Assessing methamphetamine-related cue reactivity in people with methamphetamine use disorder relative to controls

A systematic review and meta-analysis of health, functional, and cognitive outcomes in young people who use methamphetamine

Methamphetamine use typically starts in adolescence, and early onset is associated with worse outcomes. Yet, health, functional, and cognitive outcomes associated with methamphetamine use in young people are not well understood. The aim of this study was to comprehensively assess the evidence on health, functional, and cognitive outcomes in young people (10-25 years-old) who use methamphetamine. Sixty-six studies were included. The strongest association observed was with conduct disorder, with young people who use methamphetamine some 13 times more likely to meet conduct disorder criteria than controls. They were also more likely to have justice system involvement and to perpetrate violence against others. Educational problems were consistently associated with youth methamphetamine use. The cognitive domain most reliably implicated was inhibitory control. Key limitations in the literature were identified, including heterogenous measurement of exposure and outcomes, lack of adequate controls, and limited longitudinal evidence. Outcomes identified in the present review - suggesting complex and clinically significant behavioural issues in this population - are informative for the development of future research and targeted treatments.

Treating addiction with deep brain stimulation: Ethical and legal considerations

BACKGROUND

The use of neuromodulation in the treatment of psychiatric conditions is controversial despite its lengthy history. This particularly applies to the use of invasive neuromodulation, such as deep brain stimulation (DBS), to treat substance use disorder (SUD) due to the considerable risks of the procedures. However, given the advances in DBS research and the shortcomings of current treatment modalities for addiction, off-label use and clinical trials are being implemented for the management of treatment-refractory patients.

METHODS

Here we conduct an ethical and legal analysis of DBS for SUD, referencing the four foundational principles of medical ethics and key legal concepts.

RESULTS

There are major concerns related to the capacity of a SUD patient to provide informed consent, as well as the risks and benefits of DBS compared to traditional treatment methods. In addition to ethical concerns, we explore potential legal issues that may arise from DBS in the treatment of addiction. These include the potential mandate of these procedures in the context of the criminalization of substance use, and the issue of familial consent in the decision-making process. Given the paucity of relevant clinical guidelines or legal cases, general medico-legal principles serve as the reference in making decisions about the responsible use of DBS as a treatment for addiction.

CONCLUSIONS

Given the rapidly increasing evidence for DBS as a treatment for SUD, it is an urgent imperative to consider the relevant key ethical and legal issues. Incorporating IDEAL (Idea, Development, Exploration, Assessment, Long-term follow-up) framework into future research in DBS is recommended to evaluate patient safety and ethical perspectives. With the broad criminalization of SUD across the globe, legal coercion of DBS is not impossible, especially if proven to be effective to treat SUD. It is advised for stakeholders to urgently consider incorporating DBS-related drug policies so that the potential benefits of DBS within the rights of people with SUD are not hindered by the lack of clinical guidance and legislations.

Does chronic use of amphetamine-type stimulants impair interference control? - A meta-analysis

In substance use and addiction, inhibitory control is key to ignoring triggers, withstanding craving and maintaining abstinence. In amphetamine-type stimulant (ATS) users, most research focused on behavioral inhibition, but largely neglected the equally important subdomain of cognitive interference control. Given its crucial role in managing consumption, we investigated the relationship between interference control and chronic ATS use in adults. A database search (Pubmed & Web of Science) and relevant reviews were used to identify eligible studies. Effect sizes were estimated with random effects models. Subgroup, meta-regression, and sensitivity analyses explored heterogeneity in effect sizes. We identified 61 studies (53 datasets) assessing interference control in 1873 ATS users and 1905 controls. Findings revealed robust small effect sizes for ATS-related deficits in interference control, which were mainly seen in methamphetamine, as compared to MDMA users. The differential effects are likely due to tolerance-induced dopaminergic deficiencies (presumably most pronounced in methamphetamine users). Similarities between different ATS could be due to noradrenergic deficiencies; but elucidating their functional role in ATS users requires further/more research.

