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

A Systematic Review of the Effects of Repetitive Transcranial Magnetic Stimulation Combined With Pharmacological Intervention on Sleep Quality and Depressive Symptoms in Patients With Depression

To systematically evaluate the intervention effect of repetitive transcranial magnetic stimulation (rTMS) combined with pharmacological interventions on sleep quality and depressive symptoms in patients with depression, identify optimal stimulation parameters, and explore potential clinical applications to facilitate individualised therapeutic strategies. Databases including Pubmed, Web of Science, Cochrane Library, Embase, CNKI, Wanfang Medical Database, and VIP database were searched up to 31 December 2024, for randomized controlled trials (RCTs) assessing rTMS combined with pharmacological intervention for sleep disorders and depressive symptoms in patients with depression. Data analysis was performed using Stata software. 17 RCTs involving 1667 patients were included. Meta-analysis revealed that rTMS significantly improved sleep quality (SMD = -0.57, 95% CI: -1.02 to -0.12, P < 0.05) and reduced depressive symptoms (SMD = -0.73, 95% CI: -1.37 to -0.10, P < 0.05). Subgroup analyses showed that the optimal parameters for improving sleep quality were high-frequency rTMS targeting the left dorsolateral prefrontal cortex, high stimulation intensity, low total pulse count (< 1200 pulses), session duration ≤ 20 min daily, for 5-8 weeks. For depressive symptoms, a daily treatment duration of 21-30 min was more effective under similar parameter conditions. rTMS effectively improves sleep quality and alleviates depressive symptoms in patients with depression, showing a dose-dependent effect with stimulation parameters. However, in patients with a prolonged disease course or greater symptom severity, particularly those with vascular and other neurological comorbidities, rTMS alone may be insufficient. Integrating additional therapeutic strategies or tailoring personalised treatment protocols may be necessary to optimise clinical outcomes. Future research should further explore the synergistic potential of rTMS combined with orexin receptor antagonists (ORAs), offering a novel, multimodal approach for managing depression with comorbid insomnia.

rTMS as a Next Step in Antidepressant Nonresponders: A Randomized Comparison With Current Antidepressant Treatment Approaches

OBJECTIVE

Although repetitive transcranial magnetic stimulation (rTMS) is an effective treatment for depression, little is known about the comparative effectiveness of rTMS and other treatment options, such as antidepressants. In this multicenter randomized controlled trial, rTMS was compared with the next pharmacological treatment step in patients with treatment-resistant depression.

METHODS

Patients with unipolar nonpsychotic depression (N=89) with an inadequate response to at least two treatment trials were randomized to treatment with rTMS or to a switch of antidepressants, both in combination with psychotherapy. Treatment duration was 8 weeks and consisted of either 25 high-frequency rTMS sessions to the left dorsolateral prefrontal cortex or a switch of antidepressant medication following the Dutch treatment algorithm. The primary outcome was change in depression severity based on the Hamilton Depression Rating Scale (HAM-D). Secondary outcomes were response and remission rates as well as change in symptom dimensions (anhedonia, anxiety, sleep, rumination, and cognitive reactivity). Finally, expectations regarding treatment were assessed.

RESULTS

rTMS resulted in a significantly larger reduction in depressive symptoms than medication, which was also reflected in higher response (37.5% vs. 14.6%) and remission (27.1% vs. 4.9%) rates. A larger decrease in symptoms of anxiety and anhedonia was observed after rTMS compared with a switch in antidepressants, and no difference from the medication group was seen for symptom reductions in rumination, cognitive reactivity, and sleep disorders. Expectations regarding treatment correlated with changes in HAM-D scores.

CONCLUSIONS

In a sample of patients with moderately treatment-resistant depression, rTMS was more effective in reducing depressive symptoms than a switch of antidepressant medication. In addition, the findings suggest that the choice of treatment may be guided by specific symptom dimensions.

Effectiveness and tolerability of adjunctive transcranial direct current stimulation (tDCS) in management of treatment-resistant depression: A retrospective chart review

Background

There is a limited number of studies from India investigating the role of transcranial direct current stimulation (tDCS) in treatment-resistant depression (TRD). This clinic-based study reports on the effectiveness of tDCS as an add-on treatment in individuals suffering from TRD.

Materials and Methods

Twenty-six right-handed individuals suffering from major depressive disorder who failed to respond to adequate trials of at least two antidepressant drugs in the current episode received tDCS as an augmenting treatment. Twice daily sessions of conventional tDCS were given providing anodal stimulation at the left dorsolateral prefrontal cortex (DLPFC) and cathodal placement at the right DLPFC. A total of 20 sessions were given over 2 weeks. The outcome was assessed based on changes in scores of the Hamilton Rating Scale for Depression (HAMD) and Montgomery-Asberg Depression Rating Scale (MADRS).

Results

There was a significant reduction in outcome assessment after tDCS intervention as compared to baseline, with more than 50% of the participants showing response in both scales, which increased further to approximately 77% by the end of 1 month of the follow-up period.

Conclusion

Twice daily tDCS sessions with anodal stimulation of left DLPFC and cathodal stimulation of right DLPFC is an effective add-on treatment strategy in individuals with TRD.

Multidimensional Internet Use, Social Participation, and Depression Among Middle-Aged and Elderly Chinese Individuals: Nationwide Cross-Sectional Study

BACKGROUND

There is growing evidence that the internet has beneficial effects on the mental health of middle-aged and older people (≥45 years), but the evidence is inconclusive, and the underlying mechanisms are less known.

