (ATS) use disorder (ATSUD). This systematic review with meta-analysis (PROSPERO CRD42022354492) aimed to pool results from randomized placebo-controlled trials (RCTs) to evaluate efficacy and safety of prescription psychostimulants (PPs) for ATSUD.

METHODS

Major indexing sources and trial registries were searched to include records published before 29 August 2022. Eligible studies were RCTs evaluating efficacy and safety of PPs for ATSUD. Risk of bias (RoB) was assessed using the Cochrane RoB 2 tool. Risk ratio (RR) and risk difference were calculated for random-effect meta-analysis of dichotomous variables. Mean difference and standardized mean difference (SMD) were calculated for random-effect meta-analysis of continuous variables.

RESULTS

Ten RCTs (n = 561 participants) were included in the meta-analysis. Trials studied methylphenidate (n = 7), with daily doses of 54-180 mg, and dextroamphetamine (n = 3), with daily doses of 60-110 mg, for 2-24 weeks. PPs significantly decreased end-point craving [SMD  -0.29; 95% confidence interval (CI) = -0.55, -0.03], while such a decrease did not reach statistical significance for ATS use, as evaluated by urine analysis (UA) (RR = 0.93; 95% CI = 0.85-1.01). No effect was observed for self-reported ATS use, retention in treatment, dropout following adverse events, early-stage craving, withdrawal and depressive symptoms. In a sensitivity analysis, treatment was associated with a significant reduction in UA positive for ATS (RR = 0.89; 95% CI = 0.79-0.99) after removing studies with a high risk of bias. In subgroup analyses, methylphenidate and high doses of PPs were negatively associated with ATS use by UA, while higher doses of PPs and treatment duration (≥ 20 weeks) were positively associated with longer retention.

CONCLUSIONS

Among individuals with amphetamine-type stimulant use disorder, treatment with prescription psychostimulants may decrease ATS use and craving. While effect size is limited, it may increase with a higher dosage of medications.

An electroencephalographic signature predicts craving for methamphetamine

Craving is central to methamphetamine use disorder (MUD) and both characterizes the disease and predicts relapse. However, there is currently a lack of robust and reliable biomarkers for monitoring craving and diagnosing MUD. Here, we seek to identify a neurobiological signature of craving based on individual-level functional connectivity pattern differences between healthy control and MUD subjects. We train high-density electroencephalography (EEG)-based models using data recorded during the resting state and then calculate imaginary coherence features between the band-limited time series across different brain regions of interest. Our prediction model demonstrates that eyes-open beta functional connectivity networks have significant predictive value for craving at the individual level and can also identify individuals with MUD. These findings advance the neurobiological understanding of craving through an EEG-tailored computational model of the brain connectome. Dissecting neurophysiological features provides a clinical avenue for personalized treatment of MUD.

Nalmefene attenuates reinstatement of methamphetamine-seeking behavior in rats through group II metabotropic glutamate receptors (mGluR2/3)

Nalmefene, an analog to naltrexone, is an antagonist at the μ opioid receptor and a partial agonist at the κ opioid receptor. Both agents are approved for the treatment of alcohol use disorder and opioid addiction. Here, we evaluated the potential of nalmefene for treating psychostimulant dependence using a methamphetamine (METH) self-administration rat model. Rats were trained to press a lever for 0.02-mg intravenous METH infusions paired with drug-associated cues (light and tone) under a fixed ratio 1 schedule. After a 10-day METH self-administration acquisition phase, rats underwent extinction training. A reinstatement test was conducted after fulfilment of the extinction criterion under saline infusions. Re-exposure to METH-associated cues or a priming injection of METH (1.0 mg/kg, i.p.) significantly reinstated METH-seeking behaviors. Pretreatment with nalmefene (10 mg/kg, i.p.) immediately before reinstatement tests significantly attenuated the METH-seeking behaviors induced by both cues and METH priming injection. To investigate the mechanism of effect of nalmefene, we also tested the ability of a group II metabotropic glutamate receptors (mGluR2/3) antagonist, LY341495, to the ameliorating effects of nalmefene. Pretreatment with LY341495 (1.0 mg/kg, i.p.) before nalmefene administration antagonized the effect of nalmefene on reinstatement. LY341495 alone did not affect the reinstatement of lever pressing. We found that nalmefene attenuates METH-seeking behaviors during withdrawal, and this attenuation of reinstatement is mediated by the activation of mGluR2/3. The present findings suggest that nalmefene could decrease incentive motivation for drug use in psychostimulant dependence.

