Deep Brain Stimulation for Obsessive Compulsive Disorder: Evolution of Surgical Stimulation Target Parallels Changing Model of Dysfunctional Brain Circuits

What can neuroimaging of neuromodulation reveal about the basis of circuit therapies for psychiatry?

Neuromodulation is increasingly becoming a therapeutic option for treatment resistant psychiatric disorders. These non-invasive and invasive therapies are still being refined but are clinically effective and, in some cases, provide sustained symptom reduction. Neuromodulation relies on changing activity within a specific brain region or circuit, but the precise mechanisms of action of these therapies, is unclear. Here we review work in both humans and animals that has provided insight into how therapies such as deep brain and transcranial magnetic stimulation alter neural activity across the brain. We focus on studies that have combined neuromodulation with neuroimaging such as PET and MRI as these measures provide detailed information about the distributed networks that are modulated and thus insight into both the mechanisms of action of neuromodulation but also potentially the basis of psychiatric disorders. Further we highlight work in nonhuman primates that has revealed how neuromodulation changes neural activity at different scales from single neuron activity to functional connectivity, providing key insight into how neuromodulation influences the brain. Ultimately, these studies highlight the value of combining neuromodulation with neuroimaging to reveal the mechanisms through which these treatments influence the brain, knowledge vital for refining targeted neuromodulation therapies for psychiatric disorders.

Effective deep brain stimulation for obsessive-compulsive disorder after failed anterior capsulotomy: illustrative cases

BACKGROUND

Obsessive-compulsive disorder (OCD) is a psychiatric condition characterized by recurrent, unwanted thoughts (obsessions) and repetitive behaviors (compulsions) performed to relieve distress related to the obsessions. For patients with severe illness refractory to first-line pharmacotherapy and psychotherapy, neurosurgical treatments such as deep brain stimulation (DBS) and stereotactic lesioning are an option. The choice between DBS and lesioning is often driven by patient preference, but these options are not mutually exclusive. Here, the authors highlight the success of one surgical therapy (DBS) after the failure of another (lesioning).

OBSERVATIONS

Two patients with severe, treatment-refractory OCD underwent DBS lead implantation targeting the ventral capsule/ventral striatum after they did not attain any worthwhile benefit from a previous anterior capsulotomy. Both patients showed significant improvement (≥ 35% reduction in Yale-Brown Obsessive-Compulsive Scale [YBOCS] score) of their OCD symptoms at the long-term follow-up after DBS. One patient experienced a 37% reduction in symptom severity as measured by the YBOCS, and the other patient experienced a 47% reduction.

LESSONS

DBS and lesioning procedures are both effective surgical options for patients with intractable OCD. In these cases, the authors demonstrate that DBS can be utilized even after a lesioning procedure in nominally the same target (ventral portion of the anterior limb of the internal capsule). https://thejns.org/doi/10.3171/CASE24289.

Multimodal Prediction of Obsessive-Compulsive Disorder and Comorbid Depression Severity and Energy Delivered by Deep Brain Electrodes

To develop reliable, valid, and efficient measures of obsessive-compulsive disorder (OCD) severity, comorbid depression severity, and total electrical energy delivered (TEED) by deep brain stimulation (DBS), we trained and compared random forests regression models in a clinical trial of participants receiving DBS for refractory OCD. Six participants were recorded during open-ended interviews at pre- and post-surgery baselines and then at 3-month intervals following DBS activation. Ground-truth severity was assessed by clinical interview and self-report. Visual and auditory modalities included facial action units, head and facial landmarks, speech behavior and content, and voice acoustics. Mixed-effects random forest regression with Shapley feature reduction strongly predicted severity of OCD, comorbid depression, and total electrical energy delivered by the DBS electrodes (intraclass correlation, ICC, = 0.83, 0.87, and 0.81, respectively. When random effects were omitted from the regression, predictive power decreased to moderate for severity of OCD and comorbid depression and remained comparable for total electrical energy delivered (ICC = 0.60, 0.68, and 0.83, respectively). Multimodal measures of behavior outperformed ones from single modalities. Feature selection achieved large decreases in features and corresponding increases in prediction. The approach could contribute to closed-loop DBS that would automatically titrate DBS based on affect measures.