OBJECTIVE

This study aims to explore the relationship between multidimensional (devices, frequency, and purpose) internet use and depression in middle-aged and elderly Chinese, as well as the mediating effect of social participation. Moreover, this study will explore the moderating effect of the regional informatization development level (RIDL) on the relationships between individual internet use, social participation, and depression.

METHODS

Data on 17,676 participants aged 45 years or older were obtained from the China Health and Retirement Longitudinal Study (CHARLS) 2018 data set. The 10-item Center for Epidemiologic Studies Depression Scale (CES-D-10) was used to identify the presence of depression. Logistic regression was used to explore the relationship between each dimension of internet use and depression. Multiple linear regression was used to explore the mediating effect of social participation and the moderating effect of the RIDL.

RESULTS

The results showed that 28.33% (5008/17,676) of the total population had depression. In terms of regional subgroups, respondents living in the western region exhibited the highest proportion of depression (2041/5884, 34.69%). Internet use was negatively associated with depression (odds ratio 0.613, 95% CI 0.542-0.692; P<.001). Various dimensions of internet use positively contributed to individual social participation and reduced individual depression (devices: β=-.170, 95% CI -0.209 to -0.127; frequency: β=-.065, 95% CI -0.081 to -0.047; and purpose: β=-.043, 95% CI -0.053 to -0.031). In addition, the RIDL weakened the relationship between individual-level internet use and social participation (internet use: F74.12,9.82=7.55, P<.001; devices: F51.65/9.88=5.23, P=.005; frequency: F66.74/10.08=6.62, P=.001; and purpose: F66.52/9.78=6.80, P=.001), and negatively moderated the relationship between the frequency of internet use and depression (frequency: F662.67/188.79=3.51, P=.03).

CONCLUSIONS

This study found that different dimensions of internet use are associated with lower levels of depression. Social participation partially mediates the association between multidimensional internet use and depression in the eastern, central, and western regions, respectively. Additionally, the RIDL helps individuals further their internet use and social participation, reducing the impact of depression. However, this effect weakens sequentially from the western region to the central region and then to the eastern region.

Cognitive outcomes of transcranial magnetic stimulation in treatment-resistant depression: a randomized controlled study

BACKGROUND

Major depressive disorder (MDD) is a significant cause of workforce loss, and is associated with cognitive impairments which can continue even after the elimination of mood and behavioural symptoms. The aim of this study was to investigate the benefit of transcranial magnetic stimulation (TMS) on cognitive functions in treatment resistant depression.

METHODS

This randomised controlled clinical trial was conducted at a university hospital, department of psychiatry (tertiary centre) between October 2019 and July 2020. The study included 30 patients with depressive disorder, aged 18-50 years, who did not respond to at least two antidepressant medications for at least 8 weeks (one drug used was serotonin norepinephrine reuptake inhibitor [SNRI]; and 15 healthy control subjects. The patients were separated into two equal groups in a double-blind, random manner, and 20 sessions of repeated TMS was applied to one group, and 20 sessions of sham TMS to the other. The Montgomery Asberg Depression Scale (MADRS), Hamilton Depression Rating Scale (HAM-D), Stroop test, Wisconsin Card Sorting Test (WCST), Digit Span Test (DST), Trail Making Test A-B, and Verbal Memory Processes Test (VMPT) were applied to the patients before and after the TMS procedure.

RESULTS

The decrease in the HAM-D score was greater in the active magnetic stimulation (25 trains, 10 Hz, 110% motor threshold intensity) group, and with the exception of verbal memory processes, better performance was obtained by the active magnetic stimulation group than the sham group in the cognitive function tests.

DISCUSSION

TMS was seen toimprove the cognitive defects present in the active phase of treatment-resistant depression, and therefore TMS could provide early improvement in cognitive functions in clinical use. Key words: Depression, transcranial magnetic stimulation, neurocognitive functi.

Therapeutic potential of brain stimulation techniques in the treatment of mental, psychiatric, and cognitive disorders

Treatment for brain diseases has been disappointing because available medications have failed to produce clinical response across all the patients. Many patients either do not respond or show partial and inconsistent effect, and even in patients who respond to the medications have high relapse rates. Brain stimulation has been seen as an alternative and effective remedy. As a result, brain stimulation has become one of the most valuable therapeutic tools for combating against brain diseases. In last decade, studies with the application of brain stimulation techniques not only have grown exponentially but also have expanded to wide range of brain disorders. Brain stimulation involves passing electric currents into the cortical and subcortical area brain cells with the use of noninvasive as well as invasive methods to amend brain functions. Over time, technological advancements have evolved into the development of precise devices; however, at present, most used noninvasive techniques are repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), whereas the most common invasive technique is deep brain stimulation (DBS). In the current review, we will provide an overview of the potential of noninvasive (rTMS and tDCS) and invasive (DBS) brain stimulation techniques focusing on the treatment of mental, psychiatric, and cognitive disorders.

