Efficacy of neurostimulation across mental disorders: systematic review and meta-analysis of 208 randomized controlled trials

Cerebellar Neurostimulation for Boosting Social and Affective Functions: Implications for the Rehabilitation of Hereditary Ataxia Patients

Beyond motor deficits, spinocerebellar ataxia (SCA) patients also suffer cognitive decline and show socio-affective difficulties, negatively impacting on their social functioning. The possibility to modulate cerebello-cerebral networks involved in social cognition through cerebellar neurostimulation has opened up potential therapeutic applications for ameliorating social and affective difficulties. The present review offers an overview of the research on cerebellar neurostimulation for the modulation of socio-affective functions in both healthy individuals and different clinical populations, published in the time period 2000-2022. A total of 25 records reporting either transcranial magnetic stimulation (TMS) or transcranial direct current stimulation (tDCS) studies were found. The investigated clinical populations comprised different pathological conditions, including but not limited to SCA syndromes. The reviewed evidence supports that cerebellar neurostimulation is effective in improving social abilities in healthy individuals and reducing social and affective symptoms in different neurological and psychiatric populations associated with cerebellar damage or with impairments in functions that involve the cerebellum. These findings encourage to further explore the rehabilitative effects of cerebellar neurostimulation on socio-affective deficits experienced by patients with cerebellar abnormalities, as SCA patients. Nevertheless, conclusions remain tentative at this stage due to the heterogeneity characterizing stimulation protocols, study methodologies and patients' samples.

Effect of transcranial direct current stimulation with concurrent cognitive performance targeting posterior parietal cortex vs prefrontal cortex on working memory in schizophrenia: a randomized clinical trial

Working memory deficits are linked to irregularities in the dorsolateral prefrontal cortex (DLPFC) and the posterior parietal cortex (PPC) in schizophrenia, effective intervention strategies are lacking. We evaluated the differential efficacy and underlying neuromechanisms of targeting transcranial direct current stimulation (tDCS) at the DLPFC and the PPC with concurrent cognitive performance for working memory in schizophrenia. In a randomized and double-blind clinical trial, sixty clinically stable schizophrenic patients with below-average working memory were randomly assigned to active DLPFC, active PPC, and sham tDCS groups. Two sessions of tDCS during N-back task were delivered daily for five days. The primary outcome was changes in spatial span test scores from baseline to week 1. The secondary outcomes included changes in scores of color delay-estimation task, other cognitive tasks, and mismatch negativity (biomarker of N-methyl-d-aspartate receptor functioning). Compared with the active DLPFC group, the active PPC group demonstrated significantly greater improvement in spatial span test scores (p = 0.008, d = 0.94) and an augmentation in color delay-estimation task capacity at week 1; the latter sustained to week 2. Compared with the sham tDCS group, the active PPC group did not show a significant improvement in spatial span test scores at week 1 and 2; however, significant enhancement was observed in their color delay-estimation task capacity at week 2. Additionally, mismatch negativity amplitude was enhanced, and changes in theta band measures were positively correlated with working memory improvement in the active PPC group, while no such correlations were observed in the active DLPFC group or the sham tDCS group. Our results suggest that tDCS targeting the PPC relative to the DLPFC during concurrent cognitive performance may improve working memory in schizophrenia, meriting further investigation. The improvement in working memory appears to be linked to enhanced N-methyl-d-aspartate receptor functioning.

The dose-effect relationship of six stimulation parameters with rTMS over left DLPFC on treatment-resistant depression: A systematic review and meta-analysis

This study aimed to evaluate the association of the six parameters, namely stimulation intensity, stimulation frequency, pulses per session, treatment duration, number of sessions, and total number of pulses with the efficacy of conventional transcranial magnetic stimulation (rTMS) over left dorsolateral prefrontal cortex for patients with treatment-resistant depression (TRD). A random-effects dose-response meta-analysis of blinded randomized controlled trials (RCTs) involving 2391 participants were conducted to examine the dose-effect relationship of six stimulation parameters. Any of the six parameters significantly individually predicted proportion of variance in efficacy: pulses per session (R²=52.7%), treatment duration (R²=51.2%), total sessions (R²=50.9%), frequency (R²=49.6%), total pulses (R²=49.5%), and intensity (R²= 40.4%). Besides, we identified frequency as a potential parameter interacting with the other five parameters, resulting in a significant increase in variance(ΔR2) ranging from 5.0% to 16.7%. Finally, we found that RCTs using frequency > 10 Hz compared to those of 10 Hz showed better dose-effect relationships. We conclude that the six stimulation parameters significantly predict the dose-effect relationship of conventional rTMS on TRD. Besides, higher stimulation frequency, higher stimulation intensity, and adequate number of pulses were associated with treatment efficacy.

Insights into interoceptive and emotional processing: Lessons from studies on insular HD-tDCS

Interoception, the processing of internal bodily signals, is proposed as the fundamental mechanism underlying emotional experiences. Interoceptive and emotional processing appear distorted in psychiatric disorders. However, our understanding of the neural structures involved in both processes remains limited. To explore the feasibility of enhancing interoception and emotion, we conducted two studies using high-definition transcranial direct current stimulation (HD-tDCS) applied to the right anterior insula. In study one, we compared the effects of anodal HD-tDCS and sham tDCS on interoceptive abilities (sensibility, confidence, accuracy, emotional evaluation) in 52 healthy subjects. Study two additionally included physical activation through ergometer cycling at the beginning of HD-tDCS and examined changes in interoceptive and emotional processing in 39 healthy adults. In both studies, HD-tDCS was applied in a single-blind cross-over online design with two separate sessions. Study one yielded no significant effects of HD-tDCS on interoceptive dimensions. In study two, significant improvements in interoceptive sensibility and confidence were observed over time with physical preactivation, while no differential effects were found between sham and insula stimulation. The expected enhancement of interoceptive and emotional processing following insula stimulation was not observed. We conclude that HD-tDCS targeting the insula does not consistently increase interoceptive or emotional variables. The observed increase in interoceptive sensibility may be attributed to the activation of the interoceptive network through physical activity or training effects. Future research on HD-tDCS involving interoceptive network structures could benefit from protocols targeting larger regions within the network, rather than focusing solely on insula stimulation.

Transcranial magnetic stimulation and transcranial direct current stimulation in reducing depressive symptoms during the peripartum period

PURPOSE OF THE REVIEW

To present the latest data on the efficacy, safety, and acceptability of transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) in peripartum depression (PPD), complemented by notes emerging from our clinical and research experience.

RECENT FINDINGS

TMS and tDCS show promising results to manage mild to moderate depressive symptoms in the peripartum period. Evidence of TMS efficacy during pregnancy and the postpartum comes from two small randomized controlled trials (RCTs) with encouraging but still inconsistent results. Evidence of tDCS efficacy during pregnancy comes from one small RCT and in the postpartum the first RCT is just now being conducted and results are highly expected. The safety profile (with transient mild adverse effect to women and no known risk to the foetus/newborn) and acceptability by women seems overall good. However, the perspectives from health professionals and managers are unclear.

SUMMARY

Whereas TMS accelerated protocols (e.g., more than one session/day) and shorter sessions (e.g., theta burst stimulation) could address the need for fast results in PPD, home-based tDCS systems could address accessibility issues. Currently, the evidence on the efficacy of TMS and tDCS in PPD is limited warranting further research to support stronger evidence-based clinical guidelines.

Right ventrolateral and left dorsolateral 10 Hz transcranial magnetic stimulation as an add-on treatment for bipolar I and II depression: a double-blind, randomised, three-arm, sham-controlled study

OBJECTIVES

Despite the clinical importance of bipolar depression (BDE), effective treatment options are still limited. Transcranial magnetic stimulation (rTMS) has proven of moderate efficacy in major depression, but the evidence remains inconclusive for BDE.

METHODS

A 4-week, double-blind, randomised, parallel-group, sham-controlled study (trial ID ISRCTN77188420) explored the benefits of 10 Hz MRI-guided right ventrolateral (RVL) rTMS and left dorsolateral (LDL) rTMS as add-on treatments for BDE. Outcome measures included changes in the Montgomery-Åsberg Depression Rating Scale (MADRS) score, self-assessment, response and remission rates, and side effects.

RESULTS

Sixty patients were randomly assigned to study groups, and forty-six completed the double-blind phase. The mean change from baseline to Week 4 in MADRS was greater in both active groups compared to the sham, yet differences did not achieve significance (RVL vs sham: -4.50, 95%CI -10.63 to 1.64, p = 0.3; LDL vs sham: -4.07, 95%CI -10.24 to 2.10, p = 0.4). None of the other outcome measures yielded significant results.

CONCLUSIONS

While not demonstrating the superiority of either 10 Hz rTMS over sham, with the limited sample size, we can not rule out a moderate yet clinically meaningful effect. Further well-powered studies are essential to elucidate the role of rTMS in managing BDE.

