Biological markers in noninvasive brain stimulation trials in major depressive disorder: a systematic review

Gut Microbiota: A New Challenge in Mood Disorder Research

The gut microbiome has emerged as a novel and intriguing focus in mood disorder research. Emerging evidence demonstrates the significant role of the gut microbiome in influencing mental health, suggesting a bidirectional communication between the gut and the brain. This review examines the latest findings on the gut-microbiota-brain axis and elucidates how alterations in gut microbiota composition can influence this axis, leading to changes in brain function and behavior. Although dietary interventions, prebiotics, probiotics, and fecal microbiota transplantation have yielded encouraging results, significant advances are needed to establish next-generation approaches that precisely target the neurobiological mechanisms of mood disorders. Future research must focus on developing personalized treatments, facilitated by innovative therapies and technological progress, which account for individual variables such as age, sex, drug history, and lifestyle. Highlighting the potential therapeutic implications of targeting the gut microbiota, this review emphasizes the importance of integrating microbiota research into psychiatric studies to develop more effective and personalized treatment strategies for mood disorders.

The use of noninvasive brain stimulation techniques in autism spectrum disorder

Noninvasive brain stimulation (NIBS) techniques, including repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), have recently emerged as alternative, nonpharmacological interventions for a variety of psychiatric, neurological, and neurodevelopmental conditions. NIBS is beginning to be applied in both research and clinical settings for the treatment of core and associated symptoms of autism spectrum disorder (ASD) including social communication deficits, restricted and repetitive behaviors, irritability, hyperactivity, depression and impairments in executive functioning and sensorimotor integration. Though there is much promise for these targeted device-based interventions, in other disorders (including adult major depressive disorder (MDD) and obsessive compulsive disorder (OCD) where rTMS is FDA cleared), data on the safety and efficacy of these interventions in individuals with ASD is limited especially in younger children when neurodevelopmental interventions typically begin. Most studies are open-label, small scale, and/or focused on a restricted subgroup of individuals with ASD. There is a need for larger, randomized controlled trials that incorporate neuroimaging in order to develop predictive biomarkers of treatment response and optimize treatment parameters. We contend that until such studies are conducted, we do not have adequate estimates of the safety and efficacy of NIBS interventions in children across the spectrum. Thus, broad off-label use of these techniques in this population is not supported by currently available evidence. Here we discuss the existing data on the use of NIBS to treat symptoms related to ASD and discuss future directions for the field.

Immune-inflammatory markers of response to repetitive transcranial magnetic stimulation in depression: A scoping review

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) is a safe, effective and non-invasive form of neuromodulatory therapy in patients with major depressive disorder (MDD). MDD is associated with increased peripheral and brain inflammation. The current paper aims to provide an overview of research examining the relationship between immune and inflammatory markers and response to rTMS in MDD.

METHODS

A scoping review method was adopted in keeping with the PRISMA-ScR guidelines. Twelve relevant studies were retrieved from the PubMed and Scopus databases and rated for study quality using a modified version of the BIOCROSS tool.

RESULTS

Response to rTMS in MDD was associated with basal and post-treatment levels of the inflammatory markers amyloid A, antithrombin III, oxidised phosphatidylcholine, and the microRNA miR-146a-5p. Inconsistent results were observed for the cytokines interleukin-1β, interleukin-2 and tumour necrosis factor-α. Increased baseline levels of interleukin-6 and C-reactive protein were linked to a poorer response to rTMS.

DISCUSSION

These results suggest that rTMS may have effects on immune-inflammatory pathways that are distinct from those of antidepressants and electroconvulsive therapy. Because of certain methodological limitations in the included studies, these results should be interpreted with caution.

The Microbiota-Gut-Brain Axis: Psychoneuroimmunological Insights

There is growing interest in the role that the intestinal microbiota and the related autoimmune processes may have in the genesis and presentation of some psychiatric diseases. An alteration in the communication of the microbiota-gut-brain axis, which constitutes a communicative model between the central nervous system (CNS) and the gastro-enteric tract, has been identified as one of the possible causes of some psychiatric diseases. The purpose of this narrative review is to describe evidence supporting a role of the gut microbiota in psychiatric diseases and the impact of diet on microbiota and mental health. Change in the composition of the gut microbiota could determine an increase in the permeability of the intestinal barrier, leading to a cytokine storm. This could trigger a systemic inflammatory activation and immune response: this series of events could have repercussions on the release of some neurotransmitters, altering the activity of the hypothalamic-pituitary-adrenal axis, and reducing the presence of trophic brain factors. Although gut microbiota and psychiatric disorders seem to be connected, more effort is needed to understand the potential causative mechanisms underlying the interactions between these systems.

Effects of bilateral sequential theta-burst stimulation on 5-HT1A receptors in the dorsolateral prefrontal cortex in treatment-resistant depression: a proof-of-concept trial

Theta-burst stimulation (TBS) represents a brain stimulation technique effective for treatment-resistant depression (TRD) as underlined by meta-analyses. While the methodology undergoes constant refinement, bilateral stimulation of the dorsolateral prefrontal cortex (DLPFC) appears promising to restore left DLPFC hypoactivity and right hyperactivity found in depression. The post-synaptic inhibitory serotonin-1A (5-HT1A) receptor, also occurring in the DLPFC, might be involved in this mechanism of action. To test this hypothesis, we performed PET-imaging using the tracer [carbonyl-11C]WAY-100635 including arterial blood sampling before and after a three-week treatment with TBS in 11 TRD patients compared to sham stimulation (n = 8 and n = 3, respectively). Treatment groups were randomly assigned, and TBS protocol consisted of excitatory intermittent TBS to the left and inhibitory continuous TBS to the right DLPFC. A linear mixed model including group, hemisphere, time, and Hamilton Rating Scale for Depression (HAMD) score revealed a 3-way interaction effect of group, time, and HAMD on specific distribution volume (VS) of 5-HT1A receptor. While post-hoc comparisons showed no significant changes of 5-HT1A receptor VS in either group, higher 5-HT1A receptor VS after treatment correlated with greater difference in HAMD (r = -0.62). The results of this proof-of-concept trial hint towards potential effects of TBS on the distribution of the 5-HT1A receptor. Due to the small sample size, all results must, however, be regarded with caution.

Pre-frontal stimulation does not reliably increase reward responsiveness

Depression is the leading cause of disability worldwide and its effects can be fatal, with over 800,000 people dying by suicide each year. Neuromodulatory treatments such as transcranial magnetic stimulation (TMS) are being used to treat depression. Despite its endorsement by two regulatory bodies: NICE (2016) and the FDA (2008), there are major questions about the treatment efficacy and biological mechanisms of TMS. Ahn et al.'s (2013) justified the use of TMS in a clinical context in an important study indicating that excitatory TMS increases reward responsiveness. A pseudo-replication of this study by Duprat et al., (2016) also found a similar effect of active TMS, but only with the addition of an exploratory covariate to the analyses-trait reward responsiveness. Here we replicate Ahn et al.'s (2013) key study, and to test the reliability of the effects, and their dependency on trait reward responsiveness as described by Duprat et al., (2016). Using excitatory and sham TMS, we tested volunteers using the probabilistic learning task to measure their reward responsiveness both before and after stimulation. We also examined affect (positive, negative) following stimulation. Irrespective of TMS, the task was shown to be sensitive to reward responsiveness. However, we did not show TMS to be effective in increasing reward responsiveness and we did not replicate Ahn et al., (2013) or Duprat et al., (2016)'s key findings for TMS efficacy, where we provide evidence favouring the null. Moreover, exploratory analyses suggested following active stimulation, positive affect was reduced. Given our findings, we question the basic effects, which support the use of TMS for depression, particularly considering potential deleterious effects of reduced positive affect in patients with depression.