Potential biomarkers and therapeutic targets for obsessive compulsive disorder: Evidences from clinical studies

Obsessive compulsive disorder (OCD) is a prevalent behavioral disorder with a complex etiology. However, the underlying pathogenic molecular pathways and the associated risk factors are largely obscure. This has hindered both the identification of relevant prognostic biomarkers and the development of effective treatment strategies. Because of the diverse range of clinical manifestations, not all patients benefit from therapies currently practiced in the clinical setting. Nevertheless, several lines of evidence indicate that neurotrophic, neurotransmitter, and oxidative signaling are involved in the pathophysiology of OCD. Based upon evidences from clinical (and pre-clinical studies), the present review paper sets out to decipher the utilities of three parameters (i.e. brain-derived neurotrophic factor; BDNF, noradrenalin-synthesizing enzyme dopamine beta-hydroxylase; DBH; and oxidative damage marker malondialdehyde; MDA) as diagnostic peripheral biomarkers as well as bio-targets for therapeutic strategies. While the data indicates promising results, there is necessitation for future studies to further confirm and establish these. Further, based again on the available clinical data, we investigated the possibilities of exploiting the etiological links between disruptions in the sleep-wake cycle and insulin signaling, and OCD for the identification of potential anti-OCD ameliorative agents with the ability to elicit multimodal effects, including attenuation of the alterations in BDNF, noradrenergic and redox pathways. In this respect, agomelatine and metformin may represent particularly interesting candidates; however, further clinical studies are warranted to establish these as singular or complementary medications in OCD subjects.

Characterization and closed-loop control of infrared thalamocortical stimulation produces spatially constrained single-unit responses

Deep brain stimulation (DBS) is a powerful tool for the treatment of circuitopathy-related neurological and psychiatric diseases and disorders such as Parkinson's disease and obsessive-compulsive disorder, as well as a critical research tool for perturbing neural circuits and exploring neuroprostheses. Electrically mediated DBS, however, is limited by the spread of stimulus currents into tissue unrelated to disease course and treatment, potentially causing undesirable patient side effects. In this work, we utilize infrared neural stimulation (INS), an optical neuromodulation technique that uses near to midinfrared light to drive graded excitatory and inhibitory responses in nerves and neurons, to facilitate an optical and spatially constrained DBS paradigm. INS has been shown to provide spatially constrained responses in cortical neurons and, unlike other optical techniques, does not require genetic modification of the neural target. We show that INS produces graded, biophysically relevant single-unit responses with robust information transfer in rat thalamocortical circuits. Importantly, we show that cortical spread of activation from thalamic INS produces more spatially constrained response profiles than conventional electrical stimulation. Owing to observed spatial precision of INS, we used deep reinforcement learning (RL) for closed-loop control of thalamocortical circuits, creating real-time representations of stimulus-response dynamics while driving cortical neurons to precise firing patterns. Our data suggest that INS can serve as a targeted and dynamic stimulation paradigm for both open and closed-loop DBS.

Spatially specific, closed-loop infrared thalamocortical deep brain stimulation

Deep brain stimulation (DBS) is a powerful tool for the treatment of circuitopathy-related neurological and psychiatric diseases and disorders such as Parkinson's disease and obsessive-compulsive disorder, as well as a critical research tool for perturbing neural circuits and exploring neuroprostheses. Electrically-mediated DBS, however, is limited by the spread of stimulus currents into tissue unrelated to disease course and treatment, potentially causing undesirable patient side effects. In this work, we utilize infrared neural stimulation (INS), an optical neuromodulation technique that uses near to mid-infrared light to drive graded excitatory and inhibitory responses in nerves and neurons, to facilitate an optical and spatially constrained DBS paradigm. INS has been shown to provide spatially constrained responses in cortical neurons and, unlike other optical techniques, does not require genetic modification of the neural target. We show that INS produces graded, biophysically relevant single-unit responses with robust information transfer in thalamocortical circuits. Importantly, we show that cortical spread of activation from thalamic INS produces more spatially constrained response profiles than conventional electrical stimulation. Owing to observed spatial precision of INS, we used deep reinforcement learning for closed-loop control of thalamocortical circuits, creating real-time representations of stimulus-response dynamics while driving cortical neurons to precise firing patterns. Our data suggest that INS can serve as a targeted and dynamic stimulation paradigm for both open and closed-loop DBS.