GxE interaction effects of HCRTR2 single nucleotide polymorphism and adverse childhood experiences on methamphetamine use disorder

Background: Methamphetamine use disorder (MUD) is a worldwide health concern. The hypothalamic orexin system regulates stress response and addictive behaviors. The genetic variation in the hypocretin receptor 2 (HCRTR2), rs2653349, is associated with substance use disorder.Objectives: We explored the gene-environment (GxE) interaction of rs2653349 and adverse childhood experiences (ACEs) associated with MUD susceptibility.Methods: Four hundred and one individuals (336 males, 65 females) with MUD and 348 healthy controls (288 males, 60 females) completed a self-report questionnaire evaluating ACEs, encompassing childhood abuse and household dysfunction categories, and were genotyped for SNP rs2653349. Methamphetamine use variables were collected using the Diagnostic Interview for Genetic Studies. We used regression analyses to assess the GxE effect on MUD risk.Results: The MUD group had a comparable genotypic distribution for rs2653349 to the control group, albeit with a higher prevalence and number of types of ACEs, correlating with an increased MUD risk (p < .05). No significant genetic impact of rs2653349 on MUD risk was found. However, we observed a GxE interaction effect between the minor allele of rs2653349 and the number of childhood abuse or household dysfunction types, correlating with a reduced MUD risk (OR = -0.71, p = .04, Benjamini-Hochberg adjusted p = .08 and OR = -0.59, p = .045, Benjamini-Hochberg adjusted p = .09, respectively).Conclusion: HCRTR2 SNP rs2653349 has no significant impact on MUD risk, but ACEs may increase this risk. GxE results suggest that rs2653349 could offer protection against developing MUD in individuals experiencing multiple types of ACEs.

Model-based and model-free mechanisms in methamphetamine use disorder

People with methamphetamine use disorder (MUD) struggle to shift their behaviour from methamphetamine-orientated habits to goal-oriented choices. The model-based/model-free framework is well suited to understand this difficulty by unpacking the computational mechanisms that support experienced-based (model-free) and goal-directed (model-based) choices. We aimed to examine whether 1) participants with MUD differed from controls on behavioural proxies and/or computational mechanisms of model-based/model-free choices; 2) model-based/model-free decision-making correlated with MUD symptoms; and 3) model-based/model-free deficits improved over six weeks in the group with MUD. Participants with MUD and controls with similar age, IQ and socioeconomic status completed the Two-Step Task at treatment commencement (MUD n = 30, Controls n = 31) and six weeks later (MUD n = 23, Controls n = 26). We examined behavioural proxies of model-based/model-free decisions using mixed logistic regression, and their underlying mechanisms using computational modelling. At a behavioural level, participants with MUD were more likely to switch their choices following rewarded actions, although this pattern improved at follow up. At a computational level, groups were similar in their use of model-based mechanisms, but participants with MUD were less likely to apply model-free mechanisms and less likely to repeat rewarded actions. We did not find evidence that individual differences in model-based or model-free parameters were associated with greater severity of methamphetamine dependence, nor did we find that group differences in computational parameters changed between baseline and follow-up assessment. Decision-making challenges in people with MUD are likely related to difficulties in pursuing choices previously associated with positive outcomes.

Prevalence of methamphetamine use among gay, bisexual and other men who have sex with men: A systematic review and meta-analysis

BACKGROUND

International efforts have reduced the availability of methamphetamine precursors, but its distribution and use continue to rise. Methamphetamine use can lead to short- and long-term adverse effects, including addiction, physical and psychosocial health problems, socioeconomic troubles, incarceration, overdose, and death. Gay, bisexual, and other men who have sex with men (MSM) have been shown to have an elevated prevalence of methamphetamine use.

METHODS

We conducted a systematic review and meta-analysis to estimate the prevalence of methamphetamine use among MSM. We searched electronic databases, such as PubMed, for peer-reviewed literature published between 2011 and 2022. Data on methamphetamine use were extracted, including study features, location, study design, sampling method, recruitment period, specific MSM subgroups, prevalence period, and demographics. Employing a random-effects model, we computed the pooled prevalence of methamphetamine use among MSM across two prevalence periods: recent use (i.e., one month, three months, six months, one year) and lifetime use.

RESULTS

The systematic review included 56 studies with a total of 25,953 MSM who use methamphetamine. Most studies were conducted in Europe, with the highest prevalence reported in the United Kingdom. The studies primarily used cross-sectional or cohort study designs with convenience sampling. The pooled prevalence rates across recent use (i.e., past month, past three months, past six months, and past year) was 15% (95% CI [11-19%]). Additionally, we pooled lifetime use, which was 23% (95% CI [9-38%]). High heterogeneity (I2 > 99%) was observed, indicating significant variation.

CONCLUSION

This systematic review and meta-analysis provide a pooled prevalence of methamphetamine use among MSM. The analysis accounts for study design, prevalence period, specific MSM subgroups, and geographical areas to estimate methamphetamine use in diverse settings and populations. The review highlights the need for targeted interventions and harm reduction strategies focused on prevention, education, healthcare access, and stakeholder collaboration to address the multifaceted challenges of methamphetamine use among MSM.

Bupropion for treatment of amphetamine-type stimulant use disorder: A systematic review and meta-analysis of placebo-controlled randomized clinical trials

BACKGROUND

This meta-analysis (PROSPERO-ID: CRD42022362962), pooled effect estimates of outcomes, from placebo-controlled randomized clinical trials (RCTs) examining bupropion efficacy and safety for amphetamine-type stimulant use disorder (ATSUD) treatment.

METHOD

Electronic databases were searched for records published to October 31st, 2022, including MEDLINE, CINAHL, PsycINFO, EBM Reviews, EMBASE, PubMed, Web of Science, trial registries. Inclusion criteria were RCTs comparing bupropion to placebo in ATSUD. Cochrane RoB2 tool and GRADE evidence certainty assessment were employed. Outcomes included amphetamine-type stimulant (ATS) use by urinalysis, retention in treatment, treatment adherence, ATS craving, addiction severity, depressive symptom severity, drop-out following adverse events (AEs), and serious AEs. Random-effect meta-analysis was conducted presenting standardized mean difference (SMD), risk ratio (RR), and risk difference (RD).