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.

Electroencephalographic Patterns in taVNS: A Systematic Review

Transcutaneous auricular vagus nerve stimulation (taVNS) is a newer delivery system using a non-invasive stimulation device placed at the ear. taVNS research is focused on clinical trials showing potential therapeutic benefits, however the neurophysiological effects of this stimulation on brain activity are still unclear. We propose a systematic review that aims to describe the effects of taVNS on EEG measures and identify taVNS parameters that can potentially lead to consistent EEG-mediated biomarkers for this therapy. A systematic literature review was carried out following the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA) and the Cochrane handbook for systematic reviews. Clinical trials examining EEG parameters were considered, including absolute and relative power, coherence, degree of symmetry, evoked potentials, and peak frequency of all bands. According to our criteria, 18 studies (from 122 articles) were included. Our findings show a general trend towards increased EEG power spectrum activity in lower frequencies, and changes on early components of the ERP related to inhibitory tasks. This review suggests that quantitative electroencephalography can be used to assess the effects of taVNS on brain activity, however more studies are needed to systematically establish the specific effects and metrics that would reflect the non-invasive stimulation through the auricular branch of the vagus nerve.

Protocol for a prospective open-label clinical trial to investigate the utility of concurrent TBS/fNIRS for antidepressant treatment optimisation

INTRODUCTION

Repetitive transcranial magnetic stimulation (rTMS) with theta burst stimulation (i.e. TBS) of the dorsolateral prefrontal cortex (DLPFC) is an innovative treatment for major depressive disorder (MDD). However, fewer than 50% of patients show sufficient response to this treatment; markers for response prediction are urgently needed. Research shows considerable individual variability in the brain responses to rTMS. However, whether differences in individual DLPFC modulation by rTMS can be used as a predictive marker for treatment response remains to be investigated. Here, we present a research programme that will exploit the combination of functional near-infrared spectroscopy (fNIRS) with brain stimulation. Concurrent TBS/fNIRS will allow us to systematically investigate TBS-induced modulation of blood oxygenation as a proxy for induced brain activity changes. The findings from this study will (1) elucidate the immediate effects of excitatory and inhibitory TBS on prefrontal activity in TBS treatment-naïve patients with MDD and (2) validate the potential utility of TBS-induced brain modulation at baseline for the prediction of antidepressant response to 4 weeks of daily TBS treatment.

METHODS AND ANALYSIS

Open-label, parallel-group experiment consisting of two parts. In part 1, 70 patients and 37 healthy controls will be subjected to concurrent TBS/fNIRS. Intermittent TBS (iTBS) and continuous TBS (cTBS) will be applied on the left and right DLPFC, respectively. fNIRS data will be acquired before, during and several minutes after stimulation. In part 2, patients who participated in part 1 will receive a 4 week iTBS treatment of the left DLPFC, performed daily for 5 days per week. Psychometric evaluation will be performed periodically and at 1 month treatment follow-up. Statistical analysis will include a conventional, as well as a machine learning approach.

ETHICS AND DISSEMINATION

Ethics approval was obtained from the Institutional Review Board. Findings will be disseminated through scientific journals, conferences and university courses.

TRIAL REGISTRATION NUMBER

NCT04526002.

Glutamatergic System in Depression and Its Role in Neuromodulatory Techniques Optimization

Depressive disorders are among the most common psychiatric conditions and contribute to significant morbidity. Even though the use of antidepressants revolutionized the management of depression and had a tremendous positive impact on the patient's outcome, a significant proportion of patients with major depressive disorder (MDD) show no or partial or response even with adequate treatment. Given the limitations of the prevailing monoamine hypothesis-based pharmacotherapy, glutamate and glutamatergic related pathways may offer an alternative and a complementary option for designing novel intervention strategies. Over the past few decades, there has been a growing interest in understanding the neurobiological underpinnings of glutamatergic dysfunctions in the pathogenesis of depressive disorders and the development of new pharmacological and non-pharmacological treatment options. There is a growing body of evidence for the efficacy of neuromodulation techniques, including transcranial magnetic stimulation, transcutaneous direct current stimulation, transcranial alternating current stimulation, and photo-biomodulation on improving connectivity and neuroplasticity associated with depression. This review attempts to revisit the role of glutamatergic neurotransmission in the etiopathogenesis of depressive disorders and review the current neuroimaging, neurophysiological and clinical evidence of these neuromodulation techniques in the pathophysiology and treatment of depression.

Mechanisms affecting brain remodeling in depression: do all roads lead to impaired fibrinolysis?

Fibrinolysis occurs when plasminogen activators, such as tissue plasminogen activator (tPA), convert plasminogen to plasmin, which dissolves the fibrin clot. The proteolytic activity of tPA and plasmin is not restricted to fibrin degradation. In the extravascular space, these two proteases modify a variety of substrates other than fibrin, playing a crucial role in physiological and pathological tissue remodeling. In the brain, for example, tPA and plasmin mediate the conversion of brain-derived neurotrophic factor precursor (proBDNF) to mature brain-derived neurotrophic factor precursor (BDNF). Thus, the fibrinolytic system influences processes reported to be dysfunctional in depression, including neurogenesis, synaptic plasticity, and reward processing. The hypothesis that decreased fibrinolytic activity is an important element in the pathogenesis of depression is supported by the association between depression and increased levels of plasminogen activator inhibitor (PAI)-1, the main inhibitor of tPA. Also, various biochemical markers of depression induce PAI-1 synthesis, including hypercortisolism, hyperinsulinemia, hyperleptinemia, increased levels of cytokines, and hyperhomocysteinemia. Moreover, hypofibrinolysis provides a link between depression and emotional eating, binge eating, vegetarianism, and veganism. This paper discusses the role of reduced fibrinolytic activity in the bidirectional interplay between depression and its somatic manifestations and complications. It also reviews evidence that abnormal fibrinolysis links heterogeneous conditions associated with treatment-resistant depression. Understanding the role of hypofibrinolysis in depression may open new avenues for its treatment.