Interhemispheric Facilitatory Effect of High-Frequency rTMS: Perspective from Intracortical Facilitation and Inhibition

The activity of excitatory and inhibitory neural circuits in the motor cortex can be probed and modified by transcranial magnetic stimulation (TMS) and repetitive TMS (rTMS), noninvasively. At present, not only has a consensus regarding the interhemispheric effect of high frequency rTMS not been reached, but the attributes of these TMS-related circuits are also poorly understood. To address this question comprehensively, we integrated a single- and paired-pulse TMS evaluation with excitatory 20-Hz rTMS intervention in order to probe the interhemispheric effect on the intracortical circuits by high-frequency rTMS. In the rest state, after 20-Hz rTMS, a significant increase of single-pulse MEP and paired-pulse intracortical facilitation (ICF) in the non-stimulated hemisphere was observed with good test–retest reliability. Intracortical inhibition (measured by the cortical silent period) in the unstimulated hemisphere also increased after rTMS. No significant time–course change was observed in the sham-rTMS group. The results provide the evidence that 20-Hz rTMS induced a reliable interhemispheric facilitatory effect. Findings from the present study suggest that the glutamatergic facilitatory system and the GABAergic inhibitory system may vary synchronously.

Biomarkers for Deep Brain Stimulation in Animal Models of Depression

OBJECTIVES

Despite recent advances in depression treatment, many patients still do not respond to serial conventional therapies and are considered "treatment resistant." Deep brain stimulation (DBS) has therapeutic potential in this context. This comprehensive review of recent studies of DBS for depression in animal models identifies potential biomarkers for improving therapeutic efficacy and predictability of conventional DBS to aid future development of closed-loop control of DBS systems.

MATERIALS AND METHODS

A systematic search was performed in Pubmed, EMBASE, and Cochrane Review using relevant keywords. Overall, 56 animal studies satisfied the inclusion criteria.

RESULTS

Outcomes were divided into biochemical/physiological, electrophysiological, and behavioral categories. Promising biomarkers include biochemical assays (in particular, microdialysis and electrochemical measurements), which provide real-time results in awake animals. Electrophysiological tests, showing changes at both the target site and downstream structures, also revealed characteristic changes at several anatomic targets (such as the medial prefrontal cortex and locus coeruleus). However, the substantial range of models and DBS targets limits the ability to draw generalizable conclusions in animal behavioral models.

CONCLUSIONS

Overall, DBS is a promising therapeutic modality for treatment-resistant depression. Different outcomes have been used to assess its efficacy in animal studies. From the review, electrophysiological and biochemical markers appear to offer the greatest potential as biomarkers for depression. However, to develop closed-loop DBS for depression, additional preclinical and clinical studies with a focus on identifying reliable, safe, and effective biomarkers are warranted.

Repetitive transcranial magnetic stimulation (rTMS) in bipolar disorder: A systematic review

OBJECTIVES

Repetitive transcranial magnetic stimulation (rTMS) is commonly used in unipolar depression; yet, its evidence in bipolar disorder (BD) is limited. We sought to review the evidence on the use of rTMS across the different stages of BD.

METHODS

MEDLINE database was systematically searched using the PubMed interface following the PRISMA guidelines. Inclusion criteria were as follows: (i) randomized clinical trials (RCTs), open-label studies, and case series; (ii) specific evaluation of the treatment outcomes using psychometric scales; (iii) clinical studies in adults; and (iv) articles in the English language. The systematic review has been registered on PROSPERO (CRD42020192788).

RESULTS

Thirty-one papers were included in the review. Most studies included participants diagnosed with a bipolar depressive episode (N = 24), have yielded mixed findings, and have yet to reach a consensus on the most effective rTMS protocol. Few studies examined the effect of rTMS during manic (N = 5) or mixed episode (N = 1), or as maintenance treatment (N = 1). The limited data thus far suggest rTMS to be relatively safe and well tolerated. Small sample sizes, heterogeneity among study designs, patients and control groups recruited, rTMS parameters, and outcome measures are among the most significant limitations to these studies.

CONCLUSION

The current data regarding the application of rTMS in BD patients remain limited. More adequately powered sham-controlled studies are required to verify its efficacy. Large-scale clinical trials are needed to also determine whether its effects extend to manic and mixed episodes, as well as its role in mood stabilization and amelioration of suicidal behavior.

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.

A narrative review on invasive brain stimulation for treatment-resistant depression

While most patients with depression respond to pharmacotherapy and psychotherapy, about one-third will present treatment resistance to these interventions. For patients with treatment-resistant depression (TRD), invasive neurostimulation therapies such as vagus nerve stimulation, deep brain stimulation, and epidural cortical stimulation may be considered. We performed a narrative review of the published literature to identify papers discussing clinical studies with invasive neurostimulation therapies for TRD. After a database search and title and abstract screening, relevant English-language articles were analyzed. Vagus nerve stimulation, approved by the U.S. Food and Drug Administration as a TRD treatment, may take several months to show therapeutic benefits, and the average response rate varies from 15.2-83%. Deep brain stimulation studies have shown encouraging results, including rapid response rates (> 30%), despite conflicting findings from randomized controlled trials. Several brain regions, such as the subcallosal-cingulate gyrus, nucleus accumbens, ventral capsule/ventral striatum, anterior limb of the internal capsule, medial-forebrain bundle, lateral habenula, inferior-thalamic peduncle, and the bed-nucleus of the stria terminalis have been identified as key targets for TRD management. Epidural cortical stimulation, an invasive intervention with few reported cases, showed positive results (40-60% response), although more extensive trials are needed to confirm its potential in patients with TRD.

