Blinding integrity in randomized sham-controlled trials of repetitive transcranial magnetic stimulation for major depression: a systematic review and meta-analysis

One session of repetitive transcranial magnetic stimulation induces mild and transient analgesic effects among female individuals with painful temporomandibular disorders

OBJECTIVE

Temporomandibular disorders (TMD) are characterised by chronic pain and dysfunction in the jaw joint and masticatory muscles. Repetitive transcranial magnetic stimulation (rTMS) has emerged as a potential non-invasive treatment for chronic pain; however, its effectiveness in individuals with TMD has not been thoroughly investigated. This study aimed to evaluate the immediate and sustained (over seven consecutive days) effects of a single session of active rTMS compared to sham stimulation on pain intensity and pain unpleasantness in individuals with TMD.

METHODS

A randomised, double-blind, sham-controlled trial enrolled 41 female participants with chronic TMD. Pain intensity and pain unpleasantness were assessed immediately pre- and post-intervention, as well as twice daily for 21 days using electronic diaries. Secondary outcomes included pain interference, sleep quality, positive and negative affect and pain catastrophizing. Adverse effects were monitored. Repeated measures ANOVA and multilevel modelling regression analyses were employed for data analysis.

RESULT

Active rTMS demonstrated a significant immediate mild reduction in pain intensity and pain unpleasantness compared to sham stimulation. However, these effects were not sustained over the 7-day post-intervention period. No significant differences were observed between interventions for pain interference, sleep quality and negative affect. A minority of participants reported minor and transient side effects, including headaches and fatigue.

CONCLUSION

A single session of active rTMS was safe and led to immediate mild analgesic effects in individuals with TMD compared to sham stimulation. However, no significant differences were observed between interventions over the 7-day post-intervention period. Based on this study, rTMS stimulation appears to be a promising safe approach to be tested in TMD patients with longer stimulation protocols.

Blinding integrity of dorsomedial prefrontal intermittent theta burst stimulation in depression

Background

The antidepressant effect of repetitive transcranial magnetic stimulation (rTMS) is partly placebo, making blinding integrity important. Blinding of high-frequency rTMS and intermittent theta burst stimulation (iTBS) has been reported as successful at study end. However, blinding integrity at study start is rarely reported. The aim of this study was to investigate blinding integrity during a treatment course of iTBS over the dorsomedial prefrontal cortex (DMPFC) in depression.

Methods

Forty-nine patients with depression from a double-blind-designed randomized controlled trial (NCT02905604) were included. Patients received either active or sham iTBS over the DMPFC with a placebo coil. The sham group received iTBS-synchronized transcutaneous electrical nerve stimulation.

Results

After one session, 74% of participants were able to correctly guess their treatment allocation. This was above chance level (p = 0.001). The percentage dropped to 64% and 56% after the fifth and last sessions. Belonging to the active group influenced the choice to guess "active" (odds ratio: 11.7, 95% CI 2.5-53.7). A higher treatment intensity of the sham treatment increased the probability to guess "active", but pain did not influence the choice.

Conclusions

Blinding integrity in iTBS trials must be investigated at study start to avoid uncontrolled confounding. Better sham methods are needed.

The priming effect of repetitive transcranial magnetic stimulation on clinical response to electroconvulsive therapy in treatment-resistant depression: a randomized, double-blind, sham-controlled study

BACKGROUND

Electroconvulsive therapy (ECT) is one of the most effective treatments for treatment-resistant depression (TRD). However, due to response delay and cognitive impairment, ECT remains an imperfect treatment. Compared to ECT, repetitive transcranial magnetic stimulation (rTMS) is less effective at treating severe depression, but has the advantage of being quick, easy to use, and producing almost no side effects. In this study, our objective was to assess the priming effect of rTMS sessions before ECT on clinical response in patients with TRD.

METHODS

In this multicenter, randomized, double-blind, sham-controlled trial, 56 patients with TRD were assigned to active or sham rTMS before ECT treatment. Five sessions of active/sham neuronavigated rTMS were administered over the left dorsolateral prefrontal cortex (20 Hz, 90% resting motor threshold, 20 2 s trains with 60-s intervals, 800 pulses/session) before ECT (which was active for all patients) started. Any relative improvements were then compared between both groups after five ECT sessions, in order to assess the early response to treatment.

RESULTS

After ECT, the active rTMS group exhibited a significantly greater relative improvement than the sham group [43.4% (28.6%) v. 25.4% (17.2%)]. The responder rate in the active group was at least three times higher. Cognitive complaints, which were assessed using the Cognitive Failures Questionnaire, were higher in the sham rTMS group compared to the active rTMS group, but this difference was not corroborated by cognitive tests.

CONCLUSIONS

rTMS could be used to enhance the efficacy of ECT in patients with TRD. ClinicalTrials.gov: NCT02830399.

Feasibility of intermediate theta burst stimulation as sham control in therapeutic transcranial magnetic stimulation studies

A major challenge in Transcranial Magnetic Stimulation trials is that of an inefficient sham protocol. This could potentially amplify the gap in behavioral outcomes following true and control treatments. Intermediate theta-burst stimulation (imTBS) is a promising sham alternative since it uses actual TMS pulses, thus mimicking the sensory effects of stimulation without producing physiological aftereffects. Here, we critically review controlled experiments that have examined physiological and behavioral aftereffects following imTBS with the intention to further investigate what appears to be a promising sham control modality for TBS studies.

A Systematic Review Assessing Patient-Related Predictors of Response to Transcranial Magnetic Stimulation in Major Depressive Disorder

Objective

The safety and efficacy of transcranial magnetic stimulation (TMS) in the acute treatment of major depressive disorder (MDD) is well established. However, it is not well understood which patient-related factors are associated with a more robust antidepressant response. Identifying predictive factors for therapeutic response to TMS treatment in depression will guide clinicians in patient selection.

Methods

By systematic review of clinical trial data, the current study aims to identify and analyze reported patient-specific predictors of response to an acute course of TMS treatment for MDD. PubMed was searched for randomized controlled trials of TMS for patients with depression. Studies were appraised for risk of bias using components recommended by the Cochrane Collaboration and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

Results

TMS data were available from 375 studies, 18 of which were included in this review. Treatment response is inversely associated with treatment refractoriness and age.

Conclusion

Inadequate sample size and large heterogeneity in study parameters among clinical trials limit any strong conclusions from being drawn; nonetheless, despite these limitations, there is mounting evidence, which points to age and treatment refractoriness as candidate variables for predicting clinical outcome. Implications of these findings for treatment of MDD are discussed.

Bilateral theta-burst stimulation on emotional processing in major depressive disorder: A functional neuroimaging study from a randomized, double-blind, sham-controlled trial

AIM

Bilateral theta-burst stimulation (biTBS; intermittent TBS over the left dorsolateral prefrontal cortex [DLPFC] and continuous TBS over the right DLPFC) has demonstrated efficacy in improving symptoms in patients with major depressive disorder (MDD). However, the underlying brain mechanisms remain unknown. The authors aimed to investigate the antidepressant efficacy of biTBS monotherapy and its effects on the brain responses measured by functional magnetic resonance imaging (fMRI) during emotional processing in MDD.

METHODS

The authors conducted a double-blind, randomized, sham-controlled trial of patients with MDD who exhibited no responses to at least one adequate antidepressant treatment for the prevailing episode. Recruited patients were randomly assigned to 10 biTBS monotherapy or sham stimulation sessions. The fMRI scans during performing emotional recognition task were obtained at baseline and after 10 sessions of treatment. Depressive symptoms were assessed using the 21-item Hamilton Rating Scale for Depression at baseline and the weeks 4, 8, 12, 16, 20, and 24 week.

