Cognitive deficits in individuals with methamphetamine use disorder: A meta-analysis

Recent advances in nanotherapeutics for HIV-associated neurocognitive disorders and substance use disorders

Substance use disorders (SUD) and HIV-associated neurocognitive disorders (HAND) work synergistically as a significant cause of cognitive decline in adults and adolescents globally. Current therapies continue to be limited due to difficulties crossing the blood-brain barrier (BBB) leading to limited precision and effectiveness, neurotoxicity, and lack of co-treatment options for both HAND and SUD. Nanoparticle-based therapeutics have several advantages over conventional therapies including more precise targeting, the ability to cross the BBB, and high biocompatibility which decreases toxicity and optimizes sustainability. These advantages extend to other neurological disorders such as Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS). This review summarizes recent advances in nanotechnology for application to HAND, SUD, and co-treatment, as well as other neurological disorders. This review also highlights the potential challenges these therapies face in clinical translation and long-term safety.

Genes, Cognition, and Their Interplay in Methamphetamine Use Disorder

Methamphetamine use disorder is a pressing global health issue, often accompanied by significant cognitive deficits that impair daily functioning and quality of life and complicate treatment. Emerging evidence highlights the potential role of genetic factors in methamphetamine use disorder, particularly in association with cognitive function. This review examines the key genetic and cognitive dimensions and their interplay in methamphetamine use disorder. There is converging evidence from several studies that genetic polymorphisms in BDNF, FAAH, SLC18A1, and SLC18A2 are associated with protection against or susceptibility to the disorder. In addition, people with methamphetamine use disorder consistently displayed impairments in cognitive flexibility and inhibitory control compared with people without the disorder. These cognitive domains were associated with reactivity to methamphetamine cues that were positively correlated with total years of methamphetamine use history. Emerging research also suggests that inhibitory control is negatively correlated with lower blood FAAH mRNA levels, while cognitive flexibility positively correlates with higher blood SLC18A2 mRNA levels, highlighting how genetic and cognitive dimensions interact in methamphetamine use disorder. We also include some future directions, emphasizing potential personalized therapeutic strategies that integrate genetic and cognitive insights. By drawing attention to the interplay between genes and cognition, we hope to advance our understanding of methamphetamine use disorder and inform the development of targeted interventions.

Critical Review of Recently Published Studies Claiming Long-Term Neurocognitive Abnormalities in Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI) is the most common claimed personal injury condition for which neuropsychologists are retained as forensic experts in litigation. Therefore, it is critical that experts have accurate information when testifying as to neurocognitive outcome from concussion. Systematic reviews and six meta-analyses from 1997 to 2011 regarding objective neurocognitive outcome from mTBI provide no evidence that concussed individuals do not return to baseline by weeks to months post-injury. In the current manuscript, a critical review was conducted of 21 research studies published since the last meta-analysis in 2011 that have claimed to demonstrate long-term (i.e., ≥12 months post-injury) neurocognitive abnormalities in adults with mTBI. Using seven proposed methodological criteria for research investigating neurocognitive outcome from mTBI, no studies were found to be scientifically adequate. In particular, more than 50% of the 21 studies reporting cognitive dysfunction did not appropriately diagnose mTBI, employ prospective research designs, use standard neuropsychological tests, include appropriate control groups, provide information on motive to feign or use PVTs, or exclude, or adequately consider the impact of, comorbid conditions known to impact neurocognitive scores. We additionally analyzed 15 studies published during the same period that documented no longer term mTBI-related cognitive abnormalities, and demonstrate that they were generally more methodologically robust than the studies purporting to document cognitive dysfunction. The original meta-analytic conclusions remain the most empirically-sound evidence informing our current understanding of favorable outcomes following mTBI.

Decreasing β-Catenin Leads to Altered Endothelial Morphology, Increased Barrier Permeability and Cognitive Impairment During Chronic Methamphetamine Exposure

Cognitive impairment induced by chronic methamphetamine (METH) exposure exhibits similarities to neurodegenerative disorders and is associated with blood-brain barrier (BBB) dysfunction. However, the potential involvement of β-catenin in maintaining BBB integrity during METH exposure remains unexplored. In this study, Y-maze and novel object recognition tests were conducted to assess cognitive impairment in mice exposed chronically to methamphetamine for 2 and 4 weeks. Gd-DTPA and Evans blue leakage tests revealed disruption of the BBB in the hippocampus, while chronic METH exposure for 2 and 4 weeks significantly decreased β-catenin levels along with its transcriptionally regulated protein, claudin5. Additionally, various neural injury-related proteins, such as APP, Aβ1-42, p-tau (Thr181) and p-tau (Ser396), as well as neuroinflammation-related proteins, such as IL-6, IL-1β, and TNF-α, exhibited increased levels following chronic METH exposure. Furthermore, plasma analysis indicated elevated levels of p-Tau (total), neurofilament light chain, and GFAP. In vitro experiments demonstrated that exposure to METH resulted in dose-dependent and time-dependent reductions in cellular activity and connectivity of bEnd.3 and hcmec/D3 cells. Furthermore, β-catenin exhibited decreased levels and altered subcellular localization, transitioning from the cell membrane to the cytoplasm and nucleus upon METH exposure. Overexpression of β-catenin was found to alleviate endothelial toxicity and attenuate junctional weakening induced by METH. The aforementioned findings underscore the crucial involvement of β-catenin in endothelial cells during chronic METH exposure-induced disruption of the BBB, thereby presenting a potential novel target for addressing METH-associated cerebrovascular dysfunction and cognitive impairment.

Trial protocol of an open-label pilot study of oral naltrexone-bupropion combination pharmacotherapy for the treatment of methamphetamine use disorder (the NABU trial)

INTRODUCTION

Methamphetamine use disorder is a global public health concern with no approved pharmacotherapies for its treatment. One recent randomised controlled trial conducted in the USA examined a combination of bupropion and naltrexone not readily available globally. Here, we report a trial protocol for an oral formulation of combined naltrexone and bupropion.

METHODS AND ANALYSIS

This single-arm, open-label pilot study will assess the safety and feasibility of oral naltrexone and bupropion (40 mg/450 mg daily in divided doses) in adults with methamphetamine use disorder. Participants (n=20) will be outpatients of a stimulant treatment program at an inner-city hospital in Sydney, Australia. The primary endpoint is Day 84. Participants will attend weekly study visits from Baseline to Week 12 and a follow-up telephone visit at Week 16. All participants will receive treatment as usual, such as psychosocial therapy. Primary outcomes are safety (measured by treatment-emergent adverse events (AEs)/adverse reactions) and feasibility (measured by the time taken to recruit, the proportion of ineligible participants, retention in the study and study medication adherence). Secondary outcomes will assess methamphetamine use, craving and withdrawal; treatment goals and expectations; physical and psychological well-being; depression and anxiety; and treatment satisfaction. Qualitative interviews will assess the acceptability of the intervention and outcome measures.