RESULTS

Eight RCTs (total N=1239 participants) were included. Bupropion compared to placebo was associated with reduced ATS use (RR: 0.90; 95% CI: 0.84, 0.96), end-of-treatment ATS craving (SMD: -0.38; 95%CI: -0.63, -0.13), and adherence (RR: 0.91; 95%CI: 0.84, 0.99). Subgroup analysis showed greater reduction in ATS use with longer trial duration (12 weeks) (RR: 0.85; 95%CI: 0.78, 0.93) and greater reduction in end-of-treatment ATS craving in studies with mixed ATS use frequency (SMD: -0.46; 95%CI: -0.70, -0.22) and male-only samples (SMD: -1.26; 95%CI: -1.87, -0.65).

CONCLUSION

Bupropion showed a significant modest reduction in ATS use and ATS craving (both rated as very low-quality evidence), larger in males (craving), and with longer treatment (ATS use). These results may inform future studies. More research is warranted on who might benefit from bupropion as ATSUD treatment.

Modeling methamphetamine use disorder and relapse in animals: short- and long-term epigenetic, transcriptional., and biochemical consequences in the rat brain

Methamphetamine use disorder (MUD) is a neuropsychiatric disorder characterized by binge drug taking episodes, intervals of abstinence, and relapses to drug use even during treatment. MUD has been modeled in rodents and investigators are attempting to identify its molecular bases. Preclinical experiments have shown that different schedules of methamphetamine self-administration can cause diverse transcriptional changes in the dorsal striatum of Sprague-Dawley rats. In the present review, we present data on differentially expressed genes (DEGs) identified in the rat striatum following methamphetamine intake. These include genes involved in transcription regulation, potassium channel function, and neuroinflammation. We then use the striatal data to discuss the potential significance of the molecular changes induced by methamphetamine by reviewing concordant or discordant data from the literature. This review identified potential molecular targets for pharmacological interventions. Nevertheless, there is a need for more research on methamphetamine-induced transcriptional consequences in various brain regions. These data should provide a more detailed neuroanatomical map of methamphetamine-induced changes and should better inform therapeutic interventions against MUD.

Methamphetamine (MA) use and MA-induced psychosis are associated with increasing aberrations in the compensatory immunoregulatory system, interleukin-1α, and CCL5 levels

There are only a few studies reporting on the immunological profiles of methamphetamine (MA) use, MA dependency, or MA-induced psychosis (MAP). This study measured M1 macrophage, T helper (Th)-1, Th-2, growth factor, and chemokine profiles, as well as the immune inflammatory response system (IRS) and compensatory immunoregulatory system (CIRS) in peripheral blood samples from patients with MA use (n = 51), MA dependence (n = 47), and MAP (n = 43) in comparison with controls (n = 32). We discovered that persistent MA use had a robust immunosuppressive impact on all immunological profiles. The most reliable biomarker profile of MA use is the combination of substantial CIRS suppression and a rise in selected pro-inflammatory cytokines, namely CCL27 (CTACK), CCL11 (eotaxin), and interleukin (IL)-1α. In addition, MA dependency is associated with increased immunosuppression, as demonstrated by lower stem cell factor levels and higher IL-10 levels. MAP is related to a significant decrease in all immunological profiles, particularly CIRS, and an increase in CCL5 (RANTES), IL-1α, and IL-12p70 signaling. In conclusion, long-term MA use and dependency severely undermine immune homeostasis, whereas MAP may be the consequence of increased IL-1α - CCL5 signaling superimposed on strongly depleted CIRS and Th-1 functions. The widespread immunosuppression established in longstanding MA use may increase the likelihood of infectious and immune illness or exacerbate disorders such as hepatitis and AIDS. Furthermore, elevated levels of CCL5, CCL11, CCL27, IL-1α, and/or IL-12p70 may play a role in the peripheral (atherosclerosis, cutaneous inflammation, immune aberrations, hypospermatogenesis) and central (neuroinflammation, neurotoxic, neurodegenerative, depression, anxiety, and psychosis) side effects of MA use.

Effect of aerobic exercise on brain metabolite profiles in the mouse models of methamphetamine addiction: LC-MS-based metabolomics study

Methamphetamine (MA) abuse is recognized as a brain disorder, and physical activity has clear benefits for MA use disorders. The specific mechanisms by which physical activity alleviates MA use disorders are currently not fully understood. Based on this, the present study used untargeted metabolomics using liquid chromatography-mass spectrometry (LC-MS) to analyze the metabolic changes induced by MA in the brains of mice by exercise intervention. It was found that after 2 weeks of treadmill training, aerobic exercise modulated MA-induced brain metabolic disorders, in which 129 metabolites existed that were significantly differentiated in response to MA induction, and 32 metabolites were significantly affected by exercise. These differential metabolites were mainly enriched in glycerophospholipid metabolism, steroid hormone biosynthesis and degradation, and renin-angiotensin system pathways. To our knowledge, this study is the first to use LC-MS to investigate the effects of aerobic exercise on MA-induced brain metabolic profiling. The findings of this study provide new insights into exercise therapy using MA.