Reversible Cerebral Vasoconstriction Syndrome Associated With Fluoxetine

BACKGROUND

Reversible cerebral vasoconstriction syndrome (RCVS) is an increasingly recognized neurological syndrome that typically presents with a severe headache. The proposed etiology is transient and segmental constriction of cerebral arteries, which in severe cases can lead to cerebral ischemia. Multiple case reports have been identified associating the use of serotonergic medications with this syndrome.

OBJECTIVE

A review of the literature describing RCVS in patients taking selective serotonin reuptake inhibitors and other serotonergic medications is summarized. This report also describes the case of a 32-year-old woman with a complicated psychiatric history diagnosed with RCVS who presented with progressive cerebral ischemia despite intensive medical intervention. Ischemic progression did not relent until her home medication fluoxetine was recognized as the likely etiology and discontinued. The psychiatric management of this patient is described after fluoxetine was discontinued. Other potential psychiatric treatments for patients with a history of RCVS are discussed.

METHODS

A literature search was performed using PubMed with the following keywords: antidepressant, selective serotonin reuptake inhibitor, serotonin, fluoxetine, reversible cerebral vasoconstriction syndrome, RCVS, and Call-Fleming syndrome.

RESULTS

Fifteen patients were identified to have RCVS with associated use of serotonergic medications from 10 case reports published between 2002 and 2019.

CONCLUSIONS

It is important for psychiatrists to recognize the syndrome of RCVS in patients presenting with headache and ischemia due to the possibility of this syndrome being a rare but iatrogenic complication of a common psychiatric medication class. Additionally, identification of safe alternative treatments for patients with psychiatric illness who would otherwise be candidates for serotonergic medications is an important consideration for individuals affected by this disorder.

Assessment of multiple salivary biomarkers during repetitive transcranial magnetic stimulation (rTMS) treatment for major depression

Steroid hormones may serve as potential biomarkers of treatment response for major depressive disorder (MDD). Here, we assessed salivary levels of cortisol, dehydroepiandrosterone (DHEA), and DHEA sulfate (DHEA-S), as well as α-amylase activity, across 30 sessions of bilateral repetitive transcranial magnetic stimulation (rTMS) of the dorsolateral prefrontal cortex in MDD patients. While rTMS significantly improved symptoms as measured by three different symptom scales, salivary biomarker levels and their ratios showed no significant changes across sessions. These results do not support the routine clinical use of these biomarkers as reliable indicators of treatment outcome during rTMS administration for MDD.

Evidence-Based Guidelines and Secondary Meta-Analysis for the Use of Transcranial Direct Current Stimulation in Neurological and Psychiatric Disorders

BACKGROUND

Transcranial direct current stimulation has shown promising clinical results, leading to increased demand for an evidence-based review on its clinical effects.

OBJECTIVE

We convened a team of transcranial direct current stimulation experts to conduct a systematic review of clinical trials with more than 1 session of stimulation testing: pain, Parkinson's disease motor function and cognition, stroke motor function and language, epilepsy, major depressive disorder, obsessive compulsive disorder, Tourette syndrome, schizophrenia, and drug addiction.

METHODS

Experts were asked to conduct this systematic review according to the search methodology from PRISMA guidelines. Recommendations on efficacy were categorized into Levels A (definitely effective), B (probably effective), C (possibly effective), or no recommendation. We assessed risk of bias for all included studies to confirm whether results were driven by potentially biased studies.

RESULTS

Although most of the clinical trials have been designed as proof-of-concept trials, some of the indications analyzed in this review can be considered as definitely effective (Level A), such as depression, and probably effective (Level B), such as neuropathic pain, fibromyalgia, migraine, post-operative patient-controlled analgesia and pain, Parkinson's disease (motor and cognition), stroke (motor), epilepsy, schizophrenia, and alcohol addiction. Assessment of bias showed that most of the studies had low risk of biases, and sensitivity analysis for bias did not change these results. Effect sizes vary from 0.01 to 0.70 and were significant in about 8 conditions, with the largest effect size being in postoperative acute pain and smaller in stroke motor recovery (nonsignificant when combined with robotic therapy).

CONCLUSION

All recommendations listed here are based on current published PubMed-indexed data. Despite high levels of evidence in some conditions, it must be underscored that effect sizes and duration of effects are often limited; thus, real clinical impact needs to be further determined with different study designs.

Multi-channel transcranial temporally interfering stimulation (tTIS): application to living mice brain

OBJECTIVE

Transcranial temporally interfering stimulation (tTIS) is a noninvasive neuromodulation method, which has been reported to be able to affect the activity of small neuronal populations. To pinpoint smaller regions of the brain, multi-channel tTIS strategy is proposed with larger numbers of electrodes and multiple sets of interfering fields.

APPROACH

First, computational model is adopted to prove the concept of multi-channel tTIS theoretically. Besides, animal experiments are implemented to activate motor cortex neurons in living mice and different frequencies are attempted. Finally, to better understand the envelope modulation properties of the two applied fields, tissue phantom measurement is conducted.

MAIN RESULTS

The focality of six-channel (six electrode pairs) tTIS is increased by 46.7% and 70.2% respectively, compared with that of single-channel tTIS when maximal amplitude value drops by 3dB and 6dB in numerical computation experiment. Furthermore, the focality of multi-channel tTIS is less sensitive to the electrode position. Confirmed with myoelectricity signal, the movement frequencies of contralateral forepaw are consistent with the corresponding difference frequencies. What's more, compared single-channel (one electrode pair) tTIS with multi-channel (three electrode pairs) tTIS, the intensity of multi-channel tTIS stimulation is decreased by 28.5% on average in animal experiment. And the c-fos-positive neurons of target region are significantly higher than that of the non-target region. Results of the modulated envelope distribute around the whole regions and its amplitude reaches a maximum at the interfering region.