ETHICS AND DISSEMINATION

This study received ethics approval from the St Vincent's Hospital Human Research Ethics Committee (2023/ETH00549). Results will be submitted to peer-reviewed journals and scientific conferences, and a video abstract will be created to ensure that the findings are accessible to participants and people who use methamphetamines.

TRIAL REGISTRATION NUMBER

ANZCTR: ACTRN12623000866606 (protocol V.2.1 dated 08 April 2024).

Neuropsychological review of records in forensic cases: An AACN best practices paper with international perspectives

Objective: The purpose of this American Academy of Clinical Neuropsychology (AACN) best practices paper is to provide the neuropsychological community with the fundamentals of a competent forensic review of records. Method: Narrative review addressing fundamental factors related to review of records. Examples highlighted information necessary for a forensic determination of traumatic brain injury (TBI), and the data from records that can be used to address questions regarding validity of presentation. International and intra-jurisdictional perspectives within the US were used to illustrate the necessity of adhering the review to the rules. Results: Factors identified involve ethical responsibilities, completeness in obtaining and reviewing relevant records, evaluation of credibility of the records, considerations regarding examinee self-reporting, grounding of opinions within peer-reviewed science, determination of causation in the context of litigation, and avoiding bias in reporting, as well as consideration of cultural and language factors. Different jurisdictional rules require close attention. Conclusions: Neuropsychologists need to be aware of the need for a competent review of records to obtain basic facts, maintain objectivity, and provide a context for conclusions in a neuropsychological examination report. In litigation cases, opinions based solely on review of records may be challenged for reasons that might include not having personally evaluated the plaintiff, and whether opinions meet Daubert criteria pertaining to sufficient scientific bases and facts. A thorough review in the context of examination helps deal with litigant/claimant subjectivity and malleability of self-report, and it can provide critical reasoning about other factors relevant to causation.

Modulation of Glutamatergic Burst Activity by Hydrolysed Arabinoxylan Rice Bran: A Multielectrode Array Study in Human-Induced Pluripotent Stem Cell-Derived Neurones and Astrocytes

The natural product MGN-3 (Biobran) is a defatted, partially hydrolysed rice bran-derived hemicellulose enzymatically modified with an extract of Lentinus edodes. It has a high proportion of arabinoxylan. It has a protective action against intracerebroventricular streptozotocin-induced murine sporadic Alzheimer's disease and reverses spatial memory deficit in this disease model. The aim was to test the hypothesis that MGN-3 increases glutamatergic burst activity in human neuronal and glial cells by conducting an in vitro multielectrode array-based micro-electrophysiological study in a cultured mixture of human glutamatergic neurones, GABAergic neurones and astrocytes. The effects of MGN-3 at two concentrations, 0.750 g L-1 and 0.375 g L-1, and vehicle (control), on glutamatergic burst activity in a triculture of human-induced pluripotent stem cell (hiPSC)-derived GABAergic neurones, glutamatergic neurones and astrocytes were studied. The change in the number of glutamatergic bursts normalised to the vehicle control was analysed using a normal or Gaussian generalised linear model. This statistical model was highly significant (p = 1.468 × 10-17). Both MGN-3 concentrations were associated with highly significant main effects. These results provide strong evidence to reject the null hypothesis that MGN-3 does not affect glutamatergic burst activity in human neuronal and astrocytic cells. The study's strengths include the novel use of hiPSC-derived neurones and astrocytes and the robust statistical significance of the findings. Limitations include in vitro conditions that may not fully replicate in vivo conditions, potential variability in hiPSC-derived cell preparations, and the need to test other neuronal subtypes or additional doses to assess dose-dependent effects. These should be addressed in future studies.

Fusion Model Using Resting Neurophysiological Data to Help Mass Screening of Methamphetamine Use Disorder

Methamphetamine use disorder (MUD) is a substance use disorder. Because MUD has become more prevalent due to the COVID-19 pandemic, alternative ways to help the efficiency of mass screening of MUD are important. Previous studies used electroencephalogram (EEG), heart rate variability (HRV), and galvanic skin response (GSR) aberrations during the virtual reality (VR) induction of drug craving to accurately separate patients with MUD from the healthy controls. However, whether these abnormalities present without induction of drug-cue reactivity to enable separation between patients and healthy subjects remains unclear. Here, we propose a clinically comparable intelligent system using the fusion of 5-channel EEG, HRV, and GSR data during resting state to aid in detecting MUD. Forty-six patients with MUD and 26 healthy controls were recruited and machine learning methods were employed to systematically compare the classification results of different fusion models. The analytic results revealed that the fusion of HRV and GSR features leads to the most accurate separation rate of 79%. The use of EEG, HRV, and GSR features provides more robust information, leading to relatively similar and enhanced accuracy across different classifiers. In conclusion, we demonstrated that a clinically applicable intelligent system using resting-state EEG, ECG, and GSR features without the induction of drug cue reactivity enhances the detection of MUD. This system is easy to implement in the clinical setting and can save a lot of time on setting up and experimenting while maintaining excellent accuracy to assist in mass screening of MUD.

The Ubiquity of Cognitive Impairment in Human Illness: a Systematic Review of Meta-Analyses

OBJECTIVE

Cognitive dysfunction occurs in many neurological, psychiatric, and other health conditions. This review aimed to characterize the breadth and degree of cognitive morbidity associated with varied health conditions.

METHOD

We systematically reviewed Medline, EMBASE, and Cochrane databases for meta-analyses of cognitive dysfunction associated with any health condition. Meta-analyses were eligible if they reviewed studies that compared patients with health conditions to healthy controls on cognitive testing and provided effect sizes.

RESULTS

We found 91 meta-analyses for 94 health conditions. Among >800,297 participants, healthy controls out-performed clinical participants in every condition on cognitive testing. Mean effect sizes ranged from -2.02 to -0.00 across conditions and were ≤ -0.5 on average, denoting moderate to very severe dysfunction for 41% of them.

CONCLUSIONS

Cognitive dysfunction is ubiquitous in medicine. Both primary care and specialist physicians likely treat patients with cognitive dysfunction. Depending on its severity, cognitive dysfunction can affect treatment adherence, everyday functioning, quality of life, and the capacity to provide informed consent for treatment. These findings highlight the transdiagnostic nature of cognitive symptoms and the potential value of establishing collaborations between physicians and clinical neuropsychologists to integrate cognitive assessment into patient care. Even brief assessments can identify cognitive deficits that likely affect treatment adherence and functional outcomes.

The use of combined cognitive training and non-invasive brain stimulation to modulate impulsivity in adult populations: a systematic review and meta-analysis of existing studies

Introduction

Impulsivity, a tendency to act rashly and without forethought, is a core feature of many mental disorders that has been implicated in suicidality and offending behaviours. While research supports the use of non-invasive brain stimulation (NIBS) techniques, such as transcranial direct current stimulation (tDCS), to modulate brain functions, no studies specifically reviewed the use of combined cognitive training and NIBS to modulate impulsivity.

