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

Non-invasive brain stimulation for patients and healthy subjects: Current challenges and future perspectives

Non-invasive brain stimulation (NIBS) techniques have a rich historical background, yet their utilization has witnessed significant growth only recently. These techniques encompass transcranial electrical stimulation and transcranial magnetic stimulation, which were initially employed in neuroscience to explore the intricate relationship between the brain and behaviour. However, they are increasingly finding application in research contexts as a means to address various neurological, psychiatric, and neurodegenerative disorders. This article aims to fulfill two primary objectives. Firstly, it seeks to showcase the current state of the art in the clinical application of NIBS, highlighting how it can improve and complement existing treatments. Secondly, it provides a comprehensive overview of the utilization of NIBS in augmenting the brain function of healthy individuals, thereby enhancing their performance. Furthermore, the article delves into the points of convergence and divergence between these two techniques. It also addresses the existing challenges and future prospects associated with NIBS from ethical and research standpoints.

A Novel Insular/Orbital-Prelimbic Circuit That Prevents Persistent Avoidance in a Rodent Model of Compulsive Behavior

BACKGROUND

A common symptom of obsessive-compulsive disorder is the persistent avoidance of cues incorrectly associated with negative outcomes. This maladaptation becomes increasingly evident as subjects fail to respond to extinction-based treatments such as exposure-with-response prevention therapy. While previous studies have highlighted the role of the insular-orbital cortex in fine-tuning avoidance-based decisions, little is known about the projections from this area that might modulate compulsive-like avoidance.

METHODS

Here, we used anatomical tract-tracing, single-unit recording, and optogenetics to characterize the projections from the insular-orbital cortex. To model exposure-with-response prevention and persistent avoidance in rats, we used the platform-mediated avoidance task followed by extinction-with-response prevention training.

RESULTS

Using tract-tracing and unit recording, we found that projections from the agranular insular/lateral orbital (AI/LO) cortex to the prefrontal cortex predominantly target the rostral portion of the prelimbic (rPL) cortex and excite rPL neurons. Photoinhibiting this projection induced persistent avoidance after extinction-with-response prevention training, an effect that was still present 1 week later. Consistent with this, photoexcitation of this projection prevented persistent avoidance in overtrained rats. This projection to rPL appears to be key for AI/LO's effects, considering that there was no effect of photoinhibiting AI/LO projections to the ventral striatum or basolateral amygdala.

CONCLUSIONS

Our findings suggest that projections from the AI/LO to the rPL decreases the likelihood of avoidance behavior following extinction. In humans, this connectivity may share some homology of projections from lateral prefrontal cortices (i.e., ventrolateral prefrontal cortex, orbitofrontal cortex, and insula) to other prefrontal areas and the anterior cingulate cortex, suggesting that reduced activity in these pathways may contribute to obsessive-compulsive disorder.

Application of Transcranial Direct Current Stimulation in Psychiatry

Transcranial direct current stimulation (tDCS) is a neuromodulation technique, which noninvasively alters cortical excitability via weak polarizing currents between two electrodes placed on the scalp. Since it is comparably easy to handle, cheap to use and relatively well tolerated, tDCS has gained increasing interest in recent years. Based on well-known behavioral effects, a number of clinical studies have been performed in populations including patients with major depressive disorder followed by schizophrenia and substance use disorders, in sum with heterogeneous results with respect to efficacy. Nevertheless, the potential of tDCS must not be underestimated since it could be further improved by systematically investigating the various stimulation parameters to eventually increase clinical efficacy. The present article briefly explains the underlying physiology of tDCS, summarizes typical stimulation protocols and then reviews clinical efficacy for various psychiatric disorders as well as prevalent adverse effects. Future developments include combined and more complex interactions of tDCS with pharmacological or psychotherapeutic interventions. In particular, using computational models to individualize stimulation protocols, considering state dependency and applying closed-loop technologies will pave the way for tDCS-based personalized interventions as well as the development of home treatment settings promoting the role of tDCS as an effective treatment option for patients with mental health problems.

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.

Dosage-Dependent Impact of Acute Serotonin Enhancement on Transcranial Direct Current Stimulation Effects

BACKGROUND

The serotonergic system has an important impact on basic physiological and higher brain functions. Acute and chronic enhancement of serotonin levels via selective serotonin reuptake inhibitor administration impacts neuroplasticity in humans, as shown by its effects on cortical excitability alterations induced by non-invasive brain stimulation, including transcranial direct current stimulation (tDCS). Nevertheless, the interaction between serotonin activation and neuroplasticity is not fully understood, particularly considering dose-dependent effects. Our goal was to explore dosage-dependent effects of acute serotonin enhancement on stimulation-induced plasticity in healthy individuals.