RESULTS

The biTBS group (n = 17) exhibited significant decreases in depression scores compared with the sham group (n = 11) at week 8 (70% vs 40%; P = 0.02), and the significant differences persisted during the 24-week follow-up periods. At week 4, when the treatment course was completed, patients in the biTBS group, but not in the sham group, exhibited increased brain activities over the left superior and middle frontal gyrus during negative emotional stimuli.

CONCLUSION

The authors' findings provide the first evidence regarding the underlying neural mechanisms of biTBS therapy to improve clinical symptoms in patients with MDD.

A systematic review and meta-analysis of the efficacy of intermittent theta burst stimulation (iTBS) on cognitive enhancement

Intermittent theta-burst stimulation (iTBS) has been used to focally regulate excitability of neural cortex over the past decade - however there is little consensus on the generalizability of effects reported in individual studies. Many studies use small sample sizes (N < 30), and there is a considerable amount of methodological heterogeneity in application of the stimulation itself. This systematic meta-analysis aims to consolidate the extant literature and determine if up-regulatory theta-burst stimulation reliably enhances cognition through measurable behavior. Results show that iTBS - when compared to suitable control conditions - may enhance cognition when outlier studies are removed, but also that there is a significant amount of heterogeneity across studies. Significant contributors to between-study heterogeneity include location of stimulation and method of navigation to the stimulation site. Surprisingly, the type of cognitive domain investigated was not a significant contributor of heterogeneity. The findings of this meta-analysis demonstrate that standardization of iTBS is urgent and necessary to determine if neuroenhancement of particular cognitive faculties are reliable and robust, and measurable through observable behavior.

rTMS combined with CBT as a next step in antidepressant non-responders: a study protocol for a randomized comparison with current antidepressant treatment approaches

BACKGROUND

Major depressive disorder (MDD) is one of the most common psychiatric disorders, however, current treatment options are insufficiently effective for about 35% of patients, resulting in treatment-resistant depression (TRD). Repetitive transcranial magnetic stimulation (rTMS) is a form of non-invasive neuromodulation that is effective in treating TRD. Not much is known about the comparative efficacy of rTMS and other treatments and their timing within the treatment algorithm, making it difficult for the treating physician to establish when rTMS is best offered as a treatment option. This study aims to investigate the (cost-)effectiveness of rTMS (in combination with cognitive behavioral therapy (CBT) and continued antidepressant medication), compared to the next step in the treatment algorithm. This will be done in a sample of patients with treatment resistant non-psychotic unipolar depression.

METHODS

In this pragmatic multicenter randomized controlled trial 132 patients with MDD are randomized to either rTMS or the next pharmacological step within the current treatment protocol (a switch to a tricyclic antidepressant or augmentation with lithium or a second-generation antipsychotic). Both groups also receive CBT. The trial consists of 8 weeks of unblinded treatment followed by follow-up of the cohort at four and 6 months. A subgroup of patients (n = 92) will have an extended follow-up at nine and 12 months to assess effect decay or retention. We expect that rTMS is more (cost-)effective than medication in reducing depressive symptoms in patients with TRD. We will also explore the effects of both treatments on symptoms associated with depression, e.g. anhedonia and rumination, as well as the effect of expectations regarding the treatments on its effectiveness.

DISCUSSION

The present trial aims to inform clinical decision making about whether rTMS should be considered as a treatment option in patients with TRD. The results may improve treatment outcomes in patients with TRD and may facilitate adoption of rTMS in the treatment algorithm for depression and its implementation in clinical practice.

TRIAL REGISTRATION

This trial is registered within the Netherlands Trial Register (code: NL7628 , date: March 29th 2019).

Neuromodulation Treatments of Pathological Anxiety in Anxiety Disorders, Stressor-Related Disorders, and Major Depressive Disorder: A Dimensional Systematic Review and Meta-Analysis

BACKGROUND

Pathological anxiety is responsible for major functional impairments and resistance to conventional treatments in anxiety disorders (ADs), posttraumatic stress disorder (PTSD) and major depressive disorder (MDD). Focal neuromodulation therapies such as transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS) and deep brain stimulation (DBS) are being developed to treat those disorders.

METHODS

We performed a dimensional systematic review and meta-analysis to assess the evidence of the efficacy of TMS, tDCS and DBS in reducing anxiety symptoms across ADs, PTSD and MDD. Reports were identified through systematic searches in PubMed/Medline, Scopus and Cochrane library (inception to November 2020), followed by review according to the PRISMA guidelines. Controlled clinical trials examining the effectiveness of brain stimulation techniques on generic anxiety symptoms in patients with ADs, PTSD or MDD were selected.

RESULTS

Nineteen studies (RCTs) met inclusion criteria, which included 589 participants. Overall, focal brain activity modulation interventions were associated with greater reduction of anxiety levels than controls [SMD: -0.56 (95% CI, -0.93 to-0.20, I ² = 77%]. Subgroup analyses revealed positive effects for TMS across disorders, and of focal neuromodulation in generalized anxiety disorder and PTSD. Rates of clinical responses and remission were higher in the active conditions. However, the risk of bias was high in most studies.

CONCLUSIONS

There is moderate quality evidence for the efficacy of neuromodulation in treating pathological anxiety.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=233084, identifier: PROSPERO CRD42021233084. It was submitted on January 29th, 2021, and registered on March 1st, 2021. No amendment was made to the recorded protocol. A change was applied for the subgroup analyses based on target brain regions, we added the putative nature (excitatory/inhibitory) of brain activity modulation.

Transcranial Magnetic and Direct Current Stimulation in the Treatment of Depression: Basic Mechanisms and Challenges of Two Commonly Used Brain Stimulation Methods in Interventional Psychiatry

Noninvasive neuromodulation, including repetitive trans-cranial magnetic stimulation (rTMS) and direct current stimulation (tDCS), provides researchers and health care professionals with the ability to gain unique insights into brain functions and treat several neurological and psychiatric conditions. Undeniably, the number of published research and clinical papers on this topic is increasing exponentially. In parallel, several methodological and scientific caveats have emerged in the transcranial stimulation field; these include less robust and reliable effects as well as contradictory clinical findings. These inconsistencies are maybe due to the fact that research exploring the relationship between the methodological aspects and clinical efficacy of rTMS and tDCS is far from conclusive. Hence, additional work is needed to understand the mechanisms underlying the effects of magnetic stimulation and low-intensity transcranial electrical stimulation (TES) in order to optimize dosing, methodological designs, and safety aspects.

Repetitive transcranial magnetic stimulation as a potential treatment approach for cannabis use disorder

The expanding legalization of cannabis across the United States is associated with increases in cannabis use, and accordingly, an increase in the number and severity of individuals with cannabis use disorder (CUD). The lack of FDA-approved pharmacotherapies and modest efficacy of psychotherapeutic interventions means that many of those who seek treatment for CUD relapse within the first few months. Consequently, there is a pressing need for innovative, evidence-based treatment development for CUD. Preliminary evidence suggests that repetitive transcranial magnetic stimulation (rTMS) may be a novel, non-invasive therapeutic neuromodulation tool for the treatment of a variety of substance use disorders (SUDs), including recently receiving FDA clearance (August 2020) for use as a smoking cessation aid in tobacco cigarette smokers. However, the potential of rTMS for CUD has not yet been reviewed. This paper provides a primer on therapeutic neuromodulation techniques for SUDs, with a particular focus on reviewing the current status of rTMS research in people who use cannabis. Lastly, future directions are proposed for rTMS treatment development in CUD, with suggestions for study design parameters and clinical endpoints based on current gold-standard practices for therapeutic neuromodulation research.

