Modulation of affective symptoms and resting state activity by brain stimulation in a treatment-resistant case of obsessive-compulsive disorder

Immediate and long-term efficacy of transcranial direct current stimulation (tCDS) in obsessive-compulsive disorder, posttraumatic stress disorder and anxiety disorders: a systematic review and meta-analysis

Currently, there is still debate over the effectiveness of transcranial direct current stimulation (tDCS) in treating obsessive-compulsive disorder (OCD), posttraumatic stress disorder (PTSD) and anxiety disorders (ADs). To investigate the immediate and long-term effectiveness of tDCS in these diseases, we conducted a systematic review and quantitative analysis of existing literature on the treatment of OCD, PTSD, and ADs with tDCS. Following the PRISMA guidelines, we searched seven electronic databases and systematically retrieved articles published from May 2012 to June 2024 that compared the effects of active tDCS with sham stimulation in the treatment of these disorders. We included primary outcome measures such as the change scores in disorder-specific and general anxiety symptoms before and after treatment, as well as secondary outcomes such as changes in disorder-specific and general anxiety symptoms at follow-up. We also assessed the impact of tDCS on depressive symptoms. Fifteen papers met the eligibility criteria. Overall, the results of meta-analysis indicated that tDCS had a high effect in improving specific symptoms (SMD = -0.73, 95% CI: -1.09 to -0.37) and general anxiety symptoms (SMD = -0.75; 95% CI: -1.23 to -0.26) in OCD, PTSD and ADs, with effects lasting up to 1 month and showing a moderate effect size. Furthermore, tDCS demonstrated immediate and significant alleviation of depressive symptoms in these diseases. This study concludes that tDCS can serve as a non-invasive brain stimulation technology for treating these disorders, and the therapeutic effects can be maintained for a period of time.

Treating refractory obsessive compulsive disorder with cathodal transcranial direct current stimulation over the supplementary motor area: a large multisite randomized sham-controlled double-blind study

Background

The present study evaluated the therapeutic efficacy and tolerability of 10 transcranial direct current stimulation (tDCS) sessions in treatment-resistance obsessive-compulsive disorder (OCD) patients using a multisite double-blind sham-controlled design.

Methods

Eighty treatment-resistance outpatients suffering from obsessive-compulsive disorder were randomized to receive either active or sham transcranial direct current stimulation. The cathode was positioned over the supplementary motor area and the anode over the right supraorbital area. Patients were evaluated at baseline, end of treatment (day 14), one-month follow-up (day 45), and three-month follow-up (day 105) on the Yale-Brown Obsessive Compulsive Scale.

Results

Although a significant interaction between time and treatment was observed, the primary endpoint-measuring the change in Yale-Brown obsessive compulsive scale scores after two weeks-was not achieved. Conversely, the secondary endpoint, which concerned the change in Yale-Brown obsessive compulsive scale scores after three months, was successfully met. It is important to note, however, that there were no significant differences in the percentage of responders and remitters at any of the post-treatment assessments. This suggests that the treatment may not have had a clinically relevant impact. Patients well received the transcranial direct current stimulation treatment, indicating its good tolerability.

Conclusion

This is the largest controlled trial using transcranial direct current stimulation in treatment-resistance obsessive-compulsive disorder patients. Our results indicate the importance of studying the placebo effect in transcranial direct current stimulation and the necessity to consider a long follow-up time to best evaluate the effects of the intervention.

Clinical trial registration

ClinicalTrials.gov, identifier NCT03304600.

The Effects of Transcranial Direct Current Stimulation in Obsessive-Compulsive Disorder Symptoms: A Meta-Analysis and Integrated Electric Fields Modeling Analysis

Transcranial direct current stimulation (tDCS) has been showing promising effects for the treatment of obsessive-compulsive disorder (OCD), but there is still no conclusion on its efficacy for this disorder. We performed a systematic review and meta-analysis of trials using tDCS for OCD and a computer modeling analysis to evaluate the electric field (EF) strengths of different electrode assemblies in brain regions of interest (ROIs) (PROSPERO-42021262465). PubMed/MEDLINE, Embase, Cochrane Library and Web of Science databases were searched from inception to 25 September 2022. Randomized controlled trials (RCTs) and open-label studies were included. The primary aim was the effect size (Hedges' g) of continuous outcomes and potential moderators of response. For EF modeling, SimNIBS software was used. Four RCTs and four open-label trials were included (n = 241). Results revealed a large effect of tDCS in the endpoint, but no significant effect between active and sham protocols. No predictor of response was found. EF analysis revealed that montages using the main electrode over the (pre)supplementary motor area with an extracephalic reference electrode might lead to stronger EFs in the predefined ROIs. Our results revealed that tDCS might be a promising intervention to treat OCD; however, larger studies are warranted.

Transcranial Direct Current Stimulation of the Dorsolateral Prefrontal Cortex for Treatment of Neuropsychiatric Disorders

Background

The dorsolateral prefrontal cortex (DLPFC) is a key node of the frontal cognitive circuit. It is involved in executive control and many cognitive processes. Abnormal activities of DLPFC are likely associated with many psychiatric diseases. Modulation of DLPFC may have potential beneficial effects in many neural and psychiatric diseases. One of the widely used non-invasive neuromodulation technique is called transcranial direct current stimulation (or tDCS), which is a portable and affordable brain stimulation approach that uses direct electrical currents to modulate brain functions.

Objective

This review aims to discuss the results from the past two decades which have shown that tDCS can relieve clinical symptoms in various neurological and psychiatric diseases.

Methods

Here, we performed searches on PubMed to collect clinical and preclinical studies that using tDCS as neuromodulation technique, DLPFC as the stimulation target in treating neuropsychiatric disorders. We summarized the stimulation sites, stimulation parameters, and the overall effects in these studies.

Results

Overall, tDCS stimulation of DLPFC could alleviate the clinical symptoms of schizophrenia, depression, drug addiction, attention deficit hyperactivity disorder and other mental disorders.

Conclusion

The stimulation parameters used in these studies were different from each other. The lasting effect of stimulation was also not consistent. Nevertheless, DLPFC is a promising target for non-invasive stimulation in many psychiatric disorders. TDCS is a safe and affordable neuromodulation approach that has potential clinical uses. Larger clinical studies will be needed to determine the optimal stimulation parameters in each condition.

