Efficacy of Repetitive Transcranial Magnetic Stimulation in Patients With Methamphetamine Use Disorder: A Systematic Review and Meta-Analysis of Double-Blind Randomized Controlled Trials

Theta Burst Stimulation in Patients With Methamphetamine Use Disorder: A Meta-Analysis and Systematic Review

Novel interventions are urgently needed to treat methamphetamine use disorder (MUD), for which there are no FDA-approved treatments. Previous studies in patients with MUD suggest transcranial magnetic stimulation (TMS) over the left dorsolateral prefrontal cortex (L. dlPFC) decreases craving for methamphetamine. Theta burst stimulation (TBS), which includes intermittent TBS and continuous TBS (cTBS), is increasingly being used for substance use disorders, including MUD. Previous reviews of TMS in MUD performed sub-group meta-analyses of studies that delivered TBS in MUD. However, these meta-analyses included studies with overlapping participant cohorts. Given the absence of prior meta-analyses or reviews examining TBS in MUD using unique participant cohorts, we reviewed randomized controlled trials (RCTs) from three databases (PubMed/Medline, EMBASE, Google Scholar) until September 1, 2024, comparing the impact of TBS versus sham TBS on cue-induced methamphetamine cravings in patients with MUD. We performed a meta-analysis with four eligible RCTs that delivered iTBS. Results suggest iTBS was more effective in reducing cue-induced methamphetamine cravings than sham iTBS (standardized mean difference [SMD] in change = 1.04; 95% CI [0.16, 1.92]). Our systematic review included two additional RCTs that did not have sham comparator arms; one of these demonstrated a significant reduction in methamphetamine craving with accelerated iTBS. Future studies should examine if iTBS can impact clinical outcome measures other than craving, such as methamphetamine use, by measuring return to drug use. It is also pertinent to explore accelerated iTBS and cTBS for MUD and study their effects on relevant biomarkers for MUD.

Systematic review and meta-analysis: Combining transcranial magnetic stimulation or direct current stimulation with pharmacotherapy for treatment of substance use disorders

BACKGROUND AND OBJECTIVES

Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) have evidence for their potential in the treatment of substance use disorders (SUD). Medication for addiction treatment (MAT) is underutilized and not always effective. We identified randomized controlled trials (RCTs) and case studies that evaluated the effectiveness of TMS or tDCS used concurrently with MAT in SUD treatment.

METHODS

A systematic review of published literature following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted on 6/1/2023 by a medical librarian. Craving-related scales were extracted for an effect size calculation. The Physiotherapy Evidence Database (PEDro) scale assessed study quality.

RESULTS

Eight studies (7 RCT, 1 case) including 253 individuals were published from 2015 to 2022, 5 of which had available data for meta-analysis. TMS or tDCS combined with MAT significantly reduced craving-related measures relative to sham stimulation (Hedges' g = -0.42, confidence interval: -0.73 to -0.11, p < .01). Opioid use disorder, methadone, and the dorsolateral prefrontal cortex were the most commonly studied SUD, MAT, and target region.

DISCUSSION AND CONCLUSIONS

Our results show a significant effect; however, is limited by a small number of studies with heterogeneous methodology across intervention methods and SUDs. Additional trials are needed to fully assess the clinical impact and mechanisms of combined brain stimulation and pharmacotherapy. We discuss a possible mechanism for synergism from these treatment combinations.

SCIENTIFIC SIGNIFICANCE

Adds the first systematic review of combination treatment with TMS or tDCS and MAT in SUD patients to the literature and estimates its overall effect size.

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.

Effects of high-frequency transcranial magnetic stimulation on theta-gamma oscillations and coupling in the prefrontal cortex of rats during working memory task

High-frequency rTMS has been widely used to improve working memory (WM) impairment; however, the underlying neurophysiological mechanisms are unclear. We evaluated the effect of high-frequency rTMS on behaviors relevant to WM as well as coupling between theta and gamma oscillations in the prefrontal cortex (PFC) of rats. Accordingly, Wistar rats received high-frequency rTMS daily for 14 days (5 Hz, 10 Hz, and 15 Hz stimulation; 600 pulses; n = 6 per group), whereas the control group received sham stimulation. Electrophysiological signals were recorded simultaneously to obtain the local field potential (LFP) from the PFC, while the rats performed T-maze tasks for the evaluation of WM. Phase-amplitude coupling (PAC) was utilized to determine the effect of high-frequency rTMS on the theta-gamma coupling of LFPs. We observed that rats in the rTMS groups needed a smaller number of training days to complete the WM task as compared to the control group. High-frequency rTMS reinforced the coupling connection strength in the PFC of rats. Notably, the effect of rTMS at 15 Hz was the most effective among the three frequencies, i.e., 5 Hz, 10 Hz, and 15 Hz. The results suggested that rTMS can improve WM impairment in rats by modulating the coupling of theta and gamma rhythms. Hence, the current study provides a scientific basis for the optimization of TMS models, which would be relevant for clinical application.

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.