Repetitive Transcranial Magnetic Stimulation for Obsessive-Compulsive Disorder: A Meta-analysis of Randomized, Sham-Controlled Trials

BACKGROUND

Obsessive-compulsive disorder (OCD) is a chronic, disabling mental health condition with limited treatment options available to date. Numerous randomized controlled trials have explored the efficacy of repetitive transcranial magnetic stimulation (rTMS) in OCD. This meta-analysis synthesized data from selected randomized controlled trials and examined the impact of different treatment parameters to generate hypotheses that would direct future randomized controlled trials.

METHODS

A database search was performed to identify studies published in English up to October 2020. Randomized, sham-controlled studies that used rTMS to treat OCD were included. Effect sizes were calculated using Hedges' g for pre- to post-treatment Yale-Brown Obsessive Compulsive Scale scores. Subgroup analyses were conducted to assess the effects of variations in rTMS treatment parameters.

RESULTS

A total of 26 studies with 781 participants were included. Overall, rTMS demonstrated a modest effect on reduction of Yale-Brown Obsessive Compulsive Scale scores (Hedges' g = 0.64, 95% confidence interval = 0.39-0.89; p < .0001). The largest significant effect size was obtained by targeting the bilateral dorsolateral prefrontal cortex. High- and low-frequency rTMS showed comparable effects. Studies with follow-up data suggested that the effects of active rTMS remain significantly superior to those of sham 4 weeks after treatment.

CONCLUSIONS

The therapeutic effects of rTMS are superior to those of sham in the treatment of OCD. Targeting the bilateral dorsolateral prefrontal cortex was the most favorable approach in administering rTMS. Further research is required to determine the optimal frequency, total pulses per session, and duration of treatment with rTMS for OCD.

Longitudinal effects of rTMS on neuroplasticity in chronic treatment-resistant depression

Major depressive disorder (MDD) is amongst the most prevalent of psychiatric disorders. Unfortunately, a third of patients will not respond to conventional treatments and suffer from treatment-resistant depression (TRD). Repetitive transcranial magnetic stimulation (rTMS) has been proven effective in treating TRD. The research suggests that rTMS acts via neuroplastic effects on the brain, which can be measured by changes in hippocampal and amygdala volume as well as cortical thickness. This sham-controlled study investigates longitudinal effects of rTMS on the volumes of the hippocampus and amygdala and cortical thickness in patients with chronic TRD. 31 patients received 20 sessions of high-frequency rTMS (N = 15) or sham treatment (N = 16) over the left dorsolateral prefrontal cortex during 4 consecutive weeks. Using structural magnetic resonance imaging, we investigated longitudinal treatment effects on hippocampus and amygdala volume as well as thickness of the paralimbic cortex. We found no clinical differences between the active and sham rTMS group. Longitudinal changes in hippocampal and amygdala volume did not differ significantly, although males showed a significant decrease in left amygdala volume, irrespective of treatment group. Changes in cortical thickness of the paralimbic cortex differed significantly between the active and sham groups. Most notably, the increase in cortical thickness of the isthmus of the left cingulate gyrus was greater in the active as compared to the sham rTMS group. Our data suggest that rTMS can induce neuroplastic changes, particularly in cortical thickness, independent of treatment response. We also found longitudinal changes in amygdala volume in males. For clinical effects to follow these neuroplastic effects, more intensive rTMS treatment might be needed in chronically depressed patients.Trial registration number: ISRCTN 15535800, registered on 29-06-2017.

Neuroimaging mechanisms of high-frequency repetitive transcranial magnetic stimulation for treatment of amnestic mild cognitive impairment: a double-blind randomized sham-controlled trial

Individuals with amnestic mild cognitive impairment (aMCI) have a high risk of developing Alzheimer’s disease. Although repetitive transcranial magnetic stimulation (rTMS) is considered a potentially effective treatment for cognitive impairment in patients with aMCI, the neuroimaging mechanisms are poorly understood. Therefore, we performed a double-blind randomized sham-controlled trial in which rTMS was applied to the left dorsolateral prefrontal cortex of aMCI patients recruited from a community near the Third Hospital Affiliated to Sun Yat-sen University, China. Twenty-four patients with aMCI were randomly assigned to receive true rTMS (treatment group, n = 12, 6 men and 6 women; age 65.08 ± 4.89 years) or sham stimulation (sham group, n = 12, 5 men and 7 women; age 64.67 ± 4.77 years). rTMS parameters included a stimulation frequency of 10 Hz, stimulation duration of 2 seconds, stimulation interval of 8 seconds, 20 repetitions at 80% of the motor threshold, and 400 pulses per session. rTMS/sham stimulation was performed five times per week over a period of 4 consecutive weeks. Our results showed that compared with baseline, Montreal Cognitive Assessment scores were significantly increased and the value of the amplitude of low-frequency fluctuation (ALFF) was significantly increased at the end of treatment and 1 month after treatment. Compared with the sham group, the ALFF values in the right inferior frontal gyrus, triangular part of the inferior frontal gyrus, right precuneus, left angular gyrus, and right supramarginal gyrus were significantly increased, and the ALFF values in the right superior frontal gyrus were significantly decreased in the treatment group. These findings suggest that high-frequency rTMS can effectively improve cognitive function in aMCI patients and alter spontaneous brain activity in cognitive-related brain areas. This study was approved by the Ethics Committee of Shenzhen Baoan Hospital of Southern Medical University, China (approval No. BYL20190901) on September 3, 2019, and registered in the Chinese Clinical Trials Registry (registration No. ChiCTR1900028180) on December 14, 2019.

Training in the practice of noninvasive brain stimulation: Recommendations from an IFCN committee

As the field of noninvasive brain stimulation (NIBS) expands, there is a growing need for comprehensive guidelines on training practitioners in the safe and effective administration of NIBS techniques in their various research and clinical applications. This article provides recommendations on the structure and content of this training. Three different types of practitioners are considered (Technicians, Clinicians, and Scientists), to attempt to cover the range of education and responsibilities of practitioners in NIBS from the laboratory to the clinic. Basic or core competencies and more advanced knowledge and skills are discussed, and recommendations offered regarding didactic and practical curricular components. We encourage individual licensing and governing bodies to implement these guidelines.

Antidepressant efficacy and immune effects of bilateral theta burst stimulation monotherapy in major depression: A randomized, double-blind, sham-controlled study

Inflammation theory has been consolidated by accumulating evidence, and many studies have suggested that the peripheral cytokine levels could be biomarkers for disease status and treatment outcome in major depressive disorder (MDD). Theta burst stimulation (TBS), a new form of repetitive transcranial magnetic stimulation (TMS) for MDD, has been demonstrated to improve depression via modulating dysfunctional neural network or hypothalamic–pituitary–adrenal axis hyperactivities in MDD. However, there is lack of exploratory studies investigating its effect on serum inflammatory cytokines. Here, we aimed to investigate the antidepressant efficacy of bilateral TBS monotherapy and its effects on the serum cytokine levels in MDD. We conducted a double-blind, randomized, sham-controlled trial, with 53 MDD patients who exhibited no responses to at least one adequate antidepressant treatment for the prevailing episode assigned randomly to one of two groups: bilateral TBS monotherapy (n = 27) or sham stimulation (n = 26). The TBS treatment period was 22 days. Blood samples from 31 study subjects were obtained for analyses. The bilateral TBS group exhibited significantly greater decreases in depression scores than the sham group at week 4 (56.5% vs. 33.1%; p < 0.001 [effect size (Cohen ’ s d) = 1.00]) and during the 20-week follow-up periods. Significantly more responders were also found at week 4 (70.3% vs. 23.1%, p = 0.001) and during the 20-week follow-up periods. However, we did not detect any significant effects of TBS on the cytokine panels or any correlations between improvement in depressive symptoms and changes in serum inflammatory markers. Our findings provided the first evidence that the antidepressant efficacy of bilateral TBS monotherapy might not work via immune-modulating mechanisms.