Effects and safety of transcranial direct current stimulation on multiple health outcomes: an umbrella review of randomized clinical trials

Transcranial direct current stimulation (tDCS), which delivers a direct current to the brain, emerged as a non-invasive potential therapeutic in treating a range of neurological and neuropsychiatric disorders. However, a comprehensive quantitative evidence synthesis on the effects of tDCS on a broad range of mental illnesses is lacking. Here, we systematically assess the certainty of the effects and safety of tDCS on several health outcomes using an umbrella review of randomized controlled trials (RCTs). The methodological quality of each included original meta-analysis was assessed by the A Measurement Tool for Assessing Systematic Reviews 2 (AMSTAR2), and the certainty of the evidence for each effect was evaluated with Grading of Recommendations, Assessment, Development, and Evaluation (GRADE). We followed an a priori protocol (PROSPERO CRD42023458700). We identified 15 meta-analyses of RCTs (AMSTAR 2; high 3, moderate 3, and low 9) that included 282 original articles, covering 22 unique health endpoints across 22 countries and six continents. From meta-analyses of RCTs supported by very low to high certainty of evidence, it was found that tDCS improved symptoms related to post-stroke, including post-stroke depression scale score (equivalent standardized mean difference [eSMD], 1.61 [95% confidence level, 0.72-2.50]; GRADE=moderate), activities of daily living independence (7.04 [3.41-10.67]; GRADE=high), motor recovery of upper and lower extremity (upper extremity: 0.15 [0.06-0.24], GRADE=high; lower extremity: 0.10 [0.03-0.16], GRADE=high), swallowing performance (GRADE=low), and spasticity (GRADE=moderate). In addition, tDCS had treatment effects on symptoms of several neurological and neuropsychiatric disorders, including obsessive-compulsive disorder (0.81 [0.44-1.18]; GRADE=high), pain in fibromyalgia (GRADE=low), disease of consciousness (GRADE=low), insight score (GRADE=moderate) and working memory (0.34 [0.01-0.67]; GRADE=high) in schizophrenia, migraine-related pain (-1.52 [-2.91 to -0.13]; GRADE=high), attention-deficit/hyperactivity disorder (reduction in overall symptom severity: 0.24 [0.04-0.45], GRADE=low; reduction in inattention: 0.56 [0.02-1.11], GRADE=low; reduction in impulsivity: 0.28 [0.04-0.51], GRADE=low), depression (GRADE=low), cerebellar ataxia (GRADE=low), and pain (GRADE=very low). Importantly, tDCS induced an increased number of reported cases of treatment-emergent mania or hypomania (0.88 [0.62-1.13]; GRADE=moderate). We found varied levels of evidence for the effects of tDCS with multiple neurological and neuropsychiatric conditions, from very low to high certainty of evidence. tDCS was effective for people with stroke, obsessive-compulsive disorder, fibromyalgia, disease of consciousness, schizophrenia, migraine, attention-deficit/hyperactivity disorder, depression, cerebellar ataxia, and pain. Therefore, these findings suggest the benefit of tDCS for several neurological and neuropsychiatric disorders; however, further studies are needed to understand the underlying mechanism and optimize its therapeutic potential.

A systematic review of the biomarkers associated with cognition and mood state in bipolar disorder

BACKGROUND

Bipolar disorder (BD) is a severe psychiatric disorder characterized by changes in mood that alternate between (hypo) mania or depression and mixed states, often associated with functional impairment and cognitive dysfunction. But little is known about biomarkers that contribute to the development and sustainment of cognitive deficits. The aim of this study was to review the association between neurocognition and biomarkers across different mood states.

METHOD

Search databases were Web of Science, Scopus and PubMed. A systematic review was carried out following the PRISMA guidelines. Risk of bias was assessed with the Newcastle-Ottawa Scale. Studies were selected that focused on the correlation between neuroimaging, physiological, genetic or peripheral biomarkers and cognition in at least two phases of BD: depression, (hypo)mania, euthymia or mixed. PROSPERO Registration No.: CRD42023410782.

RESULTS

A total of 1824 references were screened, identifying 1023 published articles, of which 336 were considered eligible. Only 16 provided information on the association between biomarkers and cognition in the different affective states of BD. The included studies found: (i) Differences in levels of total cholesterol and C reactive protein depending on mood state; (ii) There is no association found between cognition and peripheral biomarkers; (iii) Neuroimaging biomarkers highlighted hypoactivation of frontal areas as distinctive of acute state of BD; (iv) A deactivation failure has been reported in the ventromedial prefrontal cortex (vmPFC), potentially serving as a trait marker of BD.

CONCLUSION

Only a few recent articles have investigated biomarker-cognition associations in BD mood phases. Our findings underline that there appear to be central regions involved in BD that are observed in all mood states. However, there appear to be underlying mechanisms of cognitive dysfunction that may vary across different mood states in BD. This review highlights the importance of standardizing the data and the assessment of cognition, as well as the need for biomarkers to help prevent acute symptomatic phases of the disease, and the associated functional and cognitive impairment.

Closed-Loop Transcranial Electrical Neurostimulation for Sustained Attention Enhancement: A Pilot Study towards Personalized Intervention Strategies

Sustained attention is pivotal for tasks like studying and working for which focus and low distractions are necessary for peak productivity. This study explores the effectiveness of adaptive transcranial direct current stimulation (tDCS) in either the frontal or parietal region to enhance sustained attention. The research involved ten healthy university students performing the Continuous Performance Task-AX (AX-CPT) while receiving either frontal or parietal tDCS. The study comprised three phases. First, we acquired the electroencephalography (EEG) signal to identify the most suitable metrics related to attention states. Among different spectral and complexity metrics computed on 3 s epochs of EEG, the Fuzzy Entropy and Multiscale Sample Entropy Index of frontal channels were selected. Secondly, we assessed how tDCS at a fixed 1.0 mA current affects attentional performance. Finally, a real-time experiment involving continuous metric monitoring allowed personalized dynamic optimization of the current amplitude and stimulation site (frontal or parietal). The findings reveal statistically significant improvements in mean accuracy (94.04 vs. 90.82%) and reaction times (262.93 vs. 302.03 ms) with the adaptive tDCS compared to a non-stimulation condition. Average reaction times were statistically shorter during adaptive stimulation compared to a fixed current amplitude condition (262.93 vs. 283.56 ms), while mean accuracy stayed similar (94.04 vs. 93.36%, improvement not statistically significant). Despite the limited number of subjects, this work points out the promising potential of adaptive tDCS as a tailored treatment for enhancing sustained attention.

Multichannel tDCS with Advanced Targeting for Major Depressive Disorder: A Tele-Supervised At-Home Pilot Study

Introduction

Proof-of-principle human studies suggest that transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex (DLPFC) may improve depression severity. This open-label multicenter study tested remotely supervised multichannel tDCS delivered at home in patients (N=35) with major depressive disorder (MDD). The primary aim was to assess the feasibility and safety of our protocol. As an exploratory aim, we evaluated therapeutic efficacy: the primary efficacy measure was the median percent change from baseline to the end of the 4-week post-treatment follow-up period in the observer-rated Montgomery-Asberg Depression Mood Rating Scale (MADRS).

Methods

Participants received 37 at-home stimulation sessions (30 minutes each) of specifically designed multichannel tDCS targeting the left DLPFC administered over eight weeks (4 weeks of daily treatments plus 4 weeks of taper), with a follow-up period of 4 weeks following the final stimulation session. The stimulation montage (electrode positions and currents) was optimized by employing computational models of the electric field generated by multichannel tDCS using available structural data from a similar population (group optimization). Conducted entirely remotely, the study employed the MADRS for assessment at baseline, at weeks 4 and 8 during treatment, and at 4-week follow-up visits.

Results

34 patients (85.3% women) with a mean age of 59 years, a diagnosis of MDD according to DSM-5 criteria, and a MADRS score ≥20 at the time of study enrolment completed all study visits. At baseline, the mean time since MDD diagnosis was 24.0 (SD 19.1) months. Concerning compliance, 85% of the participants (n=29) completed the complete course of 37 stimulation sessions at home, while 97% completed at least 36 sessions. No detrimental effects were observed, including suicidal ideation and/or behavior. The study observed a median MADRS score reduction of 64.5% (48.6, 72.4) 4 weeks post-treatment (Hedge's g = -3.1). We observed a response rate (≥ 50% improvement in MADRS scores) of 72.7% (n=24) from baseline to the last visit 4 weeks post-treatment. Secondary measures reflected similar improvements.

Conclusions

These results suggest that remotely supervised and supported multichannel home-based tDCS is safe and feasible, and antidepressant efficacy motivates further appropriately controlled clinical studies.

A meta-analysis of transcranial magnetic stimulation in Tourette syndrome

There is growing enthusiasm for the treatment of neuropsychiatric disorders using neuromodulation. While some reports claim that transcranial magnetic stimulation (TMS) can be used to treat Tourette Syndrome (TS), little research exists to support this assertion. This meta-analysis examined the efficacy of TMS to reduce tic severity in patients with TS. Additionally, it explored the effect of TMS to reduce premonitory urge severity-the primary mechanism implicated in the frontline evidence-based treatment of TS. Five treatment comparisons were selected using PRISMA guidelines. All studies included were required to be (1) a randomized controlled trial, (2) compare TMS to a sham condition, and (3) have all participants meet diagnostic criteria for a persistent tic disorder and/or TS. A random effects model meta-analysis examined the efficacy of using TMS to reduce tic severity and explored the effect of TMS to reduce premonitory urge severity. TMS did not significantly reduce tic severity (g = 0.44; 95% CI = -0.17, 1.05; z = 1.40; p = 0.16), but a moderate reduction in premonitory urge severity was found (g = 0.63; 95% CI = 0.9, 1.17; z = 2.27; p < 0.02). Trials with larger sample sizes and a preponderance of women were found to have greater therapeutic effects of TMS for tic severity. There is limited support for the use of TMS to reduce tic severity, though reductions in premonitory urge severity were observed. Major limitations of the existing literature are examined, with a call for research investigating newer TMS protocols and their use as a treatment augmentation strategy.