Effectiveness of TES and rTMS for the Treatment of Insomnia: Meta-Analysis and Meta-Regression of Randomized Sham-Controlled Trials

Objectives: Transcranial electric stimulation (TES) and repetitive transcranial magnetic stimulation (rTMS) have experienced significant development in treating insomnia. This review aims to examine the effectiveness of randomized sham-controlled trials of TES and rTMS in improving insomnia and examine potential moderators associated with the effect of the treatment. Methods: Nine electronic databases were searched for studies comparing the effects of TES/rTMS with sham group on insomnia from the inception of these databases to June 25, 2021, namely, Medline, Embase, PsycINFO, CINAHL, Cochrane Library, Web of Science, PubMed, ProQuest Dissertation and Thesis, and CNKI. Meta-analyses were conducted to examine the effect of TES and rTMS in treating insomnia. Univariate meta-regression was performed to explore potential treatment moderators that may influence the pooled results. Risk of bias was assessed by using the Cochrane Risk of Bias Tool. Results: A total of 16 TES studies and 27 rTMS studies were included in this review. The pooled results indicated that there was no significant difference between the TES group and the sham group in improving objective measures of sleep. rTMS was superior to its sham group in improving sleep efficiency, total sleep time, sleep onset latency, wake up after sleep onset, and number of awakenings (all p < 0.05). Both TES and rTMS were superior to their sham counterparts in improving sleep quality as measured by the Pittsburgh Sleep Quality Index at post-intervention. The weighted mean difference for TES and rTMS were -1.17 (95% CI: -1.98, -0.36) and -4.08 (95% CI: -4.86, -3.30), respectively. Gender, total treatment sessions, number of pulses per session, and length of treatment per session were associated with rTMS efficacy. No significant relationship was observed between TES efficacy and the stimulation parameters. Conclusions: It seems that TES and rTMS have a chance to play a decisive role in the therapy of insomnia. Possible dose-dependent and gender difference effects of rTMS are suggested.

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.

Is tDCS a potential first line treatment for major depression?

Transcranial direct current stimulation (tDCS) is a novel treatment option for major depression which could be provided as a first-line treatment. tDCS is a non-invasive form of transcranial stimulation which changes cortical tissue excitability by applying a weak (0.5-2 mA) direct current via scalp electrodes. Anodal and cathodal stimulation leads to depolarisation and hyperpolarisation, respectively, and cumulative effects are observed with repeated sessions. The montage in depression most often involves anodal stimulation to the left dorsolateral prefrontal cortex. Rates of clinical response, remission, and improvements in depressive symptoms following a course of active tDCS are greater in comparison to a course of placebo sham-controlled tDCS. In particular, the largest treatment effects are evident in first episode and recurrent major depression, while minimal effects have been observed in treatment-resistant depression. The proposed mechanism is neuroplasticity at the cellular and molecular level. Alterations in neural responses have been found at the stimulation site as well as subcortically in prefrontal-amygdala connectivity. A possible mediating effect could be cognitive control in emotion dysregulation. Additional beneficial effects on cognitive impairments have been reported, which would address an important unmet need. The tDCS device is portable and can be used at home. Clinical trials are required to establish the efficacy, feasibility and acceptability of home-based tDCS treatment and mechanisms.

Brain stimulation effects on serum BDNF, VEGF, and TNFα in treatment-resistant psychiatric disorders

Resistance to pharmacological treatment poses a notable challenge for psychiatry. Such cases are usually treated with brain stimulation techniques, including repetitive transcranial magnetic stimulation (rTMS) and electroconvulsive therapy (ECT). Empirical evidence links treatment resistance to insufficient brain plasticity and chronic inflammation. Therefore, this study encompasses analysis of neurotrophic and inflammatory factors in psychiatric patients undergoing rTMS and ECT in order to refine the selection of patients and predict clinical outcomes. This study enrolled 25 drug-resistant depressive patients undergoing rTMS and 31 drug-resistant schizophrenia patients undergoing ECT. Clinical efficacy of brain stimulation therapies was gauged using MADRS and HAM-D scales in the depression group and PANSS scale in the schizophrenia group. Blood-derived BDNF, VEGF, and TNFα were analysed during the treatment course. For reference, 19 healthy control subjects were also enrolled. After statistical analysis, no significant differences were detected in BDNF, VEGF, and TNFα concentrations among healthy, depressive, and schizophrenic subject groups before the treatment. However, depressive patient treatment with rTMS has increased BDNF concentration, while schizophrenic patient treatment with ECT has lowered the concentration of TNFα. Our findings suggest that a lower initial TNFα concentration could be a marker for treatment success in depressed patients undergoing rTMS, whereas in schizophrenic patient group treated with ECT, a higher concentration of VEGF correlates to milder symptoms post-treatment, especially in the negative scale.

Bacterial Metabolites of Human Gut Microbiota Correlating with Depression

Depression is a global threat to mental health that affects around 264 million people worldwide. Despite the considerable evolution in our understanding of the pathophysiology of depression, no reliable biomarkers that have contributed to objective diagnoses and clinical therapy currently exist. The discovery of the microbiota-gut-brain axis induced scientists to study the role of gut microbiota (GM) in the pathogenesis of depression. Over the last decade, many of studies were conducted in this field. The productions of metabolites and compounds with neuroactive and immunomodulatory properties among mechanisms such as the mediating effects of the GM on the brain, have been identified. This comprehensive review was focused on low molecular weight compounds implicated in depression as potential products of the GM. The other possible mechanisms of GM involvement in depression were presented, as well as changes in the composition of the microbiota of patients with depression. In conclusion, the therapeutic potential of functional foods and psychobiotics in relieving depression were considered. The described biomarkers associated with GM could potentially enhance the diagnostic criteria for depressive disorders in clinical practice and represent a potential future diagnostic tool based on metagenomic technologies for assessing the development of depressive disorders.

Peripheral vascular endothelial growth factor changes after transcranial magnetic stimulation in treatment-resistant depression

OBJECTIVES

To determine if vascular endothelial growth factor (VEGF) changes with transcranial magnetic stimulation (TMS) in treatment-resistant major depressive disorder (MDD).

METHODS

Serum from a naturalistic population of 15 patients with MDD was collected at baseline and after standard TMS treatment. VEGF concentration was determined via ELISA. Inventory of Depressive Symptomatology Self Report and Patient Health Questionnaire were used as a measure of depression symptom severity, clinical response and remission. Mann-Whitney U and Kendall's Tau Correlation were used for continuous variables.

RESULTS

VEGF increased from pre- to post-TMS (+30.3%) in remitters whereas VEGF decreased in non-remitters (-9.87%) (P < 0.05). This same pattern was observed when comparing mean %change in VEGF between responders (+14.7%) and non-responders (-14.9%) (P = 0.054). Correlation was present between change in VEGF concentration (baseline to post) and change in Inventory of Depressive Symptomatology-Self Report at Tx30 (r = -0.371, P < 0.054), reflecting greater increases in VEGF linked to greater improvement in depressive symptoms following the standard 6-week course of TMS.

CONCLUSION

Patients with a successful treatment with TMS had significantly greater increase in VEGF from baseline to after treatment compared to non-responders/non-remitters and a larger increase in VEGF was associated with greater improvement in depressive symptoms after TMS. This is the first report examining VEGF levels in depressed patients receiving TMS. This study provides correlative data supporting further investigation into VEGF's role as an important mediator in the processes underpinning TMS' antidepressant effects and as a potential biomarker of clinical outcomes.