Electroencephalogram pattern association with drug-related cues in a long-duration virtual reality environment in patients with methamphetamine use disorder

The cognitive processing of drug-related cues and the subsequent dysregulation of behaviour play a central role in the pathophysiology of substance use disorders. Prior studies are limited by small sample sizes and a lack of immersion in stimulus presentation. In the present study, we recruited patients with methamphetamine use disorder (MUD; N = 1099) from four compulsory isolated detoxification centres and healthy control participants (N = 305). With a 12-min-long virtual reality (VR) protocol stimulus, we discovered that patients showed a decrease in electroencephalogram (EEG) power across alpha to gamma bands in anterior scalp regions under methamphetamine-related VR stimuli (e.g. a glass pipe and medical tubing) compared with the control stimuli (e.g. balls and cubes). Analysis of variance (ANOVA) showed that the interaction effects of stimuli type and group were significant in five EEG bands. Using generalised linear models, we classified the stimuli type (i.e. drug-related vs. drug-unrelated cues) in MUD patients with an f1 score of 90% on an out-of-sample testing set. The decreases of EEG between drug-related cues and drug-unrelated cues in delta, theta and alpha frequency bands are more frequently seen in patients than in healthy controls, perhaps reflecting general arousal and attenuated impulsive control. Our results suggest that EEG responses elicited by long-duration methamphetamine-related VR cues showed a specific signature, which may have future clinical implications.

A 1:1 ratio of cannabidiol: tetrahydrocannabinol attenuates methamphetamine conditioned place preference in mice: A prospective study of antidopaminergic mechanism

A 1:1 ratio of cannabidiol to tetrahydrocannabinol (CT) was suggested to be safer for therapeutic purposes in many illnesses. However, CT effects on methamphetamine (METH) conditioned place preference (CPP) remained largely unexplored. This study aimed to examine the effects of CT on METH CPP mice evaluated by animal behaviors accompanied by local field potential (LFP) signals analysis. Male ICR mice were implanted with the LFP electrode in the ventral tegmental area (VTA) and the nucleus accumbens (NAc). Animals were next subjected to induce METH CPP by peritoneal injection with 1 mg/kg METH and 0.9 % NaCl on an alternate day for ten sessions and confined to the corresponding compartment for 30 min meanwhile control mice were given normal saline all day for both compartments. On testing day, either 10 mg/kg CT or 20 mg/kg bupropion (BP), a dopamine reuptake inhibitor, and VTA GABAergic suppressor were orally administered before CPP testing. The results revealed that CPP scores elevation was observed in the METH+vehicle and METH+BP mice, but this was reversed by CT treatment. Although both METH+vehicle and METH+BP enhanced the VTA delta power, NAc gamma I power, NAc delta-gamma coupling, and VTA-NAc gamma I coherence, changes in opposite trends of all mentioned parameters were seen by CT application. These improvements were postulated to involve the antidopaminergic effects of CT via modulations of neural signaling in the VTA and NAc. Altogether, the evidence-based study may suggest the use of CT as alternative drug for METH-seeking and craving therapy.

Challenges and future trends in wearable closed-loop neuromodulation to efficiently treat methamphetamine addiction

Achieving abstinence from drugs is a long journey and can be particularly challenging in the case of methamphetamine, which has a higher relapse rate than other drugs. Therefore, real-time monitoring of patients' physiological conditions before and when cravings arise to reduce the chance of relapse might help to improve clinical outcomes. Conventional treatments, such as behavior therapy and peer support, often cannot provide timely intervention, reducing the efficiency of these therapies. To more effectively treat methamphetamine addiction in real-time, we propose an intelligent closed-loop transcranial magnetic stimulation (TMS) neuromodulation system based on multimodal electroencephalogram-functional near-infrared spectroscopy (EEG-fNIRS) measurements. This review summarizes the essential modules required for a wearable system to treat addiction efficiently. First, the advantages of neuroimaging over conventional techniques such as analysis of sweat, saliva, or urine for addiction detection are discussed. The knowledge to implement wearable, compact, and user-friendly closed-loop systems with EEG and fNIRS are reviewed. The features of EEG and fNIRS signals in patients with methamphetamine use disorder are summarized. EEG biomarkers are categorized into frequency and time domain and topography-related parameters, whereas for fNIRS, hemoglobin concentration variation and functional connectivity of cortices are described. Following this, the applications of two commonly used neuromodulation technologies, transcranial direct current stimulation and TMS, in patients with methamphetamine use disorder are introduced. The challenges of implementing intelligent closed-loop TMS modulation based on multimodal EEG-fNIRS are summarized, followed by a discussion of potential research directions and the promising future of this approach, including potential applications to other substance use disorders.