Therapeutic Neurostimulation in Obsessive-Compulsive and Related Disorders: A Systematic Review

Invasive and noninvasive neurostimulation therapies for obsessive-compulsive and related disorders (OCRD) were systematically reviewed with the aim of assessing clinical characteristics, methodologies, neuroanatomical substrates, and varied stimulation parameters. Previous reviews have focused on a narrow scope, statistical rather than clinical significance, grouped together heterogenous protocols, and proposed inconclusive outcomes and directions. Herein, a comprehensive and transdiagnostic evaluation of all clinically relevant determinants is presented with translational clinical recommendations and novel response rates. Electroconvulsive therapy (ECT) studies were limited in number and quality but demonstrated greater efficacy than previously identified. Targeting the pre-SMA/SMA is recommended for transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS). TMS yielded superior outcomes, although polarity findings were conflicting, and refinement of frontal/cognitive control protocols may optimize outcomes. For both techniques, standardization of polarity, more treatment sessions (>20), and targeting multiple structures are encouraged. A deep brain stimulation (DBS) 'sweet spot' of the striatum for OCD was proposed, and CBT is strongly encouraged. Tourette's patients showed less variance and reliance on treatment optimization. Several DBS targets achieved consistent, rapid, and sustained clinical response. Analysis of fiber connectivity, as opposed to precise neural regions, should be implemented for target selection. Standardization of protocols is necessary to achieve translational outcomes.

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.

The safety and efficacy of transcranial direct current stimulation as add-on therapy to fluoxetine in obsessive-compulsive disorder: a randomized, double-blind, sham-controlled, clinical trial

BACKGROUND

Obsessive-compulsive disorder (OCD) is an anxiety disorder that causes impairment in daily activities. This study aimed to assess the safety and efficacy of transcranial direct current stimulation (tDCS) as adjunctive therapy with fluoxetine in individuals diagnosed with moderate to severe OCD.

METHODS

This is a randomized, double-blind sham-controlled trial. Individuals with OCD who had baseline Yale-Brown obsessive-compulsive scale (Y-BOCS) of > 15 were enrolled. Eligible cases were randomly assigned in 1:1 ratio to receive either 20-min-period of stimulation with tDCS and fluoxetine (experimental arm) or fluoxetine only (sham control arm). The anodal electrode of tDCS was placed over the left dorsolateral prefrontal cortex (Fp3) and the cathodal electrode was placed over the right orbitofrontal cortex (F8). Two mA electrical stimulation with the tDCS was used for 20 min in individuals of experimental group. In the control group, electrodes were placed and stimulation was administered for 30 s to induce the same skin sensation as in experimental group. This procedure was performed three times per week for 8 weeks. Y-BOCS test was assessed at baseline, week 4 (after 12th stimulation), week 8 (after 24th stimulation), and 1 month after the last stimulation. The primary endpoints were the mean changes in Y-BOCS total score from baseline to the last visit. The secondary endpoints were the mean changes in obsession and compulsion sub-scores from baseline to the last visit. Adverse events were also assessed. Mixed design repeated measures analysis of variance assessed the endpoints.

RESULTS

Sixty individuals (30 in each group) were participated. All individuals in control group and 28 cases in experimental arm completed the trial. The mean Y-BOCS (F(1.85) = 30.83; P < 0.001), OCD obsession (F(2.23) = 25.01; P < 0.001), and compulsion (F(2.06) = 10.81; P < 0.001) scores decreased significantly during the study. No statistical differences were, however, detected between experimental and control groups (P > 0.05). The tDCS was well tolerated and no major adverse events were reported.

CONCLUSION

This study showed that among individuals with moderate to severe OCD, there was no significant difference regarding OC symptoms between cases used tDCS as adjunctive therapy with fluoxetine and individuals used fluoxetine only.

TRIAL REGISTRATION

IRCT2017030632904N1 . Registered 14 July 2017, http://irct.ir/user/trial/44193/view.

Brain Stimulation in Obsessive-Compulsive Disorder (OCD): A Systematic Review

Background

Obsessive-compulsive disorder (OCD) is a highly prevalent, severe, and chronic disease. There is a need for alternative strategies for treatment-resistant OCD.

Objective

This review aims to assess the effect of brain stimulation techniques in OCD.

Method

We included papers published in peer-reviewed journals dealing with brain stimulation techniques in OCD. We conducted treatment-specific searches for OCD (Technique AND ((randomized OR randomised) AND control* AND trial) AND (magnetic AND stimulation OR (rTMS OR dTMS)) AND (obsess* OR compuls* OR OCD)) on six databases, i.e., PubMed, Cochrane, Scopus, CINAHL, PsycINFO, and Web of Science to identify randomised controlled trials and ClinicalTrials.gov for possible additional results.

Results

Different add-on stimulation techniques could be effective for severely ill OCD patients unresponsive to drugs and/or behavioural therapy. Most evidence regarded deep brain stimulation (DBS) and transcranial magnetic stimulation (TMS), while there is less evidence regarding transcranial direct current stimulation (tDCS), electroconvulsive therapy, and vagus nerve stimulation (for these last two there are no sham-controlled studies). Low-frequency TMS may be more effective over the supplementary motor area or the orbitofrontal cortex. DBS showed best results when targeting the crossroad between the nucleus accumbens and the ventral capsule or the subthalamic nucleus. Cathodal tDCS may be better than anodal in treating OCD. Limitations. We had to include methodologically inconsistent underpowered studies.

Conclusion

Different brain stimulation techniques are promising as an add-on treatment of refractory OCD, although studies frequently reported inconsistent results. TMS, DBS, and tDCS could possibly find some use with adequate testing, but their standard methodology still needs to be established.

Transcranial Direct Current Stimulation Reduces Craving in Substance Use Disorders: A Double-blind, Placebo-Controlled Study

OBJECTIVES

The use of transcranial direct current stimulation (tDCS) in addiction disorders is still on its rise in comparison with pharmacological and psychotherapeutic strategies that still show low level of evidence. In this study, we aimed to evaluate the efficacy of the anodic tDCS for the short-term treatment of substance craving and other psychiatric symptoms.

METHODS

In this randomized, double-blind, sham-controlled trial, inclusion criteria included the diagnosis of substance use disorder and/or gambling disorder. The protocol includes 5 consecutive days of active or sham tDCS session. Cathode was placed over the left dorsolateral prefrontal cortex. Hamilton Depression Rating Scale, Hamilton Anxiety Rating Scale, Young Mania Rating Scale, Barratt Impulsiveness Scale, South Oaks Gambling Screen, and visual analog scale (VAS) 1 to 10 for craving were administered at the baseline (T0) and after 5 days of treatment (T1).

RESULTS

Thirty-four treatment-seeking subjects were randomized to sham (n = 16) and active stimulation (n = 18) groups. A statistically significant reduction of values at T1 was found in all subjects considering VAS (P < 0.001), Hamilton Depression Rating Scale (P < 0.001), Hamilton Anxiety Rating Scale (P < 0.001), and Barratt Impulsiveness Scale 11 (P = 0.032). A significant reduction for VAS craving in favor of the active stimulation (P = 0.011) was found.

CONCLUSIONS

Our findings reveal a statistically significant rapid reduction of craving in the active tDCS group on the right dorsolateral prefrontal cortex with respect to sham group, confirming the scientific literature trend. Large samples, with maintenance tDCS therapy and long-term follow-up, are required to establish the potential of this noninvasive and easily delivered brain stimulation strategy.