Changes in Functional Connectivity Predict Outcome of Repetitive Transcranial Magnetic Stimulation Treatment of Major Depressive Disorder

Repetitive transcranial magnetic stimulation (rTMS) treatment of major depressive disorder (MDD) is associated with changes in brain functional connectivity (FC). These changes may be related to the mechanism of action of rTMS and explain the variability in clinical outcome. We examined changes in electroencephalographic FC during the first rTMS treatment in 109 subjects treated with 10 Hz stimulation to left dorsolateral prefrontal cortex. All subjects subsequently received 30 treatments and clinical response was defined as ≥40% improvement in the inventory of depressive symptomatology-30 SR score at treatment 30. Connectivity change was assessed with coherence, envelope correlation, and a novel measure, alpha spectral correlation (αSC). Machine learning was used to develop predictive models of outcome for each connectivity measure, which were compared with prediction based upon early clinical improvement. Significant connectivity changes were associated with clinical outcome (P < 0.001). Machine learning models based on αSC yielded the most accurate prediction (area under the curve, AUC = 0.83), and performance improved when combined with early clinical improvement measures (AUC = 0.91). The initial rTMS treatment session produced robust changes in FC, which were significant predictors of clinical outcome of a full course of treatment for MDD.

Transcranial Magnetic Stimulation: A Clinical Primer for Nonexperts

Transcranial magnetic stimulation (TMS) is a safe and effective therapeutic modality for a rapidly expanding range of neuropsychiatric indications. Among psychiatric conditions, it is presently approved by the US Food and Drug Administration for treatment-resistant unipolar major depressive disorder and obsessive-compulsive disorder, 2 highly prevalent conditions with a considerable public health impact. There is also mounting evidence for its clinical utility in numerous other neuropsychiatric conditions. Nonetheless, many mental health providers, as well as primary care and other providers, remain unfamiliar with its clinical use. In this primer, we seek to describe in nontechnical terms how the magnetic field is applied to the brain, the unmet needs that may be remediated with TMS, the present state of evidence for clinical effectiveness, particularly in major depressive disorder, the safety profile of TMS, what patients experience during TMS, and some recent developments that serve to advance the use of this still novel intervention. TMS is poised to assume an important place in the armamentarium of interventions to better serve our patients, especially those with serious, chronic conditions with high rates of resistance to more conventional treatments. Consequently, it is essential that mental health providers gain as adequate a working knowledge of device-based interventions such as TMS as they currently have of psychopharmacological and psychosocial interventions. Among other potential benefits, this information should aid the process of obtaining informed consent from patients who are candidates for these treatments.

Precision non-implantable neuromodulation therapies: a perspective for the depressed brain

Current first-line treatments for major depressive disorder (MDD) include pharmacotherapy and cognitive-behavioral therapy. However, one-third of depressed patients do not achieve remission after multiple medication trials, and psychotherapy can be costly and time-consuming. Although non-implantable neuromodulation (NIN) techniques such as transcranial magnetic stimulation, transcranial direct current stimulation, electroconvulsive therapy, and magnetic seizure therapy are gaining momentum for treating MDD, the efficacy of non-convulsive techniques is still modest, whereas use of convulsive modalities is limited by their cognitive side effects. In this context, we propose that NIN techniques could benefit from a precision-oriented approach. In this review, we discuss the challenges and opportunities in implementing such a framework, focusing on enhancing NIN effects via a combination of individualized cognitive interventions, using closed-loop approaches, identifying multimodal biomarkers, using computer electric field modeling to guide targeting and quantify dosage, and using machine learning algorithms to integrate data collected at multiple biological levels and identify clinical responders. Though promising, this framework is currently limited, as previous studies have employed small samples and did not sufficiently explore pathophysiological mechanisms associated with NIN response and side effects. Moreover, cost-effectiveness analyses have not been performed. Nevertheless, further advancements in clinical trials of NIN could shift the field toward a more “precision-oriented” practice.

Electroencephalography in Psychiatric Surgery: Past Use and Future Directions

The last two decades have seen a re-emergence of surgery for intractable psychiatric disease, in large part due to increased use of deep brain stimulation. The development of more precise, image-guided, less invasive interventions has improved the safety of these procedures, even though the relative merits of modulation at various targets remain under investigation. With an increase in the number and type of interventions for modulating mood/anxiety circuits, the need for biomarkers to guide surgeries and predict treatment response is as critical as ever. Electroencephalography (EEG) has a long history in clinical neurology, cognitive neuroscience, and functional neurosurgery, but has limited prior usage in psychiatric surgery. MEDLINE, Embase, and Psyc-INFO searches on the use of EEG in guiding psychiatric surgery yielded 611 articles, which were screened for relevance and quality. We synthesized three important themes. First, considerable evidence supports EEG as a biomarker for response to various surgical and non-surgical therapies, but large-scale investigations are lacking. Second, intraoperative EEG is likely more valuable than surface EEG for guiding target selection, but comes at the cost of greater invasiveness. Finally, EEG may be a promising tool for objective functional feedback in developing "closed-loop" psychosurgeries, but more systematic investigations are required.

Differential Neuroplastic Changes in Fibromyalgia and Depression Indexed by Up-Regulation of Motor Cortex Inhibition and Disinhibition of the Descending Pain System: An Exploratory Study

Background: Major depressive disorder (MDD) and fibromyalgia (FM) present overlapped symptoms. Although the connection between these two disorders has not been elucidated yet, the disruption of neuroplastic processes that mediate the equilibrium in the inhibitory systems stands out as a possible mechanism. Thus, the purpose of this cross-sectional exploratory study was: (i) to compare the motor cortex inhibition indexed by transcranial magnetic stimulation (TMS) measures [short intracortical inhibition (SICI) and intracortical facilitation (ICF)], as well as the function of descending pain modulatory systems (DPMS) among FM, MDD, and healthy subjects (HS); (ii) to compare SICI, ICF, and the role of DPMS evaluated by the change on Numerical Pain Scale (NPS) during the conditioned pain modulation test (CPM-test) between FM and MDD considering the BDNF-adjusted index; (iii) to assess the relationship between the role of DPMS and the BDNF-adjusted index, despite clinical diagnosis. Patients and Methods: A cohort of 63 women, aged 18 to 75 years [FM (n = 18), MDD (n = 19), and HC (n = 29)]. Results: The MANCOVA analysis revealed that the mean of SICI was 53.40% larger in FM compared to MDD [1.03 (0.50) vs. 0.55 (0.43)] and 66.99% larger compared to HC [1.03 (0.50) vs. 0.34 (0.19)], respectively. The inhibitory potency of the DPMS assessed by the change on the NPS during CPM-test was 112.29 % lower in the FM compared to MDD [0.22 (1.37) vs. -0.87 (1.49)]. The mean of BDNF from FM compared to MDD was 35.70% higher [49.82 (16.31) vs. 14.12 (8.86)]. In FM, the Spearman's coefficient between the change in the NPS during CPM-test with the SICI was Rho = -0.49, [confidence interval (CI) 95%; -0.78 to -0.03]. The BDNF-adjusted index was positively correlated with the disinhibition of the DPMS. Conclusion: These findings support the hypothesis that in FM a deteriorated function of cortical inhibition, indexed by a higher SICI parameter, a lower function of the DPMS, together with a higher level of BDNF indicate that FM has different pathological substrates from depression. They suggest that an up-regulation phenomenon of intracortical inhibitory networks associated with a disruption of the DPMS function occurs in FM.