Transcranial Magnetic Stimulation and Transcranial Direct Current Stimulation Across Mental Disorders: A Systematic Review and Dose-Response Meta-Analysis

Importance

Noninvasive brain stimulation (NIBS) interventions have been shown to be efficacious in several mental disorders, but the optimal dose stimulation parameters for each disorder are unknown.

Objective

To define NIBS dose stimulation parameters associated with the greatest efficacy in symptom improvement across mental disorders.

Data Sources

Studies were drawn from an updated (to April 30, 2023) previous systematic review based on a search of PubMed, OVID, and Web of Knowledge.

Study Selection

Randomized clinical trials were selected that tested transcranial magnetic stimulation (TMS) or transcranial direct current stimulation (tDCS) for any mental disorder in adults aged 18 years or older.

Data Extraction and Synthesis

Two authors independently extracted the data. A 1-stage dose-response meta-analysis using a random-effects model was performed. Sensitivity analyses were conducted to test robustness of the findings. This study followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline.

Main Outcomes and Measures

The main outcome was the near-maximal effective doses of total pulses received for TMS and total current dose in coulombs for tDCS.

Results

A total of 110 studies with 4820 participants (2659 men [61.4%]; mean [SD] age, 42.3 [8.8] years) were included. The following significant dose-response associations emerged with bell-shaped curves: (1) in schizophrenia, high-frequency (HF) TMS on the left dorsolateral prefrontal cortex (LDLPFC) for negative symptoms (χ2 = 9.35; df = 2; P = .009) and TMS on the left temporoparietal junction for resistant hallucinations (χ2 = 36.52; df = 2; P < .001); (2) in depression, HF-DLPFC TMS (χ2 = 14.49; df = 2; P < .001); (3) in treatment-resistant depression, LDLPFC tDCS (χ2 = 14.56; df = 2; P < .001); and (4) in substance use disorder, LDLPFC tDCS (χ2 = 33.63; df = 2; P < .001). The following significant dose-response associations emerged with plateaued or ascending curves: (1) in depression, low-frequency (LF) TMS on the right DLPFC (RDLPFC) with ascending curve (χ2 = 25.67; df = 2; P = .001); (2) for treatment-resistant depression, LF TMS on the bilateral DLPFC with ascending curve (χ2 = 5.86; df = 2; P = .004); (3) in obsessive-compulsive disorder, LF-RDLPFC TMS with ascending curve (χ2 = 20.65; df = 2; P < .001) and LF TMS on the orbitofrontal cortex with a plateaued curve (χ2 = 15.19; df = 2; P < .001); and (4) in posttraumatic stress disorder, LF-RDLPFC TMS with ascending curve (χ2 = 54.15; df = 2; P < .001). Sensitivity analyses confirmed the main findings.

Conclusions and Relevance

The study findings suggest that NIBS yields specific outcomes based on dose parameters across various mental disorders and brain regions. Clinicians should consider these dose parameters when prescribing NIBS. Additional research is needed to prospectively validate the findings in randomized, sham-controlled trials and explore how other parameters contribute to the observed dose-response association.

Heterogeneous Brain Abnormalities in Schizophrenia Converge on a Common Network Associated With Symptom Remission

BACKGROUND AND HYPOTHESIS

There is a huge heterogeneity of magnetic resonance imaging findings in schizophrenia studies. Here, we hypothesized that brain regions identified by structural and functional imaging studies of schizophrenia could be reconciled in a common network.

STUDY DESIGN

We systematically reviewed the case-control studies that estimated the brain morphology or resting-state local function for schizophrenia patients in the literature. Using the healthy human connectome (n = 652) and a validated technique "coordinate network mapping" to identify a common brain network affected in schizophrenia. Then, the specificity of this schizophrenia network was examined by independent data collected from 13 meta-analyses. The clinical relevance of this schizophrenia network was tested on independent data of medication, neuromodulation, and brain lesions.

STUDY RESULTS

We identified 83 morphological and 60 functional studies comprising 7389 patients with schizophrenia and 7408 control subjects. The "coordinate network mapping" showed that the atrophy and dysfunction coordinates were functionally connected to a common network although they were spatially distant from each other. Taking all 143 studies together, we identified the schizophrenia network with hub regions in the bilateral anterior cingulate cortex, insula, temporal lobe, and subcortical structures. Based on independent data from 13 meta-analyses, we showed that these hub regions were specifically connected with regions of cortical thickness changes in schizophrenia. More importantly, this schizophrenia network was remarkably aligned with regions involving psychotic symptom remission.

CONCLUSIONS

Neuroimaging abnormalities in cross-sectional schizophrenia studies converged into a common brain network that provided testable targets for developing precise therapies.

What impact can brain stimulation interventions have on borderline personality disorder?

INTRODUCTION

Borderline personality disorder (BPD) is a severe mental disorder characterized by emotion dysregulation, impulsivity, neuropsychological impairment, and interpersonal instability, presenting with multiple psychiatric comorbidities, functional disability and reduced life expectancy due suicidal behaviors.

AREAS COVERED

In this perspective, the authors explore the application of noninvasive brain stimulation (NIBS) (rTMS, tDCS, and MST) in BPD individuals by considering a symptom-based approach, focusing on general BPD psychopathology, impulsivity and neuropsychological impairments, suicidality and depressive/anxious symptoms, and emotion dysregulation.

EXPERT OPINION

According to a symptoms-based approach, NIBS interventions (particularly rTMS and tDCS) are promising treatment options for BPD individuals improving core symptoms such as emotional and behavioral dysregulation, neuropsychological impairments and depressive symptoms. However, the heterogeneity of stimulation protocols and of assessment tools used to detect these changes limits the possibility to provide definitive recommendations according to a symptom-based approach. To implement such armamentarium in clinical practice, future NIIBS studies should further consider a lifespan perspective due to clinical variability over time, the role of psychiatric comorbidities affecting BPD individuals and the need to combine NIBS with specialized psychotherapeutic approaches for BPD patients and with functional neuroimaging studies.

The Efficacy of Transcranial Magnetic Stimulation in the Treatment of Obsessive-Compulsive Disorder: An Umbrella Review of Meta-Analyses

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) has been increasingly used for treating obsessive-compulsive disorder (OCD). Although several meta-analyses have explored its effectiveness and safety, there is no umbrella review specifically focused on rTMS for OCD. This umbrella review followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and analyzed relevant meta-analyses on rTMS for OCD.

METHODS

Twenty-three articles were identified from PubMed, and after screening, 12 meta-analyses were included in the review. The studies analyzed in the meta-analyses ranged from 10 to 27, with total participants ranging from 282 to 791. The most commonly studied regions were the dorsolateral prefrontal cortex (DLPFC), supplementary motor area (SMA), and orbito-frontal cortex (OFC).

RESULT

The majority of the meta-analyses consistently supported the effectiveness of rTMS in reducing OCD symptoms when applied to the DLPFC and SMA. Encouraging results were also observed when targeting the medial prefrontal cortex (mPFC) and anterior cingulate cortex (ACC) through deep transcranial magnetic stimulation (dTMS). However, there was a high level of heterogeneity in the findings of nine out of 12 meta-analyses.

CONCLUSION

In conclusion, existing evidence suggests that rTMS targeting the DLPFC and SMA consistently reduces OCD symptoms, but targeting the mPFC and ACC through dTMS shows variable results. However, the high heterogeneity in the study findings indicates a need for further research and standardization in the field.

Repetitive Transcranial Magnetic Stimulation for Working Memory Deficits in Schizophrenia: A Systematic Review of Randomized Controlled Trials

Working memory (WM) deficits are a significant component of neurocognitive impairment in individuals with schizophrenia (SCZ). Two previous meta-analyses, conducted on randomized controlled trials (RCTs), examined the effectiveness of repetitive transcranial magnetic stimulation (rTMS) in addressing WM deficits in individuals diagnosed with SCZ. However, the conclusions drawn from these analyses were inconsistent. Additionally, the commonly used random effects (RE) models might underestimate statistical errors, attributing a significant portion of perceived heterogeneity between studies to variations in study quality. Therefore, this review utilized both RE and quality effects (QE) models to assess relevant RCTs comparing TMS with sham intervention in terms of clinical outcomes. A comprehensive literature search was conducted using PubMed and Scopus databases, resulting in the inclusion of 13 studies for data synthesis. Overall, regardless of whether the RE or QE model was used, eligible RCTs suggested that the TMS and sham groups exhibited comparable therapeutic effects after treatment. The current state of research regarding the use of rTMS as a treatment for WM deficits in patients with SCZ remains in its preliminary phase. Furthermore, concerning the mechanism of action, the activation of brain regions focused on the dorsolateral prefrontal cortex and alterations in gamma oscillations may hold significant relevance in the therapeutic application of rTMS for addressing WM impairments. Finally, we believe that the application of closed-loop neuromodulation may contribute to the optimization of rTMS for WM impairment in patients with SCZ.

