Cognitive deficits in methamphetamine addiction: Independent contributions of dependence and intelligence

Specific endophenotypes in EEG microstates for methamphetamine use disorder

Background

Electroencephalogram (EEG) microstates, which reflect large-scale resting-state networks of the brain, have been proposed as potential endophenotypes for methamphetamine use disorder (MUD). However, current endophenotypes lack refinement at the frequency band level, limiting their precision in identifying key frequency bands associated with MUD.

Methods

In this study, we investigated EEG microstate dynamics across various frequency bands and different tasks, utilizing machine learning to classify MUD and healthy controls.

Results

During the resting state, the highest classification accuracy for detecting MUD was 85.5%, achieved using microstate parameters in the alpha band. Among these, the coverage of microstate class A contributed the most, suggesting it as the most promising endophenotype for specifying MUD.

Discussion

We accurately categorize the endophenotype of MUD into different sub-frequency bands, thereby providing reliable biomarkers.

A multinational analysis of how emotions relate to economic decisions regarding time or risk

Emotions have been theorized to be important drivers of economic choices, such as intertemporal or risky decisions. Our systematic review and meta-analysis of the previous literature (378 results and 50,972 participants) indicates that the empirical basis for these claims is mixed and the cross-cultural generalizability of these claims has yet to be systematically tested. We analysed a dataset with representative samples from 74 countries (n = 77,242), providing a multinational test of theoretical claims that individuals' ongoing emotional states predict their economic preferences regarding time or risk. Overall, more positive self-reported emotions generally predicted a willingness to wait for delayed rewards or to take favourable risks, in line with some existing theories. Contrary to the assumption of a universal relationship between emotions and decision-making, we show that these relationships vary substantially and systematically across countries. Emotions were stronger predictors of economic decisions in more economically developed and individualistic countries.

Gender disparities in neuropsychological assessment research in drug abuse populations: A systematic review

Objective: To systematically review the literature on the neurocognitive effects of drug use to determine if there are significant gender differences. Methods: In April 2023, we conducted a broad search in MEDLINE (via PubMed), PsycINFO, and Embase for original research studies that used objective neuropsychological assessment to evaluate neurocognition in persons with drug use. Data extraction was performed in a masked, duplicate fashion. Results: Our initial search returned 22,430 records, of which 273 articles were included in our analysis. We found significant underrepresentation of women as participants in the studies. Twenty-one percent of studies had exclusively male participants; when women were included, they averaged only 23% of the sample. Only 49 studies sufficiently documented an analysis of their results by gender; due to the heterogeneity in study characteristics, no conclusions about cognitive differences between women and men could be made. Conclusions: Women are significantly underrepresented in the research on cognition in drug use. Increased efforts to include more women participants and consistent analysis and reporting of data for potential gender differences will be required to close this gap in knowledge, which may lead to improved substance abuse treatment approaches for women.

Extended ambulatory assessment of executive function: within-person reliability of working memory and inhibitory control tasks

INTRODUCTION

Ambulatory assessment of executive function - particularly in the form working memory (WM) - is increasingly common. Few studies to date, however, have also incorporated ambulatory measures of inhibitory control. Critically, the extended within-person reliability of ambulatory tasks tapping each of these constructs has been largely overlooked.

METHOD

Participants (N = 283, Mage = 23.74 years, SD = 9.04) received notifications every 3 days (for 4 weeks) to undertake ambulatory assessment versions of the n-Back and Stop-Signal Tasks (SST) via the smartphone application CheckCog. Within-person reliability of these measures was explored.

RESULTS

Compliance ranged from 66% (for eight sessions) to 89% (for four sessions). Our results reveal significant changes in performance within the first two sessions for both the n-Back and SST, with performance remaining largely consistent across the remaining (two to eight) sessions. In terms of test-retest reliability, the ICC (C, 1) values ranged from .29 to .68 on the n-Back (with overall accuracy being .51) and .31-.73 on the SST (with stop-signal reaction time being .53).

CONCLUSION

The results of the current study contribute to the literature by demonstrating the reliability of brief measures of executive function - in the form of inhibitory control and WM - delivered using smartphones in participants' natural environments. Based on our findings, the CheckCog app reliability tracks baseline systematic changes in WM and response inhibition across multiple time points and for an extended period in healthy individuals.

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.

The neuroprotective effect of LCZ696 on methamphetamine-induced cognitive impairment in mice

OBJECTIVE

Methamphetamine (METH) exposure commonly causes cognitive impairment. An angiotensin II receptor/neprilysin inhibitor (ARNI), LCZ696 has been demonstrated to inhibit inflammation, oxidative stress and apoptosis. The present study was designed to examine the effect of LCZ696 on METH-induced cognitive impairment and the underlying mechanism.