Predictors of Response to Repetitive Transcranial Magnetic Stimulation in Depression: A Review of Recent Updates

Transcranial magnetic stimulation (TMS) has been increasingly used in the treatment of various neuropsychiatric disorders including depression over the past two decades. The responses to treatment with TMS are variable as found in the recent studies. Evidences suggest that various factors influence the outcome of depression treated with TMS. Understanding the predictors of response to TMS treatment in depression will guide the clinician in appropriate selection of patients for TMS treatment as well as needful modification in the TMS technique and protocol to have a better clinical outcome. This article comprehensively reviews the factors that predict the outcome of TMS treatment in depression.

Increase of frontal cerebral blood volume during transcranial magnetic stimulation in depression is related to treatment effectiveness: A pilot study with near-infrared spectroscopy

AIM

Alterations of cerebral blood flow have been reported in studies of depression treated by transcranial magnetic stimulation (TMS). However, the relation between these changes in activity during stimulation and the effectiveness of TMS is not known. The aim of this study was to determine whether changes in frontal cerebral blood volume measured as frontal hemoglobin concentration (fHbC) during TMS are correlated with clinical outcomes of treatment.

METHODS

Fifteen drug-resistant patients with depression underwent a standard treatment regimen of TMS to the left dorsolateral prefrontal cortex. We recorded fHbC during stimulation at the start and end of the TMS treatment series using near-infrared spectroscopy. Symptom severity was determined using the Montgomery-Åsberg Depression Rating Scale.

RESULTS

At the start of the TMS series, fHbC increased during stimulation in a majority of patients with no relation to symptom severity. However, at the end of the series, fHbC increase during stimulation was negatively correlated with the Montgomery-Åsberg Depression Rating Scale score and positively with the score reduction. Patients showing a decreasing response of fHbC during TMS at the end of the series experienced less clinical improvement.

CONCLUSION

These results suggest that the maintenance of frontal activation during stimulation in the course of TMS series is related to the effectiveness in the treatment of depression. Measurement of fHbC during stimulation is informative in the clinical use of TMS.

Transcranial magnetic stimulation: A review of its evolution and current applications

Repetitive transcranial magnetic stimulation (rTMS) is a recently developed noninvasive brain stimulation method for the treatment of psychiatric and neurological disorders. Although, its exact mechanism of action is still not clear, current evidence points toward its role in causing long-term inhibition and excitation of neurons in certain brain areas. As evidence steadily grows in favor of rTMS as a therapeutic tool; there is a need to develop standardized protocols for its administration. There have been no reports of any serious side effects with rTMS, though its use is restricted in those having magnetic implants or recent adverse neurological or cardiac event. Of all the psychiatric indications of rTMS, the evidence is most robust for treatment of refractory unipolar depression. This paper reviews contemporary literature highlighting the evolution of rTMS as a diagnostic and therapeutic tool, especially in the management of treatment-resistant depression.

Cranial electrotherapy stimulation affects mood state but not levels of peripheral neurotrophic factors or hypothalamic- pituitary-adrenal axis regulation

Cranial electrotherapy stimulation (CES) is reported to aid in relieving symptoms of depression and anxiety, though the mechanism underlying this effect remains unclear. Therefore, the present study aimed to evaluate changes in the hypothalamic-pituitary-adrenal (HPA) axis response and levels of neurotrophic factors, as well as changes in mood state, in patients undergoing CES therapy. Fifty healthy postmenopausal women were randomly assigned to either a Sham CES group (n = 25) or an Active CES group (n = 25). CES treatment was conducted in 20-minute sessions, three times per week for 8 weeks, using a micro current cranial electrotherapy stimulator. Blood samples were collected prior to and following the 8-week treatment period for measurement of cortisol, adrenocorticotropic hormone (ACTH), brain-derived neurotrophic factor (BDNF), and nerve growth factor (NGF) levels. Changes in mood state were also examined at the time of blood collection using the Profile of Mood States (POMS). No significant differences in cortisol, ACTH, BDNF, or NGF were observed between the two participant groups (p > 0.05) following the treatment period. However, those in the Active CES group exhibited significantly decreased Tension-Anxiety and Depression-Dejection scores on the POMS relative to pre-treatment scores (p < 0.05). Furthermore, Depression-Dejection scores following treatment were significantly lower in the Active CES group than in the Sham CES group (p < 0.05). No significant differences were observed in any other POMS scores such as Anger-Hostility, Vigor-Activity, Fatigue-Inertia, and Confusion-Bewilderment (p > 0.05). These results suggest that 8 weeks of CES treatment does not induce changes in blood levels of neurotrophic factors or HPA-axis-related hormones, though such treatment may be effective in treating symptoms of anxiety and depression.

Transcranial direct current stimulation of 20- and 30-minutes combined with sertraline for the treatment of depression

BACKGROUND

Transcranial direct current stimulation (tDCS) can be an effective treatment for depression, however, the duration of the stimulation session, among other parameters, needs to be optimized.

METHODS

69 mild to moderately depressed patients (age 37.6±10.5years, 19 men) were randomized into three groups - 30-, 20-minute or sham tDCS. 10 daily sessions of anodal/sham tDCS of the left DLPFC (0.5mA; electrode 3,5×7cm) combined with 50mg/day of sertraline were performed. Mood, cognition and BDNF level were assessed before and after the treatment.

RESULTS

A significant difference between groups was observed in the percent change of the Hamilton Depression Rating Scale (F(2, 66)=10.1; p<0.001). Sham group (43.4%±18.1) had a smaller improvement compared to the 30-minute (63.8%±13.4; 95% CI: 11.23-29.44; p=0.00003) and 20-minute group (53.2%±15.3; 95% CI: 0.21-19.26; p=0.045). 30-minute group had significantly greater percent improvement than 20-minute group (95% CI: 1.74-19.46; p=0.02). Responders constituted 89%, 68%, and 50% and remitters - 70%, 27%, and 35% in the 30-, 20-minute and sham groups, respectively. A significant difference in the number of responders was observed between 30-minute vs. sham group (odds ratio=8; 95% CI, 2.59-24.69; p=0.001), in remission rate - between 30-minute vs. sham (odds ratio=4.40; 95% CI, 2.02-9.57; p=0.02) and vs. 20-minute (odds ratio=6.33; 95% CI, 2.85-14.10; p=0.003) groups. Two hypomania cases and one case of blood pressure elevation were detected in the 20-minute group. Among neuropsychological tests, only the change in Digit Span Backwards test showed a significant interaction between groups (TIME*GROUP; F(2, 65)=6,6, p=0.002); a greater improvement was observed in both active groups compared to sham (p<0.05). The change in BDNF level after the treatment did not show the significant difference between groups.