Hyperconnectivity of the lateral amygdala in long-term methamphetamine abstainers negatively correlated with withdrawal duration

Introduction: Several studies have reported structural and functional abnormalities of the amygdala caused by methamphetamine addiction. However, it is unknown whether abnormalities in amygdala function persist in long-term methamphetamine abstainers. Methods: In this study, 38 long-term male methamphetamine abstainers (>12 months) and 40 demographically matched male healthy controls (HCs) were recruited. Considering the heterogeneous nature of the amygdala structure and function, we chose 4 amygdala subregions (i.e., left lateral, left medial, right lateral, and right medial) as regions of interest (ROI) and compared the ROI-based resting-state functional connectivity (FC) at the whole-brain voxel-wise between the two groups. We explored the relationship between the detected abnormal connectivity, methamphetamine use factors, and the duration of withdrawal using correlation analyses. We also examined the effect of methamphetamine use factors, months of withdrawal, and sociodemographic data on detected abnormal connectivity through multiple linear regressions. Results: Compared with HCs, long-term methamphetamine abstainers showed significant hyperconnectivity between the left lateral amygdala and a continuous area extending to the left inferior/middle occipital gyrus and left middle/superior temporal gyrus. Abnormal connections negatively correlated with methamphetamine withdrawal time (r = -0.85, p < 0.001). The linear regression model further demonstrated that the months of withdrawal could identify the abnormal connectivity (βadj = -0.86, 95%CI: -1.06 to -0.65, p < 0.001). Discussion: The use of methamphetamine can impair the neural sensory system, including the visual and auditory systems, but this abnormal connectivity can gradually recover after prolonged withdrawal of methamphetamine. From a neuroimaging perspective, our results suggest that withdrawal is an effective treatment for methamphetamine.

Single-nucleus transcriptome profiling of prefrontal cortex induced by chronic methamphetamine treatment

Background

Methamphetamine (METH) addiction causes a huge burden on society. The prefrontal cortex (PFC), associated with emotion and cognitive behaviours, is also involved in addiction neurocircuitry. Although bulk RNA sequencing has shown METH-induced gene alterations in the mouse PFC, the impact on different cell types remains unknown.

Aims

To clarify the effects of METH treatment on different cell types of the PFC and the potential pathways involved in METH-related disorders.

Methods

We performed single-nucleus RNA sequencing (snRNA-seq) to examine the transcriptomes of 20 465 nuclei isolated from the PFC of chronic METH-treated and control mice. Main cell types and differentially expressed genes (DEGs) were identified and confirmed by RNA fluorescence in situ hybridization(FISH).

Results

Six main cell types were identified depending on the single-cell nucleus sequencing; of particular interest were the mature oligodendrocytes in the PFC. The DEGs of mature oligodendrocytes were enriched in the myelin sheath, adenosine triphosphate (ATP) metabolic process, mitochondrial function and components, and so on. The messenger RNA levels of Aldoc and Atp5l (FISH) and the protein level of the mitochondrial membrane pore subunit TOM40 (immunofluorescence) decreased in the mature oligodendrocytes. Fast blue staining and transmission electron microscopy image indicated myelin damage, and the myelin thickness decreased in METH brains.

Conclusions

snRNA-seq reveals altered transcriptomes of different cell types in mouse PFC induced by chronic METH treatment, underscoring potential relationships with psychiatric disorders.

Association between rumination and drug craving in Chinese male methamphetamine use disorder patients with childhood trauma

BACKGROUND

In China, males make up the majority of methamphetamine (MA) dependent individuals and the majority of treatment seekers. Childhood trauma (CT) and rumination are associated with an increased risk of MA use. However, the association between CT, rumination, and drug craving remains largely unknown.

OBJECTIVE

The present study aims to explore the association between rumination and drug craving in methamphetamine use disorder (MAUD) patients with CT.

PARTICIPANTS AND SETTING

This study recruited 404 male participants with MAUD from a male drug rehabilitation center in Southwest China.

METHODS

Patients with CT were identified by the short form of Childhood Trauma Questionnaire (CTQ-SF). Rumination and drug craving were assessed by the Ruminative Responses Scale (RRS) and the Obsessive Compulsive Drug Use Scale (OCDUS), respectively.

RESULTS

188 patients (46.5 %) experienced CT. Patients who had experienced CT showed significantly higher RRS symptom rumination score and OCDUS total score than those who had not. In patients with CT, RRS total and all subscale scores were positively associated with OCDUS interference of drug. Furthermore, the RRS brooding (β = 0.34, p < 0.001) and total scores (β = 0.38, p < 0.001) were determined to be separate contributors to the OCDUS total score in patients with CT.

CONCLUSIONS

Our study suggests that CT is common in male MAUD patients, and those who have suffered CT may exhibit higher levels of rumination and drug craving. Moreover, CT may play an influential role in the association between rumination and drug craving in patients with MAUD.