Augmentative Repetitive Transcranial Magnetic Stimulation (rTMS) in the Acute Treatment of Poor Responder Depressed Patients: A Comparison Study Between High and Low Frequency Stimulation

Background:

While the efficacy of repetitive transcranial magnetic stimulation (rTMS) in Major Depressive Disorder (MDD) is well established, the debate is still open in relation to bipolar depression and to a possible different effectiveness of high vs. low stimulation. The present study was aimed to assess and compare the efficacy and tolerability of different protocols of augmentative rTMS in a sample of patients with current Major Depressive Episode (MDE), poor drug response/treatment resistance and a diagnosis of MDD or bipolar disorder.

Methods:

Thirty-three patients were recruited in a 4-week, blind-rater, rTMS trial and randomised to the following three groups of stimulation: (1) (n = 10) right dorsolateral prefrontal cortex (DLPFC) 1 HZ, 110% of the motor threshold (MT), 420 stimuli/day; (2) (n = 10) right DLPFC, 1 Hz, 110% MT, 900 stimuli/day; (3) (n = 13) left DLPFC, 10 Hz, 80% MT, 750 stimuli/day.

Results:

Twenty-nine patients completed the treatment, showing a significant reduction of primary outcome measures (HAM-D, MADRS and CGI-S total scores: t = 8.1, P < 0.001; t = 8.6, P < 0.001; t = 4.6, P < 0.001 respectively). No significant differences in terms of efficacy and tolerability were found between high vs. low frequency and between unipolar and bipolar patients. Side effects were reported by 21% of the sample. One of the 4 dropouts was caused by a hypomanic switch.

Conclusions:

Augmentative rTMS appeared to be effective and well tolerated for the acute treatment of unipolar and bipolar depression with features of poor drug response/treatment resistance, showing a comparable effectiveness profile between protocols of high and low frequency stimulation.

Differential Effects of Left and Right Prefrontal High-Frequency Repetitive Transcranial Magnetic Stimulation on Resting-State Functional Magnetic Resonance Imaging in Healthy Individuals

High-frequency repetitive transcranial magnetic stimulation (HF-rTMS) has gained great interest in multiple clinical and research fields and is believed to accomplish its effect by influencing neuronal networks. The dorsolateral prefrontal cortex (dlPFC) is frequently chosen as the cortical target for HF-rTMS. However, very little is known about the differential effect of HF-rTMS over the left and right dlPFC on intrinsic functional connectivity networks in patients or in healthy individuals. The current study assessed the differential effects of left or right HF-rTMS (corrected for sham) on intrinsic independent component analysis (ICA)-defined functional connectivity networks in a sample of 45 healthy individuals. All subjects had a first scanning session in which baseline functional connectivity was assessed. During the second session, individuals received one session of left, right, or sham dlPFC HF-rTMS (60 5-sec trains of 10 Hz at 110% motor threshold). The sham condition was used to correct for time and placebo effects. ICAs were performed to assess baseline differences and stimulation effects on within- and between-network functional connectivity. Stimulation of the left dlPFC resulted in decreased functional connectivity in the salience network, whereas right dlPFC stimulation resulted in increased functional connectivity within this network. No differences between left or right dlPFC stimulation were found in between-network connectivity. These results suggest that left and right HF-rTMS may have differential effects, and more research is needed on the clinical consequences.

The Effect of High-Frequency Repetitive Transcranial Magnetic Stimulation on Emotion Processing, Reappraisal, and Craving in Alcohol Use Disorder Patients and Healthy Controls: A Functional Magnetic Resonance Imaging Study

Impaired cognitive-motivational functioning is present in many psychiatric disorders, including alcohol use disorder (AUD). Emotion regulation is a key intermediate factor, relating to the (cognitive) regulation of emotional and motivational states, such as in regulation of craving or negative emotions that may lead to relapse in alcohol use. These cognitive-motivational functions, including emotion regulation, are a target in cognitive behavioral therapy and may possibly be improved by neurostimulation techniques. The present between-subjects, single-blind study assesses the effects of sham-controlled high-frequency neuronavigated repetitive transcranial magnetic stimulation (10 Hz) of the right dorsolateral prefrontal cortex (dlPFC) on several aspects relevant for emotion regulation (emotion processing and reappraisal abilities) and related brain activity, as well as self-reported craving in a sample of alcohol use disorder patients (AUD; n = 39) and healthy controls (HC; n = 36). During the emotion reappraisal task, participants were instructed to either attend or reappraise their emotions related to the negative, positive, neutral, and alcohol-related images, after which they rated their experienced emotions. We found that repetitive transcranial magnetic stimulation (rTMS) reduces self-reported experienced emotions in response to positive and negative images in AUD patients, whereas experienced emotions were increased in response to neutral and positive images in HCs. In the functional magnetic resonance imaging (fMRI) analyses, we found that rTMS reduces right dlPFC activity during appraisal of affective images relative to sham stimulation only in AUD patients. We could not confirm our hypotheses regarding the effect of rTMS craving levels, or on reappraisal related brain function, since no significant effects of rTMS on craving or reappraisal related brain function were found. These findings imply that rTMS can reduce the emotional impact of images as reflected in blood oxygenation level-dependent (BOLD) response, especially in AUD patients. Future studies should replicate and expand the current study, for instance, by assessing the effect of multiple stimulation sessions on both explicit and implicit emotion regulation paradigms and craving, and assess the effect of rTMS within subgroups with specific addiction-relevant image preferences. Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT02557815.

Clinical Usefulness of Therapeutic Neuromodulation for Major Depression: A Systematic Meta-Review of Recent Meta-Analyses

The authors conducted a meta-review of meta-analyses published in the past decade on therapeutic neuromodulation (ie, repetitive transcranial magnetic stimulation, transcranial direct current stimulation, vagus nerve stimulation and deep brain stimulation) for major depression. Active repetitive transcranial magnetic stimulation and transcranial direct current stimulation have been generally associated with small to moderate effect sizes vis-à-vis their efficacy and with similar acceptability compared with sham. Vagus nerve stimulation and deep brain stimulation (although more challenging to investigate) have demonstrated preliminary effectiveness, particularly during longer-term follow-up.