METHODS

Following daily treatment of either saline or METH (5 mg/kg) for 5 consecutive days, the cognitive function was tested using the Y-maze and the Novel Object Recognition (NOR) in Experiment 1. In Experiment 2, mice were initially treated with saline or LCZ696 (60 mg/kg) for 9 consecutive days, followed by LCZ696, METH or saline for 5 days. Cognitive testing was carried out as Experiment 1. In Experiment 3, SH-SY5Y cells were treated with either METH (2.5 Mm) or ddH2O for 12 h. The apoptosis and reactive oxygen species (ROS) level of SH-SY5Y were examined. In Experiment 4, SH-SY5Y cells were pretreated with either ddH2O or LCZ696 (70um) for 30 min, followed by ddH2O or METH treatment for 12 h. Nrf2 and HO-1 protein expression was examined in the ventral tegemental area (VTA) of all the animals and SH-SY5Y cells.

RESULTS

LCZ696 significantly improved METH-induced cognitive impairment, in conjunction with decreased apoptosis and ROS levels in VTA of METH-treated mice and SH-SY5Y cells. METH significantly decreased Nrf2 and HO-1 protein expression in VTA of mice and SH-SY5Y cells, which was reversed by LCZ696 treatment.

CONCLUSION

LCZ696 yields a neuroprotective effect against METH-induced cognitive dysfunction via the Nrf2/HO-1 signaling pathway.

Analysing the behaviour change of brain regions of methamphetamine abusers using electroencephalogram signals: Hope to design a decision support system

Long-term use of methamphetamine (meth) causes cognitive and neuropsychological impairments. Analysing the impact of this substance on the human brain can aid prevention and treatment efforts. In this study, the electroencephalogram (EEG) signals of meth abusers in the abstinence period and healthy subjects were recorded during eyes-closed and eyes-opened states to distinguish the brain regions that meth can significantly influence. In addition, a decision support system (DSS) was introduced as a complementary method to recognize substance users accompanied by biochemical tests. According to these goals, the recorded EEG signals were pre-processed and decomposed into frequency bands using the discrete wavelet transform (DWT) method. For each frequency band, energy, KS entropy, Higuchi and Katz fractal dimensions of signals were calculated. Then, statistical analysis was applied to select features whose channels contain a p-value less than 0.05. These features between two groups were compared, and the location of channels containing more features was specified as discriminative brain areas. Due to evaluating the performance of features and distinguishing the two groups in each frequency band, features were fed into a k-nearest neighbour (KNN), support vector machine (SVM), multilayer perceptron neural networks (MLP) and linear discriminant analysis (LDA) classifiers. The results indicated that prolonged consumption of meth has a considerable impact on the brain areas responsible for working memory, motor function, attention, visual interpretation, and speech processing. Furthermore, the best classification accuracy, almost 95.8%, was attained in the gamma band during the eyes-closed state.

The General Neurocognitive Decline in Patients with Methamphetamine Use and Transient Methamphetamine-induced Psychosis is Primarily Determined by Oxidative and AGE-RAGE Stress

BACKGROUND

Chronic Methamphetamine (MA) usage is linked to oxidative and AGE (advanced glycation end products) - RAGE (receptors for AGEs) stress, changes in magnesium, calcium, and copper, increased psychotic symptoms, and neurocognitive deficits. Nevertheless, it is still unclear whether these biological pathways mediate the latter impairments.

OBJECTIVE

This study aimed to investigate the relationships between neurocognition, the aforementioned biomarkers, and psychotic symptoms.

METHODS

We recruited 67 participants, namely 40 patients diagnosed with MA-substance use and 27 healthy controls, and assessed the Brief Assessment of Cognition in Schizophrenia (BACS), symptoms of psychosis, excitation, and formal thought disorders, oxidative toxicity (computed as the sum of myeloperoxidase (MPO), oxidized high-density lipoprotein (HDL), oxidized low-DL, and malondialdehyde), antioxidant defenses (catalase, glutathione peroxidase, total antioxidant capacity, zinc, and HDL), and increased AGEs and RAGEs.

RESULTS

We were able to extract one validated latent vector from the Mini-Mental State Examination score and the BACS test results (including executive functions, verbal fluency, and attention), labeled general cognitive decline (G-CoDe). We found that 76.1% of the variance in the G-CoDe was explained by increased oxidative toxicity, lowered antioxidant defenses, number of psychotic episodes, and MA dose. In patients with MA use, MPO was significantly associated with the GCoDe.

CONCLUSION

The use of MA induced mild cognitive impairments through MA-induced activation of detrimental outcome pathways, including oxidative and AGE-RAGE stress, and suppression of protective antioxidant pathways. Increased MPO, oxidative, and AGE-RAGE stress are new drug targets to prevent neurocognitive deficits and psychosis due to MA use.