CONCLUSIONS

tDCS of 20- or 30-minutes combined with sertraline are efficient for the treatment of mild and moderate depression; the effect of 30min stimulation exceeds the one obtained from 20min.

Investigating the neurobiology of schizophrenia and other major psychiatric disorders with Transcranial Magnetic Stimulation

Characterizing the neurobiology of schizophrenia and other major psychiatric disorders is one of the main challenges of the current research in psychiatry. The availability of Transcranial Magnetic Stimulation (TMS) allows to directly probe virtually any cortical areas, thus providing a unique way to assess the neurophysiological properties of cortical neurons. This article presents a review of studies employing TMS in combination with Motor Evoked Potentials (TMS/MEPs) and high density Electroencephalogram (TMS/hd-EEG) in schizophrenia and other major psychiatric disorders. Studies were identified by conducting a PubMed search using the following search item: "transcranial magnetic stimulation and (Schizophrenia or OCD or MDD or ADHD)". Studies that utilized TMS/MEP and/or TMS/hd-EEG measures to characterize cortical excitability, inhibition, oscillatory activity, and/or connectivity in psychiatric patients were selected. Across disorders, patients displayed a pattern of reduced cortical inhibition, and to a lesser extent increased excitability, in the motor cortex, which was most consistently established in Schizophrenia. Furthermore, psychiatric patients showed abnormalities in a number of TMS-evoked EEG oscillations, which was most prominent in the prefrontal cortex of Schizophrenia relative to healthy comparison subjects. Overall, results from this review point to significant impairments in cortical excitability, inhibition, and oscillatory activity, especially in frontal areas, in several major psychiatric disorders. Building on these findings, future studies employing TMS-based experimental paradigms may help elucidating the neurobiology of these psychiatric disorders, and may assess the contribution of TMS-related measures in monitoring and possibly maximizing the effectiveness of treatment interventions in psychiatric populations.

Rostral anterior cingulate cortex is a structural correlate of repetitive TMS treatment response in depression

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) is an effective treatment for medication-refractory major depression, yet the mechanisms of action for this intervention are poorly understood. Here we investigate cerebral cortex thickness as a possible biomarker of rTMS treatment response.

METHODS

Longitudinal change in cortical thickness is evaluated relative to clinical outcomes across 48 participants in 2 cohorts undergoing left dorsolateral prefrontal cortex rTMS as a treatment for depression.

RESULTS

Our results reveal changes in thickness in a region of the left rostral anterior cingulate cortex that correlate with clinical response, with this region becoming thicker in patients who respond favorably to rTMS and thinner in patients with a less favorable response. Moreover, the baseline cortical thickness in this region correlates with rTMS treatment response - those patients with thinner cortex before treatment tended to have the most clinical improvement.

CONCLUSIONS

This study is the first analysis of longitudinal cortical thickness change with rTMS as a treatment for depression with similar results across two cohorts. These results support further investigation into the use of structural MRI as a possible biomarker of rTMS treatment response.

Neurostimulation in Clinical and Sub-clinical Eating Disorders: A Systematic Update of the Literature

INTRODUCTION

Whilst psychological therapies are the main approach to treatment of eating disorders (EDs), advances in aetiological research suggest the need for the development of more targeted, brain-focused treatments. A range of neurostimulation approaches, most prominently repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS) and deep brain stimulation (DBS), are rapidly emerging as potential novel interventions. We have previously reviewed these techniques as potential treatments of EDs.

AIM

To provide an update of the literature examining the effects of DBS, rTMS and tDCS on eating behaviours, body weight and associated symptoms in people with EDs and relevant analogue populations.

METHODS

Using PRISMA guidelines, we reviewed articles in PubMed, Web of Science, and PsycINFO from 1st January 2013 until 14th August 2017, to update our earlier search. Studies assessing the effects of neurostimulation techniques on eating and weight-related outcomes in people with EDs and relevant analogue populations were included. Data from both searches were combined.

RESULTS

We included a total of 32 studies (526 participants); of these, 18 were newly identified by our update search. Whilst findings are somewhat mixed for bulimia nervosa, neurostimulation techniques have shown potential in the treatment of other EDs, in terms of reduction of ED and associated symptoms. Studies exploring cognitive, neural, and hormonal correlates of these techniques are also beginning to appear.

CONCLUSIONS

Neurostimulation approaches show promise as treatments for EDs. As yet, large wellconducted randomised controlled trials are lacking. More information is needed about treatment targets, stimulation parameters and mechanisms of action.

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.

Modulation of motor cortex excitability predicts antidepressant response to prefrontal cortex repetitive transcranial magnetic stimulation

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) targeting the left dorsolateral prefrontal cortex (DLPFC) is a treatment option for patients with medication-resistant major depressive disorder (MDD). However, antidepressant response is variable and there are currently no response predictors with sufficient accuracy for clinical use.

OBJECTIVE

We report on results of an observational open-label study to determine whether the modulatory effect of 10 Hz motor cortex (MC) rTMS is predictive of the antidepressant effect of 10 Hz DLPFC rTMS.

METHODS

Fifty-one medication-resistant MDD patients were enrolled for a 10-day treatment course of DLPFC rTMS and antidepressant response was assessed according to post-treatment reduction of the 17-item Hamilton Rating Scale for Depression score. Prior to treatment, we assessed the modulation of motor evoked potential (MEP) amplitude by MC rTMS. MEP's were induced with single TMS pulses and measured using surface electromyography. MEP modulation was calculated as the change of mean MEP amplitude after MC rTMS.

RESULTS

MEP modulation proved to be a robust predictor of reduction of clinician-rated depression severity following the course of DLPFC rTMS: larger MC rTMS-induced increase of corticospinal excitability anticipated a better antidepressant response. This was found both in univariate analyses (Spearman regression: rho = 0.43, p < 0.005) and a multivariable linear regression model (β = 0.25, p < 0.0001) controlling for baseline depression severity, age and resting motor threshold.

CONCLUSIONS

These findings suggest that MC rTMS-induced modulation of corticospinal excitability warrants further evaluation as a potential predictive biomarker of antidepressant response to left DLPFC 10 Hz rTMS.