Methods

We aimed to conduct a systematic review and meta-analysis to synthesise the literature on the use of combined cognitive training and NIBS to modulate impulsivity and its subdomains (motor, delay discounting, reflection). We searched Scopus, PsychInfo, Medline, and Cinahl electronic databases, dissertations database, and Google scholar up to September 2024.

Results

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, four randomised controlled studies involving the use of combined cognitive training and tDCS in 127 subjects were included in the study. These studies included subjects with substance use disorders, obesity, and Parkinson's disease. Meta-analysis showed that combined cognitive training and tDCS had no statistically significant effects on motor impulsivity as measured using reaction times on the Stop Signal Task and Go/No Go tasks. One study that measured impulsiveness scores on a delay discounting task also showed no significant results. No studies measured reflection or cognitive impulsivity.

Discussion

There is a dearth of literature on the use of combined cognitive training and NIBS for impulsivity. This in conjunction of clinical heterogeneity across studies makes it difficult to draw definitive conclusions about the neuromodulation of impulsivity and its subdomains using combined cognitive training and NIBS. The findings of this study highlight the need to conduct more studies in the field.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD 42024511576.

Perirhinal cortex to the nucleus accumbens circuit in novelty salience following methamphetamine self-administration

Methamphetamine (meth) use disorder is part of an overarching use disorder that encompasses continued drug seeking and an increased risk of returning to drug use following periods of abstaining. Chronic meth use results in drug-induced cortical plasticity in the perirhinal cortex (PRC) that mediates responses to novelty. PRH projection targets are numerous and include the nucleus accumbens core (NAc). Whereas the PRH-prefrontal cortex is involved in object recognition; we propose that the PRH-NAc is involved in novelty salience. Rats underwent short-access (ShA, 1 hr) or long-access (LgA, 6 hr) meth self-administration (SA). We then used a dual viral strategy to inhibit or activate PRH-NAc during a novel cue test in which rats were presented with meth-associated and novel levers. Response patterns on these levers differ depending on the meth access protocol: ShA meth SA results in equal responding on both novel- and meth-associated levers, whereas LgA meth results in perseverative responding on the meth-associated lever. Inactivation of the PRH-NAc increased responding on the meth lever relative to the novel lever, resulting in a LgA behavioral phenotype. In contrast, activation in LgA rats was without a behavioral effect. We also report that male LgA sucrose SA animals perseverated on the novel lever rather than the meth-associated lever, which contrast their meth SA counter parts and female specific patterns of behavior. These data open a new line of interest in the role of the PRH-NAc circuit in novelty salience through identification of the behavioral relevance of this circuit.

Incorporating peer feedback in academic writing: a systematic review of benefits and challenges

Academic writing is paramount to students' academic success in higher education. Given the widely acknowledged benefits of peer feedback in diverse learning contexts, such as fostering a positive psychological mindset, there has been a growing interest in applying this approach to facilitate the development of academic writing. This study is launched to examine the primary features and findings of the studies that have investigated the benefits and challenges of the utilization of peer feedback in academic writing development. The methodology of this study incorporates a rigorous literature search methodology, encompassing database search, reference search, and manual search, which is subsequently followed by a content analysis of the selected studies. With the guidance of PRISMA 2020, a total of 60 related articles, spanning the period from 2014 to 2024, are selected through title screening, abstract screening and content screening, adhering to strict inclusion and exclusion criteria. The findings of this study reveal a growing global interest in peer feedback in academic writing, and highlight the need for future research on masters'/doctoral students and quantitative approaches to deepen understanding of its effects. Moreover, 16 distinct benefits of peer feedback in the academic writing context were delineated and subsequently categorized into five categories: affective benefits, cognitive benefits, behavioral benefits, social benefits, and meta-cognitive benefits. Furthermore, an analysis of the implementation challenges revealed 13 types of obstacles, which were traced to three primary sources: challenges originating from feedback receivers, those posed by feedback providers, and those stemming from the peer feedback settings. Based on these findings, several pedagogical and future research suggestions are proffered to guide both the practitioners and researchers.

The effect of paeoniflorin on the rewarding effect of methamphetamine and the associated cognitive impairment in mice

Chronic exposure to methamphetamine (METH) has been suggested to cause METH use disorder and severe cognitive impairment. Paeoniflorin (PF) is a monoterpenoid glycoside with various beneficial effects, including anti-inflammatory, antioxidant and antidepressant. The current study was designed to investigate the effect of PF (30 mg/kg, i.p.) on the rewarding effect of METH (2.5 mg/kg, i.p.) and the associated cognitive impairment, using the animal model of conditioned place preference, new location reorganization test, new object reorganization test and Y-maze test. METH induced conditioned place preference, accompanied by increased expression of synapse-associated proteins in the ventral target areas (VTA) and nucleus accumbens (NAc). In addition, METH induced significant cognitive impairment and decreased the expression of synapse-associated proteins in the hippocampus (Hip). Administration of PF decreased the rewarding effect of METH and the expression of synapse-associated proteins in the VTA or NAc. PF was also effective to improve METH-induced cognitive impairment by upregulating the expression of synapse-associated proteins in the Hip. Therefore, PF could be a potential agent for the treatment of METH use disorder and the associated cognitive impairment.

Interactive effects of ARRB2 and CHRNA5 genetic polymorphisms on cognitive function in Chinese male methamphetamine use disorder patients

BACKGROUND AND OBJECTIVES

Both β-arrestin2 and nicotinic acetylcholine receptor (nAChR) have been implicated in cognitive processes, particularly in relation to psychiatric disorders, including addiction. Previous studies have suggested that nAChR may be regulated by β-arrestin2. However, no study has investigated the interaction of β-arrestin2 and nAChR on cognition. We aimed to examine the main and interactive effects of their respective encoding genes, ARRB2 and CHRNA5, on cognitive function in MUD patients.

METHODS

We recruited 559 patients with methamphetamine use disorder (MUD) and 459 healthy controls, assessed their cognitive functioning using the Chinese version of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), and genotyped ARRB2 rs1045280 and CHRNA5 rs3829787 polymorphisms in MUD patients.

RESULTS

Compared to healthy controls, MUD patients scored significantly lower on all RBANS indexes. Neither ARRB2 rs1045280 nor CHRNA5 rs3829787 had main effects on cognitive function in MUD patients, but there were significant interactive effects between the two single nucleotide polymorphisms (SNPs) on multiple RBANS indexes, including immediate memory, visuospatial/constructional, delayed memory, and total score. In detail, among carriers of CHRNA5 rs3829787 T allele, ARRB2 rs1045280 TT carriers had higher RBANS scores than the C allele carriers, whereas among carriers of CHRNA5 rs3829787 CC genotype, ARRB2 rs1045280 TT carriers performed worse in RBANS.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

Our study identified for the first time an interactive effect between ARRB2 and CHRNA5 on cognitive function in MUD patients, which would enlarge our knowledge of genetic interaction on cognitive function.