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.

Semantic clustering on common list-learning tasks: a systematic review of the state of the literature and recommendations for future directions

INTRODUCTION

On some list-learning tasks, such as the California Verbal Learning Test (CVLT) or Hopkins Verbal Learning Test (HVLT), examinees have the opportunity to group words based on semantically related categories (i.e., semantic clustering). Semantic clustering (SC) is often considered the most efficient organizational strategy and adopting SC is presumed to improve learning and memory. In addition, SC is conceptualized as reflecting higher-order executive functioning skills. Although SC measures have intuitive appeal, to date, there are no comprehensive reviews of the SC literature base that summarize its psychometric utility. In this systematic review, we synthesize the literature to judge the validity of SC scores.

METHOD

We conducted a systematic literature search for empirical articles reporting SC from the CVLT and HVLT. We qualitatively described the relationship of SC with other list-learning and cognitive test scores and clinical diagnoses, contrasting SC with serial clustering and total learning scores when possible.

RESULTS

SC was inversely correlated with serial clustering. Higher SC was strongly associated with better learning and memory performances. When compared with cognitive tests, SC tended to have the strongest relationships with other memory measures and modest relationships with tests of executive functioning. SC had negligible to small relationships with most other cognitive domains. Traditional memory scores yielded stronger relationships to cognitive test performances than did SC. SC across clinical groups varied widely, but clinical groups tended to use SC less often than healthy comparison groups.

CONCLUSION

Our comprehensive review of the literature revealed that SC is strongly related to measures of learning and memory on the CVLT and HVLT and is correlated with a wide range of cognitive functions. SC has been understudied in relevant populations and additional research is needed to test the degree to which it adds incremental validity beyond traditional measures of learning and memory.

Methamphetamine dependence in Australia-why is 'ice' (crystal meth) so addictive?

Australia has one of the highest rates in the world of the use of the crystalline form of methamphetamine, a highly addictive stimulant that is often associated with a chronic, relapsing dependency. Methamphetamine use is associated with both acquisitive and violent offending, which cause substantial personal and societal costs. Whilst the short-term euphoria and stimulation provide a positive reinforcement to methamphetamine use, the aversive states of withdrawing from methamphetamine and the associated craving, which may last up to five weeks into abstinence, underlie the negative reinforcement to continued methamphetamine use. Although many methamphetamine-dependent users experience high levels of psychological distress, it is likely that less than half engage with treatment or support services, and current intervention and treatment programmes have high discontinuation rates. Stigma and discrimination, even from paramedics and health clinicians, are prominent barriers to methamphetamine-dependent users accessing treatment in Australia.

Prevalence and correlates of methamphetamine use in transitional age youth experiencing homelessness or housing instability in San Francisco, CA

INTRODUCTION

Substance use, including methamphetamine use, is a contributing factor in HIV acquisition and treatment. Stimulant use is linked to mental health yet there is limited data from youth in community-based settings.

DESIGN

One hundred marginally housed or homeless transitional age youth (TAY) were recruited at Larkin Street Youth Services and completed a survey on mental health and substance use.

METHODS

We conducted secondary data analysis using multivariable logistic regression models to identify the correlates of methamphetamine use among TAY.

RESULTS

The participants' mean age was 22. Of those who reported methamphetamine use in the past 3 months, 64% were Gay, Bisexual, or Pansexual. Factors independently associated with methamphetamine use were; living with HIV (adjusted odds ratio [aOR] = 3.18, 95% CI = 1.11-9.15), depressive symptoms (aOR = 6.02, 95% CI = 1.46-24.78), symptoms of PTSD (aOR = 13.38, 95% CI = 1.59-112.73), polysubstance use in the past 3 months (aOR = 50.02, 95% CI = 9.72-257.46) and a history of injection drug use (aOR = 8.38, 95% CI = 1.87-37.53).

CONCLUSIONS

Results from this study suggest a need to develop, adapt, and rapidly implement comprehensive interventions that address the combined epidemics of substance use, HIV, and mental health among TAY.

CLINICAL RELEVANCE

This article examines factors associated with methamphetamine use among transitional age youth (TAY) experiencing homelessness or housing instability. Several factors were associated with use, including depression, PTSD, HIV status, polysubstance use, and injection drug use. These findings highlight the need for nurses to assess for methamphetamine use among youth as well as associated mental health and physical health problems. Nurses should link TAY who are using methamphetamine to evidence-based treatment programs to address substance use and comorbid conditions.

Comparison of the acute effects of Tai chi versus high-intensity interval training on inhibitory control in individuals with substance use disorder

Objective

The purpose of this study is to investigate the effects of a single session of Tai chi (TC) exercise and high-intensity interval training (HIIT) on inhibitory control in individuals with substance use disorder (SUD).