Transcranial direct current stimulation in obsessive-compulsive disorder: an update in electric field modeling and investigations for optimal electrode montage

Introduction: Transcranial Direct Current Stimulation (tDCS) is a non-invasive brain stimulation intervention that has been investigated for several psychiatric disorders, including Obsessive-Compulsive Disorder (OCD). As there are several candidate brain regions for targeting OCD relevant networks, clinical studies using tDCS have considerably varied in terms of the electrode montages used. Computer modeling of electric field currents induced by tDCS can help guiding the research of relevant targets for OCD. In this review, the authors used this tool to investigate targeted brain areas from previous studies of tDCS in OCD. Areas covered: A literature search for articles with the keywords 'tDCS', 'Transcranial Direct Current Stimulation' and 'Obsessive Compulsive Disorder' was conducted to identify relevant publications. For comparing different electrode montages, electric field (EF) models were performed using high-resolution brain scan templates. Authors found 13 studies mostly showing an improvement in OCD symptoms. The electrode montages varied considerably between studies. Nonetheless, two main patterns of EFs could be identified: 'focal montages', with EFs concentrated in the prefrontal cortex, and 'diffuse montages', with widespread EFs over cortical areas. Expert opinion: Electric field simulation can guide future clinical trials in psychiatry, using personalized tDCS montages with distinct electrode positioning according to clusters of symptoms.

Aberrant functional connectivity density in patients with treatment-refractory obsessive-compulsive disorder: a pilot study

Objective

Functional connectivity (FC) is altered in patients with obsessive-compulsive disorder (OCD). Most previous studies have focused on the strength of FC in patients with OCD; few have examined the number of functional connections in these patients. The number of functional connections is an important index for assessing aberrant FC. In the present study, we used FC density (FCD) mapping to explore alterations in the number of functional connections in patients with treatment-refractory OCD (TROCD) using the FCD index.

Methods

Twenty patients with TROCD and 20 patients with OCD in clinical remission were enrolled in the study. Global FCD (gFCD) was adopted to compare the differences between the two groups of patients.

Results

The gFCD in the left middle temporal gyrus was lower in the patients with TROCD than in those with remitted OCD, suggesting that decreased information processing ability may play a significant role in TROCD.

Conclusion

The left middle temporal gyrus is a key component of the emotional processing circuit and attentional processing circuit. Decreased information processing ability in this brain region may play a significant role in TROCD; however, further well-designed follow-up studies are needed to support this hypothesis.

Noninvasive brain stimulation in obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a complex neuropsychiatric disorder with a chronic course, contributing to significant socio-occupational dysfunction. Forty percent of patients remain treatment refractive despite mainstream treatment options such as serotonin-reuptake inhibitors and cognitive behavior therapy. Noninvasive brain stimulation approaches such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) have piqued interest as add-on treatment options in OCD. This review focuses on summarizing the TMS and tDCS studies in OCD with respect to their study design and stimulation parameters and key findings. We also briefly discuss the limitations and future directions noninvasive brain stimulation in OCD.

Safety and efficacy of adjunctive transcranial direct current stimulation in treatment-resistant obsessive-compulsive disorder: An open-label trial

INTRODUCTION

The current pharmacological and psychotherapeutic approaches have limited benefit in symptom management of obsessive-compulsive disorder (OCD) urging clinicians and researchers to seek newer avenues of management. Transcranial direct current stimulation (tDCS) has shown promise in this aspect from a neuromodulatory perspective. The current study aims to study the response to tDCS as an adjunctive treatment in patients with treatment-resistant OCD.

MATERIALS AND METHODS

This open-label study was conducted among 20 patients with treatment-resistant OCD. All participants received 20 sessions of tDCS with the cathode at the supplementary motor area (SMA) and the anode at right occipital area. The primary outcome measure was the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) and the secondary outcome was evaluated on the clinical global impression (CGI) and side effect checklist for tDCS.

RESULTS

There was a significant improvement from baseline in the mean scores of Y-BOCS and CGI scales after tDCS intervention. An improvement of >35% Y-BOCS score change was observed in 15% of participants. Short-lasting side effects were reported as mild headache and localized tingling sensation.

CONCLUSION

Cathodal tDCS at SMA may be a useful approach to manage treatment-resistant OCD. The use of tDCS was not associated with any significant harmful consequence to the participants.

Transcranial direct current stimulation for Obsessive-Compulsive Disorder: patient selection and perspectives

Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique that has been increasingly examined as an alternative treatment modality for Obsessive-Compulsive Disorder (OCD), due to its low costs, ease of use, and portability. Previous studies have suggested that tDCS may achieve a reasonably good response and present a safe tolerability profile. However, at this point there is not strong evidence for the use of this modality of treatment. Considering that OCD is very heterogeneous with regard to clinical presentation, clinical severity and comorbidities, we have conducted a systematic review of studies on tDCS for OCD aiming to evaluate the clinical characteristics of the selected patients and to discuss perspectives for future studies. A literature search was conducted from inception until March 2019 at PubMed/MedLine and Scielo using the following keywords: "tdcs" or "transcranial direct current stimulation" and "obsessive compulsive disorder". Out of 45 manuscripts, twelve were included. Most of the included studies are uncontrolled. A few controlled studies reported improvement of OCD, but some limitations need to be considered. Our main findings were that the selected patients were adults with severe OCD and psychiatric comorbidities, medicated at the time of assessment and resistant to at least one previous conventional treatment. We could not find any studies including specific populations such as adolescents, elderly, pregnant and breastfeeding participants. Similarly, the potential use of tDCS has not been tested in patients with less severe OCD, as a first treatment option, or for those who do not tolerate pharmacological treatments. These opportunities should be explored in future controlled trials.

Effectiveness of tDCS augmentation for co-morbid obsessive compulsive disorder in chronic schizophrenia: A case report

Management of obsessive compulsive disorder (OCD) remains a challenge, particularly in individuals having co-existing psychotic symptoms. Even in patients with schizophrenia having a fair to good response in psychotic symptoms, these obsessive-compulsive symptoms defy response to antipsychotic and anti-obsessive pharmaco-therapeutic approach to a great extent. Recently developed neuromodulation techniques such as transcranial direct current stimulation (tDCS) can serve a viable and effective approach to manage such cases. The present paper documents the first utilization of tDCS (cathode: supplementary motor area; anode: right occipital cortex) as an add-on approach to pharmacotherapy to manage co-morbid OCD in a case of chronic schizophrenia.

Immediate Effects of Transcranial Direct Current Stimulation on Obsession-Induced Anxiety in Refractory Obsessive-Compulsive Disorder: A Pilot Study

OBJECTIVE

Studies have shown that transcranial direct current stimulation (tDCS) has immediate effects on brain activity. The aim of this study was to investigate the potential use of tDCS to regulate obsession-induced anxiety immediately after symptom provocation in patients with refractory obsessive-compulsive disorder (OCD).