Prescription psychostimulants as a harm reduction and treatment intervention for methamphetamine use disorder and the implications for nursing clinical practice: A scoping review of the literature

The global rise in methamphetamine use and its negative effects warrants the need for research exploring harm reduction and treatment interventions for individuals with methamphetamine use disorder. Agonist medications have been utilized for years for the treatment of heroin and opioid addiction, but have yet to be incorporated into mainstream Canadian practice for methamphetamine dependence. This review aims to provide an overview of the current trends of prescription psychostimulant usage for individuals with methamphetamine use disorder from a Canadian perspective, identifies the barriers to accessing prescription psychostimulants for methamphetamine use disorder and highlights the nursing clinical practice implications in caring for individuals with the disorder. Discourse on the sustained abstinence and harm reduction debate is presented from the perspective of methamphetamine abuse is provided along with the neuropsychiatric complications of chronic methamphetamine use. The impacts of specific prescription psychostimulants on cognition are discussed as is the use of neuroimaging techniques to assess neuronal damage in methamphetamine users. Sign of toxicity, overdose and the contraindications for use of these prescription psychostimulants is also presented. The implications to nursing clinical practice in caring for this population is provided, touching on the clinical presentation of methamphetamine use, completing thorough assessment and screening and patient education. The findings of this review indicate the need for further research in this area exploring the benefits of prescription psychostimulants as a harm reduction and treatment intervention for the global problem of methamphetamine dependence.

Corpus-Based Discourse Analysis of a Reddit Community of Users of Crystal Methamphetamine: Mixed Methods Study

BACKGROUND

Methamphetamine is a highly addictive stimulant that affects the central nervous system. Crystal methamphetamine is a form of the drug resembling glass fragments or shiny bluish-white rocks that can be taken through smoking, swallowing, snorting, or injecting the powder once it has been dissolved in water or alcohol.

OBJECTIVE

The objective of this study is to examine how identities are socially (discursively) constructed by people who use methamphetamine within a subreddit for people who regularly use crystal meth.

METHODS

Using a mixed methods approach, we analyzed 1000 threads (318,422 words) from a subreddit for regular crystal meth users. The qualitative component of the analysis used concordancing and corpus-based discourse analysis to identify discursive themes informed by assemblage theory. The quantitative portion of the analysis used corpus linguistic techniques including keyword analysis to identify words occurring with statistically marked frequency in the corpus and collocation analysis to analyze their discursive context.

RESULTS

Our findings reveal that the subreddit contributors use a rich and varied lexicon to describe crystal meth and other substances, ranging from a neuroscientific register (eg, methamphetamine and dopamine) to informal vernacular (eg, meth, dope, and fent) and commercial appellations (eg, Adderall and Seroquel). They also use linguistic resources to construct symbolic boundaries between different types of methamphetamine users, differentiating between the esteemed category of "functional addicts" and relegating others to the stigmatized category of "tweakers." In addition, contributors contest the dominant view that methamphetamine use inevitably leads to psychosis, arguing instead for a more nuanced understanding that considers the interplay of factors such as sleep deprivation, poor nutrition, and neglected hygiene.

CONCLUSIONS

The subreddit contributors' discourse offers a "set and setting" perspective, which provides a fresh viewpoint on drug-induced psychosis and can guide future harm reduction strategies and research. In contrast to this view, many previous studies overlook the real-world complexities of methamphetamine use, perhaps due to the use of controlled experimental settings. Actual drug use, intoxication, and addiction are complex, multifaceted, and elusive phenomena that defy straightforward characterization.

Housing Instability Associated with Return to Stimulant Use among Previously Abstaining Women

Stimulant use among unstably housed individuals is associated with increased risks of psychiatric co-morbidity, violence, HIV transmission, and overdose. Due to a lack of highly effective treatments, evidence-based policies targeting the prevention of stimulant use disorder are of critical importance. However, little empirical evidence exists on risks associated with initiating or returning to stimulant use among at-risk populations. In a longitudinal cohort of unstably housed women in San Francisco (2016-2019), self-reported data on stimulant use, housing status, and mental health were collected monthly for up to 6 months, and factors associated with initiating stimulants after a period of non-use were identified through logistic regression. Among 245 participants, 42 (17.1%) started using cocaine and 46 (18.8%) started using methamphetamine. In analyses adjusting for demographics and socio-structural exposures over the preceding month, experiencing street homelessness was associated with initiating cocaine use (AOR: 2.10; 95% CI: 1.04, 4.25) and sheltered homelessness with initiating methamphetamine use (AOR: 2.57; 95% CI: 1.37, 4.79). Other factors-including race, income, unmet subsistence needs, mental health, and treatment adherence-did not reach levels of significance, suggesting the paramount importance of policies directed toward improving access to permanent supportive housing to prevent stimulant use among unstably housed women.

EGCG attenuates METH self-administration and reinstatement of METH seeking in mice

Methamphetamine (METH) use disorder is a chronic, relapsing disorder and involves frequent failures of self-control of drug seeking and taking. Epigallocatechin-3-gallate (EGCG) is the most abundant polyphenolic compounds of green tea, which has shown great therapeutic effectiveness in neurological disorders. However, it is still unknown whether and how EGCG affects METH seeking behaviour. Here, we show nanostructured EGCG/ascorbic acid nanoparticles (EGCG/AA NPs) dose-dependently reduced METH self-administration (SA) under fixed-ratio 1 (FR1) and progressive ratio (PR) reinforcement schedules in mice and shifted METH dose-response curves downward. Furthermore, EGCG/AA NPs decreased drug- and cue-induced METH seeking. In addition, we found that METH SA led to a decrease in inhibitory postsynaptic currents (IPSCs) and increase in the AMPAR/NMDAR ratio and excitation/inhibition (E/I) ratio in ex vivo midbrain slices from ventral tegmental area (VTA) dopamine neurons. EGCG/AA NPs enhanced Gamma-aminobutyric acid (GABA)ergic inhibition and normalized the E/I ratio. EGCG restored the balance between excitation and inhibition in VTA dopamine neurons, which may contribute to the attenuation of METH SA. These findings indicate that EGCG is a promising pharmacotherapy for METH use disorder.