Associations and relative risks of pulmonary hypertension and lung diseases in individuals with methamphetamine use disorder

OBJECTIVE

Methamphetamine causes considerable short- and long-term adverse health effects. Our aim was to assess the effects of methamphetamine use on pulmonary hypertension and lung diseases at the population level.

METHODS

This population-based retrospective study used data from the Taiwan National Health Insurance Research Database between 2000 and 2018 that included 18,118 individuals with methamphetamine use disorder (MUD) and 90,590 matched participants of the same age and sex without substance use disorder as the non-exposed group. A conditional logistic regression model was used to estimate associations of methamphetamine use with pulmonary hypertension and lung diseases such as lung abscess, empyema, pneumonia, emphysema, pleurisy, pneumothorax, or pulmonary hemorrhage. Incidence rate ratios (IRRs) of pulmonary hypertension and hospitalization due to lung diseases were determined between the methamphetamine group and non-methamphetamine group using negative binomial regression models.

RESULTS

During an 8-year observation period, 32 (0.2%) individuals with MUD and 66 (0.1%) non-methamphetamine participants suffered from pulmonary hypertension, and 2652 (14.6%) individuals with MUD and 6157 (6.8%) non-methamphetamine participants suffered from lung diseases. After adjusting for demographic characteristics and comorbidities, individuals with MUD were 1.78 times (95% confidence interval (CI) = 1.07-2.95) more likely to have pulmonary hypertension and 1.98 times (95% CI = 1.88-2.08) more likely to have a lung disease, especially emphysema, lung abscess, and pneumonia in descending order. Furthermore, compared to the non-methamphetamine group, the methamphetamine group was associated with higher risks of hospitalization caused by pulmonary hypertension and lung diseases. The respective IRRs were 2.79 and 1.67. Individuals with polysubstance use disorder were associated with higher risks of empyema, lung abscess, and pneumonia compared to individuals with MUD alone, with respective adjusted odds ratios of 2.96, 2.21, and 1.67. However, pulmonary hypertension and emphysema did not differ significantly between MUD individuals with or without polysubstance use disorder.

CONCLUSIONS

Individuals with MUD were associated with higher risks of pulmonary hypertension and lung diseases. Clinicians need to ensure that a methamphetamine exposure history is obtained as part of the workup for these pulmonary diseases and provide timely management for this contributing factor.

Single-dose methamphetamine administration impairs ORM retrieval in mice via excessive DA-mediated inhibition of PrLGlu activity

Methamphetamine (METH), an abused psychostimulant, impairs cognition through prolonged or even single-dose exposure, but animal experiments have shown contradictory effects on memory deficits. In this study we investigated the effects and underlying mechanisms of single-dose METH administration on the retrieval of object recognition memory (ORM) in mice. We showed that single-dose METH administration (2 mg/kg, i.p.) significantly impaired ORM retrieval in mice. Fiber photometry recording in METH-treated mice revealed that the activity of prelimbic cortex glutamatergic neurons (PrLGlu) was significantly reduced during ORM retrieval. Chemogenetic activation of PrLGlu or glutamatergic projections from ventral CA1 to PrL (vCA1Glu-PrL) rescued ORM retrieval impairment. Fiber photometry recording revealed that dopamine (DA) levels in PrL of METH-treated mice were significantly increased, and micro-infusion of the D2 receptor (D2R) antagonist sulpiride (0.25 μg/side) into PrL rescued ORM retrieval impairment. Whole-cell recordings in brain slices containing the PrL revealed that PrLGlu intrinsic excitability and basal glutamatergic synaptic transmission were significantly reduced in METH-treated mice, and the decrease in intrinsic excitability was reversed by micro-infusion of Sulpiride into PrL in METH-treated mice. Thus, the impaired ORM retrieval caused by single-dose METH administration may be attributed to reduced PrLGlu activity, possibly due to excessive DA activity on D2R. Selective activation of PrLGlu or vCA1Glu-PrL may serve as a potential therapeutic strategy for METH-induced cognitive dysfunction.

Task-switching mechanisms under methamphetamine cravings: sex differences in cued and voluntary task-switching

Introduction

This study explored the effects of task-switching type and sex on the task-switching ability of methamphetamine abstainers, as well as the differences in brain mechanisms under drug cravings under drug cravings using near-infrared spectroscopy.

Methods

Craving-inducing videos were used to arouse 20 methamphetamine abstainers (including 10 men), whose switching ability was then assessed using voluntary and cued task-switching exercises.

Results

During task-switching under methamphetamine cravings, the activation of the premotor cortex (PMC), supplementary motor area (SMA), frontal eye field (FEF), and dorsolateral prefrontal cortex (DLPFC) in women was significantly stronger than in men, while the activation of FEF in men was significantly stronger than in women. Voluntary task-switching induced stronger FEF activation than cued task-switching. During the latter, women exhibited stronger activation in the anterior prefrontal cortex (aPFC) than men.

Discussion

Both men and women showed brain lateralization during task-switching under methamphetamine cravings. Men tended to adopt proactive control and use a top-down dominant strategy to start a new task. Women, however, tend to use a bottom-up strategy focusing on inhibiting old tasks and emotional switching. Moreover, in cued task-switching, the result shows women paid more attention to emotional processing than did men, which suggests that different task-switching training programs should be developed according to sex.

Associations between methamphetamine use disorder and SLC18A1, SLC18A2, BDNF, and FAAH gene sequence variants and expression levels

INTRODUCTION

Assessing candidate gene sequence variations and expression helps to understand methamphetamine use disorder and inform potential treatments. We investigated single nucleotide polymorphisms (SNPs) and gene expression in four candidate genes: SLC18A1, SLC18A2, BDNF, and FAAH, between controls and people with methamphetamine use disorder.

METHODS

Fifty-nine participants (29 people with methamphetamine use disorder and 30 controls) completed a clinical interview, cognitive tasks, and provided a blood sample. SLC18A1, SLC18A2, BDNF, and FAAH SNPs were genotyped, and gene expression was assessed with real-time quantitative PCR.

RESULTS

SLC18A1 Pro4Thr was associated with methamphetamine use disorder (OR = 6.22; p = .007). SLC18A2 variants, rs363227 and rs363387, were negatively associated with methamphetamine use severity (p = .003) and positively associated with inhibitory control performance (p = .006), respectively. BDNF Val66Met was associated with the severity of use (p = .008). SLC18A2 and FAAH mRNA levels were lower in people who use methamphetamine relative to controls (p = .021 and .010, respectively).

CONCLUSIONS

SLC18A1 is identified for the first time to play a potential role in methamphetamine use disorder. Lower levels of blood SLC18A2 and FAAH mRNA in people with methamphetamine use disorder suggest reduced monoamine reuptake, recycling, or release, and higher anandamide levels in this clinical group, which may be potential therapeutic targets.