METHODS

Twelve patients with refractory OCD received cathode, anode, and sham transcranial direct current stimulation over the medial prefrontal cortex conjugant to pharmacological treatment in a crossover design. Before and after the DC stimulation, patients graded the intensity of their anxiety after a short exposure to a provoking stimulus using the visual analogue scale. Clinical questionnaires assessing symptoms severity were also applied before each stimulation mode.

RESULTS

We found a statistically significant decrease in the severity of the obsession-induced anxiety (decreased visual analogue scale) as a result of cathode tDCS in comparison with the anode and sham stimulation. Reduction in obsession-induced anxiety was consistent, yet short lasting, and was independent of symptom severity.

CONCLUSIONS

Cathode tDCS could be potentially used to regulate obsession-induced anxiety in refractory OCD patients. Further studies are warranted to confirm our results as well as to determine whether tDCS can achieve prolonged benefits in OCD and be of aid in behavioral treatments based on exposure.

Transcranial Direct Current Stimulation in Psychiatric Disorders: A Comprehensive Review

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that has been gaining favor as a viable tool in Psychiatry. The purpose of this review is to summarize the evidence of tDCS as a treatment of disorders such as depression, schizophrenia, and obsessive-compulsive disorder (OCD). Current findings indicate that tDCS is probably effective in non-treatment-resistant depressive patients. Regarding schizophrenia and OCD, present evidence is not robust enough, although preliminary results indicate that tDCS is a promising technique. Therefore, more trials are needed before using tDCS in a clinical setting.

Transcranial Direct Current Stimulation in Obsessive-Compulsive Disorder, Posttraumatic Stress Disorder, and Anxiety Disorders

Obsessive-compulsive disorder (OCD), posttraumatic stress disorder (PTSD), and anxiety disorders share the basic clinical feature of anxiety, which probably explains their common response to similar pharmacological and psychological interventions. Transcranial direct current stimulation (tDCS) is a neuromodulation technique that has proved effective in reducing the symptoms of a number of neuropsychiatric disorders. It was also used in healthy subjects to modulate neuropsychological processes that are involved in the pathophysiology of anxiety. We review the published studies in which tDCS was administered to patients with OCD, PTSD, or anxiety disorders. Our systematic search in the major electronic databases resulted in 14 articles for OCD, 1 for an OCD-related disorder (ie, hoarding disorder), 2 for PTSD, and 2 for anxiety disorders. In the studies involving OCD patients, tDCS was targeted to either the dorsolateral prefrontal cortex or the orbitofrontal cortex or the pre-supplementary motor area and induced a clear reduction of obsessive-compulsive symptoms. However, the lack of sham control groups and the great diversity in sample selection and tDCS protocols among studies prevent us from generalizing these results. In the studies involving PTSD and anxiety disorders patients, tDCS was applied over the dorsolateral prefrontal cortex and reduced symptoms, but the number of treated patients is too little to draw any conclusion on efficacy. However, these reports highlighted the importance of combining tDCS with different procedures, including computerized tasks and behavioral paradigms. In conclusion, even in its infancy, the use of tDCS for the treatment of OCD, PTSD, and anxiety disorders does show promise and deserves extensive research effort.

Normal Electrical Activity of the Brain in Obsessive-Compulsive Patients After Anodal Stimulation of the Left Dorsolateral Prefrontal Cortex

Introduction:

Transcranial Direct Current Stimulation (tDCS) has been used as a non-invasive method to increase the plasticity of brain. Growing evidence has shown several brain disorders such as depression, anxiety disorders, and chronic pain syndrome are improved following tDCS. In patients with Obsessive-Compulsive Disorder (OCD), increased brain rhythm activity particularly in the frontal lobe has been reported in several studies using Eectroencephalogram (EEG). To our knowledge, no research has been done on the effects of electrical stimulation on brain signals of patients with OCD. We measured the electrical activity of the brain using EEG in patients with OCD before and after tDCS and compared it to normal participants.

Methods:

Eight patients with OCD (3 males) and 8 matched healthy controls were recruited. A 64-channel EEG was used to record a 5-min resting state before and after application of tDCS in both groups. The intervention of tDCS was applied for 15 minutes with 2 mA amplitude where anode was placed on the left Dorsolateral Prefrontal Cortex (DLPFC) and cathode on the right DLPFC.

Results:

In line with previous studies, the results showed that the power of Delta frequency band in OCD patients are significantly higher than the normal group. Following anodal tDCS, hyperactivity in Delta and Theta bands declined in most channels, particularly in DLPFC (F3, F4) and became similar to normal signals pattern. The reduction in Delta band was significantly more than the other bands.

Conclusion:

Anodal tDCS over the left DLPFC significantly decreased the power of frequency bands of Delta and Theta in Patients with OCD. The pattern of EEG activity after tDCS became particularly similar to normal, so tDCS may have potential clinical application in these patients.

Modulation of Electrophysiology by Transcranial Direct Current Stimulation in Psychiatric Disorders: A Systematic Review

OBJECTIVE

Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique increasingly used to relieve symptoms of psychiatric disorders. Electrophysiologic markers, such as electroencephalography (EEG) and event-related potentials (ERP), have high temporal resolution sensitive to detect plastic changes of the brain associated with symptomatic improvement following tDCS application.

METHODS

We performed systematic review to identify electrophysiological markers that reflect tDCS effects on plastic brain changes in psychiatric disorders. A total of 638 studies were identified by searching PubMed, Embase, psychINFPO. Of these, 21 full-text articles were assessed eligible and included in the review.

RESULTS

Although the reviewed studies were heterogeneous in their choices of tDCS protocols, targeted electrophysiological markers, and disease entities, their results strongly support EEG/ERPs to sensitively reflect plastic brain changes and the associated symptomatic improvement following tDCS.

CONCLUSION

EEG/ERPs may serve a potent tool in revealing the mechanisms underlying psychiatric symptoms, as well as in localizing the brain area targeted for stimulation. Future studies in each disease entities employing consistent tDCS protocols and electrophysiological markers would be necessary in order to substantiate and further elaborate the findings of studies included in the present systematic review.

Transcranial Direct Current Stimulation for Obsessive-Compulsive Disorder: A Systematic Review

Despite the advances in psychopharmacology and established psychotherapeutic interventions, more than 40% of patients with obsessive-compulsive disorder (OCD) do not respond to conventional treatment approaches. Transcranial direct current stimulation (tDCS) has been recently proposed as a therapeutic tool to alleviate treatment-resistant symptoms in patients with OCD. The aim of this review was to provide a comprehensive overview of the current state of the art and future clinical applications of tDCS in patients with OCD. A literature search conducted on the PubMed database following PRISMA guidelines and completed by a manual search yielded 12 results: eight case reports, three open-label studies (with 5, 8, and 42 participants), and one randomized trial with two active conditions (12 patients). There was no sham-controlled study. A total of 77 patients received active tDCS with a large diversity of electrode montages mainly targeting the dorsolateral prefrontal cortex, the orbitofrontal cortex or the (pre-) supplementary motor area. Despite methodological limitations and the heterogeneity of stimulation parameters, tDCS appears to be a promising tool to decrease obsessive-compulsive symptoms as well as comorbid depression and anxiety in patients with treatment-resistant OCD. Further sham-controlled studies are needed to confirm these preliminary results.