Methods

A total 47 males with methamphetamine dependence were recruited from a compulsory drug rehabilitation center; participation in this study was voluntary. The participants were randomly assigned to the TC group or the HIIT group, and computer-based Go/No-go and Stroop tasks were used to assess inhibitory control in an indoor setting prior to and following exercise. Independent sample t-test was applied for baseline comparison of continuous variables, while analysis of variance was applied to test differences in the effect of each intervention before and after a single session of exercise.

Results

In Go/No-go test, the reaction time of the TC and HIIT groups in the post-test was shorter than that at the baseline, and the response accuracy of the post-test were higher than that of the baseline. In the Stroop task, the reaction time of two groups in the post-test was shorter than that at the baseline; while, greater improvement in response accuracy was observed in HIIT group in the post-test than that of the baseline.

Conclusion

Both TC and HIIT can promote inhibitory control in individuals with SUD. Compared with the TC group, the HIIT group showed greater improvements in response accuracy. These findings demonstrate the potential of TC and HIIT in improving cognition in SUD.

Clinical trial registration

[http://www.chictr.org.cn/], identifier [ChiCTR1900022158].

Protocol for a cluster randomised crossover pilot trial of Goal Management Training+ (GMT+) for methamphetamine use disorder

Background

Methamphetamine use disorder (MUD) is associated with executive dysfunctions, which are linked with poorer treatment outcomes. However, current treatments for MUD do not directly address cognition. We recently modified Goal Management Training (now Goal Management Training⁺; GMT⁺), a group-based intervention originally designed to improve executive functions after brain injury, to enhance suitability for MUD. Here, we describe the rationale and design of a trial which aims to determine the acceptability and feasibility of GMT⁺ during residential rehabilitation for MUD, and its impact on executive functions and clinical outcomes.

Methods

We used a cluster randomised crossover design: participants are randomised at the cluster level to receive either GMT⁺ or psychoeducation-control (Brain Health Workshop; BHW). GMT⁺ is delivered in four 90-min weekly sessions and includes a between-session journal with 10-min daily activities. The program targets attention, impulse control, goal-setting, and decision-making. BHW is a health-oriented intervention that delivers information about the brain and promotes healthy exercise, diet, and sleep. It is matched to GMT⁺ on program format, length, and time with therapists. We will recruit forty-eight participants with MUD from residential treatment services. Our primary outcomes are acceptability, feasibility, and self-reported executive functioning. Secondary outcomes include craving, quality of life and cognitive performance. Outcome assessments are performed at baseline, post-interventions, 4-week follow-up, and 12-week follow-up.

Conclusions

This study will provide GMT⁺ feasibility and acceptability data and will indicate initial efficacy on executive functions and clinical outcomes in residential treatment for MUD. Information from this pilot trial will inform a powered RCT.

The quantitative analysis of EEG during resting and cognitive states related to neurological dysfunctions and cognitive impairments in methamphetamine abusers

Several lines of evidence demonstrated the deleterious effect of methamphetamine (MA) on neurological and psychological functions. However, recent evidence on the neurological dysfunctions related to cognitive performance and psychosis in MA abusers needs to be elucidated. Therefore, the present study aimed to investigate the neurological functions using EEG measurement during cognitive tests in MA abusers with (MWP) or without (MWOP) psychosis compared to age-matched normal participants. The quantitative EEG (qEEG) was used to reveal the absolute power in 4 brain-wave frequencies including delta, theta, alpha, and beta waves. The results demonstrated poor attention in both groups of MA abusers. The deficit in mental flexibility was observed in MWP. The deficit in inhibition control and working memory were observed in MWOP. The greater delta, alpha and beta brain waves in multiple brain areas were observed in MWP during the resting (eyes-open) state. The greater alpha wave in multiple brain areas of MWP correlated with poor attention. The greater delta wave and lesser beta wave in the frontal brain correlated with poor inhibition and working memory in MWOP respectively. These findings demonstrated the applicability of EEG to determine neurological dysfunction related to cognitive impairments in MA abusers.

Assessing the mediating role of impulsivity between methamphetamine-induced psychotic disorders and increased gambling severity in methamphetamine-dependent individuals

Pathological gambling (PG) and methamphetamine-induced psychotic disorders (MIPD) both frequently occurs in methamphetamine-dependent individuals. The current study examined whether impulsivity mediated the relationship between MIPD and gambling severity. The sample consisted of 320 pathological gamblers with methamphetamine dependence (mean age 32.6 years, ranging from 15 to 64 years) voluntarily recruited from three rehabilitation centers in Hunan, China. The semistructured clinical interview of DSM-IV-TR Axis I Disorders Patient Edition was used to diagnosis the presence of MIPD and PG by registered psychiatrists. The severity of gambling symptoms was assessed using the global assessment of functioning scale, and the Barratt Impulsiveness Scale-11 provided a measure of impulsivity. Of the sample, 53.4% of participants (n = 171) met diagnostic criteria for MIPD. Individuals with a dual diagnosis of MIPD were associated with higher levels of impulsivity and greater gambling severity. Notably, support for our hypothesized mediation model was found such that impulsivity mediated the association between MIPD and gambling severity. Our findings imply that impulsivity appears to be a transdiagnostic process, which may be targeted in treatment among pathological gamblers with a dual diagnosis of MIPD to reduce gambling behaviors. Limits and future directions for research are discussed.