Efficacy of non-invasive brain stimulation combined with antidepressant medications for depression: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Antidepressants, noninvasive brain stimulation (NIBS), and their combination are commonly used in routine clinical practice. Nevertheless, there is a continuous dispute regarding whether the effectiveness of NIBS in combination with antidepressants exceeds that of antidepressants alone. This meta-analysis aimed to evaluate the existing evidence and draw a definitive conclusion on this issue.

METHODS

We conducted a comprehensive search of five databases: Embase, PubMed, Web of Science, SinoMed, and the Cochrane Database of Randomized Controlled Trials. The search was conducted until October 6, 2023. The primary outcomes were the pre- and post-intervention depression and anxiety scores. Secondary outcomes included dropout rates, response rates, and certain levels of neurotransmitters [ 5-hydroxytryptamine (5-HT), dopamine (DA), and gamma-aminobutyric acid (GABA)] at the end of the intervention. Subgroup, meta-regression, and sensitivity analyses were performed to explore the sources of heterogeneity. The data were analysed using R 4.2.2.

RESULTS

We included 18 RCTs [1357 participants; 11 studies used repetitive transcranial magnetic stimulation (rTMS) and 7 studies used transcranial direct current stimulation (tDCS)]. The follow-up duration varied from two weeks to three months. Overall, whether in combination with rTMS or tDCS, antidepressants proved more effective in alleviating depressive symptoms compared to when used as monotherapy. However, this advantage was not evident during the follow-up period. (p > 0.05). And the combination's efficacy in improving anxiety was found to be lacking. Post-treatment serum levels of 5-HT, DA, and GABA were higher in the rTMS group were higher than antidepressant medication group (p < 0.05). Furthermore, subgroup analysis results indicated that only the rTMS + antidepressant medication treatment significantly improved remission and remission rates. The meta-regression results showed that the type of antidepressant and the sex of the participants had a significant association with the depression score.

CONCLUSION

Combination treatment with NIBS was significantly more effective in improving depression symptoms than medication alone. rTMS combined with antidepressants appears to be more effective in improving response and remission rates. However, efficacy may be influenced by the type of medicine used in combination, and long-term efficacy data is lacking.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42023388259.

Group-common and individual-specific effects of structure-function coupling in human brain networks with graph neural networks

The human cerebral cortex is organized into functionally segregated but synchronized regions bridged by the structural connectivity of white matter pathways. While structure-function coupling has been implicated in cognitive development and neuropsychiatric disorders, studies yield inconsistent findings. The extent to which the structure-function coupling reflects reliable individual differences or primarily group-common characteristics remains unclear, at both the global and regional brain levels. By leveraging two independent, high-quality datasets, we found that the graph neural network accurately predicted unseen individuals' functional connectivity from structural connectivity, reflecting a strong structure-function coupling. This coupling was primarily driven by network topology and was substantially stronger than that of the linear models. Moreover, we observed that structure-function coupling was dominated by group-common effects, with subtle yet significant individual-specific effects. The regional group and individual effects of coupling were hierarchically organized across the cortex along a sensorimotor-association axis, with lower group and higher individual effects in association cortices. These findings emphasize the importance of considering both group and individual effects in understanding cortical structure-function coupling, suggesting insights into interpreting individual differences of the coupling and informing connectivity-guided therapeutics.

Improving depressive symptoms in patients with schizophrenia using bilateral bipolar-nonbalanced prefrontal tDCS: Results from a double-blind sham-controlled trial

BACKGROUND

Treating depressive symptoms in patients with schizophrenia is challenging. While transcranical Dicrect Current Stimulation (tDCS) improved other core symptoms of schizophrenia, conflicting results have been obtained on depressive symptoms. Thus, we aimed to expand current evidence on tDCS efficacy to improve depressive symptoms in patients with schizophrenia.

METHODS

A double-blind RCT was performed with patients randomized to 2 mA active-tDCS or sham-tDCS (15 daily sessions) with a bilateral bipolar-nonbalanced prefrontal placement (anode: left Dorsolateral prefrontal cortex; cathode: right orbitofrontal region). Clinical outcomes included variations of Calgary Depression Scale for Schizophrenia total score (CDSS) and of Depression-hopelessness and Guilty idea of reference-pathological guilt factors. Analysis of covariance was performed evaluating between-group changes over time. The presence/absence of probable clinically significant depression was determined when CDSS > 6.

RESULTS

As 50 outpatients were included (both groups, n = 25), significant improvements following active-tDCS were observed for CDSS total score (p = 0.001), Depression-hopelessness (p = 0.001) and Guilty idea of reference-pathological guilt (p = 0.03). Considering patients with CDSS>6 (n = 23), compared to sham, active-tDCS significantly improved CDSS total score (p < 0.001), Depression-hopelessness (p = 0.001) but Guilty idea of reference-pathological guilt only marginally improved (p = 0.051). Considering response rates of clinically significant depression, important reductions of CDSS score were observed (78 % of the sample scored ≤6; active-tDCS, n = 23; sham-tDCS, n = 16; p = 0.017). Early wakening item did not significantly change in any group.

LIMITATIONS

The study lacks a follow-up period and evaluation of tDCS effects on psychosocial functioning.

CONCLUSIONS

Bilateral bipolar-nonbalanced prefrontal tDCS is a successful protocol for the treatment of depressive symptoms in patients with schizophrenia.

Efficacy of repetitive transcranial magnetic stimulation (rTMS) on negative symptoms and cognitive functioning in schizophrenia: An umbrella review of systematic reviews and meta-analyses

Negative symptoms and cognitive dysfunction are core characteristics of schizophrenia that profoundly impact daily function and quality of life. As a noninvasive brain stimulation, repetitive transcranial magnetic stimulation (rTMS) has been proposed as a relatively new treatment for ameliorating negative symptoms and cognitive dysfunction in schizophrenia. However, there is controversy over the treatment methods and efficacy. We aimed to provide a quantitative integration of the published evidence regarding the efficacy of rTMS and analyze the feasibility of rTMS for treating negative symptoms and cognitive dysfunction in schizophrenia. A total of twenty reviews were ultimately selected and divided into thirty-three latitudes. Twenty-six analyses showed that rTMS significantly decreased the negative symptom score, and seventeen analyses were performed. Six analyses showed that rTMS treatment can increase working memory scores, and two of them had significant effects. Two analyses from the same review showed that rTMS had a long-term significant effect on treating language function. Only one analysis showed that rTMS had a significant effect on treating executive function. The analyses showed that rTMS had no significant effect on attention function and processing speed. Most reviews indicate that rTMS has an effect on negative symptoms, executive function, working memory, and language function in patients with schizophrenia. Although the quality of evidence was not high, these results are still positive and worthwhile for further study.

Repetitive deep TMS in alcohol dependent patients halts progression of white matter changes in early abstinence

AIM

Alcohol use disorder (AUD) is the most prevalent form of addiction, with a great burden on society and limited treatment options. A recent clinical trial reported significant clinical benefits of deep transcranial magnetic stimulations (Deep TMS) targeting midline frontocortical areas. However, the underlying biological substrate remained elusive. Here, we report the effect of Deep TMS on the microstructure of white matter.

METHODS

A total of 37 (14 females) AUD treatment-seeking patients were randomized to sham or active Deep TMS. Twenty (six females) age-matched healthy controls were included. White matter integrity was evaluated by fractional anisotropy (FA). Secondary measures included brain functional connectivity and self-reports of craving and drinking units in the 3 months of follow-up period.

RESULTS

White matter integrity was compromised in patients with AUD relative to healthy controls, as reflected by the widespread reduction in FA. This alteration progressed during early abstinence (3 weeks) in the absence of Deep TMS. However, stimulation of midline frontocortical areas arrested the progression of FA changes in association with decreased craving and relapse scores. Reconstruction of axonal tracts from white-matter regions showing preserved FA values identified cortical regions in the posterior cingulate and dorsomedial prefrontal cortices where functional connectivity was persistently modulated. These effects were absent in the sham-stimulated group.

CONCLUSIONS

By integrating brain structure and function to characterize the alcohol-dependent brain, this study provides mechanistic insights into the TMS effect, pointing to myelin plasticity as a possible mediator.

Attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD; also known as hyperkinetic disorder) is a common neurodevelopmental condition that affects children and adults worldwide. ADHD has a predominantly genetic aetiology that involves common and rare genetic variants. Some environmental correlates of the disorder have been discovered but causation has been difficult to establish. The heterogeneity of the condition is evident in the diverse presentation of symptoms and levels of impairment, the numerous co-occurring mental and physical conditions, the various domains of neurocognitive impairment, and extensive minor structural and functional brain differences. The diagnosis of ADHD is reliable and valid when evaluated with standard diagnostic criteria. Curative treatments for ADHD do not exist but evidence-based treatments substantially reduce symptoms and/or functional impairment. Medications are effective for core symptoms and are usually well tolerated. Some non-pharmacological treatments are valuable, especially for improving adaptive functioning. Clinical and neurobiological research is ongoing and could lead to the creation of personalized diagnostic and therapeutic approaches for this disorder.