METHODS

Twelve healthy adults participated in 7 sessions conducted in a crossover, partially double-blinded, randomized, and sham-controlled study design. Anodal and cathodal tDCS was applied to the motor cortex under selective serotonin reuptake inhibitor (20 mg/40 mg citalopram) or placebo medication. Motor cortex excitability was monitored by single-pulse transcranial magnetic stimulation.

RESULTS

Under placebo medication, anodal tDCS enhanced, and cathodal tDCS reduced, excitability for approximately 60-120 minutes after the intervention. Citalopram enhanced and prolonged the facilitation induced by anodal tDCS regardless of the dosage while turning cathodal tDCS-induced excitability diminution into facilitation. For the latter, prolonged effects were observed when 40 mg was administrated.

CONCLUSIONS

Acute serotonin enhancement modulates tDCS after-effects and has largely similar modulatory effects on motor cortex neuroplasticity regardless of the specific dosage. A minor dosage-dependent effect was observed only for cathodal tDCS. The present findings support the concept of boosting the neuroplastic effects of anodal tDCS by serotonergic enhancement, a potential clinical approach for the treatment of neurological and psychiatric disorders.

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.

Efficacy and safety of transcranial direct current stimulation as an add-on treatment for obsessive-compulsive disorder: a randomized, sham-controlled trial

Obsessive-compulsive disorder (OCD) is a frequent, disabling disorder with high rates of treatment resistance. Transcranial direct current stimulation (tDCS) is a safe, tolerable noninvasive neuromodulation therapy with scarce evidence for OCD. This double-blind, randomized, and sham-controlled study investigates the efficacy of tDCS as add-on treatment for treatment-resistant OCD (failure to respond to at least one previous pharmacological treatment). On 20 consecutive weekdays (4 weeks), 43 patients with treatment-resistant OCD underwent 30 min active or sham tDCS sessions, followed by a 8 week follow-up. The cathode was positioned over the supplementary motor area (SMA) and the anode over the left deltoid. The primary outcome was the change in baseline Y-BOCS score at week 12. Secondary outcomes were changes in mood and anxiety and the occurrence of adverse events. Response was evaluated considering percent decrease of baseline Y-BOCS scores and the Improvement subscale of the Clinical Global Impression (CGI-I) between baseline and week 12. Patients that received active tDCS achieved a significant reduction of OCD symptoms than sham, with mean (SD) Y-BOCS score changes of 6.68 (5.83) and 2.84 (6.3) points, respectively (Cohen's d: 0.62 (0.06-1.18), p = 0.03). We found no between-group differences in responders (four patients in the active tDCS and one in the sham group). Active tDCS of the SMA was not superior to sham in reducing symptoms of depression or anxiety. Patients in both groups reported mild adverse events. Our results suggest that cathodal tDCS over the SMA is an effective add-on strategy in treatment-resistant OCD.

Neuromodulation for Mild Traumatic Brain Injury Rehabilitation: A Systematic Review

Background: Mild traumatic brain injury (mTBI) results from an external force to the head or body causing neurophysiological changes within the brain. The number and severity of symptoms can vary, with some individuals experiencing rapid recovery, and others having persistent symptoms for months to years, impacting their quality of life. Current rehabilitation is limited in its ability to treat persistent symptoms and novel approaches are being sought to improve outcomes following mTBI. Neuromodulation is one technique used to encourage adaptive neuroplasticity within the brain.

Objective: To systematically review the literature on the efficacy of neuromodulation in the mTBI population.

Method: A systematic review was conducted using Medline, Embase, PsycINFO, PsycARTICLES and EBM Review. Preferred Reporting Items for Systematic Reviews and the Synthesis Without Meta-analysis reporting guidelines were used and a narrative review of the selected studies was completed. Fourteen articles fulfilled the inclusion criteria which were published in English, investigating an adult sample and using a pre- and post-intervention design. Studies were excluded if they included non-mild TBI severities, pediatric or older adult populations.

Results: Thirteen of fourteen studies reported positive reductions in mTBI symptomatology following neuromodulation. Specifically, improvements were reported in post-concussion symptom ratings, headaches, dizziness, depression, anxiety, sleep disturbance, general disability, cognition, return to work and quality of life. Normalization of working memory activation patterns, vestibular field potentials, hemodynamics of the dorsolateral prefrontal cortex and excessive delta wave activity were also seen. The studies reviewed had several methodological limitations including small, heterogenous samples and varied intervention protocols, limiting generalisability. Further research is required to understand the context in which neuromodulation may be beneficial.

Conclusions: While these positive effects are observed, limitations included unequal representation of neuromodulation modalities in the literature, and lack of literature describing the efficacy of neuromodulation on the development or duration of persistent mTBI symptoms. Better clarity regarding neuromodulation efficacy could have a significant impact on mTBI patients, researchers, clinicians, and policy makers, facilitating a more productive post-mTBI population. Despite the limitations, the literature indicates that neuromodulation warrants further investigation. PROSPERO registration number: CRD42020161279.

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.