Thirty Years of Global Deep Brain Stimulation: "Plus ça change, plus c'est la même chose"?

BACKGROUND

The advent of deep brain stimulation (DBS) of the subthalamic nucleus (STN) for Parkinson's disease 30 years ago has ushered a global breakthrough of DBS as a universal method for therapy and research in wide areas of neurology and psychiatry. The literature of the last three decades has described numerous concepts and practices of DBS, often branded as novelties or discoveries. However, reading the contemporary publications often elicits a sense of déjà vu in relation to several methods, attributes, and practices of DBS. Here, we review various applications and techniques of the modern-era DBS and compare them with practices of the past.

SUMMARY

Compared with modern literature, publications of the old-era functional stereotactic neurosurgery, including old-era DBS, show that from the very beginning multidisciplinarity and teamwork were often prevalent and insisted upon, ethical concerns were recognized, brain circuitries and rational for brain targets were discussed, surgical indications were similar, closed-loop stimulation was attempted, evaluations of surgical results were debated, and controversies were common. Thus, it appears that virtually everything done today in the field of DBS bears resemblance to old-time practices, or has been done before, albeit with partly other tools and techniques. Movement disorders remain the main indications for modern DBS as was the case for lesional surgery and old-era DBS. The novelties today consist of the STN as the dominant target for DBS, the tremendous advances in computerized brain imaging, the sophistication and versatility of implantable DBS hardware, and the large potential for research.

KEY MESSAGES

Many aspects of contemporary DBS bear strong resemblance to practices of the past. The dominant clinical indications remain movement disorders with virtually the same brain targets as in the past, with one exception: the STN. Other novel brain targets - that are so far subject to DBS trials - are the pedunculopontine nucleus for gait freezing, the anteromedial internal pallidum for Gilles de la Tourette and the fornix for Alzheimer's disease. The major innovations and novelties compared to the past concern mainly the unmatched level of research activity, its high degree of sponsorship, and the outstanding advances in technology that have enabled multimodal brain imaging and the miniaturization, versatility, and sophistication of implantable hardware. The greatest benefit for patients today, compared to the past, is the higher level of precision and safety of DBS, and of all functional stereotactic neurosurgery.

Intraoperative valence testing to adjudicate between ventral capsule/ventral striatum and bed nucleus of the stria terminalis target selection in deep brain stimulation for obsessive-compulsive disorder

OBJECTIVE

Deep brain stimulation (DBS) is an accepted therapy for severe, treatment-refractory obsessive-compulsive disorder (trOCD). The optimal DBS target location within the anterior limb of the internal capsule, particularly along the anterior-posterior axis, remains elusive. Empirical evidence from several studies in the past decade has suggested that the ideal target lies in the vicinity of the anterior commissure (AC), either just anterior to the AC, above the ventral striatum (VS), or just posterior to the AC, above the bed nucleus of the stria terminalis (BNST). Various methods have been utilized to optimize target selection for trOCD DBS. The authors describe their practice of planning trajectories to both the VS and BNST and adjudicating between them with awake intraoperative valence testing to individualize permanent target selection.

METHODS

Eight patients with trOCD underwent awake DBS with trajectories planned for both VS and BNST targets bilaterally. The authors intraoperatively assessed the acute effects of stimulation on mood, energy, and anxiety and implanted the trajectory with the most reliable positive valence responses and least stimulation-induced side effects. The method of intraoperative target adjudication is described, and the OCD outcome at last follow-up is reported.