Pharmacology of R-(-)-Methamphetamine in Humans: A Systematic Review of the Literature

Methamphetamine exists as two stereoisomers: S-(+)-methamphetamine ((+)-MAMP) and R-(-)-methamphetamine ((-)-MAMP). The (+)-MAMP stereoisomer is a well-known central nervous system stimulant, available as a pharmaceutical and clandestine drug of abuse. However, the (-)-MAMP stereoisomer is less well understood despite commercial availability for over 30 years as an over-the-counter (OTC) nasal decongestant in the Vicks Vapor Inhaler (a product of Procter & Gamble). Recently, several generic versions have become available, decreasing the cost and increasing the availability of (-)-MAMP-containing nasal sprays to consumers. Despite widespread commercial availability and use in the United States, a paucity of literature exists on the pharmacology of (-)-MAMP in humans. This knowledge gap is problematic, given the difficulty in separating (-)-MAMP and (+)-MAMP isomers in laboratory assays for workplace drug testing, suspected impaired drivers, post-mortem investigations, and assessment of drug involvement in crimes. In response, this systematic review of the literature coalesces and summarizes available knowledge of (-)-MAMP pharmacology in humans. It was found that available knowledge relies heavily on urine drug and metabolite concentrations, systematic pharmacokinetics studies are lacking, and existing knowledge has been derived from a total of 99 unique participants. The impacts of highlighted gaps in the literature are discussed, focusing on forensic toxicology and law enforcement, and future research directions are suggested.

Identification of PROK2 gene polymorphisms as predictors of methamphetamine use disorder risk and indicators of craving scale in the Chinese Han population

Background: Methamphetamine use disorder (MUD) has become a global problem due to the highly addictive nature of methamphetamine. Earlier research have demonstrated that PROK2 functions as a compensatory and protective response against neurotoxic stress by stimulating astrocyte reactivity. The aim of our study was to evaluate the correlation between the PROK2 gene and both MUD risk susceptibility and craving scale in the Chinese Han population. Methods: A total of 5,282 participants (1,796 MUD patients and 3,486 controls) were recruited. Seven tag SNPs of the PROK2 gene were chosen and genotyped in the samples. Genetic association analyses were performed to capture the significant SNPs. To investigate the relationship between PROK2 levels and craving scores with the associated-SNP genotypes, we conducted a linear model. Results: SNP rs75433452 was significantly linked with MUD risk (p-value = 1.54 × 10^-8), with the A allele being positively correlated with an increased risk of MUD. Moreover, the average serum level of PROK2 decreased when more copies of the A allele were presented in both MUD patients (p-value = 4.57 × 10^-6) and controls (p-value = 1.13 × 10^-5). Furthermore, the genotypes of SNP rs75433452 were strongly correlated with the craving scores in MUD patients (p-value = 4.05 × 10^-4). Conclusion: Our study identified a significant association signal of the PROK2 gene with MUD risk susceptibility and methamphetamine craving scores in the Chinese Han population, providing potential valuable insights into the underlying mechanisms of METH dependence.

Serum Methamphetamine Positivity in Trauma Patients Undergoing Surgery has No Negative Effect on Postoperative Morbidity and Mortality

Introduction

The link between methamphetamine (METH) use and mortality or morbidity, particularly perioperative complications, associated with trauma surgery are not well characterized. This study aims to address this by performing a comparison of surgical outcomes between METH-negative (METH-) and METH-positive (METH+) trauma patients.

Methods

An Institutional Review Board-approved retrospective chart review was performed on all trauma patients admitted to our Level 1 trauma center who underwent surgical operations between 2015 and 2020. Patients were categorized into METH- and METH+ groups. Patient characteristics such as age, sex, race, Injury Severity Score (ISS), presence of peri-operative complications, and mortality, amongst others, were used to perform univariate comparisons. Additional multi-variate comparisons were performed across both the whole cohort and with age, sex, and ISS-matched groups.

Results

Of 571 patients who met the final inclusion criteria, 421 were METH- and 150 METH+. The METH+ group also possessed a lower median ISS (P = 0.0478) and did not possess significantly different mortality or morbidity than their METH- counterparts in univariate analysis. Multivariate analysis in whole-group and matched-group cohorts indicated that METH was not a positive predictor of mortality or morbidity. Instead, ISS predicted mortality (P = 0.048) and morbidity (P < 0.001).

Conclusion

Our results suggest that METH use does not exert a positive effect on mortality or morbidity in the acute trauma surgery setting and that ISS may be a more significant contributor, suggesting severity, and etiology of injury are also important considerations for trauma surgery evaluation.