Methamphetamine-related working memory difficulties underpinned by reduced frontoparietal responses

Working memory difficulties are common, debilitating, and may pose barriers to recovery for people who use methamphetamine. Yet, little is known regarding the neural dysfunctions accompanying these difficulties. Here, we acquired cross-sectional, functional magnetic resonance imaging while people with problematic methamphetamine-use experience (MA+, n = 65) and people without methamphetamine-use experience (MA-, n = 44) performed a parametric n-back task (0-back through 2-back). Performance on tasks administered outside of the scanner, together with n-back performance, afforded to determine a latent dimension of participants' working memory ability. Behavioural results indicated that MA+ participants exhibited lower scores on this dimension compared to MA- participants (d = -1.39, p < .001). Whole-brain imaging results also revealed that MA+ participants exhibited alterations in load-induced responses predominantly in frontoparietal and default-mode areas. Specifically, while the MA- group exhibited monotonic activation increases within frontoparietal areas and monotonic decreases within default-mode areas from 0-back to 2-back, MA+ participants showed a relative attenuation of these load-induced activation patterns (d = -1.55, p < .001). Moreover, increased activations in frontoparietal areas from 0- to 2-back were related to greater working memory ability among MA+ participants (r = .560, p = .004). No such effects were observed for default-mode areas. In sum, reductions in working memory ability were observed alongside load-induced dysfunctions in frontoparietal and default-mode areas for people with problematic methamphetamine-use experience. Among them, load-induced activations within frontoparietal areas were found to have a strong and specific relationship to individual differences in working memory ability, indicating a putative neural signature of the working memory difficulties associated with chronic methamphetamine use.

The dual nature of working memory deficits: methamphetamine abusers have more impaired social working memory capacity than canonical working memory capacity

Social working memory (WM) temporarily retains and manipulates various aspects of social information. Extensive research has highlighted impaired social cognitive functions in individuals with substance addiction. However, the specific deficit in social WM within this population remains notably understudied. Bridging this gap, we investigated social WM capacity using biological motion (BM) stimuli in methamphetamine (MA) abusers compared to an inmate control group, alongside contrasting these findings with their canonical WM deficits. Across two studies, we recruited female MA abusers (N = 80) undergoing post-isolation rehabilitation within a mandatory confinement circumstance. To ensure a pertinent comparison, we recruited female inmates (N = 80) subjected to comparable confinement. Results show substantial BM WM impairment in MA abusers, yet non-BM WM remains mostly intact. These findings highlight a pronounced social WM deficit in MA abusers, surpassing their canonical WM deficit relative to inmate controls. This suggests a distinct dissociation between social and canonical WM processing.

Methamphetamine abuse impairs sequential working memory

The ability to maintain and manipulate sequential information in working memory, referred to as sequential working memory, plays a vital role in our daily life. While research has shown that methamphetamine abuse affects the neural substrates and the overall functioning of working memory, its specific impact on sequential working memory remains unclear. In this study, we asked 62 abstinent methamphetamine-dependent participants and 59 control participants to complete a digit ordering task in which they saw four digits one-by-one over time and subsequently rearranged them in ascending order. The four digits were presented either randomly in the experimental condition or in ascending order in the control condition. Results show that methamphetamine-dependent participants performed worse than the controls in the experimental condition in which sequential working memory was needed to complete the task, but not in the control condition in which only short-term memory was needed. This finding demonstrates that methamphetamine abuse impairs sequential working memory.

Understanding the shift to compulsion in addiction: insights from personality traits, social factors, and neurobiology

Compulsion stands as a central symptom of drug addiction; however, only a small fraction of individuals who use drugs exhibit compulsive characteristics. Differences observed in Sign-trackers (ST) and Goal-trackers (GT) during Pavlovian conditioning may shed light on individual variances in drug addiction. Here, we focus on the behavioral attributes, formation processes, and neural mechanisms underlying ST and how they drive addiction toward compulsivity in humans. We will explore addiction from three interconnected levels: individual personality traits, social factors, and neurobiology. Furthermore, we distinguish between the processes of sensitization and habituation within ST. These nuanced distinctions across various aspects of addiction will contribute to our understanding of the addiction development process and the formulation of targeted preventive strategies.

Human laboratory models of reward in substance use disorder

Human laboratory models in substance use disorder provide a key intermediary step between highly controlled and mechanistically informative non-human preclinical methods and clinical trials conducted in human populations. Much like preclinical models, the variety of human laboratory methods provide insights into specific features of substance use disorder rather than modelling the diverse causes and consequences simultaneously in a single model. This narrative review provides a discussion of popular models of reward used in human laboratory research on substance use disorder with a focus on the specific contributions that each model has towards informing clinical outcomes (forward translation) and analogs within preclinical models (backward translation). Four core areas of human laboratory research are discussed: drug self-administration, subjective effects, behavioral economics, and cognitive and executive function. Discussion of common measures and models used, the features of substance use disorder that these methods are purported to evaluate, unique issues for measure validity and application, and translational links to preclinical models and special considerations for studies wishing to evaluate homology across species is provided.

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.

Does acute cannabidiol (CBD) use impair performance? A meta-analysis and comparison with placebo and delta-9-tetrahydrocannabinol (THC)

Cannabidiol (CBD) is widely used and believed to be non-intoxicating, lacking acute performance effects (e.g., non-impairing). However, a synthesis of data has not evaluated this. This meta-analysis synthesized data from controlled human laboratory studies that evaluated if acute CBD use impairs performance. Performance on objective and subjective measures of cognitive and psychomotor function were used as markers for potential performance changes and impairment. Studies were identified through systematic database searches. Adult clinical trials measuring acute CBD effects (within 0-8 h of administration) were included. The primary outcome was the peak mean difference in performance measures between CBD and placebo. A secondary analysis utilizing delta-9-tetrahydrocannabinol (Δ9-THC) as a positive control for comparison to CBD was completed. Pooled Hedges' g estimates were calculated using robust variance estimation (RVE) meta-regression. The omnibus RVE meta-analysis indicated a statistically significant, but small effect size (Hedge's g < 0.2) for impaired performance following acute CBD consumption compared to placebo (N = 16 trials, Hedges' g = 0.122, 95% CI: 0.023-0.221, p = 0.019). Measure type was a significant moderator with larger mean differences between CBD and placebo when subjective measures, specifically self-reported sedation, were used versus objective performance tasks (Hedges' gSubjective = 0.288 versus Hedges' gObjective = 0.048). Δ9-THC had a significantly greater magnitude of impairment compared to CBD (N = 8, Hedges' g = 0.416, 95% CI: 0.017-0.816, p = 0.043). In summary, acute CBD consumption was associated with a small increase in subjective ratings of sedation, but no difference from placebo was observed across multiple domains of objectively assessed cognitive or psychomotor performance. These findings suggest that acute CBD alone is unlikely to significantly impair daily functioning or workplace performance.