RESULTS

The mean patient age at surgery was 41.25 ± 15.1 years, and the mean disease duration was 22.75 ± 10.2 years. The median preoperative Yale-Brown Obsessive Compulsive Scale (Y-BOCS) score was 39 (range 34-40). Two patients had previously undergone capsulotomy, with insufficient response. Seven (44%) of 16 leads were moved to the second target based on intraoperative stimulation findings, 4 of them to avoid strong negative valence effects. Three patients had an asymmetric implant (1 lead in each target). All 8 patients (100%) met full response criteria, and the mean Y-BOCS score reduction across the full cohort was 51.2% ± 12.8%.

CONCLUSIONS

Planning and intraoperatively testing trajectories flanking the AC-superjacent to the VS anteriorly and to the BNST posteriorly-allowed identification of positive valence responses and acute adverse effects. Awake testing helped to select between possible trajectories and identify individually optimized targets in DBS for trOCD.

The current state, challenges, and future directions of deep brain stimulation for obsessive compulsive disorder

INTRODUCTION

Obsessive-compulsive disorder (OCD) is clinically and pathologically heterogenous, with symptoms often refractory to first-line treatments. Deep brain stimulation (DBS) for the treatment of refractory OCD provides an opportunity to adjust and individualize neuromodulation targeting aberrant circuitry underlying OCD. The tailoring of DBS therapy may allow precision in symptom control based on patient-specific pathology. Progress has been made in understanding the potential targets for DBS intervention; however, a consensus on an optimal target has not been agreed upon.

AREAS COVERED

A literature review of DBS for OCD was performed by querying the PubMed database. The following topics were covered: the evolution of DBS targeting in OCD, the concept of an underlying unified connectomic network, current DBS targets, challenges facing the field, and future directions which could advance personalized DBS in this challenging population.

EXPERT OPINION

To continue the increasing efficacy of DBS for OCD, we must further explore the optimal DBS response across clinical profiles and neuropsychiatric domains of OCD as well as how interventions targeting multiple points in an aberrant circuit, multiple aberrant circuits, or a connectivity hub impact clinical response. Additionally, biomarkers would be invaluable in programming adjustments and creating a closed-loop paradigm to address symptom fluctuation in daily life.

Prevalence and predicors of COVID-centred obsessive compulsive disorder among Iranian COVID-19 recovered individuals: a Bayesian analysis

BACKGROUND

The evidence on the psychological consequences of coronavirus 2019 mainly relates to general psychiatric problems, and a few studies have reported the incidence and predictors of obsessive-compulsive disorder.

OBJECTIVE

To determine the prevalence of obsessive-compulsive disorder (OCD) and its predictors in Iranian COVID - 19 recovered individuals at 3-6 months, 6-12 months, and 12-18 months after recovery.

METHOD

In this cross-sectional analytical study, 300 participants were randomly selected based on the inclusion criteria from three hospitals in three different regions of Tehran, Iran, and were assessed by the Clinical Demographic Information Questionnaire, the Obsessive Compulsive Inventory-Revised (OCI-R), the Depression, Anxiety and Stress Scale 21 (DASS21), The Pittsburgh Sleep Quality Index (PSQI) and Posttraumatic Stress Disorder Checklist for DSM-5 (PCL-5). The obtained data were analyzed with SPSS version 26.

RESULTS

The results showed that the mean score of OCD is 30.58 ± 15.22, with a prevalence of 71% (n = 213). Female gender (BF = 0.50, p = 0.01), sleep disturbance (BF = 0.02, p = 0.001), PTSD (BF = 0.009, p = 0.0001), depression (BF = 0.0001, p = 0.0001), and stress (BF = 0.0001, p = 0.001) are the strongest predictors of the presence of OCD in recovered COVID - 19 individuals.

CONCLUSION

OCD-like symptoms was observed in the majority of COVID - 19 recovered individuals with mild to moderate severity. In addition, the stated prevalence, severity, and significance varied according to sociodemographic and health inequalities.