Heroin Addiction Induces Axonal Transport Dysfunction in the Brain Detected by In Vivo MRI

Heroin is a highly addictive drug that causes axonal damage. Here, manganese-enhanced magnetic resonance imaging (MEMRI) was used to dynamically monitor axonal transport at different stages of heroin addiction. Rat models of heroin addiction (HA) and prolonged heroin addiction (PHA) were established by injecting rats with heroin at different stages. Heroin-induced learning and memory deficits were evaluated in the Morris water maze (MWM), and MEMRI was used to dynamically evaluate axonal transport in the olfactory pathway. The expression of proteins related to axonal structure and function was also assessed by Western blotting. Transmission electron microscopy (TEM) was used to observe ultrastructural changes, and protein levels of neurofilament heavy chain (NF-H) were analyzed by immunofluorescence staining. HA rats, especially PHA rats, exhibited worse spatial learning and memory than control rats. Compared with HA rats and control rats, PHA rats exhibited significantly longer escape latencies, significantly fewer platform-location crossings, and significantly more time in the target quadrant during the MWM test. Mn²⁺ transport was accelerated in HA rats. PHA rats exhibited severely reduced Mn²⁺ transport, and the axonal transport rate (ATR) was significantly lower in these rats than in control rats (P < 0.001). The levels of cytoplasmic dynein and kinesin-1 were significantly decreased in the PHA group than in the control group (P < 0.001); additionally, the levels of energy-related proteins, including cytochrome c oxidase (COX) IV and ATP synthase subunit beta (ATPB), were lower in the PHA group (P < 0.001). The brains of heroin-exposed rats displayed an abnormal ultrastructure, with neuronal apoptosis and mitochondrial dysfunction. Heroin exposure decreased the expression of NF-H, as indicated by significantly reduced staining intensities in tissues from HA and PHA rats (P < 0.05). MEMRI detected axonal transport dysfunction caused by long-term repeated exposure to heroin. The main causes of axonal transport impairment may be decreases in the levels of motor proteins and mitochondrial dysfunction. This study shows that MEMRI is a potential tool for visualizing axonal transport in individuals with drug addictions, providing a new way to evaluate addictive encephalopathy.

Cannabidiol inhibits methamphetamine-induced dopamine release via modulation of the DRD1-MeCP2-BDNF-TrkB signaling pathway

RATIONALE

Adaptive alteration of dopamine (DA) system in mesocorticolimbic circuits is an extremely intricate and dynamic process, which contributes to maintaining methamphetamine (METH)-related disorders. There are no approved pharmacotherapies for METH-related disorders. Cannabidiol (CBD), a major non-psychoactive constituent of cannabis, has received attention for its therapeutic potential in treating METH-related disorders. However, the major research obstacles of CBD are the yet to be clarified mechanisms behind its therapeutic potential. Recent evidence showed that DA system may be active target of CBD. CBD could be a promising dopaminergic medication for METH-related disorders.

OBJECTIVES

We investigated the role of the DA receptor D1 (DRD1)-methyl-CpG-binding protein 2 (MeCP2)-brain-derived neurotrophic factor (BDNF)-tyrosine receptor kinase B (TrkB) signaling pathway in DA release induced by METH. Investigating the intervention effects of CBD on the DRD1-MeCP2-BDNF-TrkB signaling pathway could help clarify the underlying mechanisms and therapeutic potential of CBD in METH-related disorders.

RESULTS

METH (400 μM) significantly increased DA release from primary neurons in vitro, which was blocked by CBD (1 μM) pretreatment. METH (400 μM) significantly increased the expression levels of DRD1, BDNF, and TrkB, but decreased the expression of MeCP2 in the neurons, whereas CBD (1 μM) pretreatment notably inhibited the protein changes induced by METH. In addition, DRD1 antagonist SCH23390 (10 μM) inhibited the DA release and protein change induced by METH in vitro. However, DRD1 agonist SKF81297 (10 μM) induced DA release and protein change in vitro, which was also blocked by CBD (1 μM) pretreatment. METH (2 mg/kg) significantly increased the DA level in the nucleus accumbens (NAc) of rats with activation of the DRD1-MeCP2-BDNF-TrkB signaling pathway, but these changes were blocked by CBD (40 or 80 mg/kg) pretreatment.