Limited output transcranial electrical stimulation (LOTES-2017): Engineering principles, regulatory statutes, and industry standards for wellness, over-the-counter, or prescription devices with low risk

We present device standards for low-power non-invasive electrical brain stimulation devices classified as limited output transcranial electrical stimulation (tES). Emerging applications of limited output tES to modulate brain function span techniques to stimulate brain or nerve structures, including transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), and transcranial pulsed current stimulation (tPCS), have engendered discussion on how access to technology should be regulated. In regards to legal regulations and manufacturing standards for comparable technologies, a comprehensive framework already exists, including quality systems (QS), risk management, and (inter)national electrotechnical standards (IEC). In Part 1, relevant statutes are described for medical and wellness application. While agencies overseeing medical devices have broad jurisdiction, enforcement typically focuses on those devices with medical claims or posing significant risk. Consumer protections regarding responsible marketing and manufacture apply regardless. In Part 2 of this paper, we classify the electrical output performance of devices cleared by the United States Food and Drug Administration (FDA) including over-the-counter (OTC) and prescription electrostimulation devices, devices available for therapeutic or cosmetic purposes, and devices indicated for stimulation of the body or head. Examples include iontophoresis devices, powered muscle stimulators (PMS), cranial electrotherapy stimulation (CES), and transcutaneous electrical nerve stimulation (TENS) devices. Spanning over 13 FDA product codes, more than 1200 electrical stimulators have been cleared for marketing since 1977. The output characteristics of conventional tDCS, tACS, and tPCS techniques are well below those of most FDA cleared devices, including devices that are available OTC and those intended for stimulation on the head. This engineering analysis demonstrates that with regard to output performance and standing regulation, the availability of tDCS, tACS, or tPCS to the public would not introduce risk, provided such devices are responsibly manufactured and legally marketed. In Part 3, we develop voluntary manufacturer guidance for limited output tES that is aligned with current regulatory standards. Based on established medical engineering and scientific principles, we outline a robust and transparent technical framework for ensuring limited output tES devices are designed to minimize risks, while also supporting access and innovation. Alongside applicable medical and government activities, this voluntary industry standard (LOTES-2017) further serves an important role in supporting informed decisions by the public.

Anodal transcranial direct current stimulation over right dorsolateral prefrontal cortex alters decision making during approach-avoidance conflict

Approach-avoidance conflict (AAC) refers to situations associated with both rewarding and threatening outcomes. The AAC task was developed to measure AAC decision-making. Approach behavior during this task has been linked to self-reported anxiety sensitivity and has elicited anterior cingulate, insula, caudate and right dorsolateral prefrontal cortex (dlPFC) activity, with right lateral PFC tracking the extent of approach behavior. Guided by these results, we used excitatory transcranial direct current stimulation (tDCS) to demonstrate the causal involvement of right dlPFC in AAC decision-making. Participants received anodal tDCS at 1.5mA over either left or right dlPFC or sham stimulation, while performing the AAC task and a control short-term memory task. Analyses of variance (ANOVA) revealed that for individuals with high anxiety sensitivity excitatory right (but not left or sham) dlPFC stimulation elicited measurable decreases in approach behavior during conflict. Excitatory left (but not right or sham) dlPFC simulation improved performance on the control task. These results support a possible asymmetry between the contributions of right and left dlPFC to AAC resolution during emotional decision-making. Increased activity in right dlPFC may contribute to anxiety-related symptoms and, as such, serve as a neurobehavioral target of anxiolytic treatments aiming to decrease avoidance behavior.

Efficacy of Transcranial Direct Current Stimulation in the Treatment: Resistant Patients who Suffer from Severe Obsessive-compulsive Disorder

BACKGROUND

During the past years, significant efforts have been made to explain the biological backgrounds of obsessive-compulsive disorder (OCD). Cortical-subcortical and neurotransmitter models are used for explaining the symptoms of OCD, so our hypothesis is that brain's transcranial direct current stimulation (TDCS) can regulate the brain activities of the OCD patients. Thus, based on the mentioned issues, this research seeks to investigate the efficacy of TDCS in treatment-resistant patients who suffer from severe OCD.

MATERIALS AND METHODS

The present study is a clinical trial research which was based on the available sampling method, 42 treatment-resistant patients who suffer from severe OCD were selected as research's samples (2015-2016). Medical intervention protocol in this study is TDCS cathode type that was done in 15 sessions for 3 consecutive weeks (each session was conducted for 30 min daily). Yale-Brown Obsessive-Compulsive Scale was used for evaluating the efficacy of TDCS method during the 1^st, 5^th, 10^th, and 15^th sessions and it was also used for checking the 1^st and 3^rd monthly follow-up phases.

RESULTS

Variance within-group analysis (repeated measure) showed that the mean differences in the different stages of evaluation are significant (seven stages of evaluation).

CONCLUSION

TDCS can be introduced as an appropriate, strong tool for regulating the brain - behavioral systems and it can also be introduced as a suitable alternative treatment for treatment-resistant patients who suffer from severe OCD.

Transcranial direct current stimulation as a motor neurorehabilitation tool: an empirical review

The present review collects the most relevant empirical evidence available in the literature until date regarding the effects of transcranial direct current stimulation (tDCS) on the human motor function. tDCS in a non-invasive neurostimulation technique that delivers a weak current through the brain scalp altering the cortical excitability on the target brain area. The electrical current modulates the resting membrane potential of a variety of neuronal population (as pyramidal and gabaergic neurons); raising or dropping the firing rate up or down, depending on the nature of the electrode and the applied intensity. These local changes additionally have shown long-lasting effects, evidenced by its promotion of the brain-derived neurotrophic factor. Due to its easy and safe application and its neuromodulatory effects, tDCS has attracted a big attention in the motor neurorehabilitation field among the last years. Therefore, the present manuscript updates the knowledge available about the main concept of tDCS, its practical use, safety considerations, and its underlying mechanisms of action. Moreover, we will focus on the empirical data obtained by studies regarding the application of tDCS on the motor function of healthy and clinical population, comprising motor deficiencies of a variety of pathologies as Parkinson's disease, stroke, multiple sclerosis and cerebral palsy, among others. Finally, we will discuss the main current issues and future directions of tDCS as a motor neurorehabilitation tool.