Incisionless MR-guided focused ultrasound: technical considerations and current therapeutic approaches in psychiatric disorders

INTRODUCTION

MR-guided focused ultrasound operating at higher intensities have been reported to effectively and precisely ablate deeper brain structures like the basal ganglia or the thalamic nuclei for the treatment of refractory movement disorders, neuropathic pain and most recently neuropsychiatric disorders, while low-intensity focused ultrasound represents an approach promoting mechanical blood-brain-barrier opening and neuromodulation. This narrative review summarizes the technical development and the therapeutic potential of incisionless MRgFUS in order to treat neuropsychiatric disorders.

AREAS COVERED

A narrative review of clinical trials assessing the safety and efficacy of MRgFUS. A literature review was performed using the following search terms: MR-guided focused ultrasound, psychiatric disorders, noninvasive and invasive brain modulation/stimulation techniques.

EXPERT OPINION

MRgFUS ablation is under clinical investigation (unblinded study design) for obsessive-compulsive disorders (OCDs) [capsulotomy; ALIC] and depression/anxiety disorders [capsulotomy] and has demonstrated an improvement in OCD and depression, although of preliminary character. Low-intensity ultrasound applications have been explored in Alzheimer´s disease (phase 1 study) and healthy subjects. Currently, limited evidence hinders comparison and selection between MRgFUS and noninvasive/invasive brain modulation therapies. However, comparative, sham-controlled trials are needed to reexamine the preliminary findings for the treatment of psychiatric disorders.

Bifrontal transcranial direct current stimulation modulates fatigue in multiple sclerosis: a randomized sham-controlled study

Fatigue is a frequent and debilitating symptom in patients with central nervous system diseases. Up to 90% of patients with multiple sclerosis (MS) suffer from fatigue that drastically affects the quality of life. MS patients also complain of anxiety and depressive symptoms and these three manifestations tend to cluster together in this clinical population. The objective of this work was to assess the effects of transcranial direct stimulation (tDCS), a noninvasive brain stimulation technique, on fatigue as well as anxiety and depressive symptoms. Eleven fatigued MS patients randomly received two blocks (active and sham tDCS) of five consecutive daily sessions of bifrontal tDCS (anode/cathode over the left/right prefrontal cortices, respectively) in a crossover manner, separated by a 3-week washout interval. Evaluation took place at day 1, day 5 (right after each block) and 1 week later. Active but not sham tDCS resulted in a significant improvement of fatigue at day 5 (p < 0.05), an effect that seems to last at least 1 week following the stimulation (p = 0.05). Active tDCS also significantly improved anxiety symptoms, but the effect emerged 1 week later (p < 0.05). No significant effects were obtained regarding depression (p > 0.05). Bifrontal tDCS seems to modulate fatigue in PwMS. The observed anxiolytic effects could constitute delayed after effects of tDCS or might be mediated by fatigue improvement. These findings merit to be addressed in large-scale controlled trials.

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 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.

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.

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 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.

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.

Neuromodulation for the treatment of eating disorders and obesity

Eating disorders and obesity adversely affect individuals both medically and psychologically, leading to reduced life expectancy and poor quality of life. While there exist a number of treatments for anorexia, morbid obesity and bulimia, many patients do not respond favorably to current behavioral, medical or bariatric surgical management. Neuromodulation has been postulated as a potential treatment for eating disorders and obesity. In particular, deep brain stimulation and transcranial non-invasive brain stimulation have been studied for these indications across a variety of brain targets. Here, we review the neurobiology behind eating and eating disorders as well as the current status of preclinical and clinical neuromodulation trials for eating disorders and obesity.

The Role of Transcranial Direct Current Stimulation (tDCS) in Tourette Syndrome: A Review and Preliminary Findings

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that is being investigated for a variety of neurological and psychiatric conditions. Preliminary evidence suggests that tDCS may be useful in the treatment of Tourette Syndrome (TS). This paper reviews the literature on the use of tDCS in commonly occurring comorbid conditions that are relevant to its proposed use in TS. We describe the protocol for a double-blind, crossover, sham-controlled trial of tDCS (Trial ID: ACTRN12615000592549, registered at www.anzctr.org.au) investigating the efficacy, feasibility, safety, and tolerability of tDCS in patients with TS aged 12 years and over. The intervention consists of cathodal tDCS positioned over the Supplementary Motor Area. Patients receive either sham tDCS for three weeks followed by six weeks of active tDCS (1.4 mA, 18 sessions over six weeks), or six weeks of active sessions followed by three weeks of sham sessions, with follow-up at three and six months. Pilot findings from two patients are presented. There was a reduction in the frequency and intensity of patients’ tics and premonitory urges, as well as evidence of improvements in inhibitory function, over the course of treatment. Larger scale studies are indicated to ascertain the maintenance of symptom improvement over time, as well as the long-term consequences of the repetitions of sessions.