CONCLUSIONS

This study indicates that METH induces DA release via the DRD1-MeCP2-BDNF-TrkB signaling pathway. Furthermore, CBD significantly inhibits DA release induced by METH through modulation of this pathway.

Computational models of exploration and exploitation characterise onset and efficacy of treatment in methamphetamine use disorder

People with Methamphetamine Use Disorder (PwMUD) spend substantial time and resources on substance use, which hinders their ability to explore alternate reinforcers. Gold‐standard behavioural treatments attempt to remedy this by encouraging action towards non‐drug reinforcers, but substance use often persists. We aimed to unravel the mechanistic drivers of this behaviour by applying a computational model of explore/exploit behaviour to decision‐making data (Iowa Gambling Task) from 106 PwMUD and 48 controls. We then examined the longitudinal link between explore/exploit mechanisms and changes in methamphetamine use 6 weeks later. Exploitation parameters included reinforcement sensitivity and inverse decay (i.e., number of past outcomes used to guide choices). Exploration parameters included maximum directed exploration value (i.e., value of trying novel actions). The Timeline Follow Back measured changes in methamphetamine use. Compared to controls, PwMUD showed deficits in exploitative decision‐making, characterised by reduced reinforcement sensitivity, U = 3065, p = 0.009, and less use of previous choice outcomes, U = 3062, p = 0.010. This was accompanied by a behavioural pattern of frequent shifting between choices, which appeared consistent with random exploration. Furthermore, PwMUD with greater reductions of methamphetamine use at 6 weeks had increased directed exploration (β = 0.22, p = 0.045); greater use of past choice outcomes (β = −0.39, p = 0.002) and greater choice consistency (β = −0.39, p = 0.002). Therefore, limited computational exploitation and increased behavioural exploration characterise PwMUD's presentation to treatment, while increased directed exploration, use of past choice outcomes and choice consistency predict greater reductions of methamphetamine use.

Goofballing of Opioid and Methamphetamine: The Science Behind the Deadly Cocktail

Globally, millions of people suffer from various substance use disorders (SUD), including mono-and polydrug use of opioids and methamphetamine. Brain regions such as the cingulate cortex, infralimbic cortex, dorsal striatum, nucleus accumbens, basolateral and central amygdala have been shown to play important roles in addiction-related behavioral changes. Clinical and pre-clinical studies have characterized these brain regions and their corresponding neurochemical changes in numerous phases of drug dependence such as acute drug use, intoxication, craving, withdrawal, and relapse. At present, many studies have reported the individual effects of opioids and methamphetamine. However, little is known about their combined effects. Co-use of these drugs produces effects greater than either drug alone, where one decreases the side effects of the other, and the combination produces a prolonged intoxication period or a more desirable intoxication effect. An increasing number of studies have associated polydrug abuse with poorer treatment outcomes, drug-related deaths, and more severe psychopathologies. To date, the pharmacological treatment efficacy for polydrug abuse is vague, and still at the experimental stage. This present review discusses the human and animal behavioral, neuroanatomical, and neurochemical changes underlying both morphine and methamphetamine dependence separately, as well as its combination. This narrative review also delineates the recent advances in the pharmacotherapy of mono- and poly drug-use of opioids and methamphetamine at clinical and preclinical stages.

Recovery of superior frontal gyrus cortical thickness and resting-state functional connectivity in abstinent heroin users after 8 months of follow-up

Compared with healthy controls, heroin users (HUs) show evidence of structural and functional brain alterations. However, little is known about the possibility of brain recovery after protracted heroin abstinence. The purpose of this study was to investigate whether brain recovery is possible after protracted abstinence in HUs. A total of 108 subjects with heroin addiction completed structural and functional scans, and 61 of those subjects completed 8-month follow-up scans. Resting-state data and 3D-T1 MR images were collected for all participants, first at baseline and again after 8 months. Cognitive function and craving were measured by the Trail Making Test-A (TMT-A) and Visual Analog Scale for Craving, respectively. The cortical thickness and resting-state functional connectivity (RSFC) differences were then analyzed and compared between baseline and follow-up, and correlations were obtained between neuroimaging and behavioral changes. HUs demonstrated improved cognition (shorter TMT-A time) and reduced craving at the follow-up (HU2) relative to baseline (HU1), and the cortical thickness in the bilateral superior frontal gyrus (SFG) was significantly greater at HU2 than at HU1. Additionally, the RSFC of the left SFG with the inferior frontal gyrus (IFG), insula, and nucleus accumbens and that of the right SFG with the IFG, insula and orbitofrontal cortex (OFC) were increased at HU2. The changes in TMT-A time were negatively correlated with the RSFC changes between the left SFG and the bilateral IFG, the bilateral caudate, and the right insula. The changes in craving were negatively correlated with the RSFC changes between the left OFC and the bilateral SFG. Our results demonstrated that impaired frontal-limbic neurocircuitry can be partially restored, which might enable improved cognition as well as reduced craving in substance-abusing individuals. We provided novel scientific evidence for the partial recovery of brain circuits implicated in cognition and craving after protracted abstinence.