New Treatment Strategies of Depression: Based on Mechanisms Related to Neuroplasticity

Major depressive disorder is a severe and complex mental disorder. Impaired neurotransmission and disrupted signalling pathways may influence neuroplasticity, which is involved in the brain dysfunction in depression. Traditional neurobiological theories of depression, such as monoamine hypothesis, cannot fully explain the whole picture of depressive disorders. In this review, we discussed new treatment directions of depression, including modulation of glutamatergic system and noninvasive brain stimulation. Dysfunction of glutamatergic neurotransmission plays an important role in the pathophysiology of depression. Ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, has rapid and lasting antidepressive effects in previous studies. In addition to ketamine, other glutamatergic modulators, such as sarcosine, also show potential antidepressant effect in animal models or clinical trials. Noninvasive brain stimulation is another new treatment strategy beyond pharmacotherapy. Growing evidence has demonstrated that superficial brain stimulations, such as transcranial magnetic stimulation, transcranial direct current stimulation, cranial electrotherapy stimulation, and magnetic seizure therapy, can improve depressive symptoms. The antidepressive effect of these brain stimulations may be through modulating neuroplasticity. In conclusion, drugs that modulate neurotransmission via NMDA receptor and noninvasive brain stimulation may provide new directions of treatment for depression. Furthermore, exploring the underlying mechanisms will help in developing novel therapies for depression in the future.

A naturalistic, multi-site study of repetitive transcranial magnetic stimulation therapy for depression

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) was approved in 2008 in the United States, and there are relatively few studies describing its use in regular clinical practice since approval.

METHODS

From April 2011 to October 2014, ten sites within the National Network of Depression Centers (NNDC) provided data on 62 evaluable patients with a depressive episode. Treatment was determined naturalistically. Response was assessed by the Quick Inventory of Depressive Symptoms, Self-Report (QIDS-SR) as the primary outcome, and the Patient Health Questionnaire-9 (PHQ-9) and the clinician-rated Clinical Global Impression (CGI) as secondary depression measures.

RESULTS

Enrolled patients exhibited significant treatment resistance, with 70.2% reporting more than 4 prior depressive episodes. Most patients received treatment with standard parameters (10Hz over the left dorsolateral prefrontal cortex), although 22.6% of the patients received 1 or 5Hz stimulation at some point. Over 6 weeks of treatment, response and remission rates were 29.4% and 5.9%, respectively, for the QIDS-SR; 39.2% and 15.7%, respectively, for the PHQ-9; and 50.9% and 17.9%, respectively, for the CGI. Moderator analyses revealed no effect of prior depressive episodes, history of ECT or gender, although early life stress predicted a better response to rTMS therapy.

LIMITATIONS

The study was an open-label, registry trial, with relatively coarse clinical data, reflecting practice only in academic, depression-specialty centers. Because of the relatively small size and heterogeneity of the sample, type 2 errors are possible and positive findings are in need of replication.

CONCLUSION

rTMS demonstrates effectiveness in clinical practice within the NNDC, although remission rates appear slightly lower in comparison with other recent naturalistic studies.

Psychometric properties of the Brazilian version of the Personal Experience Screening Questionnaire

Introduction:

The Personal Experience Screening Questionnaire (PESQ) is an instrument devised for assessing the magnitude of drug misuse among adolescents. However, its psychometric properties have not been evaluated in adolescent samples outside the United States.

Objective:

To assess the internal reliability and validity of the Brazilian version of the PESQ.

Method:

A cross-sectional study was carried out with 84 adolescents from a clinical sample and a community-based sample. All of them answered the PESQ.

Results:

Among adolescents from the community, the PESQ problem severity index, which can vary from 18 to 72, was 26.48±9.28, whereas the clinical sample scored 42.89±10.02 (p<0.001). Cronbach's alpha was 0.91. Factor analysis resulted in a four-factor solution. Furthermore, both samples also had different mean scores for the other distinct content areas measured by the instrument.

Conclusion:

Evidence to support the reliability and validity of the Brazilian version of the Personal Experience Questionnaire was found.

Neurophysiologic predictors of motor function in stroke

PURPOSE

Understanding the neural mechanisms of stroke recovery is of paramount importance for neurorehabilitation.

METHODS

For this purpose, we analyzed several TMS and EEG variables and their association with motor recovery. Thirty-five subjects with chronic stroke were recruited. The neurophysiological examination included assessments by transcranial magnetic stimulation (TMS), intra- and inter-hemispheric EEG coherence in different frequency bands (e.g. alpha (8-13 Hz)) as determined by quantitative electroencephalography (qEEG). Motor function was measured by Fugl-Meyer (FM). Multiple univariate and multivariate linear regression analyses were performed to identify the predictors for FM.

RESULTS

Multivariate analyses, showed a significant interaction effect of motor threshold (MT) in the lesioned hemisphere and beta coherence in the unlesioned hemisphere. This interaction suggests that higher beta activity in the unlesioned hemisphere strengthens the negative association between MT and FM scores.

CONCLUSIONS

Our results suggest that MT in the lesioned hemisphere is the strongest predictors of motor recovery after stroke. Moreover, cortical activity in the unlesioned hemisphere measured by qEEG provides additional information, specifying the association between MT and FM scores. Therefore, complementary application of EEG and TMS can help constitute a better model of the lesioned and the unlesioned hemispheres that supports the importance of bihemispheric activity in recovery.

Spared Primary Motor Cortex and The Presence of MEP in Cerebral Palsy Dictate the Responsiveness to tDCS during Gait Training

The current priority of investigations involving transcranial direct current stimulation (tDCS) and neurorehabilitation is to identify biomarkers associated with the positive results of the interventions such that respondent and non-respondent patients can be identified in the early phases of treatment. The aims were to determine whether: (1) present motor evoked potential (MEP); and (2) injuries involving the primary motor cortex, are associated with tDCS-enhancement in functional outcome following gait training in children with cerebral palsy (CP). We reviewed the data from our parallel, randomized, sham-controlled, double-blind studies. Fifty-six children with spastic CP received gait training (either treadmill training or virtual reality training) and tDCS (active or sham). Univariate and multivariate logistic regression analyses were employed to identify clinical, neurophysiologic and neuroanatomic predictors associated with the responsiveness to treatment with tDCS. MEP presence during the initial evaluation and the subcortical injury were associated with positive effects in the functional results. The logistic regression revealed that present MEP was a significant predictor for the six-minute walk test (6MWT; p = 0.003) and gait speed (p = 0.028), whereas the subcortical injury was a significant predictor of gait kinematics (p = 0.013) and gross motor function (p = 0.021). In this preliminary study involving children with CP, two important prediction factors of good responses to anodal tDCS combined with gait training were identified. Apparently, MEP (integrity of the corticospinal tract) and subcortical location of the brain injury exerted different influences on aspects related to gait, such as velocity and kinematics.

Transcranial Electrical Stimulation (tES) for the Treatment of Neuropsychiatric Disorders Across Lifespan

Abstract. Transcranial electrical stimulation (tES) is a safe, painless, and inexpensive noninvasive brain stimulation (NIBS) technique. tES has been shown to reduce symptoms in a variety of neuropsychiatric conditions such as depression, schizophrenia, anxiety, autism, and craving. There are many factors that can influence the effects of tES, such as current intensity, duration, baseline level of activity, gender, and age. Age is a critical variable, since the human brain undergoes several anatomic and functional changes across the lifespan. Therefore, tES-induced effects may not be the same across the lifespan. In this review we summarize the effects of tES, including tDCS, tACS, and tRNS, on clinical outcomes in several neuropsychiatric conditions, using a framework in which studies are organized according to the age of subjects. The use of tES in neuropsychiatric disorders has yielded promising results with mild, if any, adverse effects. Most of the published studies with tES have been conducted with tDCS in adult population. Future studies should focus on interventions guided by surrogate outcomes of neuroplasticity. A better understanding of neuroplasticity across the lifespan will help optimize current tES stimulation parameters, especially for use with children and elderly populations.