SIGNIFICANCE

Both computational modeling and animal experiment validate the feasibility of the proposed multi-channel tTIS strategy and confirm that it can enhance focality and reduce scalp sensation.

Vagus nerve stimulation for treatment-resistant depression: is this therapy distinct from other antidepressant treatments?

BACKGROUND

The treatment-resistant depression (TRD) is a very disabling disease.

OBJECTIVE

The aim of this article is to provide an overview of the therapeutic activity of vagus nerve stimulation (VNS) therapy system in TRD. We summarised the progress made during the last decade in this area.

METHODS

We conducted a non-systematic review on the efficacy and safety of the VNS therapy for this disease. We analysed the results from acute and long-term studies that utilised this technique. Major electronic databases were searched.

RESULTS

The patients with TRD may show acute and long-term benefit when treated with this technique. There are promising results for VNS therapy for these patients. The level of evidence as an acute treatment option is only 3, but as chronic treatment is 2. This therapy should be offered as an added long-term treatment option for patients with chronic and recurrent difficult to treat depression.

CONCLUSIONS

The antidepressant effects of this procedure remain controversial. The clinical trials have produced mixed results, but VNS therapy for TRD has two distinct features that differentiate it from other antidepressant treatments: a sustained therapeutic response obtained in highly resistant depressive disorders, a favourable safety profile and guaranteed compliance.

Adjunctive Vagus Nerve Stimulation for Treatment-Resistant Depression: a Quantitative Analysis

Vagus nerve stimulation (VNS) has been increasingly studied in treating treatment-resistant depression (TRD), but the findings have been mixed. This updated meta-analysis was conducted to examine the efficacy and safety of adjunctive VNS for TRD. Controlled studies reporting on the efficacy and safety of adjunctive VNS for TRD were screened, identified and analyzed. Standardized mean difference (SMD), risk ratio (RR) and their 95% confidence intervals (CIs) were analyzed using RevMan version 5.3. Three controlled studies with a total of 1048 patients with TRD compared VNS (n = 622) with control (n = 426) groups. Only one study was rated as 'high quality' using the Jadad scale. Adjunctive VNS was significantly superior to the control group regarding study-defined response [SMD:1.96 (95%CI:1.60, 2.40), P < 0.00001, I² = 0%]. Patient-reported voice alteration occurred more frequently with adjunctive VNS for patients with TRD. No significant group differences were found regarding discontinuation due to any reason [RR:0.50 (95%CI:0.12, 2.09), P = 0.34, I² = 85%]. Adjunctive VNS appeared to be effective and relatively safe treatment for TRD. Further randomized controlled trials are needed to confirm the efficacy and safety of VNS for TRD.

Neuroimmune Communication in the Kidney

Recent studies have clarified the interaction between nervous systems and immunity regarding the manner in which local inflammation is regulated and systemic homeostasis is maintained. The cholinergic anti-inflammatory pathway (CAP) is a neuroimmune pathway activated by vagus nerve stimulation. Following afferent vagus nerve stimulation, signals are transmitted to immune cells in the spleen, including β2-adrenergic receptor-positive CD4-positive T cells and α7 nicotinic acetylcholine receptor-expressing macrophages. These immune cells release the neurotransmitters norepinephrine and acetylcholine, inducing a series of reactions that reduce proinflammatory cytokines, relieving inflammation. CAP contributes to various inflammatory diseases such as endotoxemia, rheumatoid arthritis, and inflammatory bowel disease. Moreover, emerging studies have revealed that vagus nerve stimulation ameliorates kidney damage in an animal model of acute kidney injury. These studies suggest that the link between the nervous system and kidneys is associated with the pathophysiology of kidney injury. Here, we review the current knowledge of the neuroimmune circuit and kidney disease, as well as potential for therapeutic strategies based on this knowledge for treating kidney disease in clinical settings.