Combining transcranial magnetic stimulation with training to improve social cognition impairment in schizophrenia: a pilot randomized controlled trial

Schizophrenia is a severe, chronic mental disorder that profoundly impacts patients' everyday lives. The illness's core features include positive and negative symptoms and cognitive impairments. In particular, deficits in the social cognition domain showed a tighter connection to patients' everyday functioning than the other symptoms. Social remediation interventions have been developed, providing heterogeneous results considering the possibility of generalizing the acquired improvements in patients' daily activities. In this pilot randomized controlled trial, we investigated the feasibility of combining fifteen daily cognitive and social training sessions with non-invasive brain stimulation to boost the effectiveness of the two interventions. We delivered intermittent theta burst stimulation (iTBS) over the left dorsolateral prefrontal cortex (DLPFC). Twenty-one patients were randomized into four groups, varying for the assigned stimulation condition (real vs. sham iTBS) and the type of cognitive intervention (training vs. no training). Clinical symptoms and social cognition tests were administered at five time points, i.e., before and after the treatment, and at three follow-ups at one, three, and six months after the treatments' end. Preliminary data show a trend in improving the competence in managing emotion in participants performing the training. Conversely, no differences were found in pre and post-treatment scores for emotion recognition, theory of mind, and attribution of intentions scores. The iTBS intervention did not induce additional effects on individuals' performance. The methodological approach's novelty and limitations of the present study are discussed.

Clinical application of transcutaneous auricular vagus nerve stimulation: a scoping review

PURPOSE

Transcutaneous auricular vagus nerve stimulation (taVNS) is an emerging non-invasive neuromodulation therapy. This study aimed to explore the therapeutic use of taVNS, optimal stimulation parameters, effective sham protocols, and safety.

METHODS

A scoping review was conducted. Five databases and grey literature were searched. The data extracted included stimulation parameters, adverse events (AEs), and therapeutic effects on clinical outcomes.

RESULTS

109 studies were included. taVNS was used across 21 different clinical populations, most commonly in psychiatric, cardiac, and neurological disorders. Overall, 2,214 adults received active taVNS and 1,017 received sham taVNS. Reporting of stimulation parameters was limited and inconsistent. taVNS appeared to have a favourable therapeutic effect across a wide range of clinical populations with varied parameters. Three sham protocols were reported but their effectiveness was documented in only two of the 54 sham-controlled studies. Most reported adverse events were localised to stimulation site.

CONCLUSION

There is growing evidence for taVNS therapeutic effect. taVNS appears safe and tolerable. Sham protocols need evaluation. Standardised and comprehensive reporting of both stimulation parameters and adverse events is required. Two different questionnaires have been proposed to evaluate adverse events and the effectiveness of sham methods in blinding participants.

Efficacy and safety of non-invasive brain stimulation in combination with antidepressants in adolescents with depression: a systematic review and meta-analysis

Objective

Non-invasive brain stimulation (NIBS) is beneficial to adult patients with depression, but its safety and efficacy in combination with antidepressants in children and adolescents with depression are not clear. We conducted a preliminary meta-analysis to objectively evaluate its clinical effect and provide information for future research and clinical practice.

Methods

PubMed, Cochrane Library, Embase, and Web of Science were searched systematically to find clinical trials published in English before April 11, 2023. Stata software was used for meta-analysis, and random or fixed effect models were used to combine effect sizes.

Results

Nine studies were eligible and included (n = 393). No articles about children were included in the analysis. The results showed that the remission rate was 40% (95% confidence interval [CI]: 13% to 71%). The scores of Children's Depression Rating Scale (CRDS) and Hamilton's depression scale (HAMD) significantly decreased compared to baseline value (MD = -27.04, 95% CI: -30.95, -23.12 and MD = -12.78, 95% CI: -19.55 to -6.01). In addition, the incidence of all adverse events was 13% (95% CI: 5%, 23%), and all were minor pain-related events.

Conclusion

The combination of NIBS and antidepressants has been shown to notably alleviate depressive symptoms in adolescents, offering a considerable level of safety. This therapeutic synergy is particularly effective in patients with major depressive disorder, where repetitive transcranial magnetic stimulation augmented with antidepressants can enhance the amelioration of depressive symptoms.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023442215, PROSPERO CRD42023442215.

Short-term and long-term efficacy of accelerated transcranial magnetic stimulation for depression: a systematic review and meta-analysis

BACKGROUND

In recent years, accelerated transcranial magnetic stimulation (aTMS) has been developed, which has a shortened treatment period. The aim of this study was to evaluate the efficacy and long-term maintenance effects of aTMS in patients with major depressive disorder (MDD).

METHODS

We systematically searched online databases for aTMS studies in patients with MDD published before February 2023 and performed a meta-analysis on the extracted data.

RESULTS

Four randomized controlled trials (RCTs) and 10 before-and-after controlled studies were included. The findings showed that depression scores significantly decreased following the intervention (SMD = 1.80, 95% CI (1.31, 2.30), p < 0.00001). There was no significant difference in antidepressant effectiveness between aTMS and standard TMS (SMD = -0.67, 95% CI (-1.62, 0.27), p = 0.16). Depression scores at follow-up were lower than those directly after the intervention based on the depression rating scale (SMD = 0.22, 95% CI (0.06, 0.37), p = 0.006), suggesting a potential long-term maintenance effect of aTMS. Subgroup meta-analysis results indicated that different modes of aTMS may have diverse long-term effects. At the end of treatment with the accelerated repetitive transcranial magnetic stimulation (arTMS) mode, depressive symptoms may continue to improve (SMD = 0.29, 95% CI (0.10, 0.49), I2 = 22%, p = 0.003), while the accelerated intermittent theta burst stimulation (aiTBS) mode only maintains posttreatment effects (SMD = 0.01, 95% CI (-0.45, 0.47), I2 = 66%, p = 0.98).

CONCLUSIONS

Compared with standard TMS, aTMS can rapidly improve depressive symptoms, but there is no significant difference in efficacy. aTMS may also have long-term maintenance effects, but longer follow-up periods are needed to assess this possibility.

TRIAL REGISTRATION

This article is original and not under simultaneous consideration for publication. The study was registered on PROSPERO ( https://www.crd.york.ac.uk/prospero/ ) (number: CRD42023406590).

The association of total pulses with the efficacy of repetitive transcranial magnetic stimulation for treatment-resistant major depression: A dose-response meta-analysis

AIM

This study aimed to examine dose-effects of total pulses on improvement of depressive symptoms in patients with treatment-resistant depression (TRD) receiving repetitive transcranial magnetic stimulation (rTMS) over the left dorsal lateral prefrontal cortex (DLPFC).

MATERIALS AND METHODS

The MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE, PsycINFO, and ClinicalTrial.gov databases were systematically searched. We included randomized, double-blind, placebo-controlled trials (RCT) that used rTMS over left DLPFC in patients with TRD. Excluded studies were non-TRD, non-RCTs, or combined other brain stimulation interventions. The outcome of interest was the difference between rTMS arms and sham controls in improvement of depressive symptoms in a dose-response manner. A random-effects meta-analysis and dose-response meta-analysis(DRMA) was used to examine antidepressant efficacy of rTMS and association with total pulses.

RESULTS

We found that rTMS over left DLPFC is superior to sham controls (reported as standardized mean difference[SMD] with 95% confidence interval: 0.77; 0.56-0.98). The best-fitting model of DRMA was bell-shaped (estimated using restricted cubic spline model; R2 =0.42), indicating that higher doses (>26,660 total pulses) were not associated with increased improvement of depressive symptoms. Stimulation frequency(R2 =0.53) and age(R2 =0.51) were significant moderators for the dose-response curve. Furthermore, 15-20 Hz rTMS was superior to 10 Hz rTMS (0.61, 0.15-1.10) when combining all doses.

CONCLUSIONS

Our findings suggest higher doses(total pulses) of rTMS were not always associated with increased improvement of depressive symptoms in patients with TRD, and that the dose-response relationship was moderated by stimulation frequency and age. These associations emphasize the importance of determining dosing parameters to achieve maximum efficacy.

Transcranial direct current stimulation (tDCS) in the treatment of neuropsychiatric symptoms of long COVID

The study aimed to assess the efficacy of transcranial direct current stimulation (tDCS) in the treatment of neuropsychiatric (NP) symptoms of the post-acute sequelae of SARS-CoV-2 infection (PASC), known as the long COVID. A double-blind, randomized, sham-controlled study compared the efficacy and safety of prefrontal cortex active tDCS to sham-tDCS in treating NP-PASC. Patients diagnosed with NP-PASC, with a Fatigue Impact Scale (FIS) score ≥ 40, were eligible for the study. Twenty tDCS sessions were administered within four weeks, with continuous, end-of-treatment, and follow-up measurements. The primary outcome was a change in the FIS at the end-of-treatment, analyzed in the intention-to-treat population. Data from 33 patients assigned to active (n = 16) or sham-tDCS (n = 17) were analyzed. After the treatment, a decrease in the FIS score was more pronounced in the sham than in the active group, yet the intergroup difference was insignificant (11.7 [95% CI -11.1 to 34.5], p = 0.6). Furthermore, no significant intergroup differences were observed regarding anxiety, depression, quality of life, and cognitive performance. The small cohort sample, differences in baseline FIS scores between groups (non-stratified randomization), or chosen stimulation parameters may have influenced our findings. However, it might also be possible that the expected mechanism of action of tDCS is insufficient to treat these conditions.