Closed-Loop Deep Brain Stimulation for Psychiatric Disorders

ABSTRACT

Deep brain stimulation (DBS) is a well-established approach to treating medication-refractory neurological disorders and holds promise for treating psychiatric disorders. Despite strong open-label results in extremely refractory patients, DBS has struggled to meet endpoints in randomized controlled trials. A major challenge is stimulation "dosing"-DBS systems have many adjustable parameters, and clinicians receive little feedback on whether they have chosen the correct parameters for an individual patient. Multiple groups have proposed closed loop technologies as a solution. These systems sense electrical activity, identify markers of an (un)desired state, then automatically deliver or adjust stimulation to alter that electrical state. Closed loop DBS has been successfully deployed in movement disorders and epilepsy. The availability of that technology, as well as advances in opportunities for invasive research with neurosurgical patients, has yielded multiple pilot demonstrations in psychiatric illness. Those demonstrations split into two schools of thought, one rooted in well-established diagnoses and symptom scales, the other in the more experimental Research Domain Criteria (RDoC) framework. Both are promising, and both are limited by the boundaries of current stimulation technology. They are in turn driving advances in implantable recording hardware, signal processing, and stimulation paradigms. The combination of these advances is likely to change both our understanding of psychiatric neurobiology and our treatment toolbox, though the timeframe may be limited by the realities of implantable device development.

Gamma knife capsulotomy for intractable OCD: Neuroimage analysis of lesion size, location, and clinical response

Obsessive-compulsive disorder (OCD) affects 2-3% of the population. One-third of patients are poorly responsive to conventional therapies, and for a subgroup, gamma knife capsulotomy (GKC) is an option. We examined lesion characteristics in patients previously treated with GKC through well-established programs in Providence, RI (Butler Hospital/Rhode Island Hospital/Alpert Medical School of Brown University) and São Paulo, Brazil (University of São Paolo). Lesions were traced on T1 images from 26 patients who had received GKC targeting the ventral half of the anterior limb of the internal capsule (ALIC), and the masks were transformed into MNI space. Voxel-wise lesion-symptom mapping was performed to assess the influence of lesion location on Y-BOCS ratings. General linear models were built to compare the relationship between lesion size/location along different axes of the ALIC and above or below-average change in Y-BOCS ratings. Sixty-nine percent of this sample were full responders (≥35% improvement in OCD). Lesion occurrence anywhere within the targeted region was associated with clinical improvement, but modeling results demonstrated that lesions occurring posteriorly (closer to the anterior commissure) and dorsally (closer to the mid-ALIC) were associated with the greatest Y-BOCS reduction. No association was found between Y-BOCS reduction and overall lesion volume. GKC remains an effective treatment for refractory OCD. Our data suggest that continuing to target the bottom half of the ALIC in the coronal plane is likely to provide the dorsal-ventral height required to achieve optimal outcomes, as it will cover the white matter pathways relevant to change. Further analysis of individual variability will be essential for improving targeting and clinical outcomes, and potentially further reducing the lesion size necessary for beneficial outcomes.

Tomographic tract tracing and data driven approaches to unravel complex 3D fiber anatomy of DBS relevant prefrontal projections to the diencephalic-mesencephalic junction in the marmoset

BACKGROUND

Understanding prefrontal cortex projections to diencephalic-mesencephalic junction (DMJ), especially to subthalamic nucleus (STN) and ventral mesencephalic tegmentum (VMT) helps our comprehension of Deep Brain Stimulation (DBS) in major depression (MD) and obsessive-compulsive disorder (OCD). Fiber routes are complex and tract tracing studies in non-human primate species (NHP) have yielded conflicting results. The superolateral medial forebrain bundle (slMFB) is a promising target for DBS in MD and OCD. It has become a focus of criticism owing to its name and its diffusion weighted-imaging based primary description.

OBJECTIVE

To investigate DMJ connectivity in NHP with a special focus on slMFB and the limbic hyperdirect pathway utilizing three-dimensional and data driven techniques.