Electrical stimulation of cranial nerves in cognition and disease

The cranial nerves are the pathways through which environmental information (sensation) is directly communicated to the brain, leading to perception, and giving rise to higher cognition. Because cranial nerves determine and modulate brain function, invasive and non-invasive cranial nerve electrical stimulation methods have applications in the clinical, behavioral, and cognitive domains. Among other neuromodulation approaches such as peripheral, transcranial and deep brain stimulation, cranial nerve stimulation is unique in allowing axon pathway-specific engagement of brain circuits, including thalamo-cortical networks. In this review we amalgamate relevant knowledge of 1) cranial nerve anatomy and biophysics; 2) evidence of the modulatory effects of cranial nerves on cognition; 3) clinical and behavioral outcomes of cranial nerve stimulation; and 4) biomarkers of nerve target engagement including physiology, electroencephalography, neuroimaging, and behavioral metrics. Existing non-invasive stimulation methods cannot feasibly activate the axons of only individual cranial nerves. Even with invasive stimulation methods, selective targeting of one nerve fiber type requires nuance since each nerve is composed of functionally distinct axon-types that differentially branch and can anastomose onto other nerves. None-the-less, precisely controlling stimulation parameters can aid in affecting distinct sets of axons, thus supporting specific actions on cognition and behavior. To this end, a rubric for reproducible dose-response stimulation parameters is defined here. Given that afferent cranial nerve axons project directly to the brain, targeting structures (e.g. thalamus, cortex) that are critical nodes in higher order brain networks, potent effects on cognition are plausible. We propose an intervention design framework based on driving cranial nerve pathways in targeted brain circuits, which are in turn linked to specific higher cognitive processes. State-of-the-art current flow models that are used to explain and design cranial-nerve-activating stimulation technology require multi-scale detail that includes: gross anatomy; skull foramina and superficial tissue layers; and precise nerve morphology. Detailed simulations also predict that some non-invasive electrical or magnetic stimulation approaches that do not intend to modulate cranial nerves per se, such as transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS), may also modulate activity of specific cranial nerves. Much prior cranial nerve stimulation work was conceptually limited to the production of sensory perception, with individual titration of intensity based on the level of perception and tolerability. However, disregarding sensory emulation allows consideration of temporal stimulation patterns (axon recruitment) that modulate the tone of cortical networks independent of sensory cortices, without necessarily titrating perception. For example, leveraging the role of the thalamus as a gatekeeper for information to the cerebral cortex, preventing or enhancing the passage of specific information depending on the behavioral state. We show that properly parameterized computational models at multiple scales are needed to rationally optimize neuromodulation that target sets of cranial nerves, determining which and how specific brain circuitries are modulated, which can in turn influence cognition in a designed manner.

Cost-utility analysis of curative and maintenance repetitive transcranial magnetic stimulation (rTMS) for treatment-resistant unipolar depression: a randomized controlled trial protocol

Background

Depression is a debilitating and costly disease for our society, especially in the case of treatment-resistant depression (TRD). Repetitive transcranial magnetic stimulation (rTMS) is an effective adjuvant therapy in treatment-resistant unipolar and non-psychotic depression. It can be applied according to two therapeutic strategies after an initial rTMS cure: a further rTMS cure can be performed at the first sign of relapse or recurrence, or systematic maintenance rTMS (M-rTMS) can be proposed. TMS adjuvant to treatment as usual (TAU) could improve long-term prognosis. However, no controlled study has yet compared the cost-effectiveness of these two additional rTMS therapeutic strategies versus TAU alone.

Methods/design

This paper focuses on the design of a health-economic, prospective, randomized, double-blind, multicenter study with three parallel arms carried out in France. This study assesses the cost-effectiveness of the adjunctive and maintenance low frequency rTMS on the right dorsolateral prefrontal cortex versus TAU alone. A total of 318 patients suffering from a current TRD will be enrolled. The primary endpoint is to investigate the incremental cost-effectiveness ratio (ICER) (ratio costs / quality-adjusted life-years [QALY] measured by the Euroqol Five Dimension Questionnaire) over 12 months in a population of patients assigned to one of three arms: systematic M-rTMS for responders (arm A); additional new rTMS cure in case of mood deterioration among responders (arm B); and a placebo arm (arm C) in which responders are allocated in two subgroups: sham systematic M-rTMS and supplementary rTMS course in case of mood deterioration. ICER and QALYs will be compared between arm A or B versus arm C. The secondary endpoints in each three arms will be: ICER at 24 months; the cost-utility ratio analysis at 12 and 24 months; 5-year budget impact analysis; and prognosis factors of rTMS. The following criteria will be compared between arm A or B and arm C: rates of responders; remission and disease-free survival; clinical evolution; tolerance; observance; treatment modifications; hospitalization; suicide attempts; work stoppage; marital / professional statues; and quality of life at 12 and 24 months.

Discussion

The purpose of our study is to check the cost-effectiveness of rTMS and we will discuss its economic impact over time. In the case of significant decrease in the depression costs and expenditures associated with a good long-term prognosis (sustained response and remission) and tolerance, rTMS could be considered as an efficient treatment within the armamentarium for resistant unipolar depression.

Trial registration

ClinicalTrials.gov, NCT03701724. Registered on 10 October 2018. Protocol Amendment Version 2.0 accepted on 29 June 2019.

Personality Trait Predictive Utility and Stability in Transcranial Magnetic Stimulation (rTMS) for Major Depression: Dissociation of Neuroticism and Self-Criticism: Utilité prédictive et stabilité des traits de personnalité dans la stimulation magnétique transcrânienne répétitive (SMTr) pour la dépression majeure : dissociation du neuroticisme et de l’autocritique

Background:

Cost-efficient and non-invasive predictors of antidepressant response to repetitive transcranial magnetic stimulation (rTMS) are required. The personality vulnerabilities—neuroticism and self-criticism—are associated with antidepressant outcomes in other modalities; however, self-criticism has not been examined in response to rTMS, and the literature on neuroticism and rTMS is inconsistent.

Methods:

This naturalistic, 4-week study involved daily dorsolateral prefrontal cortex (DLFPC) rTMS for major depression (15 unipolar, 2 bipolar). Participants completed the Big Five Inventory (neuroticism) and the Depressive Experiences Questionnaire (self-criticism) at baseline and at the end of treatment. Changes in depressive symptoms, as rated by the clinician, were quantified using the 21-item Hamilton Depression Rating Scale. Given the inconsistencies in data regarding the stability of neuroticism in patients receiving rTMS, we performed a systematic review and quantitative meta-analysis of trials examining rTMS and neuroticism.

