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Addiction Biology Jan 2024People with methamphetamine use disorder (MUD) struggle to shift their behaviour from methamphetamine-orientated habits to goal-oriented choices. The...
People with methamphetamine use disorder (MUD) struggle to shift their behaviour from methamphetamine-orientated habits to goal-oriented choices. The model-based/model-free framework is well suited to understand this difficulty by unpacking the computational mechanisms that support experienced-based (model-free) and goal-directed (model-based) choices. We aimed to examine whether 1) participants with MUD differed from controls on behavioural proxies and/or computational mechanisms of model-based/model-free choices; 2) model-based/model-free decision-making correlated with MUD symptoms; and 3) model-based/model-free deficits improved over six weeks in the group with MUD. Participants with MUD and controls with similar age, IQ and socioeconomic status completed the Two-Step Task at treatment commencement (MUD n = 30, Controls n = 31) and six weeks later (MUD n = 23, Controls n = 26). We examined behavioural proxies of model-based/model-free decisions using mixed logistic regression, and their underlying mechanisms using computational modelling. At a behavioural level, participants with MUD were more likely to switch their choices following rewarded actions, although this pattern improved at follow up. At a computational level, groups were similar in their use of model-based mechanisms, but participants with MUD were less likely to apply model-free mechanisms and less likely to repeat rewarded actions. We did not find evidence that individual differences in model-based or model-free parameters were associated with greater severity of methamphetamine dependence, nor did we find that group differences in computational parameters changed between baseline and follow-up assessment. Decision-making challenges in people with MUD are likely related to difficulties in pursuing choices previously associated with positive outcomes.
Topics: Humans; Infant, Newborn; Methamphetamine; Amphetamine-Related Disorders; Reward; Motivation
PubMed: 38221809
DOI: 10.1111/adb.13356 -
Acta Neurobiologiae Experimentalis Dec 2023Methamphetamine (METH) is a highly addictive psychostimulant known for its profound impact on the nervous system. Chronic METH use leads to neurotoxicity characterized... (Review)
Review
Methamphetamine (METH) is a highly addictive psychostimulant known for its profound impact on the nervous system. Chronic METH use leads to neurotoxicity characterized by various molecular and structural alterations in the brain. This review article primarily aims to elucidate the mechanisms underlying METH‑induced neurotoxicity. METH's mechanism of action involves the inhibition of dopamine, serotonin, and norepinephrine reuptake, resulting in altered synaptic function. Prolonged METH exposure triggers oxidative stress, endoplasmic reticulum stress, mitochondrial dysfunction, impaired axonal transport, autophagy, and programmed cell death, ultimately contributing to neurotoxicity. These neurotoxic effects manifest as increased neuronal firing rate, disruptions in intracellular ion balance (Ca2+ and Na+), energy production imbalances, and excessive reactive oxygen species production. The blood‑brain barrier is compromised, leading to structural, functional, and neurochemical alterations, particularly in the fronto‑striatal circuit. While our comprehensive review addresses these intricate molecular and structural changes induced by METH, we also examined the latest therapeutic strategies designed to mitigate neurotoxicity. Our investigation sheds light on the critical need to comprehend the complex pathways underlying METH‑induced neurotoxicity and develop effective treatment approaches.