Navigated and individual α-peak-frequency-guided transcranial magnetic stimulation in male patients with treatment-refractory schizophrenia

BACKGROUND

Previous electroencephalography (EEG) studies have indicated altered brain oscillatory α-band activity in schizophrenia, and treatment with repetitive transcranial magnetic stimulation (rTMS) using individualized α-frequency has shown therapeutic effects. Magnetic resonance imaging-based neuronavigation methods allow stimulation of a specific cortical region and improve targeting of rTMS; therefore, we sought to study the efficacy of navigated, individual α-peak-frequency-guided rTMS (αTMS) on treatment-refractory schizophrenia.

METHODS

We recruited medication-refractory male patients with schizophrenia or schizoaffective disorder in this doubleblind, sham-controlled study. We randomized patients to a 3-week course of either active αTMS or sham stimulation applied to the left dorsolateral prefrontal cortex (DLPFC). We assessed participants with the Positive and Negative Syndrome Scale (PANSS) and the Clinical Global Impression Scale (CGI) at baseline and after treatment. We conducted a follow-up assessment with the PANSS 3 months after intervention.

RESULTS

We included 44 patients. After treatment, we observed a significantly higher PANSS total score (p = 0.029), PANSS general psychopathology score (p = 0.027) and PANSS 5-factor model cognitive-disorganized factor score (p = 0.011) in the αTMS group than the sham group. In addition, the CGI-Improvement score was significantly higher among those who received αTMS compared with sham stimulation (p = 0.048).

LIMITATIONS

The limited number of study participants included only male patients. Depression was not formally evaluated.

CONCLUSION

Navigated αTMS to the left DLPFC reduced total, general psychopathological, and cognitive-disorganized symptoms of schizophrenia. These results provide evidence for the therapeutic efficacy of individual α-peak-frequency-guided rTMS in treatment-refractory schizophrenia.

CLINICAL TRIAL REGISTRATION

NCT01941251; ClinicalTrials.gov.

Targeting cravings in substance addiction with transcranial direct current stimulation: insights from a meta-analysis of sham-controlled trials

Addiction is a substantial health concern; craving-the core symptom of addiction-is strongly associated with relapse. Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that reduces cravings by altering cortical excitability and connectivity in brain regions. This systematic review and meta-analysis was conducted (following the PRISMA guidelines) to evaluate the efficacy of tDCS in reducing cravings for substances. Our analysis included 43 randomized, sham-controlled trials involving 1,095 and 913 participants receiving tDCS and sham stimulation, respectively. We analyzed the changes in craving scores and found that tDCS led to a moderate reduction in cravings compared with the sham effects. This effect was particularly pronounced when bilateral stimulation was used, the anodal electrode was placed on the right dorsolateral prefrontal cortex, current intensities ranged from 1.5 to 2 mA, stimulation sessions lasted 20 minutes, and the electrodes size was ≥35 cm². Notably, tDCS effectively reduced cravings for opioids, methamphetamine, cocaine, and tobacco but not for alcohol or cannabis. Our findings indicate tDCS as a promising, noninvasive, and low-risk intervention for reducing cravings for opioids, methamphetamine, cocaine, and tobacco. Additional studies are warranted to refine stimulation parameters and evaluate the long-term efficacy of tDCS in managing substance cravings.

A paucity of evidence in youth: The curious case of transcranial direct current stimulation for depression

A significant proportion of youth with depression do not respond to available treatment. Transcranial direct current stimulation (tDCS) is a promising third-line treatment in depressed adults, but evidence in youth seems scarce. Following the PRISMA guidelines, we conducted a systematic literature review on tDCS treatment for depression in children and adolescents. No published studies were found on the use of tDCS in youth with depression. Given the null-findings, no conclusion can be drawn about the effectiveness of tDCS treatment for adolescent depression. The reasons for this paucity of evidence in light of existing regulatory frameworks and technical challenges are discussed.

A pilot, randomized clinical trial: Left dorsolateral prefrontal cortex intermittent theta burst stimulation improves treatment outcomes in veterans with alcohol use disorder

BACKGROUND

Transcranial magnetic stimulation (TMS) offers a promising treatment avenue to modulate brain function in alcohol use disorder (AUD). To the best of our knowledge, this pilot study is the first randomized, double-blind, sham-controlled trial to deliver intermittent theta burst stimulation to the left dorsolateral prefrontal cortex (DLPFC) among US veterans with AUD. We hypothesized that 20 sessions of real TMS are tolerable and feasible. As a secondary line of inquiry, we hypothesized that, relative to sham TMS, individuals receiving real TMS would experience greater reductions in 6-month relapse rates, anhedonia, and alcohol cue-reactivity.

METHODS

Veterans (n = 17, one woman) were enrolled in a double-blind, sham-controlled trial (2-3 sessions/day; 7-10 days; 600 pulses/session; 20 sessions). Pre- and posttreatment assessments included responses to self-report questionnaires and functional magnetic resonance imaging measures of alcohol cue-reactivity. Alcohol consumption was assessed for 6 months. Linear mixed-effects models were constructed to predict posttreatment craving, mood, and cue-reactivity.

RESULTS

Individuals who received active iTBS (n = 8) were less likely to relapse within 3 months after treatment than the sham-treated group (n = 9) (OR = 12.0). Greater reductions in anhedonia were observed following active iTBS (Cohen's d = -0.59), relative to sham (d = -0.25). Alcohol cue-reactivity was reduced following active iTBS and increased following sham within the left insula (d = -0.19 vs. 0.51), left thalamus (d = -0.28 vs. 0.77), right insula (d = 0.18 vs. 0.52), and right thalamus (d = -0.06 vs. 0.62).

CONCLUSIONS

Relative to sham, we demonstrate that 20 sessions of real left DLPFC iTBS reduced the likelihood of relapse for at least 3 months. The potential utility of this approach is underscored by observed decreases in anhedonia and alcohol cue-reactivity-strong predictors of relapse among veterans. These initial data offer a valuable set of effect sizes to inform future clinical trials in this patient population.

Pre-clinical indications of brain stimulation treatments for non-affective psychiatric disorders, a status update

Over the past two decades noninvasive brain stimulation (NIBS) techniques have emerged as powerful therapeutic options for a range of psychiatric and neurological disorders. NIBS are hypothesized to rebalance pathological brain networks thus reducing symptoms and improving functioning. This development has been fueled by controlled studies with increasing size and rigor aiming to characterize how treatments induce clinically effective change. Clinical trials of NIBS for specific indications have resulted in federal approval for unipolar depression, bipolar depression, smoking cessation, and obsessive-compulsive disorder in the United States, and several other indications worldwide. As a rapidly emerging field, there are numerous pre-clinical indications currently in development using a variety of electrical and magnetic, non-convulsive, and convulsive approaches. This review discusses the state-of-the-science surrounding promising avenues of NIBS currently in pre-approval stages for non-affective psychiatric disorders. We consider emerging therapies for psychosis, anxiety disorders, obsessive-compulsive disorder, and borderline personality disorder, utilizing transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), and magnetic seizure therapy (MST), with an additional brief section for early-stage techniques including transcranial focused ultrasound stimulation (tFUS) and transcranial alternating current stimulation (tACS). As revealed in this review, there is considerable promise across all four psychiatric indications with different NIBS approaches. Positive findings are notable for the treatment of psychosis using tDCS, MST, and rTMS. While rTMS is already FDA approved for the treatment of obsessive-compulsive disorder, methodologies such as tDCS also demonstrate potential in this condition. Emerging techniques show promise for treating non-affective disorders likely leading to future regulatory approvals.

Brain stimulation techniques as novel treatment options for insomnia: A systematic review

Despite the success of cognitive behavioural therapy for insomnia and recent advances in pharmacotherapy, many patients with insomnia do not sufficiently respond to available treatments. This systematic review aims to present the state of science regarding the use of brain stimulation approaches in treating insomnia. To this end, we searched MEDLINE, Embase and PsycINFO from inception to 24 March 2023. We evaluated studies that compared conditions of active stimulation with a control condition or group. Outcome measures included standardized insomnia questionnaires and/or polysomnography in adults with a clinical diagnosis of insomnia. Our search identified 17 controlled trials that met inclusion criteria, and assessed a total of 967 participants using repetitive transcranial magnetic stimulation, transcranial electric stimulation, transcutaneous auricular vagus nerve stimulation or forehead cooling. No trials using other techniques such as deep brain stimulation, vestibular stimulation or auditory stimulation met the inclusion criteria. While several studies report improvements of subjective and objective sleep parameters for different repetitive transcranial magnetic stimulation and transcranial electric stimulation protocols, important methodological limitations and risk of bias limit their interpretability. A forehead cooling study found no significant group differences in the primary endpoints, but better sleep initiation in the active condition. Two transcutaneous auricular vagus nerve stimulation trials found no superiority of active stimulation for most outcome measures. Although modulating sleep through brain stimulation appears feasible, gaps in the prevailing models of sleep physiology and insomnia pathophysiology remain to be filled. Optimized stimulation protocols and proof of superiority over reliable sham conditions are indispensable before brain stimulation becomes a viable treatment option for insomnia.