Results:

rTMS significantly improved depressive symptoms, and this was predicted by higher levels of self-criticism but not neuroticism. Self-criticism was stable over the 4 weeks of rTMS; however, neuroticism decreased, and this was not related to decreases in depressive symptoms. Our quantitative meta-analysis of 4 rTMS trials in major depression (n = 52 patients) revealed decreases in neuroticism, with a moderate effect size.

Limitations:

Our results are limited by a small sample size, and the absence of a sham-rTMS group. Our meta-analysis included only 4 trials.

Conclusion:

Highly self-critical patients appear to benefit more from rTMS than less self-critical patients. Neuroticism, a conceptually similar but distinct personality domain, does not appear to predict antidepressant response, yet this vulnerability factor for depression decreases after rTMS.

Hypoactivity in the Paraterminal Gyrus Following Bilateral Anterior Capsulotomy

OBJECTIVE

Bilateral anterior capsulotomy (BAC) is one of the ablative neurosurgical procedures used to treat major depressive disorder or obsessive-compulsive disorder when all other therapies fail. Tristolysis, a reduction in sadness, is the most striking clinical effect of BAC and is seen in the first 1 to 2 weeks after surgery. This retrospective study measured regional cerebral blood flow (rCBF) following surgery to identify which cortical regions were impacted and could account for this clinical effect.

METHODS

All patients had their capsulotomies done in Vancouver by the same team. Pre- and postoperative single-photon emission computed tomography perfusion scans were analyzed for 10 patients with major depressive disorder and 3 with obsessive-compulsive disorder. rCBF was measured semiquantitatively by calculating the ratio between an identified region of interest and a whole brain reference area.

RESULTS

Decreased rCBF was found in the paraterminal gyri. Increased rCBF was found in the dorsolateral prefrontal cortices and in the left lateral temporal lobe.

CONCLUSIONS

BAC causes hypoactivity in the paraterminal gyri and is the most likely explanation for its tristolytic effect, suggesting that the paraterminal gyrus is the limbic cortical locus for the emotion of sadness. Increased activity in the dorsolateral prefrontal cortices may be occurring via connectional diaschisis, and suppression by overactive paraterminal gyri during depression may account for some of the neurocognitive deficits observed during depressive episodes.

Vagus nerve stimulation (VNS) therapy in patients with treatment resistant depression: A systematic review and meta-analysis

BACKGROUND

Vagus nerve stimulation (VNS) therapy is approved for treatment-resistant depression (TRD). A recent 5-year comparative study prompted this review of its impact in this very severe population. Previous systematic literature reviews (SLR) cited concerns in terms of missing studies or patient duplication.

METHODS

This SLR addressed these criticisms, assessed all outcomes of longer-term adjunctive VNS in all studies, irrespective of TRD severity, comparing where feasible with treatment-as-usual (TAU). We searched for adult VNS+TAU studies (January 1, 2000 to June 24, 2019). Comparative and single-arm studies were eligible. All reported efficacy, safety and quality of life (QOL) outcomes were assessed. Where possible, meta-analysis was used to calculate overall pooled effect estimates across studies at several time points.

RESULTS

Of 22 identified studies, there were two randomized controlled (RCT), sixteen single-arm and four non-randomized comparative studies. Numerous depression-specific, safety and QOL measures were reported. Meta-analysis was possible for three efficacy [Montgomery-Asberg Depression Rating Scale, Clinician Global Impression-Improvement, Hamilton Rating Scale for Depression] and three safety [serious adverse events, study drop-outs and all-cause mortality] but no QOL measures. Data beyond 2 years was not poolable. Analyses demonstrated that antidepressant benefits improved to 24 months and safety issues were minimal. Heterogeneity was high and statistically significant.

CONCLUSIONS

Despite limitations in the evidence base, our comprehensive summary of VNS+TAU outcomes suggests that this treatment provides improving benefit and hope for this very hard-to-treat chronic population. More comparative TRD studies should describe safety and QOL.

Effect of a 10-day transcutaneous trigeminal nerve stimulation (TNS) protocol for depression amelioration: A randomized, double blind, and sham-controlled phase II clinical trial

BACKGROUND

Major depressive disorder (MDD) is one of the leading causes of disability in the world. However, treatment options are still limited, and marked by high refractoriness rates, new approaches are needed to optimize clinical improvement. Trigeminal nerve stimulation (TNS) is an innovative neuromodulation strategy consisting on the application of an electric current over the trigeminal nerve that propagates stimuli towards brain areas involved in mood control.

OBJECTIVE

We examined the effects of TNS in MDD after a 10-day experimental protocol.

METHODS

This was a randomized, double blind, and sham-controlled phase II study with 24 patients with severe MDD. Patients underwent a 10-day intervention protocol and were assessed with the 17-item Hamilton Depression Rating Scale (HDRS-17) at following three observation points: baseline (T1), after 10 days (T2), and after one month of the last stimulation session (T3). Main clinical outcome analysis of variance (ANOVA) was performed.

RESULTS

Patients in the active group presented a mean reduction of 36.15% in depressive symptoms after the stimulation protocol. There was a significant interaction between group and time regarding HDRS-17 scores (F = 3.18; df = 2; p = 0.0456). Post hoc analyses exhibited a statistically significant difference between active and sham group symptoms at T2 (p = 0.040) and T3 (p = 0.026), which highlights the sustained amelioration of depressive symptoms.

CONCLUSION

The present study found amelioration of depressive symptoms for patients undergoing a 10-day stimulation protocol of TNS, and this was sustained after one month of follow-up.