Prenatal methamphetamine-impact on the mother and child-a review

Methamphetamine (MA) is the second most commonly used illicit drug in the world, after cannabis. There are limited data on the outcomes of pregnant MA users but there is rapidly emerging evidence to suggest that they are more vulnerable, marginalized and impoverished compared with other drug-using mothers. MA use during pregnancy is associated with worse pregnancy outcomes and significantly higher rates of co-existing health and psychosocial problems. Newborn infants exposed to MA are at increased risk of perinatal complications, present differently at birth to infants exposed to other drugs of dependency such as opioids and have poorer neurological adaptation and feeding difficulties. Sparse literature from neuroimaging and cohort studies suggests that the neurocognitive deficits in MA exposed children persist, even into adulthood. Current clinical practice guidelines for the care of substance exposed pregnant women are opioid-centric with little attention paid to the consequences of prenatal MA exposure.

Impact of adolescent methamphetamine use on social cognition: A human-mice reverse translation study

BACKGROUND

Methamphetamine dependence is associated with social cognition deficits that may underpin negative social outcomes. However, there are considerable inter-individual differences in social cognition within people with methamphetamine dependence, with age of onset of methamphetamine use being a potential contributing factor.

MATERIALS AND METHODS

We conducted two sequential studies examining the link between age of onset of methamphetamine use (adolescence versus young adulthood) and performance in social cognition tests: (1) a human cross-sectional study in 95 participants with methamphetamine dependence varying in age of onset (38 with adolescent onset and 57 with adult onset) and 49 drug-naïve controls; (2) a mice study in which we tested the effects of methamphetamine exposure during adolescence versus young adulthood on social interaction and aggression, and their potential neurochemical substrates in the striatal dopaminergic system.

RESULTS

We initially showed that people with methamphetamine dependence who started use in adolescence had higher antisocial beliefs (p = 0.046, Cohen's d=0.42) and worse emotion recognition (p = 0.031, Cohen's d=0.44) than those who started use during adulthood. We reasoned that this could be due to either social cognition deficits leading to earlier onset of methamphetamine use, or methamphetamine-induced neuroadaptive effects specific to adolescence. Mice experiments showed that methamphetamine exposure during adolescence specifically decreased social investigation during social interaction and upregulated striatal tyrosine hydroxylase (p < 0.05, Bonferroni corrected). There was no evidence of adolescent-specific methamphetamine effects on aggression or other measures of dopaminergic function.

CONCLUSION

Together, translational findings demonstrate heightened sensitivity to methamphetamine effects on social cognition during adolescence.

Training and transfer effects of working memory updating training in male abstinent long-term methamphetamine users

Methamphetamine use is associated with cognitive impairments, including executive functioning. These impairments might be cause and/or effect of the drug (re-)use and have, therefore, motivated interventions to improve cognitive functioning. Until now, only very few studies have examined the effect of training working memory updating (WMU), one of the core executive functions, in this population. In the present study, 32 long-term male abstinent methamphetamine inpatients received either a multiple-session WMU training or an active control treatment. All participants performed a number of tasks assessing WMU, inhibition, and task-switching ability- before and after treatment. The WMU-trained patients improved their performance on the trained task and on a non-trained WMU task, reflecting near transfer. However, there was no beneficial training-induced effect for the other tasks, indicating the absence of far transfer. Possible treatment implications of these findings were discussed.

Methamphetamine Dysregulation of the Central Nervous System and Peripheral Immunity

Methamphetamine (METH) is a potent psychostimulant that increases extracellular monoamines, such as dopamine and norepinephrine, and affects multiple tissue and cell types in the central nervous system (CNS) and peripheral immune cells. The reinforcing properties of METH underlie its significant abuse potential and dysregulation of peripheral immunity and central nervous system functions. Together, the constellation of METH's effects on cellular targets and regulatory processes has led to immune suppression and neurodegeneration in METH addicts and animal models of METH exposure. Here we extensively review many of the cell types and mechanisms of METH-induced dysregulation of the central nervous and peripheral immune systems. SIGNIFICANCE STATEMENT: Emerging research has begun to show that methamphetamine regulates dopaminergic neuronal activity. In addition, METH affects non-neuronal brain cells, such as microglia and astrocytes, and immunological cells of the periphery. Concurrent disruption of bidirectional communication between dopaminergic neurons and glia in the CNS and peripheral immune cell dysregulation gives rise to a constellation of dysfunctional neuronal, cell, and tissue types. Therefore, understanding the pathophysiology of METH requires consideration of the multiple targets at the interface between basic and clinical neuroscience.