Brain mGlu5 Is Linked to Cognition and Cigarette Smoking but Does Not Differ From Control in Early Abstinence From Chronic Methamphetamine Use

BACKGROUND

The group-I metabotropic glutamate receptor subtype 5 (mGlu5) has been implicated in methamphetamine exposure in animals and in human cognition. Because people with methamphetamine use disorder (MUD) exhibit cognitive deficits, we evaluated mGlu5 in people with MUD and controls and tested its association with cognitive performance.

METHODS

Positron emission tomography was performed to measure the total VT of [18F]FPEB, a radiotracer for mGlu5, in brains of participants with MUD (abstinent from methamphetamine for at least 2 weeks, N = 14) and a control group (N = 14). Drug use history questionnaires and tests of verbal learning, spatial working memory, and executive function were administered. Associations of VT with methamphetamine use, tobacco use, and cognitive performance were tested.

RESULTS

MUD participants did not differ from controls in global or regional VT, and measures of methamphetamine use were not correlated with VT. VT was significantly higher globally in nonsmoking vs smoking participants (main effect, P = .0041). MUD participants showed nonsignificant weakness on the Rey Auditory Verbal Learning Task and the Stroop test vs controls (P = .08 and P = .13, respectively) with moderate to large effect sizes, and significantly underperformed controls on the Spatial Capacity Delayed Response Test (P = .015). Across groups, Rey Auditory Verbal Learning Task performance correlated with VT in the dorsolateral prefrontal cortex and superior frontal gyrus.

CONCLUSION

Abstinent MUD patients show no evidence of mGlu5 downregulation in brain, but association of VT in dorsolateral prefrontal cortex with verbal learning suggests that medications that target mGlu5 may improve cognitive performance.

Efficacy of probiotic supplements in improving the symptoms of psychosis, anxiety, insomnia, and anorexia due to amphetamine and methamphetamine use: a randomized clinical trial

RATIONALE

Changes in the density and diversity of gut microbiota in chronic use of methamphetamine have been mentioned as contributors to psychotic and anxiety symptoms, sleep problems, and loss of appetite.

OBJECTIVE

In this placebo-controlled clinical trial, we investigated the effect of the probiotic Lactobacillus Acidophilus in improving psychiatric symptoms among hospitalized patients with chronic methamphetamine use along with psychotic symptoms.

METHODS

60 inpatients with a history of more than 3 years of methamphetamine use, were randomly assigned to one of two groups receiving either a probiotic capsule or placebo along with risperidone for 8 weeks based on a simple randomization method. In weeks 0, 4, and 8, patients were evaluated using the Brief Psychiatric Rating Scale (BPRS), Beck Anxiety Inventory (BAI), Pittsburgh Sleep Quality Index (PSQI), Simple Appetite Nutritional Questionnaire (SANQ), and Body Mass Index (BMI).

RESULTS

Compared to the control group, patients receiving probiotics had better sleep quality, greater appetite, and higher body mass index (there were significant interaction effects of group and time at Week 8 in these variables (t = -3.32, B = -1.83, p = .001, d = 0.89), (t = 10.50, B = 2.65, p <.001, d = 1.25) and (t = 3.40, B = 0.76, p <.001, d = 0.30), respectively. In terms of the improvement of psychotic and anxiety symptoms, there was no statistically significant difference between the two groups.

CONCLUSIONS

The use of probiotics was associated with improved sleep quality, increased appetite, and increased body mass index in patients with chronic methamphetamine use. Conducting more definitive clinical trials with larger sample sizes and longer-term follow-up of cases is recommended.

Dysfunctional feedback processing in male methamphetamine abusers: Evidence from neurophysiological and computational approaches

Methamphetamine use disorder (MUD) as a major public health risk is associated with dysfunctional neural feedback processing. Although dysfunctional feedback processing in people who are substance dependent has been explored in several behavioral, computational, and electrocortical studies, this mechanism in MUDs requires to be well understood. Furthermore, the current understanding of latent components of their behavior such as learning speed and exploration-exploitation dilemma is still limited. In addition, the association between the latent cognitive components and the related neural mechanisms also needs to be explored. Therefore, in this study, the underlying neurocognitive mechanisms of feedback processing of such impairment, and age/gender-matched healthy controls are evaluated within a probabilistic learning task with rewards and punishments. Mathematical modeling results based on the Q-learning paradigm suggested that MUDs show less sensitivity in distinguishing optimal options. Additionally, it may be worth noting that MUDs exhibited a slight decrease in their ability to learn from negative feedback compared to healthy controls. Also through the lens of underlying neural mechanisms, MUDs showed lower theta power at the medial-frontal areas while responding to negative feedback. However, other EEG measures of reinforcement learning including feedback-related negativity, parietal-P300, and activity flow from the medial frontal to lateral prefrontal regions, remained intact in MUDs. On the other hand, the elimination of the linkage between value sensitivity and medial-frontal theta activity in MUDs was observed. The observed dysfunction could be due to the adverse effects of methamphetamine on the cortico-striatal dopamine circuit, which is reflected in the anterior cingulate cortex activity as the most likely region responsible for efficient behavior adjustment. These findings could help us to pave the way toward tailored therapeutic approaches.

Trans-generational effects of parental exposure to drugs of abuse on offspring memory functions

Recent evidence reported that parental-derived phenotypes can be passed on to the next generations. Within the inheritance of epigenetic characteristics allowing the transmission of information related to the ancestral environment to the offspring, the specific case of the trans-generational effects of parental drug addiction has been extensively studied. Drug addiction is a chronic disorder resulting from complex interactions among environmental, genetic, and drug-related factors. Repeated exposures to drugs induce epigenetic changes in the reward circuitry that in turn mediate enduring changes in brain function. Addictive drugs can exert their effects trans-generally and influence the offspring of addicted parents. Although there is growing evidence that shows a wide range of behavioral, physiological, and molecular phenotypes in inter-, multi-, and trans-generational studies, transmitted phenotypes often vary widely even within similar protocols. Given the breadth of literature findings, in the present review, we restricted our investigation to learning and memory performances, as examples of the offspring's complex behavioral outcomes following parental exposure to drugs of abuse, including morphine, cocaine, cannabinoids, nicotine, heroin, and alcohol.

Crystal methamphetamine and its effects on mental and oral health: A narrative review

The purpose of this comprehensive literature review is to present the available evidence on the effects of methamphetamine on mental and oral health, as well as provide an overview of the most widely used medical and dental care strategies in the management of meth mouth. For this purpose, PubMed and Google Scholar electronic databases were searched for relevant articles, yielding 115 search results, which were further scrutinized for their relevance, leaving 55 for a detailed review. The analysis of the gathered data indicates that a comprehensive patient-centered approach that takes into consideration the physical, mental, and social aspects is crucial for mitigating the detrimental effects of increasing methamphetamine use.