Test-retest reliability of prefrontal transcranial Direct Current Stimulation (tDCS) effects on functional MRI connectivity in healthy subjects

Transcranial Direct Current Stimulation (tDCS) of the prefrontal cortex (PFC) can be used for probing functional brain connectivity and meets general interest as novel therapeutic intervention in psychiatric and neurological disorders. Along with a more extensive use, it is important to understand the interplay between neural systems and stimulation protocols requiring basic methodological work. Here, we examined the test-retest (TRT) characteristics of tDCS-induced modulations in resting-state functional-connectivity MRI (RS fcMRI). Twenty healthy subjects received 20minutes of either active or sham tDCS of the dorsolateral PFC (2mA, anode over F3 and cathode over F4, international 10-20 system), preceded and ensued by a RS fcMRI (10minutes each). All subject underwent three tDCS sessions with one-week intervals in between. Effects of tDCS on RS fcMRI were determined at an individual as well as at a group level using both ROI-based and independent-component analyses (ICA). To evaluate the TRT reliability of individual active-tDCS and sham effects on RS fcMRI, voxel-wise intra-class correlation coefficients (ICC) of post-tDCS maps between testing sessions were calculated. For both approaches, results revealed low reliability of RS fcMRI after active tDCS (ICC_(2,1) = -0.09 - 0.16). Reliability of RS fcMRI (baselines only) was low to moderate for ROI-derived (ICC_(2,1) = 0.13 - 0.50) and low for ICA-derived connectivity (ICC_(2,1) = 0.19 - 0.34). Thus, for ROI-based analyses, the distribution of voxel-wise ICC was shifted to lower TRT reliability after active, but not after sham tDCS, for which the distribution was similar to baseline. The intra-individual variation observed here resembles variability of tDCS effects in motor regions and may be one reason why in this study robust tDCS effects at a group level were missing. The data can be used for appropriately designing large scale studies investigating methodological issues such as sources of variability and localisation of tDCS effects.

The application of tDCS for the treatment of psychiatric diseases

Neuroplasticity represents the dynamic structural and functional reorganization of the central nervous system, including its connectivity, due to environmental and internal demands. It is recognized as a major physiological basis for adaption of cognition and behaviour, and, thus, of utmost importance for normal brain function. Cognitive dysfunctions are major symptoms in psychiatric disorders, which are often associated with pathological alteration of neuroplasticity. Transcranial direct current stimulation (tDCS), a recently developed non-invasive brain stimulation technique, is able to induce and modulate cortical plasticity in humans via the application of relatively weak current through the scalp of the head. It has the potential to alter pathological plasticity and restore dysfunctional cognitions in psychiatric diseases. In the last decades, its efficacy to treat psychiatric disorders has been explored increasingly. This review will give an overview of pathological alterations of plasticity in psychiatric diseases, gather clinical studies involving tDCS to ameliorate symptoms, and discuss future directions of application, with an emphasis on optimizing stimulation effects.

Prefrontal tDCS and sertraline in obsessive compulsive disorder: a case report and review of the literature

Obsessive-compulsive (OC) disorder is a disabling disorder resulting in tremendous individual and social burden. It has a large overlap with depression and anxiety disorders and shows treatment resistance in a relevant proportion of patients. Since a couple of years, different noninvasive brain stimulation methods have been investigated to improve OC symptoms. The application of transcranial direct current stimulation (tDCS) has shown inconsistent results which can probably be attributed to a lack in randomized controlled trials with adequate sample size. Anodal stimulation of pre-supplementary motor areas has shown promising results, and there is also sparse data on orbitofrontal and prefrontal stimulation. Here, we provide the first report on a patient with treatment-refractory OC disorder treated with sertraline and an enhanced prefrontal tDCS protocol (twice per day, 10 days) with a classic left-anodal/right cathodal montage, experiencing a 22% reduction of OC symptoms as well as reduction in depression (-10%) and anxiety symptoms (-21%). Due to multifactorial origin of OC disorder and the variety of brain circuits involved, there are probably multiple approaches for brain stimulation regarding site, polarity, and frequency to be assessed in future studies.

Transcranial direct current stimulation for obsessive-compulsive disorder: A randomized, controlled, partial crossover trial

BACKGROUND

Presupplementary motor area (pre-SMA) hyperactivity has been detected in obsessive-compulsive disorder (OCD) patients. However, it is not understood whether this is a putative primary cause or a compensatory mechanism in OCD pathophysiology. Considering the polarity-dependent effects on cortical excitability of transcranial direct current stimulation (tDCS), we applied cathodal and/or anodal tDCS to the pre-SMA of OCD patients to test which current polarity might better improve symptoms.

METHODS

Twelve OCD patients received initially 10 anodal (n = 6) or cathodal (n = 6) daily consecutive 2 mA/20 min tDCS sessions with the active electrode placed bilaterally on the pre-SMA. In case of improvement or no change in symptoms severity, the subjects were maintained on the same current polarity for 10 more sessions. In case of symptoms worsening after the first 10 sessions they were switched to the other polarity for 10 more sessions to test the hypothesis of a polarity-dependent effect. Therefore, each subject received 20 tDCS sessions. The Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) and the Sheehan Disability Scale (SDS) were administered biweekly to assess changes in symptoms severity.

RESULTS

After 10 sessions, 50% of patients who initially received anodal stimulation were switched to cathodal, while 100% of patients initially assigned to cathodal stimulation continued on the same polarity. At the end of the study, a statistically significant decrease was observed in the mean Y-BOCS scores of those patients who underwent cathodal tDCS. No pre-post difference was found in the scores of patients following anodal tDCS.

CONCLUSIONS

Cathodal but not anodal tDCS over the pre-SMA significantly improved OCD symptoms.

Transcranial magnetic stimulation and transcranial direct current stimulation appear to be safe neuromodulatory techniques useful in the treatment of anxiety disorders and other neuropsychiatric disorders

ABSTRACT Transcranial magnetic stimulation (TMS) has recently been investigated as a possible adjuvant treatment for many neuropsychiatric disorders, and has already been approved for the treatment of drug-resistant depression in the United States and in Brazil, among other countries. Although its use in other neuropsychiatric disorders is still largely experimental, many physicians have been using it as an off-label add-on therapy for various disorders. More recently, another technique, transcranial direct current stimulation (tDCS), has also become available as a much cheaper and portable alternative to TMS, although its mechanisms of action are different from those of TMS. The use of off-label therapeutic TMS or tDCS tends to occur in the setting of diseases that are notoriously resistant to other treatment modalities. Here we discuss the case of anxiety disorders, namely panic and post-traumatic stress disorders, highlighting the uncertainties and potential problems and benefits of the clinical use of these neuromodulatory techniques at the current stage of knowledge.