Lack of longitudinal changes in cognition in individuals with methamphetamine use disorder during the first 6 weeks after commencing treatment

Background: Methamphetamine use disorder (MUD) associates with cognitive impulsivity deficits. However, few studies have examined longitudinal changes in cognition, and it remains unclear if deficits resolve during early recovery.Objectives: To compare: (1) cognitive function of individuals with MUD at treatment onset and six-weeks later with controls tested over the same period; (2) cognitive changes in MUD-individuals who remained abstinent versus relapsed.Method: We recruited 108 participants meeting DSM-IV-TR criteria for methamphetamine dependence (81 males) and 50 demographically matched controls (38 males); 77 methamphetamine- dependent participants (59 males) and 48 controls (36 males) were retained at follow-up. We administered response inhibition, delay discounting and uncertainty-based decision-making tests at both endpoints. Relapse was defined as methamphetamine concentrations >0.4 ng/mg at follow-up in hair toxicology.Results: We found a significant time-by-group interaction on uncertainty-based decision-making (effect size: η² = .05), although post-hoc tests to disentangle this interaction yielded inconclusive results (p-range = .14-.40; BF₁₀-range = 0.43-1.67). There were no significant time-by-group interactions on response inhibition or delay discounting, with the former likely a null effect (η²-interaction = .003 and .02; BF_incl = 0.23 and 0.71). There were no significant differences in cognitive recovery between individuals who maintained abstinence (n = 12) versus relapsed (n = 65) (η²-range = .003-.04), although evidence was inconclusive toward whether findings reflected true null effects (BF_incl-range = 0.33-0.75).Conclusion: We did not find evidence that MUD-related cognitive impulsivity deficits improve beyond practice effects over 6 weeks. Findings do not support previous, albeit conflicting, evidence of early recovery of cognitive deficits in MUD.

AMPed-up adolescents: The role of age in the abuse of amphetamines and its consequences on cognition and prefrontal cortex development

Adolescent use of amphetamine and its closely related, methylated version methamphetamine, is alarmingly high in those who use drugs for nonmedical purposes. This raises serious concerns about the potential for this drug use to have a long-lasting, detrimental impact on the normal development of the brain and behavior that is ongoing during adolescence. In this review, we explore recent findings from both human and laboratory animal studies that investigate the consequences of amphetamine and methamphetamine exposure during this stage of life. We highlight studies that assess sex differences in adolescence, as well as those that are designed specifically to address the potential unique effects of adolescent exposure by including groups at other life stages (typically young adulthood). We consider epidemiological studies on age and sex as vulnerability factors for developing problems with the use of amphetamines, as well as human and animal laboratory studies that tap into age differences in use, its short-term effects on behavior, and the long-lasting consequences of this exposure on cognition. We also focus on studies of drug effects in the prefrontal cortex, which is known to be critically important for cognition and is among the later maturing brain regions. Finally, we discuss important issues that should be addressed in future studies so that the field can further our understanding of the mechanisms underlying adolescent use of amphetamines and its outcomes on the developing brain and behavior.

Neurocognitive Dysfunctions and Their Therapeutic Modulation in Patients With Methamphetamine Dependence: A Pilot Study

AIM

Methamphetamine (MA) abuse and dependence are increasing worldwide and are commonly associated with cognitive deficits. Some studies indicate that such impairments can improve if users become abstinent, but overall results remain inconclusive. Hence, we have performed a longitudinal case-control study investigating key surrogates for attention and impulsive decision-making before and after treatment.

METHODS

Thirty patients with MA dependence and 24 non-substance-abusing control participants were recruited. Groups were matched on age, sex and education. All subjects performed a baseline assessment to obtain neurocognitive measures of sustained attention and delay discounting. Patients subsequently participated in an MA-specific relapse prevention program including repeated monitoring of relapse status. After 3 months, participants of both groups were reevaluated for neurocognitive performance.

RESULTS

At baseline, MA patients showed a significantly higher number of omissions compared to controls, indicative of lower sustained attention. Interestingly, we observed a steep decrease of omissions in MA patients to control-group level post treatment. On the other hand, MA patients discounted delayed rewards significantly stronger than controls, indicating a more impulsive choice behavior both before and after treatment.

LIMITATION

The results should be interpreted with care because of the small sample and short follow-up period.

CONCLUSION

Our data support earlier findings on partial recovery of cognitive deficits in MA patients. They also strengthen the indication for recently recommended psychotherapeutic interventions and may provide a behavioral monitoring tool to inform treatment progress.