Both active and sham low-frequency rTMS single sessions over the right DLPFC decrease cue-induced cravings among pathological gamblers seeking treatment: A randomized, double-blind, sham-controlled crossover trial

Background Craving is a core symptom of addictive disorders, such as pathological gambling for example. Over the last decade, several studies have assessed the efficacy of repetitive transcranial magnetic stimulation (rTMS) in the addiction field, which triggers the dorsolateral prefrontal cortex (DLPFC) to decrease craving. The STIMJEU study investigated whether a single session of low-frequency (LF, i.e., 1 Hz) rTMS applied to the right DLPFC reduced cue-induced gambling craving in a sample of treatment-seeking pathological gamblers. Methods Thirty patients received both active and sham rTMS in random order and were blinded to the condition in a within-subject crossover design. Outcome measures included self-reported gambling craving (Visual Analog Scale and Gambling Craving Scale) and physiological measures (heart rate and blood pressure). Results The rTMS sessions were associated with a significant decrease in the gambling urge, regardless of whether the session was active or sham. When controlling cue-induced craving levels, no effects were observed on craving for active rTMS. Overall, rTMS was well-tolerated, and the credibility of the sham procedure was assessed and appeared to be appropriate. Conclusions We failed to demonstrate the specific efficacy of one session of LF rTMS to decrease cue-induced craving in pathological gamblers. A strong placebo-effect and rTMS parameters may partly explain these results. Yet, we are convinced that rTMS remains a promising therapeutic method. Further studies are required to examine its potential effect.

Preventing relapse to smoking with transcranial magnetic stimulation: Feasibility and potential efficacy

Many smokers attempt to quit every year, but 90% relapse within 12 months. Converging evidence suggests relapse is associated with insufficient activation of the prefrontal cortex. Delay discounting rate reflects relative activity in brain regions associated with relapse. High-frequency repetitive transcranial magnetic stimulation (rTMS) of the left dorsolateral prefrontal cortex (LDLPFC) increases cortical excitability and reduces delay discounting rates, but little is known about feasibility, tolerability, and potential efficacy for smoking cessation. We hypothesized that 8 sessions of 20Hz rTMS of the LDLPFC combined with an evidence-based self-help intervention will demonstrate feasibility, tolerability, and potential efficacy in a limited double-blind randomized control trial. Smokers (n=29), abstinent for 24h, motivated to quit, and not using cessation medications, were randomized to active 20Hz rTMS at 110% of Motor Threshold or sham stimulation that replicated the look and sound of active stimulation. Stimulation site was located using the 6cm rule and neuro-navigation. Multiple clinical, feasibility, tolerability, and efficacy measures were examined. Active rTMS decreased delay discounting of $100 (F (1, 25.3694)=4.14, p=.05) and $1000 (F (1, 25.169)=8.42, p<.01), reduced the relative risk of relapse 3-fold (RR 0.29, CI 0.10-0.76, Likelihood ratio χ2 with 1 df=6.40, p=.01), increased abstinence rates (active 50% vs. sham 15.4%, Χ² (df=1)=3.80, p=.05), and increased uptake of the self-help intervention. Clinical, feasibility, and tolerability assessments were favorable. Combining 20Hz rTMS of the LDLPFC with an evidence-based self-help intervention is feasible, well-tolerated, and demonstrates potential efficacy.

Dorsomedial prefrontal cortex repetitive transcranial magnetic stimulation treatment of posttraumatic stress disorder in eating disorders: An open-label case series

Posttraumatic stress disorder (PTSD) is a common comorbid condition in anorexia nervosa (AN) and bulimia nervosa (BN), and may be associated with reduced response to treatment. We report on a case series employing repetitive transcranial magnetic stimulation (rTMS) with a novel target, the dorsomedial prefrontal cortex (DMPFC). Fourteen subjects with eating disorders and comorbid PTSD received 20-30 neuronavigated DMPFC-rTMS treatments on an open-label basis. PTSD symptoms were assessed pretreatment and posttreatment with the PTSD checklist-Civilian (PCL-C) and the Difficulties in Emotional Regulation Scale (DERS). PCL-C scores were reduced by 51.99% ± 27.24% overall, from a mean of 54.29 ± 19.34 pretreatment to 24.86 ± 17.43 posttreatment (p < .001). Of the 14, 8 showed an improvement of >50%. DERS scores improved by 36.02% ± 24.24% overall, from 140.00 ± 22.09 at pretreatment to 89.29 ± 38.31 at posttreatment (p < .001). OF the 14 subjects, 5 achieved >50% improvement. These data may suggest that DMPFC-rTMS could be helpful in the treatment of PTSD in some ED patients.

Two Versus One High-Frequency Repetitive Transcranial Magnetic Stimulation Session per Day for Treatment-Resistant Depression: A Randomized Sham-Controlled Trial

OBJECTIVES

High-frequency repetitive transcranial magnetic stimulation (HF-rTMS) has proven antidepressant effects, but the optimal frequency of sessions remains unclear.

METHODS

We conducted a 3-week, sham-controlled trial to assess the antidepressant efficacy of 1 active HF-rTMS session per day (A1 group) compared with 2 per day (A2 group) and equivalent sham sessions (once a day, S1 group; twice a day, S2 group) in patients with treatment-resistant major depression with a subsequent 2-week follow-up period. One hundred seventy-seven patients were screened, of whom 105 met eligibility criteria and 98 consented and were randomized. The HF-rTMS (20 Hz) was targeted to the left prefrontal cortex in sessions of approximately 40 trains (2 seconds each) at 100% resting motor threshold with an intertrain interval of 1 minute. Treatment response was defined as a 50% or greater decrease in the Hamilton Depression Rating Scale (HDRS) score and/or Clinician Global Impressions-Severity of Illness (CGI-S) score of 3 or less. Remission was defined as HDRS score less than 8 and/or CGI-S score of 2 or less.

RESULTS

Practically none of the subjects in either sham groups achieved remission. Increased odds of remission were present for CGI-S by stimulating twice rather than once per day (odds ratio [OR] = 1.5, P = 0.018), whereas there was a marginal result for HDRS (OR = 3.9, P = 0.066). Patients who had lower baseline HDRS (OR = 0.75, P = 0.014) and CGI-S scores (OR = 0.18, P = 0.001) were more likely to achieve remission.

CONCLUSIONS

Twice per day active HF-rTMS might be more effective than once per day active HF-rTMS or sham stimulation.

Efficacy of theta burst stimulation (TBS) for major depression: An exploratory meta-analysis of randomized and sham-controlled trials

Theta burst stimulation (TBS) has been proposed as a novel treatment for major depression (MD). However, randomized and sham-controlled trials (RCTs) published to date have yielded heterogeneous clinical results and we have thus carried out the present systematic review and exploratory meta-analysis of RCTs to evaluate this issue. We searched the literature for RCTs on TBS for MD from January 2001 through September 2016 using MEDLINE, EMBASE, PsycINFO, and CENTRAL. We then performed a random-effects meta-analysis with the main outcome measures including pre-post score changes in the Hamilton Depression Rating Scale (HAM-D) as well as rates of response, remission and dropout. Data were obtained from 5 RCTs, totalling 221 subjects with MD. The pooled Hedges' g for pre-post change in HAM-D scores was 1.0 (p = 0.003), indicating a significant and large-sized difference in outcome favouring active TBS. Furthermore, active TBS was associated with significantly higher response rates when compared to sham TBS (35.6% vs. 17.5%, respectively; p = 0.005), although the groups did not differ in terms of rates of remission (18.6% vs. 10.7%, respectively; p = 0.1) and dropout (4.2% vs. 7.8%, respectively; p = 0.5). Finally, subgroup analyses indicated that bilateral TBS and unilateral intermittent TBS seem to be the most promising protocols. In conclusion, although TBS is a promising novel therapeutic intervention for MD, future studies should identify more clinically-relevant stimulation parameters as well as neurobiological predictors of treatment outcome, and include larger sample sizes, active comparators and longer follow-up periods.