A Meta-Analysis of Functional Neuroimaging Studies of Ketamine Administration in Healthy Volunteers

Ketamine administration leads to a psychotomimetic state when taken in large bolus doses, making it a valid model of psychosis. Therefore, understanding ketamine's effects on brain functioning is particularly relevant. This meta-analysis focused on neuroimaging studies that examined ketamine-induced brain activation at rest and during a task. Included are 10 resting-state studies and 23 task-based studies, 9 of which were measuring executive functions. Using a stringent statistical threshold (TFCE <0.05), the results showed increased activity at rest in the dorsal anterior cingulate cortex (ACC), and increased activation of the right Heschl's gyrus during executive tasks, following ketamine administration. Uncorrected results showed increased activation at rest in the right (anterior) insula and the right-fusiform gyrus, as well as increased activation during executive tasks in the rostral ACC. Rest-state studies highlighted alterations in core hubs of the salience network, while task-based studies suggested an impact on task-irrelevant brain regions. Increased activation in the rostral ACC may indicate a failure to deactivate the default mode network during executive tasks following ketamine administration. The results are coherent with alterations found in schizophrenia, which confer external validity to the ketamine model of psychosis. Studies investigating the neural mechanisms of ketamine's antidepressant action are warranted.

Altered spontaneous neurological activity in methamphetamine use disorders and its association with cognitive function

BACKGROUND

Methamphetamine (MA) is a widely used and detrimental drug, yet the precise mechanisms by which MA affects cognitive function remain unclear. This study aims to investigate the relationship between cognitive function and brain functional imaging in individuals with MA use disorder (MUD).

METHODS

This study involved 45 patients diagnosed with MUD and 43 healthy controls (HC). Cognitive function assessment utilized the MATRICS Consensus Cognitive Battery, and functional data were acquired using a 3.0 Tesla magnetic resonance imaging scanner.

RESULTS

The MUD group exhibited lower regional homogeneity (ReHo) values in the bilateral postcentral, the left superior temporal, and the left lingual regions compared to the HC group. Additionally, the MUD group displayed higher amplitude of low-frequency fluctuation (ALFF) values in the bilateral fusiform and the left putamen compared to the HC group, along with lower ALFF values in the bilateral postcentral cortices and the left middle cingulate cortex compared to the HC group (all p < 0.05, with false discovery rate corrected). Linear regression analysis revealed a positive correlation between the ReHo value in the right postcentral cortex and the neuropsychology assessment battery-mazes test (p = 0.014). Furthermore, the ALFF value in the left putamen showed negative correlations with the scores of the digit-symbol coding test (p = 0.027), continuous performance test (p = 0.037), and battery-mazes test (p = 0.024).

CONCLUSION

Patients with MUD exhibit altered brain spontaneous neurological activities, and the intensity of spontaneous neurological activity in the left putamen is strongly associated with cognitive function.

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.

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.

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.

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.

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 impact of depressive symptoms on cognitive impairments in chronic ketamine users

BACKGROUND

Chronic ketamine use has been associated with cognitive impairments, while depressive symptoms are commonly observed in individuals using ketamine. However, the influence of depressive symptoms on cognitive impairments in chronic ketamine users remains unclear. This study aimed to examine the impact of depressive symptoms on cognitive function in this population.

METHODS

A cross-sectional study was conducted with a sample of chronic ketamine users. Participants underwent comprehensive cognitive assessments, including measures of attention, executive function, working memory, verbal and visual memory. Depressive symptoms were assessed using Beck Depression Inventory (BDI) scores. Multivariate analyses were utilized to compare the cognitive performance of individuals who use ketamine, both with and without depressive symptoms, as well as a control group, while controlling for relevant covariates.

RESULTS

The results revealed a significant negative impact of depressive symptoms on cognitive impairments, particularly in the domains of memory and executive function, among chronic ketamine users. The analysis of partial correlations revealed that among individuals who use ketamine and have depressive symptoms, those with higher levels of depressive symptoms demonstrated poorer cognitive performance compared to individuals with lower levels of depressive symptoms, controlling for potential confounding factors.

CONCLUSIONS

The findings suggest that depressive symptoms contribute to cognitive impairments, specifically in memory and executive function, in chronic ketamine users. Therefore, it is crucial to evaluate depressive symptoms when considering cognitive enhancement treatment for this population.

Alterations in the brain functional network of abstinent male individuals with methamphetamine use disorder

Methamphetamine is a highly addictive psychostimulant drug that is abused globally and is a serious threat to health worldwide. Unfortunately, the specific mechanism underlying addiction remains unclear. Thus, this study aimed to investigate the characteristics of functional connectivity in the brain network and the factors influencing methamphetamine use disorder in patients using magnetic resonance imaging. We included 96 abstinent male participants with methamphetamine use disorder and 46 age- and sex-matched healthy controls for magnetic resonance imaging. Compared with healthy controls, participants with methamphetamine use disorder had greater impulsivity, fewer small-world attributes of the resting-state network, more nodal topological attributes in the cerebellum, greater functional connectivity strength within the cerebellum and between the cerebellum and brain, and decreased frontoparietal functional connectivity strength. In addition, after controlling for covariates, the partial correlation analysis showed that small-world properties were significantly associated with methamphetamine use frequency, psychological craving, and impulsivity. Furthermore, we revealed that the small-word attribute significantly mediated the effect of methamphetamine use frequency on motor impulsivity in the methamphetamine use disorder group. These findings may further improve our understanding of the neural mechanism of impulse control dysfunction underlying methamphetamine addiction and assist in exploring the neuropathological mechanism underlying methamphetamine use disorder-related dysfunction and rehabilitation.

The interplay of childhood trauma, oxytocin, and impulsivity in predicting the onset of methamphetamine use

BACKGROUND

Childhood trauma is associated with substance use disorders, including methamphetamine use disorder (MUD). Oxytocin, involved in social bonding, stress regulation, and reward processing, may influence addiction vulnerability and impulsivity in individuals with a history of childhood trauma.

OBJECTIVE

To investigate the relationships among childhood trauma, oxytocin levels, impulsivity, and the age of first methamphetamine use in individuals with MUD.

PARTICIPANTS AND SETTING

The study included 298 male participants (148 individuals with MUD and 150 healthy controls) from both probation offices and psychiatric clinics.

METHODS

Childhood trauma was assessed using the Childhood Trauma Questionnaire-Short Form (CTQ-SF), impulsivity with the Barratt Impulsiveness Scale-11 (BIS-11), and plasma oxytocin levels were obtained.

RESULTS

Individuals with MUD exhibited higher levels of childhood trauma, impulsivity, and lower plasma oxytocin levels compared to healthy controls. Childhood trauma was associated with a younger age of first methamphetamine use, higher impulsivity, and lower oxytocin levels among individuals with MUD. Plasma oxytocin levels partially mediated the relationship between childhood trauma and both the age of first methamphetamine use and impulsivity. Serial mediation analysis demonstrated that oxytocin levels and impulsivity sequentially mediated the relationship between childhood trauma and the age of first methamphetamine use.

CONCLUSIONS

The findings reveal the complex interplay among childhood trauma, oxytocin, impulsivity, and methamphetamine use, emphasizing the importance of considering these factors in prevention and intervention strategies for MUD. Future research should explore oxytocin and impulsivity-focused interventions to mitigate the effects of childhood trauma and reduce MUD development risk.