[Transcranial direct current stimulation: new clinical roadmaps for psychiatric research]

Transcranial direct current stimulation (tDCS) is a neuromodulatory technique that has undergone intensive research over the past decade with promising results. tDCS is based on the application of weak, direct current over the scalp, leading to cortical hypo- or hyperpolarization according to the specified parameters. Recent studies have shown that tDCS is able to induce potent changes in cortical excitability as well as to elicit long-lasting modifications in brain activity. Over the last decade, tDCS physiological mechanisms of action have been intensively investigated. This research has given support for the investigation of tDCS applications in a wide range of clinical populations, including patients with post-stroke motor and language deficits, chronic pain, and tinnitus. Recently, its efficacy to treat psychiatric conditions has been explored increasingly. In this review, we will gather clinical studies involving tDCS to ameliorate psychiatric symptoms and discuss reasonable next steps in this direction.

Current Status of Transcranial Direct Current Stimulation in Posttraumatic Stress and Other Anxiety Disorders

Several empirically supported treatments have been identified for post-traumatic stress disorder (PTSD), yet a sizable number of patients are either unable to tolerate these approaches or remain symptomatic following treatment. Transcranial direct current stimulation (tDCS) is a well-tolerated method of modulating neuronal excitability that may hold promise as a novel intervention in PTSD and related disorders. The current review summarizes literature on the disrupted neural circuitry in PTSD and discusses the rationale for the commonly targeted prefrontal cortex (PFC) as it relates to PTSD. We then review the few prior (case) studies that have evaluated tDCS in patients with PTSD (1 study) and other anxiety disorders (4 studies). There was considerable variability in both the methods/justification for selecting the targeted brain region(s) and the tDCS montage used, which obscured any clear trends in the data. Finally, we describe the rationale for our ongoing study that specifically targets the lateral temporal cortex as a method of treating the symptoms of hyperarousal and re-experiencing in PTSD. Overall, it is clear that additional work is needed to establish dosing (e.g., intensity and duration of sessions, number of sessions) and optimal treatment targets as well as to identify synergistic effects with existing treatments.

The application of tDCS in psychiatric disorders: a brain imaging view

Background

Transcranial direct current stimulation (tDCS) is a non-invasive, non-convulsive technique for modulating brain function. In contrast to other non-invasive brain stimulation techniques, where costs, clinical applicability, and availability limit their large-scale use in clinical practices, the low-cost, portable, and easy-to-use tDCS devices may overcome these restrictions.

Objective

Despite numerous clinical applications in large numbers of patients suffering from psychiatric disorders, it is not quite clear how tDCS influences the mentally affected human brain. In order to decipher potential neural mechanisms of action of tDCS in patients with psychiatric conditions, we focused on the combination of tDCS with neuroimaging techniques.

Design

We propose a contemporary overview on the currently available neurophysiological and neuroimaging data where tDCS has been used as a research or treatment tool in patients with psychiatric disorders.

Results

Over a reasonably short period of time, tDCS has been broadly used as a research tool to examine neuronal processes in the healthy brain. tDCS has also commonly been applied as a treatment application in a variety of mental disorders, with to date no straightforward clinical outcome and not always accompanied by brain imaging techniques.

Conclusion

tDCS, as do other neuromodulation devices, clearly affects the underlying neuronal processes. However, research on these mechanisms in psychiatric patients is rather limited. A better comprehension of how tDCS modulates brain function will help us to define optimal parameters of stimulation in each indication and may result in the detection of biomarkers in favor of clinical response.

A systematic review of the clinical efficacy of transcranial direct current stimulation (tDCS) in psychiatric disorders

Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique, which can be used to selectively disrupt patterns of neural activity that are associated with symptoms of mental illness. tDCS has been implemented in numerous therapeutic trials across a range of patient populations, with a rapidly increasing number of studies being published each year. This systematic review aimed to evaluate the efficacy of tDCS in the treatment of psychiatric disorders. Four electronic databases were searched from inception until December 2015 by two independent reviewers, and 66 eligible studies were identified. Depression was the most extensively researched condition, followed by schizophrenia and substance use disorders. Data on obsessive compulsive disorder, generalised anxiety disorder, and anorexia nervosa were also obtained. The quality of included studies was appraised using a standardised assessment framework, which yielded a median score corresponding to "weak" on the three-point scale. This improved to "moderate" when case reports/series were excluded from the analysis. Overall, data suggested that tDCS interventions comprising multiple sessions can ameliorate symptoms of several major psychiatric disorders, both acutely and in the long-term. Nevertheless, the tDCS field is still in its infancy, and several methodological and ethical issues must be addressed before clinical efficacy can truly be determined. Studies probing the mechanisms of action of tDCS and those facilitating the definition of optimised stimulation protocols are warranted. Furthermore, evidence from large-scale, multi-centre randomised controlled trials is required if the transition of this therapy from the laboratory to the clinic is to be considered.

Transcranial direct current stimulation in treatment-resistant obsessive-compulsive disorder: An open-label pilot study

BACKGROUND

Obsessive-compulsive disorder (OCD) is a severe mental illness. OCD symptoms are often resistant to available treatments. Abnormalities within the orbitofronto-striato-pallido-thalamic circuitry, especially orbitofrontal cortex (OFC) hyperactivity and cerebellar hypoactivity have been observed in patients. Non-invasive brain stimulation studies have indicated that transcranial direct current stimulation (tDCS) may be a useful alternative to alleviate treatment-resistant symptoms in various neuropsychiatric conditions.

METHODS

In an open-label pilot study, 8 patients with treatment-resistant OCD received 10 sessions (twice a day) of 2mA tDCS applied with the cathode over the left OFC and the anode over the right cerebellum. OCD (Y-BOCS and OCD-VAS) as well as depressive (MADRS) symptoms were measured 4 times: one time before tDCS and 3 times after (immediately after, 1 and 3months after the 10th tDCS session).

RESULTS

We reported a significant 26.4% (±15.8) decrease of Y-BOCS score (p=0.002). The beneficial effect lasted during the 3month follow-up. No effect of tDCS was observed on depressive symptoms. At end point, 5 out of 8 patients had a decrease of ≥25%; and 3 out of 8 patients had a decrease of ≥35% in Y-BOCS score. tDCS was well tolerated.

CONCLUSION

tDCS with the cathode placed over the left OFC combined with the anode placed over the right cerebellum is a suitable and safe approach to decrease OCD symptoms in patients with treatment-resistant OCD. Large scale randomized controlled studies are needed to confirm this promising result.

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.

Polarity-dependent effects of transcranial direct current stimulation in obsessive-compulsive disorder

About one third of patients with obsessive-compulsive disorder (OCD) fail to experience significant clinical benefit from currently available treatments. Hyperactivity of the presupplementary motor area (pre-SMA) has been detected in OCD patients, but it is not clear whether it is the primary cause or a secondary compensatory mechanism in OCD pathophysiology. Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique with polarity-dependent effects on motor cortical excitability. A 33-year-old woman with treatment-resistant OCD received 20 daily consecutive 2 mA/20 min tDCS sessions with the active electrode placed on the pre-SMA, according to the 10-20 EEG system, and the reference electrode on the right deltoid. The first 10 sessions were anodal, while the last 10 were cathodal. Symptoms severity was assessed using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) severity score. In the end of anodal stimulation, OCD symptoms had worsened. Subsequent cathodal stimulation induced a dramatic clinical improvement, which led to an overall 30% reduction in baseline symptoms severity score on the Y-BOCS. Our study supports the hypothesis that pre-SMA hyperfunction might be responsible for OCD symptoms and shows that cathodal inhibitory tDCS over this area might be an option when dealing with treatment-resistant OCD.