The role of prefrontal cortex dopamine D2 and D3 receptors in the mechanism of action of venlafaxine and deep brain stimulation in animal models of treatment-responsive and treatment-resistant depression

AIMS

The Wistar-Kyoto rat has been validated as an animal model of treatment-resistant depression. Here we investigated a role of dopamine D2 and D3 receptors in the ventro-medial prefrontal cortex in the mechanism of action of deep brain stimulation in Wistar-Kyoto rats and venlafaxine in Wistar rats.

METHODS

Wistar or Wistar-Kyoto rats were exposed chronically to chronic mild stress. Wistar rats were treated chronically with venlafaxine (10 mg/kg) beginning after two weeks of chronic mild stress; Wistar-Kyoto rats received two sessions of deep brain stimulation before behavioural tests. L-742,626 (1 µg), a D2 receptor agonist, or 7-OH DPAT (3 µg), a D3 receptor antagonist, were infused into the ventro-medial prefrontal cortex immediately following the exposure trial in the Novel Object Recognition Test, and discrimination between novel and familiar object was tested one hour later.

RESULTS

Chronic mild stress decreased sucrose intake and impaired memory consolidation; these effects were reversed by venlafaxine in Wistar rats and deep brain stimulation in Wistar-Kyoto rats. In control animals, L-742,626 and 7-OH DPAT also impaired memory consolidation. In Wistar rats, venlafaxine reversed the effect of L-742,626 in controls, but not in the chronic mild stress group, and venlafaxine did not reverse the effect of 7-OH DPAT in either group. In Wistar-Kyoto rats, deep brain stimulation reversed the effect of both L-742,626 and 7-OH DPAT in both control and chronic mild stress groups.

CONCLUSIONS

We conclude that the action of venlafaxine to reverse the impairment of memory consolidation caused by chronic mild stress in Wistar rats involves D2 receptors in the ventro-medial prefrontal cortex; but the effect of deep brain stimulation to reverse the same effect in Wistar-Kyoto rats does not.

[Interest of transcranial stimulation in pelvic and perineal disorders]

OBJECTIVE

The aim of this article was to describe the diagnostic and therapeutic value of transcranial stimulation in pelvic and perineal disorders.

METHODS

A literature review (Medline database and Google scholar) with no time limit was performed using keywords: "transcranial direct stimulation", "transcranial magnetic stimulation", "neurogenic bladder", "urinary incontinence", "Parkinson disease", "multiple sclerosis", "stroke", "muscle spasticity", "pelvic pain", "visceral pain".

RESULTS

Twelve articles have been selected. Transcranial magnetic or electrical stimulation is a noninvasive neuromodulation technique widely used to establish brain maps to highlight causal relationships between brain and function. Regarding pelvic-perineal disorders, repeated transcranial stimulation has shown significant effects for the treatment of overactive bladder in Parkinson's disease (P<0.05) and multiple sclerosis, but also for the treatment of refractory chronic pelvic pain (P=0.026). Finally, therapeutic effects have also been demonstrated in irritable bowel syndrome. No evidence of efficacy was found on genito-sexual disorders.

CONCLUSION

Data from the literature suggest that transcranial stimulation is a noninvasive treatment that may have a role in the management of pelvic and perineal disorders. Its promising field of action would require prospective and randomized studies on a larger scale.

Vagus Nerve Stimulation for Depression: A Systematic Review

Background: Depression is a common mental disorder worldwide. Psychological treatments and antidepressant medication are the usual treatments for depression. However, a large proportion of patients with depression do not respond to the treatments. In 2005, Vagus nerve stimulation was approved for the adjunctive long-term treatment of chronic or recurrent depression in adult patients experiencing a major depressive episode who had failed to respond to four or more adequate antidepressant treatments. However, the efficacy of VNS for treating depression remains unclear. Accordingly, we performed a systematic review to evaluate the efficacy and safety of VNS. Methods: We conducted a systematic review in accordance with the Cochrane Handbook for Systematic Reviews of Interventions. Systematic search was performed in the database of Pubmed, Embase, CENTRAL, and Web of science for identifying the suitable trials. Suicidal rate was considered as the primary outcome in this review. Result: Only two randomized sham controlled add-on studies including 255 cases (134 with VNS treatment and 121 control cases) were included in this review. None of the studies reported suicidal rate. We performed a qualitative analysis and it is suggested that there was no significant statistic difference between VNS and sham VNS on the score of 24-item Hamilton Rating Scale for Depression (HAMD₂₄) (MD: -2.40, 95% CI: -7.90 to 3.10). Similar findings were also reported on improvement percentage of HAMD₂₄ (MD: 1.00, 95%CI: -6.06 to 8.06), Montgomery-Asberg Depression Rating Scale (MADRS) (MD: 4.70, 95%CI: -2.98 to 12.38) and 30 item Inventory of Depressive Symptomalogy-Self-Report (IDS-SR₃₀) (MD: 4.9, 95%CI: -1.89 to 11.69). However, a marginal difference of Beck Depression Inventory self-rating score was detected between the real and sham treatment (MD: 7.80, 95% CI: 0.34 to 15.26). Aminor effect of IDS-SR₃₀was also found in real VNS group (RR: 2.33, 95% CI: 1.07 to 5.10). Conclusion: The efficacy and safety of VNS for depression is still unclear. Further randomized controlled trials are needed to confirm the efficacy and safety of VNS.