Patients with Methamphetamine Use Disorder Show Highly Utilized Proactive Inhibitory Control and Intact Reactive Inhibitory Control with Long-Term Abstinence

Methamphetamine use disorder (MUD) is a chronic brain disorder that involves frequent failures of inhibitory control and relapses into methamphetamine intake. However, it remains unclear whether the impairment of inhibitory control in MUD is proactive, reactive or both. To address this issue, the current study used the conditional stop-signal task to assess proactive and reactive inhibitory control in 35 MUD patients with long-term abstinence and 35 matched healthy controls. The results showed that MUD patients with long-term abstinence had greater preparation costs than healthy controls, but did not differ in performance, implying a less efficient utilization of proactive inhibitory control. In contrast, MUD patients exhibited intact reactive inhibitory control; reactive but not proactive inhibitory control was associated with high sensation seeking in MUD patients with long-term abstinence. These findings suggest that proactive and reactive inhibitory control may be two different important endophenotypes of addiction in MUD patients with long-term abstinence. The current study provides new insight into the uses of proactive and reactive inhibitory control to effectively evaluate and precisely treat MUD patients with long-term abstinence.

Examining Sex Differences in Conditioned Place Preference or Aversion to Methamphetamine in Adolescent and Adult Mice

Adolescence marks a particularly vulnerable period to developing substance use disorders. Human and rodent studies suggest that hypersensitivity to reward may contribute towards such vulnerability when adolescents are exposed to casual drug use. Methamphetamine is a popular illicit substance used by male and female youths. However, age- and sex-specific research in methamphetamine is scarce. The present study therefore aimed to examine potential sex differences in methamphetamine-conditioned place preference in adolescent and adult mice. Mice (n = 16–24/group) were conditioned to methamphetamine (0.1 mg/kg). We observed that regardless of age, females were more hyperactive compared to males. Individually normalized score against baseline preference indicated that on average, adolescents formed stronger preference compared to adults in both sexes. This suggests that adolescents are more sensitive to the rewarding effects of methamphetamine compared to adults. Surprisingly, individual data showed that some mice formed a conditioned place aversion instead of preference, with females less likely to form an aversion compared to males. These results suggest that adolescents may be hypersensitive to methamphetamine’s rewarding effects. In addition, female resistance to the aversive effects of methamphetamine may relate to the sex-specific findings in humans, including quicker transition to regular methamphetamine use observed in females compared to males.

Age of Onset and Its Related Factors in Cocaine or Methamphetamine Use in Adults from the United States: Results from NHANES 2005-2018

Cocaine and methamphetamine are widely used illicit psychostimulants worldwide, with steadily increasing global markets that may impact on the frequency of use. Importantly, their use typically begins in youth. This is a particular concern because there is a link between the early age of first substance use and severity of substance use disorder later in life. The aim of the present study was therefore to investigate trends in prevalence, frequency, and age of onset of cocaine or methamphetamine use between 2005 and 2018 in the United States, using the nationally representative NHANES datasets. Factors associated with the ages of cocaine or methamphetamine use onset were also identified. From 2005 to 2018, prevalence and frequencies of cocaine or methamphetamine use increased, while age of onset remained relatively stable (~20 years of age). Annual household income, use of other substances, and intravenous drug use were identified as factors associated with early onset cocaine or methamphetamine use. These factors have important implications toward developing new prevention programs to reduce psychostimulant use.