Stimulant and hallucinogenic novel psychoactive substances; an update

INTRODUCTION

The renewed interest in considering a range of stimulants, psychedelics and dissociatives as therapeutics emphasizes the need to draft an updated overview of these drugs' clinical and pharmacological issues.

AREAS COVERED

The focus here was on: stimulants (e.g. amphetamines, methamphetamine, and pseudoephedrine; phenethylamines; synthetic cathinones; benzofurans; piperazines; aminoindanes; aminorex derivatives; phenmetrazine derivatives; phenidates); classical (e.g. ergolines; tryptamines; psychedelic phenethylamines), and atypical (e.g. PCP/ketamine-like dissociatives) psychedelics.Stimulant and psychedelics are associated with: a) increased central DA levels (psychedelic phenethylamines, synthetic cathinones and stimulants); b) 5-HT receptor subtypes' activation (psychedelic phenethylamines; recent tryptamine and lysergamide derivatives); and c) antagonist activity at NMDA receptors, (phencyclidine-like dissociatives).

EXPERT OPINION

Clinicians should be regularly informed about the range of NPS and their medical, psychobiological and psychopathological risks both in the acute and long term. Future research should focus on an integrative model in which pro-drug websites' analyses are combined with advanced research approaches, including computational chemistry studies so that in vitro and in vivo preclinical studies of index novel psychoactives can be organized. The future of psychedelic research should focus on identifying robust study designs to convincingly assess the potential therapeutic benefits of psychedelics, molecules likely to present with limited dependence liability levels.

A gender-based secondary analysis of the ADAPT-2 combination naltrexone and bupropion treatment for methamphetamine use disorder trial

BACKGROUND AND AIMS

Socio-cultural (gender) and biological (sex)-based differences contribute to psychostimulant susceptibility, potentially affecting treatment responsiveness among women with methamphetamine use disorder (MUD). The aims were to measure (i) how women with MUD independently and compared with men respond to treatment versus placebo and (ii) among women, how the hormonal method of contraception (HMC) affects treatment responsiveness.

DESIGN

This was a secondary analysis of ADAPT-2, a randomized, double-blind, placebo-controlled, multicenter, two-stage sequential parallel comparison design trial.

SETTING

United States.

PARTICIPANTS

This study comprised 126 women (403 total participants); average age = 40.1 years (standard deviation = 9.6) with moderate to severe MUD.

INTERVENTIONS

Interventions were combination intramuscular naltrexone (380 mg/3 weeks) and oral bupropion (450 mg daily) versus placebo.

MEASUREMENTS

Treatment response was measured using a minimum of three of four negative methamphetamine urine drug tests during the last 2 weeks of each stage; treatment effect was the difference between weighted treatment responses of each stage.

FINDINGS

At baseline, women used methamphetamine intravenously fewer days than men [15.4 versus 23.1% days, P = 0.050, difference = -7.7, 95% confidence interval (CI) = -15.0 to -0.3] and more women than men had anxiety (59.5 versus 47.6%, P = 0.027, difference = 11.9%, 95% CI = 1.5 to 22.3%). Of 113 (89.7%) women capable of pregnancy, 31 (27.4%) used HMC. In Stage 1 29% and Stage 2 5.6% of women on treatment had a response compared with 3.2% and 0% on placebo, respectively. A treatment effect was found independently for females and males (P < 0.001); with no between-gender treatment effect (0.144 females versus 0.100 males; P = 0.363, difference = 0.044, 95% CI = -0.050 to 0.137). Treatment effect did not differ by HMC use (0.156 HMC versus 0.128 none; P = 0.769, difference = 0.028, 95% CI -0.157 to 0.212).

CONCLUSIONS

Women with methamphetamine use disorder receiving combined intramuscular naltrexone and oral bupropion treatment achieve greater treatment response than placebo. Treatment effect does not differ by HMC.

Neuroprotective Effects of Selegiline Agent Methamphetamine-Prompted Mood-Related Behavior Disorder Mediated Via 5-HT2 and D2 Receptors

Background

Many previous studies demonstrated that methamphetamine (METH) abuses can cause mood-related behavioral changes. Previous studies indicated neuroprotective effects of Selegiline.

Methods

Seventy male Wistar rats were randomly divided into eight groups (10 rats in each group). Group 1 and Group 2 received normal saline and methamphetamine (10 mg/kg) for 21 days, respectively. Groups 3, 4, and 5 were treated simultaneously with methamphetamine and Selegiline with doses of 10, 15, and 20 mg/kg for 21 days. Groups 6 and 7 are methamphetamine-dependent groups which received 15 mg/kg of Selegiline with haloperidol (as D2 receptor antagonist) and trazodone (as 5-HT2 receptor antagonist) for 21 days, respectively. In days 23 and 24, elevated plus maze (EPM) and open-field test (OFT) were conducted to assess motor activity and mood (anxiety and depression) levels.

Results

METH as 10 mg/kg causes reduction of rearing number, ambulation distances, time spent in central square and also number of central square entries in OFT. Also METH administration causes decreases of time spent in open arm and number of open arm entries and increases of time spent in closed arm and number of closed arm entries in EPM. In contrast, Selegiline (of 10, 15, and 20 mg/kg) inhibited behavioral effects of methamphetamine in both OFT and EPM. Also administration of haloperidol and trazodone inhibited these behavioral protective effects of Selegiline and caused decrease of OFT behaviors (rearing number, ambulation distances, time spent in central square, and also number of central square entries) and also caused decreases of spend times in open arm, number of open arm entries, and also increased closed arm time spending and number of entries in closed arm in EPM.