Transcranial direct current stimulation in obsessive-compulsive disorder: emerging clinical evidence and considerations for optimal montage of electrodes

BACKGROUND

Neuromodulation techniques for obsessive-compulsive disorder (OCD) treatment have expanded with greater understanding of the brain circuits involved. Transcranial direct current stimulation (tDCS) might be a potential new treatment for OCD, although the optimal montage is unclear.

OBJECTIVE

To perform a systematic review on meta-analyses of repetitive transcranianal magnetic stimulation (rTMS) and deep brain stimulation (DBS) trials for OCD, aiming to identify brain stimulation targets for future tDCS trials and to support the empirical evidence with computer head modeling analysis.

METHODS

Systematic reviews of rTMS and DBS trials on OCD in Pubmed/MEDLINE were searched. For the tDCS computational analysis, we employed head models with the goal of optimally targeting current delivery to structures of interest.

RESULTS

Only three references matched our eligibility criteria. We simulated four different electrodes montages and analyzed current direction and intensity.

CONCLUSION

Although DBS, rTMS and tDCS are not directly comparable and our theoretical model, based on DBS and rTMS targets, needs empirical validation, we found that the tDCS montage with the cathode over the pre-supplementary motor area and extra-cephalic anode seems to activate most of the areas related to OCD.

Transcranial cortical stimulation in the treatment of obsessive-compulsive disorders: efficacy studies

Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) are non-invasive brain stimulation methods that became widely used as therapeutic tools during the past two decades especially in cases of depression and schizophrenia. Low frequency rTMS and cathodal effect of tDCS inhibits cortical functioning while high frequency and anodal effect of tDCS have the opposite effect. Prolonged and repetitive application of either methods leads to changes in excitability of the human cortex that outlast the period of stimulation. Both rTMS and tDCS induce functional changes in the brain-modulating neural activity at cortical level. This paper reviews rTMS and tDCS effects in clinical trials for obsessive-compulsive disorder (OCD). Low frequency rTMS, particularly targeting the supplementary motor area and the orbital frontal cortex, seems to be the most promising in terms of therapeutic efficacy while older studies targeting the prefrontal dorsal cortex were not as successful. tDCS clearly needs to be investigated in large scale and sufficiently powered randomized control studies. From a general point of view, these non-invasive techniques hold promise as novel therapeutic tools for OCD patients.

Transcranial direct current stimulation in psychiatric disorders

The interest in non-invasive brain stimulation techniques is increasing in recent years. Among these techniques, transcranial direct current stimulation (tDCS) has been the subject of great interest among researchers because of its easiness to use, low cost, benign profile of side effects and encouraging results of research in the field. This interest has generated several studies and randomized clinical trials, particularly in psychiatry. In this review, we provide a summary of the development of the technique and its mechanism of action as well as a review of the methodological aspects of randomized clinical trials in psychiatry, including studies in affective disorders, schizophrenia, obsessive compulsive disorder, child psychiatry and substance use disorder. Finally, we provide an overview of tDCS use in cognitive enhancement as well as a discussion regarding its clinical use and regulatory and ethical issues. Although many promising results regarding tDCS efficacy were described, the total number of studies is still low, highlighting the need of further studies aiming to replicate these findings in larger samples as to provide a definite picture regarding tDCS efficacy in psychiatry.

Alterations in interhemispheric functional and anatomical connectivity are associated with tobacco smoking in humans

Abnormal interhemispheric functional connectivity correlates with several neurologic and psychiatric conditions, including depression, obsessive-compulsive disorder, schizophrenia, and stroke. Abnormal interhemispheric functional connectivity also correlates with abuse of cannabis and cocaine. In the current report, we evaluated whether tobacco abuse (i.e., cigarette smoking) is associated with altered interhemispheric connectivity. To that end, we examined resting state functional connectivity (RSFC) using magnetic resonance imaging (MRI) in short term tobacco deprived and smoking as usual tobacco smokers, and in non-smoker controls. Additionally, we compared diffusion tensor imaging (DTI) in the same subjects to study differences in white matter. The data reveal a significant increase in interhemispheric functional connectivity in sated tobacco smokers when compared to controls. This difference was larger in frontal regions, and was positively correlated with the average number of cigarettes smoked per day. In addition, we found a negative correlation between the number of DTI streamlines in the genual corpus callosum and the number of cigarettes smoked per day. Taken together, our results implicate changes in interhemispheric functional and anatomical connectivity in current cigarette smokers.

Neuromodulation in obsessive-compulsive disorder

Neuromodulation techniques in obsessive-compulsive disorder (OCD) involve electroconvulsive therapy (ECT), transcranial direct current stimulation (tDCS), transcranial magnetic stimulation (TMS), and deep brain stimulation (DBS). This article reviews the available literature on the efficacy and applicability of these techniques in OCD. ECT is used for the treatment of comorbid depression or psychosis. One case report on tDCS showed no effects in OCD. Low-frequency TMS provides significant but mostly transient improvement of obsessive-compulsive symptoms. DBS shows a response rate of 60% in open and sham-controlled studies. In OCD, it can be concluded that DBS, although more invasive, is the most efficacious technique.

Can transcranial direct current stimulation (tDCS) alleviate symptoms and improve cognition in psychiatric disorders?

OBJECTIVES

Since the discovery of psychopharmacological treatments in the early 1950s, followed by the development of second-generation antidepressants and antipsychotics, biological psychiatry has not achieved much progress. Recent technological advances in the field of non-invasive brain stimulation open new perspectives in the treatment of psychiatric disorders. Amongst them, transcranial direct current stimulation (tDCS) modulates cortical excitability and induces long-lasting effects. Here, we aimed at evaluating whether tDCS has potential to be developed as an innovative treatment in psychiatry.

METHODS

We conducted a systematic review of the current state of development and application of tDCS in psychiatric disorders, exploring clinical and cognitive effects, especially in major depressive disorder (MDD), schizophrenia and substance use disorder.

RESULTS

Systematic literature search yielded 40 publications: 22 in MDD, nine in schizophrenia, seven in substance use disorder, one in obsessive-compulsive disorder and one in mania. Our findings indicated beneficial clinical effects of tDCS for MDD and a promising literature in schizophrenia and substance use disorder.

CONCLUSIONS

Despite methodological differences, the data published to date are promising and supports the use of tDCS as a treatment for psychiatric disorders. However, its place regarding other treatments still has to be determined before becoming a routine clinical treatment.