METHODS

We performed left prefrontal adeno-associated virus - tracer based injections in the common marmoset monkey (n = 52). Histology and two-photon microscopy were integrated into a common space. Manual and data driven cluster analyses of DMJ, subthalamic nucleus and VMT together, followed by anterior tract tracing streamline (ATTS) tractography were deployed.

RESULTS

Typical pre- and supplementary motor hyperdirect connectivity was confirmed. The advanced tract tracing unraveled the complex connectivity to the DMJ. Limbic prefrontal territories directly projected to the VMT but not STN.

DISCUSSION

Intricate results of tract tracing studies warrant the application of advanced three-dimensional analyses to understand complex fiber-anatomical routes. The applied three-dimensional techniques can enhance anatomical understanding also in other regions with complex fiber anatomy.

CONCLUSION

Our work confirms slMFB anatomy and enfeebles previous misconceptions. The rigorous NHP approach strengthens the role of the slMFB as a target structure for DBS predominantly in psychiatric indications like MD and OCD.

A comparison of how deep brain stimulation in two targets with anti-compulsive efficacy modulates brain activity using fMRI in awake rats

Deep brain stimulation (DBS) is an established neuromodulatory intervention against otherwise treatment-refractory obsessive-compulsive disorder (OCD). Several DBS targets, all of which are part of brain networks connecting basal ganglia and prefrontal cortex, alleviate OCD symptoms. Stimulation of these targets is thought to unfold its therapeutic effect by modulation of network activity through internal capsule (IC) connections. Research into DBS-induced network changes and the nature of IC-related effects of DBS in OCD is needed to further improve DBS. Here, we studied the effects of DBS at the ventral medial striatum (VMS) and IC on blood-oxygen level dependent (BOLD) responses in awake rats using functional magnetic resonance imaging (fMRI). BOLD-signal intensity was measured in five regions of interest (ROIs): medial and orbital prefrontal cortex, nucleus accumbens (NAc), IC area, and mediodorsal thalamus. In previous rodent studies, stimulation at both target locations resulted in a reduction of OCD-like behavior and activation of prefrontal cortical areas. Therefore, we hypothesized that stimulation at both targets would result in partially overlapping BOLD responses. Both differential and overlapping activity between VMS and IC stimulation was found. Stimulating the caudal part of the IC resulted in activation around the electrode, while stimulating the rostral part of the IC resulted in increased cross-correlations between the IC area, orbitofrontal cortex, and NAc. Stimulation of the dorsal part of the VMS resulted in increased activity in the IC area, suggesting this area is activated during both VMS and IC stimulation. This activation is also indicative of VMS-DBS impacting corticofugal fibers running through the medial caudate into the anterior IC, and both VMS and IC DBS might act on these fibers to induce OCD-reducing effects. These results show that rodent fMRI with simultaneous electrode stimulation is a promising approach to study the neural mechanisms of DBS. Comparing the effects of DBS in different target areas has the potential to improve our understanding of the neuromodulatory changes that take place across various networks and connections in the brain. Performing this research in animal disease models will lead to translational insights in the mechanisms underlying DBS, and can aid improvement and optimization of DBS in patient populations.

Neurosurgical Approaches for Treatment-Resistant Obsessive-Compulsive Disorder

Treatment-resistant obsessive-compulsive disorder (trOCD) is a severely disabling, life-threatening psychiatric disorder affecting ∼0.5% of the US population. Following the failure of multiple medical and psychotherapeutic treatment lines, patients with trOCD, like others with functional disorders, may benefit from invasive neuromodulation. Cumulative evidence suggests that disrupting abnormal hyperdirect cortico-striato-thalamo-cortical (CSTC) pathway activity offers sustainable, robust symptomatic relief in most patients. Multiple surgical approaches allow for modulation of the CSTC pathway, including stereotactic lesions and electrical stimulation. This review aims to describe the modern neurosurgical approaches for trOCD, recent advances in our understanding of pathophysiology, and future therapeutic directions.