Topics: Humans; Methamphetamine; Neurotoxicity Syndromes; Central Nervous System Stimulants; Inflammation; Apoptosis
PubMed: 38224280
DOI: 10.55782/ane-2023-2488 -
Frontiers in Neurology 2024Methamphetamine (meth) is a potent and addictive central nervous system stimulant with increasing use. Stroke is one severe possible complication of meth use. Due to... (Review)
Review
Methamphetamine (meth) is a potent and addictive central nervous system stimulant with increasing use. Stroke is one severe possible complication of meth use. Due to high levels of manufacturing in Mexico, the western United States has experienced greater consequences of meth use. The literature reviewed herein is comprised of case studies and series, and it suggests that hemorrhagic stroke (including hypertensive-like intracerebral hemorrhage and aneurysmal subarachnoid hemorrhage), as opposed to ischemic stroke, is the more common type of neurovascular complication of meth use. Meth-related strokes are a particular concern for younger patients with stroke and may be a partial explanation for increasing stroke rates in this age group. We describe two cases (one intraparenchymal hemorrhage and one ischemic stroke) in young patients (<50 years old) with recent meth use to illustrate clinical characteristics and therapeutic considerations. There are several proposed pathophysiological explanations for meth-associated hemorrhagic stroke including an induced hypertensive surge, vasospasm, blood brain barrier breakdown, chronic hypertension, aneurysm development and rupture, and very rarely associated vasculitis. The increased risk of ischemic stroke related to meth use is less well supported in the literature, but this may, in part, be related to a lack of appropriately designed and powered research studies. Proposed mechanisms for ischemic stroke complications of meth use include those affecting blood vessels such as accelerated atherosclerosis, chronic hypertension, vasospasm, and vasculitis, plus mechanisms that affect the heart including cardiomyopathy, arrhythmias, and infective endocarditis (especially with injection drug use). Standard therapeutic interventions for acute stroke and approaches to secondary stroke prevention seem appropriate for meth-associated strokes, with the addition of abstinence from continued meth use. There is no evidence for any meth-specific stroke treatments. Finally, the prolonged duration of meth withdrawal is described. Larger, prospective studies of meth-related strokes are needed to allow for a better understanding and improved care for this often-devastating consequence of an increasingly prevalent cause of strokes in young patients.
PubMed: 38721123
DOI: 10.3389/fneur.2024.1397677 -
Proceedings of the National Academy of... Jul 2023The serotonin transporter (SERT) is a member of the SLC6 neurotransmitter transporter family that mediates serotonin reuptake at presynaptic nerve terminals. SERT is the...
The serotonin transporter (SERT) is a member of the SLC6 neurotransmitter transporter family that mediates serotonin reuptake at presynaptic nerve terminals. SERT is the target of both therapeutic antidepressant drugs and psychostimulant substances such as cocaine and methamphetamines, which are small molecules that perturb normal serotonergic transmission by interfering with serotonin transport. Despite decades of studies, important functional aspects of SERT such as the oligomerization state of native SERT and its interactions with potential proteins remain unresolved. Here, we develop methods to isolate SERT from porcine brain (pSERT) using a mild, nonionic detergent, utilize fluorescence-detection size-exclusion chromatography to investigate its oligomerization state and interactions with other proteins, and employ single-particle cryo-electron microscopy to elucidate the structures of pSERT in complexes with methamphetamine or cocaine, providing structural insights into psychostimulant recognition and accompanying pSERT conformations. Methamphetamine and cocaine both bind to the central site, stabilizing the transporter in an outward open conformation. We also identify densities attributable to multiple cholesterol or cholesteryl hemisuccinate (CHS) molecules, as well as to a detergent molecule bound to the pSERT allosteric site. Under our conditions of isolation, we find that pSERT is best described as a monomeric entity, isolated without interacting proteins, and is ensconced by multiple cholesterol or CHS molecules.
Topics: Animals; Swine; Serotonin Plasma Membrane Transport Proteins; Cryoelectron Microscopy; Detergents; Serotonin; Central Nervous System Stimulants; Cocaine; Methamphetamine
PubMed: 37436958
DOI: 10.1073/pnas.2304602120 -
Addiction Biology Jun 2024Abuse of methamphetamine has aroused concern worldwide. Stimulant use and sexual behaviours have been linked in behavioural and epidemiological studies. Although...
AIMS
Abuse of methamphetamine has aroused concern worldwide. Stimulant use and sexual behaviours have been linked in behavioural and epidemiological studies. Although methamphetamine-related neurofunctional differences are reported in previous studies, only few studies have examined neurofunctional changes related to methamphetamine and sexual cues in methamphetamine dependence from short- to long-term abstinence.
METHODS
Neurofunctional changes were measured using a cue-reactivity task involving methamphetamine, sexual, and neutral cues in 20 methamphetamine abusers who were evaluated after a short- (1 week to 3 months) and long-term (10-15 months) abstinence.