Accelerated intermittent theta burst stimulation treatment in medication-resistant major depression: A fast road to remission?

Although accelerated repetitive Transcranial Magnetic Stimulation (rTMS) paradigms and intermittent Theta-burst Stimulation (iTBS) may have the potency to result in superior clinical outcomes in Treatment Resistant Depression (TRD), accelerated iTBS treatment has not yet been studied. In this registered randomized double-blind sham-controlled crossover study, spread over four successive days, 50 TRD patients received 20 iTBS sessions applied to the left dorsolateral prefrontal cortex (DLPFC). The accelerated iTBS treatment procedure was found to be safe and resulted in immediate statistically significant decreases in depressive symptoms regardless of order/type of stimulation (real/sham). While only 28% of the patients showed a 50% reduction of their initial Hamilton Depression Rating Scale score at the end of the two-week procedure, this response rate increased to 38% when assessed two weeks after the end of the sham-controlled iTBS protocol, indicating delayed clinical effects. Importantly, 30% of the responders were considered in clinical remission. We found no demographic predictors for response. Our findings indicate that only four days of accelerated iTBS treatment applied to the left DLPFC in TRD may lead to meaningful clinical responses within two weeks post stimulation.

Transcranial magnetic stimulation and sedation as treatment for functional neurologic disorders

Functional neurologic disorder (FND), also known as conversion disorder, is common and often associated with a poor prognosis. It has been relatively neglected by research and as such there is a conspicuous lack of evidence-based treatments. Physical and psychologic therapies are the main treatment modalities, over and above reassurance and sensitive explanation of the diagnosis. However there are two other historic treatments that have seen a recent resurgence of interest and use. The first is electric stimulation, which was initially pioneered with direct stimulation of nerves but now used indirectly (and therefore noninvasively) in the form of transcranial magnetic stimulation (TMS). The second is (therapeutic) sedation, previously known as "abreaction," where it was mostly used in the context of psychologic investigation and treatment, but now increasingly advocated during rehabilitation as a way to therapeutically demonstrate reversibility of symptoms. This chapter introduces the background of these treatment modalities, their evolution into their current applications before critically evaluating their current evidence base and exploring possible mechanisms of action. It also tentatively suggests when they should be considered in current practice and briefly considers their future potential. In summary there is encouraging preliminary evidence to suggest that both TMS and sedation may be effective treatments for FNDs.

Resting state connectivity in alcohol dependent patients and the effect of repetitive transcranial magnetic stimulation

Alcohol dependence is thought to result from an overactive neural motivation system and a deficient cognitive control system, and rebalancing these systems may mitigate excessive alcohol use. This study examines the differences in functional connectivity of the fronto-parietal cognitive control network (FPn) and the motivational network (striatum and orbitofrontal cortex) between alcohol dependent patients (ADPs) and healthy controls (HCs), and the effect of repetitive transcranial magnetic stimulation (rTMS) on these networks. This randomized controlled trial included 38 ADPs and 37 HCs, matched on age, gender and education. Participants were randomly assigned to sham or right dorsolateral prefrontal cortex (dlPFC) stimulation with rTMS. A 3T resting state functional Magnetic Resonance Imaging (fMRI) scan was acquired before and after active or sham 10Hz rTMS. Group differences of within and between network connectivity and the effect of rTMS on network connectivity was assessed using independent component analysis. Results showed higher connectivity within the left FPn (p=0.012) and the left fronto-striatal motivational network (p=0.03) in ADPs versus HCs, and a further increase in connectivity within the left FPn after active stimulation in ADPs. ADPs also showed higher connectivity between the left and the right FPns (p=0.025), and this higher connectivity was related to fewer alcohol related problems (r=0.30, p=0.06). The results show higher within and between network connectivity in ADPs and a further increase in fronto-parietal connectivity after right dlPFC rTMS in ADPs, suggesting that frontal rTMS may have a beneficial influence on cognitive control and may result in lower relapse rates.

The Impact of Accelerated Right Prefrontal High-Frequency Repetitive Transcranial Magnetic Stimulation (rTMS) on Cue-Reactivity: An fMRI Study on Craving in Recently Detoxified Alcohol-Dependent Patients

In alcohol-dependent patients craving is a difficult-to-treat phenomenon. It has been suggested that high-frequency (HF) repetitive transcranial magnetic stimulation (rTMS) may have beneficial effects. However, exactly how this application exerts its effect on the underlying craving neurocircuit is currently unclear. In an effort to induce alcohol craving and to maximize detection of HF-rTMS effects to cue-induced alcohol craving, patients were exposed to a block and event-related alcohol cue-reactivity paradigm while being scanned with fMRI. Hence, we assessed the effect of right dorsolateral prefrontal cortex (DLPFC) stimulation on cue-induced and general alcohol craving, and the related craving neurocircuit. Twenty-six recently detoxified alcohol-dependent patients were included. First, we evaluated the impact of one sham-controlled stimulation session. Second, we examined the effect of accelerated right DLPFC HF-rTMS treatment: here patients received 15 sessions in an open label accelerated design, spread over 4 consecutive days. General craving significantly decreased after 15 active HF-rTMS sessions. However, cue-induced alcohol craving was not altered. Our brain imaging results did not show that the cue-exposure affected the underlying craving neurocircuit after both one and fifteen active HF-rTMS sessions. Yet, brain activation changes after one and 15 HF-rTMS sessions, respectively, were observed in regions associated with the extended reward system and the default mode network, but only during the presentation of the event-related paradigm. Our findings indicate that accelerated HF-rTMS applied to the right DLPFC does not manifestly affect the craving neurocircuit during an alcohol-related cue-exposure, but instead it may influence the attentional network.

MRI-guided dmPFC-rTMS as a Treatment for Treatment-resistant Major Depressive Disorder

Here we outline the protocol for magnetic resonance imaging (MRI) guided repetitive transcranial magnetic stimulation (rTMS) to the dorsal medial prefrontal cortex (dmPFC) in patients with major depressive disorder (MDD). Technicians used a neuronavigation system to process patient MRIs to generate a 3-dimensional head model. The head model was subsequently used to identify patient-specific stimulatory targets. The dmPFC was stimulated daily for 20 sessions. Stimulation intensity was titrated to address scalp pain associated with rTMS. Weekly assessments were conducted on the patients using the Hamilton Rating Scale for Depression (HamD17) and Beck Depression Index II (BDI-II). Treatment-resistant MDD patients achieved significant improvements on both HAMD and BDI-II. Of note, angled, double-cone coil rTMS at 120% resting motor threshold allows for optimal stimulation of deeper midline prefrontal regions, which results in a possible therapeutic application for MDD. One major limitation of the rTMS field is the heterogeneity of treatment parameters across studies, including duty cycle, number of pulses per session and intensity. Further work should be done to clarify the effect of stimulation parameters on outcome. Future dmPFC-rTMS work should include sham-controlled studies to confirm its clinical efficacy in MDD.

Left prefrontal high-frequency repetitive transcranial magnetic stimulation for the treatment of schizophrenia with predominant negative symptoms: a sham-controlled, randomized multicenter trial

BACKGROUND

Investigators are urgently searching for options to treat negative symptoms in schizophrenia because these symptoms are disabling and do not respond adequately to antipsychotic or psychosocial treatment. Meta-analyses based on small proof-of-principle trials suggest efficacy of repetitive transcranial magnetic stimulation (rTMS) for the treatment of negative symptoms and call for adequately powered multicenter trials. This study evaluated the efficacy of 10-Hz rTMS applied to the left dorsolateral prefrontal cortex for the treatment of predominant negative symptoms in schizophrenia.