Conclusions

Current research showed that Selegiline via mediation of D2 and 5-HT2 receptors inhibits METH-induced neurobehavioral changes, mood-related behavior, and motor activity disturbances.

Practice Considerations for the Methamphetamine Use Disorder Patient

Methamphetamine substance use disorders (SUD) are a topic of increasing concern in the United States or America and continue to impact families and communities throughout the United States. Methamphetamine users account for approximately 1.6 million individuals. It is important for health care providers to be aware of the potential lethal impacts of restraining aggressive individuals. It is equally important to understand the impacts of increased circulating catecholamines or subsequent dearth after methamphetamine use and how medications may impact either state. Methamphetamine SUD patients can pose challenges to health care workers, however, safe and effective care is obtainable.

Histone modifications in cocaine, methamphetamine and opioids

Cocaine, methamphetamine and opioids are leading causes of drug abuse-related deaths worldwide. In recent decades, several studies revealed the connection between and epigenetics. Neural cells acquire epigenetic alterations that drive the onset and progress of the SUD by modifying the histone residues in brain reward circuitry. Histone modifications, especially acetylation and methylation, participate in the regulation of gene expression. These alterations, as well as other host and microenvironment factors, are associated with a serious of negative neurocognitive disfunctions in various patient populations. In this review, we highlight the evidence that substantially increase the field's ability to understand the molecular actions underlying SUD and summarize the potential approaches for SUD pharmacotherapy.

The impact of opioid-stimulant co-use on tonic and cue-induced craving

The twin opioid-stimulant epidemics have led to increased overdose deaths and present unique challenges for individuals entering treatment with opioid-stimulant polysubstance use. This study examined tonic and cue-induced craving as a primary outcome among persons in substance use treatment who reported primary substances of opioids, methamphetamine, or cocaine. The sample consisted of 1974 individuals in 55 residential substance-use treatment centers in the United States in 2021. Weekly surveys were delivered via a third-party outcomes tracking system, including measures of tonic and cue-induced craving. Initial comparisons on tonic and cue-induced craving were made among those who primarily used opioids, cocaine, or methamphetamine. Further, the effect of opioid/stimulant polysubstance use on tonic and cue-induced craving was evaluated using marginal effect regression models. Primary methamphetamine use was associated with decreased tonic craving compared to primary opioid use (β = -5.63, p < 0.001) and primary cocaine use was also associate with decreased tonic craving compared to primary opioid use (β = -6.14, p < 0.001). Primary cocaine use was also associated with lower cue-induced cravings compared to primary opioid use (β = -0.53, p = 0.037). Opioid-methamphetamine polysubstance use was associated with higher tonic craving (β = 3.81, p = <0.001) and higher cue-induced craving (β = 1.55, p = 0.001); however, this was not the case for opioid-cocaine polysubstance use. The results of this study indicate that individuals who primarily use opioids and have secondary methamphetamine use experience higher cue-induced and tonic-induced craving, suggesting that these individuals may benefit from additional interventions that target craving and mitigate relapse risk and other negative sequelae.

Rhynchophylline inhibits methamphetamine dependence via modulating the miR-181a-5p/GABRA1 axis

ETHNOPHARMACOLOGICAL RELEVANCE

Uncaria rhynchophylla (Miq.) Miq. ex Havil. is a plant species that is routinely devoted in traditional Chinese medicine to treat central nervous system disorders. Rhynchophylline (Rhy), a predominant alkaloid isolated from Uncaria rhynchophylla (Miq.) Miq. ex Havil., has been demonstrated to reverse methamphetamine-induced (METH-induced) conditioned place preference (CPP) effects in mice, rats and zebrafish. The precise mechanism is still poorly understood, thus further research is necessary.

AIM OF STUDY

This study aimed to investigate the role of miRNAs in the inhibitory effect of Rhy on METH dependence.

MATERIALS AND METHODS

A rat CPP paradigm and a PC12 cell addiction model were established. Microarray assays were used to screen and identify the candidate miRNA. Behavioral assessment, real-time PCR, dual-luciferase reporter assay, western blotting, stereotaxic injection of antagomir/agomir and cell transfection experiments were performed to elucidate the effect of the candidate miRNA and intervention mechanism of Rhy on METH dependence.

RESULTS

Rhy successfully reversed METH-induced CPP effect and the upregulated miR-181a-5p expression in METH-dependent rat hippocampus and PC12 cells. Moreover, suppression of miR-181a-5p by antagomir 181a reversed METH-induced CPP effect. Meanwhile, overexpression of miR-181a-5p by agomir 181a in combination with low-dose METH (0.5 mg/kg) elicited a significant CPP effect, which was blocked by Rhy through inhibiting miR-181a-5p. Finally, the result demonstrated that miR-181a-5p exerted its regulatory role by targeting γ-aminobutyric acid A receptor α1 (GABRA1) both in vivo and in vitro.

CONCLUSION

This finding reveals that Rhy inhibits METH dependence via modulating the miR-181a-5p/GABRA1 axis, which may be a promising target for treatment of METH dependence.