RESULTS
Five brain regions mainly involved in the occipital lobe and the parietal lobe were found with the group-by-condition interaction. Region-of-interest analyses found higher sexual-cue-related activation than other two activations in all five brain regions in the long-term methamphetamine abstinence group while no group differences were found. Negative relationships between motor impulsivity and methamphetamine- or sexual-cue-related activations in the left middle occipital gyrus, the superior parietal gyrus and the right angular gyrus were found.
CONCLUSIONS
The findings suggested that methamphetamine abstinence may change the neural response of methamphetamine abusers to methamphetamine and sexual cues, and the neurofunction of the five brain regions reported in this study may partly recover with long-term methamphetamine abstinence. Given the use and relapse of methamphetamine for sexual purposes, the findings of this study may have particular clinical relevance.
Topics: Humans; Cues; Amphetamine-Related Disorders; Methamphetamine; Male; Adult; Sexual Behavior; Magnetic Resonance Imaging; Parietal Lobe; Female; Occipital Lobe; Brain; Central Nervous System Stimulants; Young Adult; Impulsive Behavior; Brain Mapping; Time Factors
PubMed: 38837586
DOI: 10.1111/adb.13405 -
Drug and Alcohol Dependence Nov 2023Overdose deaths involving stimulants and opioids simultaneously have raised the specter of widespread contamination of the stimulant supply with fentanyl.
BACKGROUND
Overdose deaths involving stimulants and opioids simultaneously have raised the specter of widespread contamination of the stimulant supply with fentanyl.
METHODS
We quantified prevalence of fentanyl in street methamphetamine and cocaine, stratified by crystalline texture, analyzing samples sent voluntarily to a public mail-in drug checking service (May 2021-June 2023). Samples from 77 harm reduction programs and clinics originated in 25 US states. Sample donors reported expected drug and physical descriptions. Substances were identified by gas chromatography-mass spectrometry. Negative binomial models were used to calculate fentanyl prevalence, adjusting for potential confounders related to sample selection. We also examined if xylazine changed donors' accuracy of detecting fentanyl.
RESULTS
We analyzed 718 lab-confirmed samples of methamphetamine (64%) and cocaine (36%). The adjusted prevalence of fentanyl was 12.5% (95% CI: 2.2%, 22.9%) in powder methamphetamine and 14.8% (2.3%, 27.2%) in powder cocaine, with notable geographic variation. Crystalline forms of both methamphetamine (Chisq=57, p<0.001) and cocaine (Chisq=18, p<0.001) were less likely to contain fentanyl: less than 1% of crystal methamphetamine (2/276) and no crack cocaine (0/53). Heroin was present in 6.6% of powder cocaine samples. Xylazine reduced donors' ability to detect fentanyl, with correct classification dropping from 92% to 42%.
CONCLUSIONS
Fentanyl was detected primarily in powder forms of methamphetamine and cocaine. Recommended interventions include expanding community-based drug checking, naloxone and fentanyl test strip distribution for people who use stimulants , and supervised drug consumption sites. New strategies to dampen variability in street drug composition are needed to reduce inadvertent fentanyl exposure.
Topics: Humans; Fentanyl; Cocaine; Methamphetamine; Xylazine; Powders; Prevalence; Community Health Services; Analgesics, Opioid; Drug Overdose; Crack Cocaine; Central Nervous System Stimulants
PubMed: 37826988
DOI: 10.1016/j.drugalcdep.2023.110985 -
The Saudi Dental Journal May 2024The 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... (Review)
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.
PubMed: 38766295
DOI: 10.1016/j.sdentj.2024.02.011 -
International Journal of Molecular... Dec 2023Substance addiction is a chronic and relapsing brain disorder characterized by compulsive seeking and continued substance use, despite adverse consequences. The high... (Review)
Review
Substance addiction is a chronic and relapsing brain disorder characterized by compulsive seeking and continued substance use, despite adverse consequences. The high prevalence and social burden of addiction are indisputable; however, the available intervention is insufficient. The modulation of gene expression and aberrant adaptation of neural networks are attributed to the changes in brain functions under repeated exposure to addictive substances. Considerable studies have demonstrated that miRNAs are strong modulators of post-transcriptional gene expression in substance addiction. The emerging role of microRNA (miRNA) provides new insights into many biological and pathological processes in the central nervous system: their variable expression in different regions of the brain and tissues may play a key role in regulating the pathophysiological events of addiction. This work provides an overview of the current literature on miRNAs involved in addiction, evaluating their impaired expression and regulatory role in neuroadaptation and synaptic plasticity. Clinical implications of such modulatory capacities will be estimated. Specifically, it will evaluate the potential diagnostic role of miRNAs in the various stages of drug and substance addiction. Future perspectives about miRNAs as potential novel therapeutic targets for substance addiction and abuse will also be provided.