Impaired Non-Selective Response Inhibition in Obsessive-Compulsive Disorder

Two prominent features of obsessive-compulsive disorder (OCD) are the inability to inhibit intrusive thoughts and behaviors and pathological doubt or intolerance of uncertainty. Previous study showed that uncertain context modeled by equiprobable presentation of excitatory (Go) and inhibitory (NoGo) stimuli requires non-selective response inhibition in healthy subjects. In other words, it requires transient global inhibition triggered not only by excitatory stimuli but also by inhibitory stimuli. Meanwhile, it is unknown whether OCD patients show abnormal brain activity of the non-selective response inhibition system. In order to test this assumption, we performed an fMRI study with an equiprobable Go/NoGo task involving fourteen patients with OCD and compared them with 34 healthy controls. Patients with OCD showed pathological slowness in the Go/NoGo task. The non-selective response inhibition system in OCD included all brain areas seen in healthy controls and, in addition, involved the right anterior cingulate cortex (ACC) and the anterior insula/frontal operculum (AIFO). Moreover, a between-group comparison revealed hypoactivation of brain regions within cingulo-opercular and cortico-striato-thalamo-cortical (CSTC) circuits in OCD. Among hypoactivated areas, the right ACC and the right dorsolateral prefrontal cortex (DLPFC) were associated with non-selective inhibition. Furthermore, regression analysis showed that OCD slowness was associated with decreased activation in cingulate regions and two brain areas related to non-selective inhibition: the right DLPFC and the right inferior parietal lobule (IPL). These results suggest that non-selective response inhibition is impaired in OCD, which could be a potential explanation for a relationship between inhibitory deficits and the other remarkable characteristic of OCD known as intolerance of uncertainty.

Treatment of disgust in specific emotional disorders

Although conditioning approaches have highlighted potential characteristics of disgust in anxiety disorders, obsessive-compulsive disorder (OCD), and posttraumatic stress disorder (PTSD), these findings have yet to be translated into evidence-based treatments. Examination of the literature suggests various indicators of disgust that predict treatment outcome in these disorders. However, mechanisms remain unclear because studies examining disgust during the course of treatment are limited. Increasingly, the field has moved toward experimental investigation of strategies that reduce disgust. While cognitive reappraisal and imagery techniques appear promising, such techniques have yet to be examined as anxiety disorder treatments in large-scale randomized clinical trials. The literature also points to novel approaches to treating disgust, ranging from an inhibitory-informed approach to exposure therapy to transcranial direct current stimulation. However, the development of novel treatment approaches will require more rigorous experimental psychopathology approaches that can further elucidate processes that contribute to the etiology and/or maintenance of disorders of disgust.

Obsessive-compulsive symptoms are negatively correlated with motor severity in patients with generalized dystonia

We aimed to clarify the correlations between motor symptoms and obsessive-compulsive symptoms and between the volumes of basal ganglia components and obsessive-compulsive symptoms. We retrospectively included 14 patients with medically intractable, moderate and severe generalized dystonia. The Burke-Fahn-Marsden Dystonia Rating Scale and Maudsley Obsessional Compulsive Inventory were used to evaluate the severity of dystonia and obsessive-compulsive symptoms, respectively. Patients with generalized dystonia were divided into two groups; patients whose Maudsley Obsessional Compulsive Inventory score was lower than 13 (Group 1) and 13 or more (Group 2). Additionally, the total Maudsley Obsessional Compulsive Inventory scores in patients with dystonia were significantly higher than normal volunteers' scores (p = 0.025). Unexpectedly, Group 2 (high Maudsley Obsessional Compulsive Inventory scores) showed milder motor symptoms than Group 1 (low Maudsley Obsessional Compulsive Inventory scores) (p = 0.016). "Checking" rituals had a strong and significant negative correlation with the Burke-Fahn-Marsden Dystonia Rating Scale (ρ = - 0.71, p = 0.024) and a strong positive correlation with the volumes of both sides of the nucleus accumbens (right: ρ = 0.72, p = 0.023; left: ρ = 0.70, p = 0.034). Our results may provide insights into the pathogenesis of obsessive-compulsive disorder and dystonia.