Circulating Brain-Derived Neurotrophic Factor Has Diagnostic and Prognostic Value in Traumatic Brain Injury

Brain-derived neurotrophic factor (BDNF) is important for neuronal survival and regeneration. We investigated the diagnostic and prognostic values of serum BDNF in traumatic brain injury (TBI). We examined serum BDNF in two independent cohorts of TBI cases presenting to the emergency departments (EDs) of the Johns Hopkins Hospital (JHH; n = 76) and San Francisco General Hospital (SFGH, n = 80), and a control group of JHH ED patients without TBI (n = 150). Findings were subsequently validated in the prospective, multi-center Transforming Research and Clinical Knowledge in TBI (TRACK-TBI) Pilot study (n = 159). We investigated the association between BDNF, glial fibrillary acidic protein (GFAP), and ubiquitin C-terminal hydrolase-L1 (UCH-L1) and recovery from TBI at 6 months in the TRACK-TBI Pilot cohort. Incomplete recovery was defined as having either post-concussive syndrome or a Glasgow Outcome Scale Extended score <8 at 6 months. Median day-of-injury BDNF concentrations (ng/mL) were lower among TBI cases (JHH TBI, 17.5 and SFGH TBI, 13.8) than in JHH controls (60.3; p = 0.0001). Among TRACK-TBI Pilot subjects, median BDNF concentrations (ng/mL) were higher in mild (8.3) than in moderate (4.3) or severe TBI (4.0; p = 0.004. In the TRACK-TBI cohort, the 75 (71.4%) subjects with very low BDNF values (i.e., <the 1st percentile for non-TBI controls, <14.2 ng/mL) had higher odds of incomplete recovery than those who did not have very low values (odds ratio, 4.0; 95% confidence interval [CI]: 1.5-11.0). The area under the receiver operator curve for discriminating complete and incomplete recovery was 0.65 (95% CI: 0.52-0.78) for BDNF, 0.61 (95% CI: 0.49-0.73) for GFAP, and 0.55 (95% CI: 0.43-0.66) for UCH-L1. The addition of GFAP/UCH-L1 to BDNF did not improve outcome prediction significantly. Day-of-injury serum BDNF is associated with TBI diagnosis and also provides 6-month prognostic information regarding recovery from TBI. Thus, day-of-injury BDNF values may aid in TBI risk stratification.

Assessment of non-BDNF neurotrophins and GDNF levels after depression treatment with sertraline and transcranial direct current stimulation in a factorial, randomized, sham-controlled trial (SELECT-TDCS): an exploratory analysis

The neurotrophic hypothesis of depression states that the major depressive episode is associated with lower neurotrophic factors levels, which increase with amelioration of depressive symptoms. However, this hypothesis has not been extended to investigate neurotrophic factors other than the brain-derived neurotrophic factor (BDNF). We therefore explored whether plasma levels of neurotrophins 3 (NT-3) and 4 (NT-4), nerve growth factor (NGF) and glial cell line derived neurotrophic factor (GDNF) changed after antidepressant treatment and correlated with treatment response. Seventy-three patients with moderate-to-severe, antidepressant-free unipolar depression were assigned to a pharmacological (sertraline) and a non-pharmacological (transcranial direct current stimulation, tDCS) intervention in a randomized, 2 × 2, placebo-controlled design. The plasma levels of NT-3, NT-4, NGF and GDNF were determined by enzyme-linked immunosorbent assay before and after a 6-week treatment course and analyzed according to clinical response and allocation group. We found that tDCS and sertraline (separately and combined) produced significant improvement in depressive symptoms. Plasma levels of all neurotrophic factors were similar across groups at baseline and remained significantly unchanged regardless of the intervention and of clinical response. Also, baseline plasma levels were not associated with clinical response. To conclude, in this 6-week placebo-controlled trial, NT-3, NT-4, NGF and GDNF plasma levels did not significantly change with sertraline or tDCS. These data suggest that these neurotrophic factors are not surrogate biomarkers of treatment response or involved in the antidepressant mechanisms of tDCS.

Transcranial magnetic stimulation for the treatment of major depression

Major depression is often difficult to diagnose accurately. Even when the diagnosis is properly made, standard treatment approaches (eg, psychotherapy, medications, or their combination) are often inadequate to control acute symptoms or maintain initial benefit. Additional obstacles involve safety and tolerability problems, which frequently preclude an adequate course of treatment. This leaves an important gap in our ability to properly manage major depression in a substantial proportion of patients, leaving them vulnerable to ensuing complications (eg, employment-related disability, increased risk of suicide, comorbid medical disorders, and substance abuse). Thus, there is a need for more effective and better tolerated approaches. Transcranial magnetic stimulation is a neuromodulation technique increasingly used to partly fill this therapeutic void. In the context of treating depression, we critically review the development of transcranial magnetic stimulation, focusing on the results of controlled and pragmatic trials for depression, which consider its efficacy, safety, and tolerability.

Cytokines plasma levels during antidepressant treatment with sertraline and transcranial direct current stimulation (tDCS): results from a factorial, randomized, controlled trial

RATIONALE

The inflammatory hypothesis of depression states that increased levels of pro-inflammatory cytokines triggered by external and internal stressors are correlated to the acute depressive state. This hypothesis also suggests that pharmacotherapy partly acts in depression through anti-inflammatory effects. Transcranial direct current stimulation (tDCS) is a novel, promising, non-invasive somatic treatment for depression, although its antidepressant mechanisms are only partly understood.

OBJECTIVES

We explored the effects of tDCS and sertraline over the immune system during an antidepressant treatment trial.

METHODS

In a 6-week, double-blind, placebo-controlled trial, 73 antidepressant-free patients with unipolar depression were randomized to active/sham tDCS and sertraline/placebo (2 × 2 design). Plasma levels of several cytokines (IL-2, IL-4, IL-6, IL-10, IL-17a, IFN-γ, and TNF-α) were determined to investigate the effects of the interventions and of clinical response on them.

RESULTS

All cytokines, except TNF-α, decreased over time, these effects being similar across the different intervention-groups and in responders vs. non-responders.

CONCLUSIONS

tDCS and sertraline (separately and combined) acute antidepressant effects might not specifically involve normalization of the immune system. In addition, being one of the first placebo-controlled trials measuring cytokines over an antidepressant treatment course, our study showed that the decrease in cytokine levels during the acute depressive episode could involve a placebo effect, highlighting the need of further placebo-controlled trials and observational studies examining cytokine changes during depression treatment and also after remission of the acute depressive episode.