Cannabis use may attenuate neurocognitive performance deficits resulting from methamphetamine use disorder

OBJECTIVE

Methamphetamine and cannabis are two widely used, and frequently co-used, substances with possibly opposing effects on the central nervous system. Evidence of neurocognitive deficits related to use is robust for methamphetamine and mixed for cannabis. Findings regarding their combined use are inconclusive. We aimed to compare neurocognitive performance in people with lifetime cannabis or methamphetamine use disorder diagnoses, or both, relative to people without substance use disorders.

METHOD

423 (71.9% male, aged 44.6 ± 14.2 years) participants, stratified by presence or absence of lifetime methamphetamine (M-/M+) and/or cannabis (C-/C+) DSM-IV abuse/dependence, completed a comprehensive neuropsychological, substance use, and psychiatric assessment. Neurocognitive domain T-scores and impairment rates were examined using multiple linear and binomial regression, respectively, controlling for covariates that may impact cognition.

RESULTS

Globally, M+C+ performed worse than M-C- but better than M+C-. M+C+ outperformed M+C- on measures of verbal fluency, information processing speed, learning, memory, and working memory. M-C+ did not display lower performance than M-C- globally or on any domain measures, and M-C+ even performed better than M-C- on measures of learning, memory, and working memory.

CONCLUSIONS

Our findings are consistent with prior work showing that methamphetamine use confers risk for worse neurocognitive outcomes, and that cannabis use does not appear to exacerbate and may even reduce this risk. People with a history of cannabis use disorders performed similarly to our nonsubstance using comparison group and outperformed them in some domains. These findings warrant further investigation as to whether cannabis use may ameliorate methamphetamine neurotoxicity.

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.

Effects of Aerobic Exercise Combined With Attentional Bias Modification in the Care of Male Patients With a Methamphetamine Use Disorder

OBJECTIVE

It remains unclear which individual or combined strategies are most beneficial for methamphetamine use disorders (MUDs). We compared the effects of aerobic exercise, attentional bias modification, and combined intervention on male patients with MUD.

METHOD

One hundred male patients with MUD were randomly assigned to combined intervention, aerobic exercise, attentional bias modification, or control groups (25 patients per group). The 8-week intervention protocol included three 60-minute sessions of aerobic exercises per week. Primary outcomes included high- and low-frequency heart rate variability, executive function, and cardiorespiratory fitness measured by customized software, computerized tests, and the Harvard step test, respectively. Secondary outcomes included psychiatric symptoms, drug craving, training acceptability, and persistence.

RESULTS

Participant characteristics were matched between groups at baseline. Executive function, heart rate variability, cardiorespiratory fitness, drug craving, and most psychiatric symptoms had significant time-group interactions at posttest (p < .05, η2 = .08-.28). Compared with the attentional bias modification and control groups, the combined intervention and aerobic exercise groups improved significantly in executive function, heart rate variability, cardiorespiratory fitness, and most secondary outcomes. In addition, high-frequency heart rate variability and cardiorespiratory fitness in the aerobic exercise group were significantly higher than those in the combined intervention group.

CONCLUSIONS

Combination strategies showed comparable efficacy to aerobic exercise alone in improving executive function, psychiatric symptoms, and drug craving and significantly exceeded other conditions. For heart rate variability and cardiorespiratory fitness, aerobic exercise alone was the most effective. For acceptability and persistence, combination strategies were preferred over single-domain training and health education intervention.

Perirhinal to prefrontal circuit in methamphetamine induced recognition memory deficits

Return to methamphetamine (meth) use is part of an overarching addictive disorder hallmarked by cognitive sequela and cortical dysfunction in individuals who use meth chronically. In rats, long access meth self-administration produces object recognition memory deficits due to drug-induced plasticity within the perirhinal cortex (PRH). PRH projections are numerous and include the medial prefrontal cortex (mPFC). To evaluate the role of the PRH-mPFC reciprocal circuit in novel object recognition memory, a rgAAV encoding GFP-tagged Cre recombinase was infused into the PRH or the mPFC and rats were tested for recognition memory. On test day, one group explored both familiar and novel objects. A second group explored only familiar objects. GFP and Fos expression were visualized in the mPFC or PRH. During exploration, PRH neurons receiving input from the mPFC were equally activated by exploration of novel and familiar objects. In contrast, PRH neurons that provide input to the mPFC were disproportionately activated by novel objects. Further, the percent of Fos + cells in the PRH positively correlated with recognition memory. As such, the flow of communication appears to be from the PRH to the mPFC. In agreement with this proposed directionality, chemogenetic inhibition of the PRH-mPFC circuit impaired object recognition memory, whereas chemogenetic activation in animals with a history of long access meth self-administration reversed the meth-induced recognition memory deficit. This finding informs future work aimed at understanding the role of the PRH, mPFC, and their connectivity in meth associated memory deficits. These data suggest a more complex circuitry governing recognition memory than previously indicated with anatomical or lesion studies.

The Atypical Dopamine Transporter Inhibitor CE-158 Enhances Dopamine Neurotransmission in the Prefrontal Cortex of Male Rats: A Behavioral, Electrophysiological, and Microdialysis Study

BACKGROUND

Dopamine plays a key role in several physiological functions such as motor control, learning and memory, and motivation and reward. The atypical dopamine transporter inhibitor S,S stereoisomer of 5-(((S)-((S)-(3-bromophenyl)(phenyl)methyl)sulfinyl)methyl)thiazole (CE-158) has been recently reported to promote behavioral flexibility and restore learning and memory in aged rats.

METHODS

Adult male rats were i.p. administered for 1 or 10 days with CE-158 at the dose of 1 or 10 mg/kg and tested for extracellular dopamine in the medial prefrontal cortex by means of intracerebral microdialysis and single unit cell recording in the same brain area. Moreover, the effects of acute and chronic CE-158 on exploratory behavior, locomotor activity, prepulse inhibition, working memory, and behavioral flexibility were also investigated.

RESULTS

CE-158 dose-dependently potentiated dopamine neurotransmission in the medial prefrontal cortex as assessed by intracerebral microdialysis. Moreover, repeated exposure to CE-158 at 1 mg/kg was sufficient to increase the number of active pyramidal neurons and their firing frequency in the same brain area. In addition, CE-158 at the dose of 10 mg/kg stimulates exploratory behavior to the same extent after acute or chronic treatment. Noteworthy, the chronic treatment at both doses did not induce any behavioral alterations suggestive of abuse potential (e.g., motor behavioral sensitization) or pro-psychotic-like effects such as disruption of sensorimotor gating or impairments in working memory and behavioral flexibility as measured by prepulse inhibition and Y maze.

CONCLUSIONS

Altogether, these findings confirm CE-158 as a promising pro-cognitive agent and contribute to assessing its preclinical safety profile in a chronic administration regimen for further translational testing.