Network-level mechanisms underlying effects of transcranial direct current stimulation (tDCS) on visuomotor learning in schizophrenia

Motor learning is a fundamental skill to our daily lives. Dysfunction in motor performance in schizophrenia (Sz) has been associated with poor social and functional outcomes. Transcranial direct current stimulation (tDCS), a non-invasive electrical brain stimulation approach, can influence underlying brain function with potential for improving motor learning in Sz. We used a well-established Serial Reaction Time Task (SRTT) to study motor learning, in combination with simultaneous tDCS and EEG recording, to investigate mechanisms of motor and procedural learning deficits in Sz, and to develop refined non-invasive brain stimulation approaches to improve neurocognitive dysfunction. We recruited 27 individuals with Sz and 21 healthy controls (HC). Individuals performed the SRTT task as they received sham and active tDCS with simultaneous EEG recording. Reaction time (RT), neuropsychological, and measures of global functioning were assessed. SRTT performance was significantly impaired in Sz and showed significant correlations with motor-related and working memory measures as well as global function. Source-space time-frequency decomposition of EEG showed beta-band coherence across supplementary-motor, primary-motor and visual cortex forming a network involved in SRTT performance. Motor-cathodal and visual-cathodal stimulations resulted in significant modulation in coherence particularly across the motor-visual nodes of the network accompanied by significant improvement in motor learning in both controls and patients. Here, we confirm earlier reports of SRTT impairment in Sz and demonstrate significant reversal of the deficits with tDCS. The findings support continued development of tDCS for enhancement of plasticity-based interventions in Sz, as well as source-space EEG analytic approaches for evaluating underlying neural mechanisms.

Manipulating critical memory periods to treat psychiatry disorders

The persistence of pathological memory is the basis of several psychiatric disorders. Memory retrieval induces "reconsolidation", a time interval during which the original memory becomes labile and destabilized. Time- and retrieval-dependent processes and memory reconsolidation are critical periods for memory interference. Modulating memory reconsolidation has received considerable research attention as a treatment protocol for several psychiatric conditions such as posttraumatic stress disorder, addiction, anxiety, and trauma-related disorders. This specific time window provides an opportunity for intervention regarding mental diseases. This article reviews the effect of modulating memory reconsolidation using behavioral-, brain stimulation-, and pharmacological-based interventions, which may help bridge the gap between intervention in laboratories and application in clinical practice. The potential advantages, limitations, challenges, and opportunities for memory reconsolidation manipulations were discussed.

Targeting the insula with transcranial direct current stimulation; A simulation study

Insula is considered an important region of the brain in the generation and maintenance of a wide range of psychiatric symptoms, possibly due to being key in fundamental functions such as interoception and cognition in general. Investigating the possibility of targeting this area using non-invasive brain stimulation techniques can open new possibilities to probe the normal and abnormal functioning of the brain and potentially new treatment protocols to alleviate symptoms of different psychiatric disorders. In the current study, COMETS2, a MATLAB based toolbox was used to simulate the magnitude of the current density and electric field in the brain caused by different transcranial direct current stimulation (tDCS) protocols to find an optimum montage to target the insula and its 6 subregions for three different current intensities, namely 2, 3, and 4 mA. Frontal and occipital regions were found to be optimal candidate regions.. The results of the current study showed that it is viable to reach the insula and its individual subregions using tDCS.

The Rehabilitation Potential of Neurostimulation for Mild Traumatic Brain Injury in Animal and Human Studies

Neurostimulation carries high therapeutic potential, accompanied by an excellent safety profile. In this review, we argue that an arena in which these tools could provide breakthrough benefits is traumatic brain injury (TBI). TBI is a major health problem worldwide, with the majority of cases identified as mild TBI (mTBI). MTBI is of concern because it is a modifiable risk factor for dementia. A major challenge in studying mTBI is its inherent heterogeneity across a large feature space (e.g., etiology, age of injury, sex, treatment, initial health status, etc.). Parallel lines of research in human and rodent mTBI can be collated to take advantage of the full suite of neuroscience tools, from neuroimaging (electroencephalography: EEG; functional magnetic resonance imaging: fMRI; diffusion tensor imaging: DTI) to biochemical assays. Despite these attractive components and the need for effective treatments, there are at least two major challenges to implementation. First, there is insufficient understanding of how neurostimulation alters neural mechanisms. Second, there is insufficient understanding of how mTBI alters neural function. The goal of this review is to assemble interrelated but disparate areas of research to identify important gaps in knowledge impeding the implementation of neurostimulation.

Posterior cingulate cortex spontaneous activity associated with motor response inhibition in patients with obsessive-compulsive disorder: A resting-state fMRI study

Recent evidence suggests that broad brain regions, not limited to the fronto-striato-thalamo-cortical circuit, play an important role in motor response inhibition. However, it is still unclear which specific key brain region is responsible for impaired motor response inhibition observed in obsessive-compulsive disorder (OCD). We calculated the fractional amplitude of low-frequency fluctuations (fALFF) and measured response inhibition ability using the stop-signal task in 41 medication-free patients with OCD and 49 healthy control (HC) participants. We explored the brain region that shows different association between the fALFF and the ability of motor response inhibition. Significant differences in fALFF associated with the ability of motor response inhibition were identified in dorsal posterior cingulate cortex (PCC). There was a positive correlation between increased fALFF in the dorsal PCC and impaired motor response inhibition in OCD. In the HC group, there was a negative correlation between the two variables. Our results suggest that the magnitude of resting-state blood oxygen level-dependent oscillation of the dorsal PCC is a key brain region for the underlying mechanisms of impaired motor response inhibition in OCD. Future studies should examine whether this characteristic of dorsal PCC affects other large-scale networks responsible for motor response inhibition of OCD.

An umbrella review of candidate predictors of response, remission, recovery, and relapse across mental disorders

We aimed to identify diagnosis-specific/transdiagnostic/transoutcome multivariable candidate predictors (MCPs) of key outcomes in mental disorders. We conducted an umbrella review (protocol  link ), searching MEDLINE/Embase (19/07/2022), including systematic reviews of studies reporting on MCPs of response, remission, recovery, or relapse, in DSM/ICD-defined mental disorders. From published predictors, we filtered MCPs, validating MCP criteria. AMSTAR2/PROBAST measured quality/risk of bias of systematic reviews/individual studies. We included 117 systematic reviews, 403 studies, 299,888 individuals with mental disorders, testing 796 prediction models. Only 4.3%/1.2% of the systematic reviews/individual studies were at low risk of bias. The most frequently targeted outcome was remission (36.9%), the least frequent was recovery (2.5%). Studies mainly focused on depressive (39.4%), substance-use (17.9%), and schizophrenia-spectrum (11.9%) disorders. We identified numerous MCPs within disorders for response, remission and relapse, but none for recovery. Transdiagnostic MCPs of remission included lower disease-specific symptoms (disorders = 5), female sex/higher education (disorders = 3), and quality of life/functioning (disorders = 2). Transdiagnostic MCPs of relapse included higher disease-specific symptoms (disorders = 5), higher depressive symptoms (disorders = 3), and younger age/higher anxiety symptoms/global illness severity/ number of previous episodes/negative life events (disorders = 2). Finally, positive trans-outcome MCPs for depression included less negative life events/depressive symptoms (response, remission, less relapse), female sex (response, remission) and better functioning (response, less relapse); for schizophrenia, less positive symptoms/higher depressive symptoms (remission, less relapse); for substance use disorder, marital status/higher education (remission, less relapse). Male sex, younger age, more clinical symptoms and comorbid mental/physical symptoms/disorders were poor prognostic factors, while positive factors included social contacts and employment, absent negative life events, higher education, early access/intervention, lower disease-specific and comorbid mental and physical symptoms/conditions, across mental disorders. Current data limitations include high risk of bias of studies and extraction of single predictors from multivariable models. Identified MCPs can inform future development, validation or refinement of prediction models of key outcomes in mental disorders.

A century of research on neuromodulation interventions: A scientometric analysis of trends and knowledge maps

Interest in neurostimulation interventions has significantly grown in recent decades, yet a scientometric analysis objectively mapping scientific knowledge and recent trends remains unpublished. Using relevant keywords, we conducted a search in the Web of Science Core Collection on September 23, 2022, retrieving a total of 47,681 documents with 987,979 references. We identified two prominent research trends: 'noninvasive brain stimulation' and 'invasive brain stimulation.' These methods have interconnected over time, forming a cluster focused on evidence synthesis. Noteworthy emerging research trends encompassed 'transcutaneous auricular vagus nerve stimulation,' 'DBS/epilepsy in the pediatric population,' 'spinal cord stimulation,' and 'brain-machine interface.' While progress has been made for various neurostimulation interventions, their approval as adjuvant treatments remains limited, and optimal stimulation parameters lack consensus. Enhancing communication between experts of both neurostimulation types and encouraging novel translational research could foster further development. These findings offer valuable insights for funding agencies and research groups, guiding future directions in the field.