METHODS

A multicenter randomized, sham-controlled, rater-blinded and patient-blinded trial was conducted from 2007-2011. Investigators randomly assigned 175 patients with schizophrenia with predominant negative symptoms and a high-degree of illness severity into two treatment groups. After a 2-week pretreatment phase, 76 patients were treated with 10-Hz rTMS applied 5 days per week for 3 weeks to the left dorsolateral prefrontal cortex (added to the ongoing treatment), and 81 patients were subjected to sham rTMS applied similarly.

RESULTS

There was no statistically significant difference in improvement in negative symptoms between the two groups at day 21 (p = .53, effect size = .09) or subsequently through day 105. Also, symptoms of depression and cognitive function showed no differences in change between groups. There was a small, but statistically significant, improvement in positive symptoms in the active rTMS group (p = .047, effect size = .30), limited to day 21.

CONCLUSIONS

Application of active 10-Hz rTMS to the left dorsolateral prefrontal cortex was well tolerated but was not superior compared with sham rTMS in improving negative symptoms; this is in contrast to findings from three meta-analyses.

Rethinking the role of sham TMS

Sham transcranial magnetic stimulation (TMS) approaches are widely used in basic and clinical research to ensure that observed effects are due to the intended neural manipulation instead of being caused by various possible side effects. We here critically discuss several methodological aspects of sham TMS. Importantly, we propose to carefully distinguish between the placebo versus sensory side effects of TMS. In line with this conceptual distinction, we describe current limitations of sham TMS approaches in the context of placebo effects and blinding success, followed by a short review of our own work demonstrating that the sensory side effects of sham TMS are not unspecific as often falsely assumed. Lastly, we argue that sham TMS approaches are inherently insufficient as full-fledged control conditions as they fail to demonstrate the specificity of TMS effects to a particular brain area or time point of stimulation. Sham TMS should therefore only complement alternative control strategies in TMS research.

Short-term efficacy of repetitive transcranial magnetic stimulation (rTMS) in depression- reanalysis of data from meta-analyses up to 2010

BACKGROUND

According to a narrative review of 13 meta-analyses (published up to 2010), repetitive transcranial magnetic stimulation (rTMS) has a moderate, short-term antidepressant effect in the treatment of major depression. The aim of the current study was to reanalyse the data from these 13 meta-analyses with a uniform meta-analytical procedure and to investigate predictors of such an antidepressant response.

METHODS

A total of 40 double-blind, randomised, sham-controlled trials with parallel designs, utilising rTMS of the dorsolateral prefrontal cortex in the treatment of major depression, was included in the current meta-analysis. The studies were conducted in 15 countries on 1583 patients and published between 1997-2008. Depression severity was measured using the Hamilton Depression Rating Scale, Beck Depression Inventory, or Montgomery Åsberg Depression Rating Scale at baseline and after the last rTMS. A random-effects model with the inverse-variance weights was used to compute the overall mean weighted effect size, Cohen's d.

RESULTS

There was a significant and moderate reduction in depression scores from baseline to final, favouring rTMS over sham (overall d = -.54, 95% CI: -.68, -.41, N = 40 studies). Predictors of such a response were investigated in the largest group of studies (N = 32) with high-frequency (>1 Hz) left (HFL) rTMS. The antidepressant effect of HFL rTMS was present univariately in studies with patients receiving antidepressants (at stable doses or started concurrently with rTMS), with treatment-resistance, and with unipolar (or bipolar) depression without psychotic features. Univariate meta-regressions showed that depression scores were significantly lower after HFL rTMS in studies with higher proportion of female patients. There was little evidence for publication bias in the current analysis.

CONCLUSIONS

Daily rTMS (with any parameters) has a moderate, short-term antidepressant effect in studies published up to 2008. The clinical efficacy of HFL rTMS may be better in female patients not controlling for any other study parameters.

Repetitive transcranial magnetic stimulation over the dorsolateral prefrontal cortex for treating posttraumatic stress disorder: an exploratory meta-analysis of randomized, double-blind and sham-controlled trials

OBJECTIVE

Repetitive transcranial magnetic stimulation (rTMS) applied to the dorsolateral prefrontal cortex (DLPFC) has yielded promising results as a treatment for posttraumatic stress disorder (PTSD). However, to date, no quantitative review of its clinical utility has been published.

METHOD

We searched for randomized and sham-controlled trials from 1995 to March 2013 using MEDLINE, Embase, PsycINFO, CENTRAL, and SCOPUS. We then performed an exploratory random effects meta-analysis.

RESULTS

Studies on rTMS applied to the right DLPFC included 64 adults with PTSD. The pooled Hedges g effect size for pre and post changes in clinician-rated and self-reported PTSD symptoms were, respectively, 1.65 (P < 0.001) and 1.91 (P < 0.001), indicating significant and large-sized differences in outcome favouring active rTMS. Also, there were significant pre and post decreases with active rTMS in overall anxiety (Hedges g = 1.24; P = 0.02) and depressive (Hedges g = 0.85; P < 0.001) symptoms. Dropout rates at study end did not differ between active and sham rTMS groups. Regarding rTMS applied to the left DLPFC, there is only one study published to date (using a high frequency protocol), and its results showed that active rTMS seems to be superior overall to sham rTMS.

CONCLUSIONS

Our exploratory meta-analysis shows that active rTMS applied to the DLPFC seems to be effective and acceptable for treating PTSD. However, the small number of subjects included in the analyses limits the generalizability of these findings. Future studies should include larger samples and deliver optimized stimulation parameters.

Transcranial magnetic stimulation in the treatment of substance addiction

Transcranial magnetic stimulation (TMS) is a noninvasive method of brain stimulation used to treat a variety of neuropsychiatric disorders, but is still in the early stages of study as addiction treatment. We identified 19 human studies using repetitive TMS (rTMS) to manipulate drug craving or use, which exposed a total of 316 adults to active rTMS. Nine studies involved tobacco, six alcohol, three cocaine, and one methamphetamine. The majority of studies targeted high-frequency (5-20 Hz; expected to stimulate neuronal activity) rTMS pulses to the dorsolateral prefrontal cortex. Only five studies were controlled clinical trials: two of four nicotine trials found decreased cigarette smoking; the cocaine trial found decreased cocaine use. Many aspects of optimal treatment remain unknown, including rTMS parameters, duration of treatment, relationship to cue-induced craving, and concomitant treatment. The mechanisms of rTMS potential therapeutic action in treating addictions are poorly understood, but may involve increased dopamine and glutamate function in corticomesolimbic brain circuits and modulation of neural activity in brain circuits that mediate cognitive processes relevant to addiction, such as response inhibition, selective attention, and reactivity to drug-associated cues. rTMS treatment of addiction must be considered experimental at this time, but appears to have a promising future.