Topics: Humans; MicroRNAs; Substance-Related Disorders; Behavior, Addictive; Brain
PubMed: 38069445
DOI: 10.3390/ijms242317122 -
Cell Reports. Medicine Jan 2024Craving is central to methamphetamine use disorder (MUD) and both characterizes the disease and predicts relapse. However, there is currently a lack of robust and...
Craving is central to methamphetamine use disorder (MUD) and both characterizes the disease and predicts relapse. However, there is currently a lack of robust and reliable biomarkers for monitoring craving and diagnosing MUD. Here, we seek to identify a neurobiological signature of craving based on individual-level functional connectivity pattern differences between healthy control and MUD subjects. We train high-density electroencephalography (EEG)-based models using data recorded during the resting state and then calculate imaginary coherence features between the band-limited time series across different brain regions of interest. Our prediction model demonstrates that eyes-open beta functional connectivity networks have significant predictive value for craving at the individual level and can also identify individuals with MUD. These findings advance the neurobiological understanding of craving through an EEG-tailored computational model of the brain connectome. Dissecting neurophysiological features provides a clinical avenue for personalized treatment of MUD.
Topics: Humans; Methamphetamine; Craving; Electroencephalography; Brain
PubMed: 38151021
DOI: 10.1016/j.xcrm.2023.101347 -
PloS One 2023Methamphetamine use and related harms have risen at alarming rates. While several psychosocial and pharmacologic interventions have been described in the literature,... (Review)
Review
RATIONALE
Methamphetamine use and related harms have risen at alarming rates. While several psychosocial and pharmacologic interventions have been described in the literature, there is uncertainty regarding the best approach for the management of methamphetamine use disorder (MUD) and problematic methamphetamine use (PMU). We conducted a scoping review of recent systematic reviews (SR), clinical practice guidelines (CPG), and primary controlled studies of psychosocial and pharmacologic treatments for MUD/PMU.
METHODS
Guided by an a priori protocol, electronic database search updates (e.g., MEDLINE, Embase) were performed in February 2022. Screening was performed following a two-stage process, leveraging artificial intelligence to increase efficiency of title and abstract screening. Studies involving individuals who use methamphetamine, including key subgroups (e.g. those with mental health comorbidities; adolescents/youths; gay, bisexual, and other men who have sex with men) were sought. We examined evidence related to methamphetamine use, relapse, use of other substances, risk behaviors, mental health, harms, and retention. Figures, tables and descriptive synthesis were used to present findings from the identified literature.
RESULTS
We identified 2 SRs, one CPG, and 54 primary studies reported in 69 publications that met our eligibility criteria. Amongst SRs, one concluded that psychostimulants had no effect on methamphetamine abstinence or treatment retention while the other reported no effect of topiramate on cravings. The CPG strongly recommended psychosocial interventions as well as self-help and family support groups for post-acute management of methamphetamine-related disorders. Amongst primary studies, many interventions were assessed by only single studies; contingency management was the therapy most commonly associated with evidence of potential effectiveness, while bupropion and modafinil were analogously the most common pharmacologic interventions. Nearly all interventions showed signs of potential benefit on at least one methamphetamine-related outcome measure.
DISCUSSION
This scoping review provides an overview of available interventions for the treatment of MUD/PMU. As most interventions were reported by a single study, the effectiveness of available interventions remains uncertain. Primary studies with longer durations of treatment and follow-up, larger sample sizes, and of special populations are required for conclusive recommendations of best approaches for the treatment of MUD/PMU.
Topics: Male; Adolescent; Humans; Methamphetamine; Homosexuality, Male; Sexual and Gender Minorities; Artificial Intelligence; Central Nervous System Stimulants
PubMed: 37819931
DOI: 10.1371/journal.pone.0292745