Major depressive disorder

Major depressive disorder (MDD) is characterized by persistent depressed mood, loss of interest or pleasure in previously enjoyable activities, recurrent thoughts of death, and physical and cognitive symptoms. People with MDD can have reduced quality of life owing to the disorder itself as well as related medical comorbidities, social factors, and impaired functional outcomes. MDD is a complex disorder that cannot be fully explained by any one single established biological or environmental pathway. Instead, MDD seems to be caused by a combination of genetic, environmental, psychological and biological factors. Treatment for MDD commonly involves pharmacological therapy with antidepressant medications, psychotherapy or a combination of both. In people with severe and/or treatment-resistant MDD, other biological therapies, such as electroconvulsive therapy, may also be offered.

Transcranial direct current stimulation as an additional treatment to selective serotonin reuptake inhibitors in adults with major depressive disorder in Germany (DepressionDC): a triple-blind, randomised, sham-controlled, multicentre trial

BACKGROUND

Transcranial direct current stimulation (tDCS) has been proposed as a feasible treatment for major depressive disorder (MDD). However, meta-analytic evidence is heterogenous and data from multicentre trials are scarce. We aimed to assess the efficacy of tDCS versus sham stimulation as an additional treatment to a stable dose of selective serotonin reuptake inhibitors (SSRIs) in adults with MDD.

METHODS

The DepressionDC trial was triple-blind, randomised, and sham-controlled and conducted at eight hospitals in Germany. Patients being treated at a participating hospital aged 18-65 years were eligible if they had a diagnosis of MDD, a score of at least 15 on the Hamilton Depression Rating Scale (21-item version), no response to at least one antidepressant trial in their current depressive episode, and treatment with an SSRI at a stable dose for at least 4 weeks before inclusion; the SSRI was continued at the same dose during stimulation. Patients were allocated (1:1) by fixed-blocked randomisation to receive either 30 min of 2 mA bifrontal tDCS every weekday for 4 weeks, then two tDCS sessions per week for 2 weeks, or sham stimulation at the same intervals. Randomisation was stratified by site and baseline Montgomery-Åsberg Depression Rating Scale (MADRS) score (ie, <31 or ≥31). Participants, raters, and operators were masked to treatment assignment. The primary outcome was change on the MADRS at week 6, analysed in the intention-to-treat population. Safety was assessed in all patients who received at least one treatment session. The trial was registered with ClinicalTrials.gov (NCT02530164).

FINDINGS

Between Jan 19, 2016, and June 15, 2020, 3601 individuals were assessed for eligibility. 160 patients were included and randomly assigned to receive either active tDCS (n=83) or sham tDCS (n=77). Six patients withdrew consent and four patients were found to have been wrongly included, so data from 150 patients were analysed (89 [59%] were female and 61 [41%] were male). No intergroup difference was found in mean improvement on the MADRS at week 6 between the active tDCS group (n=77; -8·2, SD 7·2) and the sham tDCS group (n=73; -8·0, 9·3; difference 0·3 [95% CI -2·4 to 2·9]). Significantly more participants had one or more mild adverse events in the active tDCS group (50 [60%] of 83) than in the sham tDCS group (33 [43%] of 77; p=0·028).

INTERPRETATION

Active tDCS was not superior to sham stimulation during a 6-week period. Our trial does not support the efficacy of tDCS as an additional treatment to SSRIs in adults with MDD.

FUNDING

German Federal Ministry of Education and Research.

The effects of transcranial direct current stimulation on corticospinal excitability: A systematic review of nonsignificant findings

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that can modulate brain activity through the application of low-intensity electrical currents. Based on its reported effects on corticospinal excitability (CSE), tDCS has been used to study cognition in healthy individuals and reduce symptoms in a variety of clinical conditions. Despite its increasing popularity as a research and clinical tool, high interindividual variability has been reported in the response to protocols using transcranial magnetic stimulation (TMS) to assess tDCS-induced changes in CSE leading to several nonsignificant findings. In this systematic review, studies that reported no significant modulation of CSE following tDCS were identified from PubMed and Embase (Ovid) databases. Forty-three articles were identified where demographic, TMS and tDCS parameters were extracted. Overall, stimulation parameters, CSE measurements and participant characteristics were similar to those described in studies reporting positive results and were likewise heterogeneous between studies. Small sample sizes and inadequate blinding were notable features of the reviewed studies. This systematic review suggests that studies reporting nonsignificant findings do not markedly differ from those reporting significant modulation of CSE.

Network perturbation-based biomarkers of depression and treatment response

Using concurrent TMS-EEG, Han et al.¹ identified temporal and spectral signatures of depression in a prefrontal-orbitofrontal-hippocampal network, which renormalized after rTMS. This highlights the relevance of causal network perturbation for the assessment of disease-related network states and their therapeutic modulation.

Effect of transdermal drug delivery therapy on anxiety symptoms in schizophrenic patients

Objective

To evaluate the efficacy and safety of transdermal drug delivery therapy for schizophrenia with anxiety symptoms.

Methods

A total of 80 schizophrenic patients (34 males and 56 females) with comorbid anxiety disorders were randomly assigned to the treatment group (n = 40) and the control group (n = 40) with 6 weeks of follow-up. The patients in the treatment group received the standard antipsychotic drug treatment along with transdermal drug delivery therapy. The evaluation of the patients included the Hamilton Anxiety Scale (HAMA), Hamilton Depression Scale (HAMD-17), and treatment emergent symptom scale (TESS) at baseline, 3 weeks, and 6 weeks after transdermal drug delivery therapy. The Positive and Negative Symptom Scale (PANSS) was assessed at baseline and after 6 weeks of treatment.

Results

After 3 and 6 weeks of treatment, the HAMA scale scores in the treatment group were lower than those in the control group (p < 0.001). However, there were no significant differences in the HAMD-17 scale scores, PANSS total scores, and subscale scores between the two groups (p > 0.05). Additionally, no significant differences in adverse effects were observed between the two groups during the intervention period (p > 0.05). After 6 weeks of penetration therapy, there was a low negative correlation between total disease duration and the change in HAMA scale score (pretreatment-posttreatment) in the treatment group.

Conclusion

Combined traditional Chinese medicine directed penetration therapy can improve the anxiety symptoms of patients with schizophrenia and has a safe profile.

Efficacy of Repetitive Transcranial Magnetic Stimulation on Comorbid Anxiety and Depression Symptoms in Obsessive-Compulsive Disorder: A Meta-Analysis of Randomized Sham-Controlled Trials

OBJECTIVE

To systematically evaluate the efficacy of repetitive transcranial magnetic stimulation (rTMS) in reducing comorbid anxiety and depressive symptoms in patients with obsessive-compulsive disorder (OCD).

METHODS

Three electronic databases were searched for randomized, sham-controlled clinical trials evaluating rTMS for the treatment of OCD. Hedge's g was calculated as the effect size for anxiety/depression symptom severity (primary outcome) and OCD severity (secondary outcome). Subgroup analyses and meta-regression analyses were carried out to evaluate the most promising target and whether a reduction in OCD severity moderates the change in anxiety or depression scores.

RESULTS

Twenty studies (n = 688) were included in the meta-analysis. rTMS had small-medium effect size on OCD (Hedge's g = 0.43; 95% confidence interval [CI]: [0.20, 0.65]; P < 0.001), anxiety (Hedge's g = 0.3; 95% CI: [0.11, 0.48]; P = 0.001) and depression (Hedge's g = 0.24; 95% CI: [0.07, 0.40]; P = 0.003) symptoms. Subgroup analysis showed that protocols targeting dorsolateral prefrontal cortex (DLPFC) were effective for 3 outcome measures. The change in anxiety, but not depression severity, was moderated by a change in OCD symptom scores. However, the findings are uncertain as a majority of the studies had some concerns or a high risk of bias.

CONCLUSIONS

Active rTMS protocol targeting DLPFC is effective in reducing the comorbid anxiety/depression symptoms along with OCD severity. The antidepressant effect is not moderated by the anti-obsessive effect of rTMS.

Bifrontal-transcranial direct current stimulation as an early augmentation strategy in major depressive disorder: A single-blind randomised controlled trial

BACKGROUND

Patients with major depressive disorder who have a poor or inconsistent response to antidepressants have been treated using transcranial direct current stimulation (tDCS). Early tDCS augmentation may help with the early amelioration of symptoms. In this study, the efficacy and safety of tDCS as early augmentation therapy in major depressive disorder were evaluated.

METHODS

Fifty adults were randomized into two groups and were administered either active tDCS or sham tDCS, along with escitalopram 10 mg/day. A total of 10 tDCS sessions with anodal stimulation at the left dorsolateral prefrontal cortex (DLPFC) and cathode at the right DLPFC were given over two weeks. Assessments were done using Hamilton Depression Rating Scale (HAM-D), Beck's Depression Inventory (BDI), and Hamilton Anxiety Rating Scale (HAM-A) at baseline, two weeks, and four weeks. A tDCS side effect checklist was administered during therapy.

RESULTS

A significant reduction in HAM-D, BDI, and HAM-A scores were observed in both groups from baseline to week-4. At week-2, the active group had a significantly greater reduction in HAM-D and BDI scores than the sham group. However, at the end of therapy, both groups were comparable. The active group was 1.12 times more likely to experience any side effect than the sham group, but the intensity ranged from mild to moderate.

CONCLUSION

tDCS is an effective and safe strategy for managing depression as an early augmentation strategy, and it produces an early reduction of depressive symptoms and is well tolerated in moderate to severe depressive episodes.