Evidence-based guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS)

A group of European experts was commissioned to establish guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS) from evidence published up until March 2014, regarding pain, movement disorders, stroke, amyotrophic lateral sclerosis, multiple sclerosis, epilepsy, consciousness disorders, tinnitus, depression, anxiety disorders, obsessive-compulsive disorder, schizophrenia, craving/addiction, and conversion. Despite unavoidable inhomogeneities, there is a sufficient body of evidence to accept with level A (definite efficacy) the analgesic effect of high-frequency (HF) rTMS of the primary motor cortex (M1) contralateral to the pain and the antidepressant effect of HF-rTMS of the left dorsolateral prefrontal cortex (DLPFC). A Level B recommendation (probable efficacy) is proposed for the antidepressant effect of low-frequency (LF) rTMS of the right DLPFC, HF-rTMS of the left DLPFC for the negative symptoms of schizophrenia, and LF-rTMS of contralesional M1 in chronic motor stroke. The effects of rTMS in a number of indications reach level C (possible efficacy), including LF-rTMS of the left temporoparietal cortex in tinnitus and auditory hallucinations. It remains to determine how to optimize rTMS protocols and techniques to give them relevance in routine clinical practice. In addition, professionals carrying out rTMS protocols should undergo rigorous training to ensure the quality of the technical realization, guarantee the proper care of patients, and maximize the chances of success. Under these conditions, the therapeutic use of rTMS should be able to develop in the coming years.

Accelerated HF-rTMS in treatment-resistant unipolar depression: Insights from subgenual anterior cingulate functional connectivity

OBJECTIVES

Intensified repetitive transcranial magnetic stimulation (rTMS) applied to the left dorsolateral prefrontal cortex (DLPFC) may result in fast clinical responses in treatment resistant depression (TRD). In these kinds of patients, subgenual anterior cingulate cortex (sgACC) functional connectivity (FC) seems to be consistently disturbed. So far, no de novo data on the relationship between sgACC FC changes and clinical efficacy of accelerated rTMS were available.

METHODS

Twenty unipolar TRD patients, all at least stage III treatment resistant, were recruited in a randomized sham-controlled crossover high-frequency (HF)-rTMS treatment study. Resting-state (rs) functional MRI scans were collected at baseline and at the end of treatment.

RESULTS

HF-rTMS responders showed significantly stronger resting-state functional connectivity (rsFC) anti-correlation between the sgACC and parts of the left superior medial prefrontal cortex. After successful treatment an inverted relative strength of the anti-correlations was observed in the perigenual prefrontal cortex (pgPFC). No effects on sgACC rsFC were observed in non-responders.

CONCLUSIONS

Strong rsFC anti-correlation between the sgACC and parts of the left prefrontal cortex could be indicative of a beneficial outcome. Accelerated HF-rTMS treatment designs have the potential to acutely adjust deregulated sgACC neuronal networks in TRD patients.

More female patients and fewer stimuli per session are associated with the short-term antidepressant properties of repetitive transcranial magnetic stimulation (rTMS): a meta-analysis of 54 sham-controlled studies published between 1997-2013

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) of the dorsolateral prefrontal cortex (DLPFC) appears to have short-term antidepressant properties. The aim of the current study was to update our previous meta-analysis and to investigate factors associated with the antidepressant properties of rTMS.

METHOD

Following a systematic literature search conducted in Medline and PsycInfo, N=14 sham-controlled, parallel design studies (published after 2008 to August 2013) that had utilized rTMS of the DLPFC in major depression were included in the current meta-analysis. The sensitivity and moderator analyses also included data from N=40 studies (published in 1997-2008) from our previous meta-analysis. The effect size (Cohen's d) in each study was the standardized difference in mean depression scores (on Hamilton Depression Rating Scale, Beck Depression Inventory, Montgomery Åsberg Depression Rating Scale) from baseline to final (after last session) in rTMS compared to sham groups.

RESULTS

According to a random-effects model with inverse-variance weights, depression scores were significantly reduced after rTMS compared to sham in studies published from 2008-2013 based on N=659 patients (overall mean weighted d=-0.42, 95% confidence interval: -0.66, -0.18, P=0.001). Combining studies from our past and current meta-analyses (published in 1997-2013; N=54) revealed that depression was significantly reduced after left-fast (>1 Hz), right-slow (≤1 Hz), and bilateral (or sequential) rTMS of DLPFC compared to sham. Significant antidepressant properties of rTMS were observed in studies with patients who were treatment resistant, unipolar (or bipolar), non-psychotic, medication-free (or started on antidepressants concurrently with rTMS). According to univariate meta-regressions, depression scores were significantly lower in studies with more female patients and fewer stimuli per session. There was little evidence that publication bias occurred in the analysis.

CONCLUSION

According to this study, the largest meta-analysis to date, short-term antidepressant properties of rTMS are independent of concurrent antidepressants and might depend on sex and the number of stimuli per session.

Intensive HF-rTMS treatment in refractory medication-resistant unipolar depressed patients

BACKGROUND

Major depression is a worldwide severe mental health problem. Unfortunately, not all depressed patients respond to pharmacotherapy or psychotherapy, even when adhering to treatment guidelines. Even though current guidelines do not in particular advocate repetitive Transcranial Magnetic Stimulation (rTMS) in refractory treatment resistant depression (TRD), using more intensive stimulation parameters might hold promise as a valuable alternative.

OBJECTIVE

Consequently, in this randomized sham-controlled crossover study, we wanted to evaluate clinical outcome of intensive HF-rTMS treatment in TRD when applied to the left dorsolateral prefrontal cortex (DLPFC).

METHODS

After a 2-week antidepressant washout, 20 unipolar TRD patients, at least stage III, received 20 sham-controlled high-frequency (HF)-rTMS sessions, in a crossover design. Five daily suprathreshold HF-rTMS sessions were spread over four successive days delivering in total 31,200 stimuli.

RESULTS

Overall, the procedure resulted in immediate statistical significant decreases in depressive symptoms regardless of order/type of stimulation (real/sham), suggesting possible placebo responses. On the other hand, albeit only 35% (7/20) of the patients showed a 50% reduction of their initial Hamilton Depression rating score at the end of the two-week procedure, all these patients showed a prompt clinical response after real HF-rTMS treatment, not after sham. Furthermore, a shorter duration of the current depressive episode was a predictor for beneficial clinical outcome. Unresponsiveness to former ECT could be indicative for negative clinical outcome in these kinds of patients.

LIMITATIONS

Single center setup with relatively small sample size and no follow-up.

CONCLUSIONS

Our findings indicate that intensive HF-rTMS treatment might have the potential to result in fast clinical response when confronted with a refractory TRD patient.

Comparison of blinding effectiveness between sham tDCS and placebo sertraline in a 6-week major depression randomized clinical trial

OBJECTIVE

To compare blinding integrity and associated factors for transcranial direct current stimulation (tDCS) vs. placebo-pill, the gold standard blinding method.

METHODS

Parallel trial. Depressed participants were randomized to verum/placebo sertraline and active/sham tDCS (2mA, 30-min 10-daily sessions and two additional, fortnight sessions) over 6weeks. Blinding was assessed in completers (n=102) and in a random subgroup (n=35) of raters and participants, in which we also inquired to qualitatively describe their strongest guessing reason.

RESULTS

Participants and raters presented similar performance for predicting treatment assignment at endpoint, correctly guessing tDCS and sertraline beyond chance. Nevertheless, clinical response was associated with correct prediction and tDCS non-responders failed to predict the allocation group. For tDCS, "trouble concentrating" was inversely associated with correct prediction. "Skin redness" was more reported for active-tDCS, but did not predict the allocation group. The qualitative reasons for raters' guessing were not associated with correct prediction, whereas for participants clinical response and adverse effects were directly and inversely associated with correct prediction, respectively.

CONCLUSION

Blinding integrity of tDCS and sertraline were comparable and mainly associated with efficacy rather than blinding failure.

SIGNIFICANCE

TDCS blinding can be improved by adopting parallel designs and avoiding subjects' awareness of skin redness.