Clinical neuroscience and neurotechnology: An amazing symbiosis

In the last decades, clinical neuroscience found a novel ally in neurotechnologies, devices able to record and stimulate electrical activity in the nervous system. These technologies improved the ability to diagnose and treat neural disorders. Neurotechnologies are concurrently enabling a deeper understanding of healthy and pathological dynamics of the nervous system through stimulation and recordings during brain implants. On the other hand, clinical neurosciences are not only driving neuroengineering toward the most relevant clinical issues, but are also shaping the neurotechnologies thanks to clinical advancements. For instance, understanding the etiology of a disease informs the location of a therapeutic stimulation, but also the way stimulation patterns should be designed to be more effective/naturalistic. Here, we describe cases of fruitful integration such as Deep Brain Stimulation and cortical interfaces to highlight how this symbiosis between clinical neuroscience and neurotechnology is closer to a novel integrated framework than to a simple interdisciplinary interaction.

Neuromodulation of OCD: A review of invasive and non-invasive methods

Early research into neural correlates of obsessive compulsive disorder (OCD) has focused on individual components, several network-based models have emerged from more recent data on dysfunction within brain networks, including the the lateral orbitofrontal cortex (lOFC)-ventromedial caudate, limbic, salience, and default mode networks. Moreover, the interplay between multiple brain networks has been increasingly recognized. As the understanding of the neural circuitry underlying the pathophysiology of OCD continues to evolve, so will too our ability to specifically target these networks using invasive and noninvasive methods. This review discusses the rationale for and theory behind neuromodulation in the treatment of OCD.

Efficacy of Non-Invasive Brain Stimulation for Refractory Obsessive-Compulsive Disorder: A Meta-Analysis of Randomized Controlled Trials

Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder, with 30−40% of OCD patients being unresponsive to adequate trials of anti-OCD drugs and cognitive behavior therapy. The aim of this paper is to investigate the efficacy of non-invasive brain stimulation (NIBS) on treating refractory OCD. With PubMed, Embase, PsycInfo, and Cochrane Library used on 15 February 2022, 24 randomized controlled trials involving 663 patients were included. According to this analysis, NIBS including repetitive transcranial magnetic stimulation (rTMS), theta-burst stimulation (TBS), and transcranial direct current stimulation (tDCS), had a moderate effect on the reduction of Yale-Brown Obsessive Compulsive Scale (Y-BOCS) scores (SMD = 0.54, 95% CI: 0.26−0.81; p < 0.01). In the subgroup analysis, rTMS seemed to produce a better therapeutic effect (SMD = 0.73, 95% CI: 0.38−1.08; p < 0.01). Moreover, excitatory (SMD = 1.13, 95% CI: 0.24−2.01; p = 0.01) and inhibitory (SMD = 0.81, 95% CI: 0.26−1.36; p < 0.01) stimulation of the dorsolateral prefrontal cortex (DLPFC) both alleviated OCD symptoms. In the secondary outcome of clinical response rates, NIBS treatment led to an increase in response rates (RR = 2.26, 95% CI: 1.57−3.25; p < 0.01).

Gamma Knife radiosurgery for obsessive compulsive disorder

Gamma Knife radiosurgical capsulotomy has been performed for over 40 years as a rarely used surgical intervention for the treatment of obsessive-compulsive disorder. Over time, the procedure has evolved in many ways with most significant modifications being made in target location, number of isocenters and prescribed dose, subsequently producing changes in lesion size and geometry. Long-term clinical response data and adverse outcomes to the earlier empiric treatment parameters have resulted in shifting the target from its initial location within the midpoint of the anterior limb of internal capsule to a currently used point that includes its most ventral portion as well as the ventral striatum. This led to the contemporary Gamma Knife ventral capsulotomy procedure that focuses on ventral capsule/ventral striatum. Many of the early studies, despite demonstrating efficacy in some patients, were complicated by clinically relevant radiation-induced adverse effects. More recent studies have demonstrated strong efficacy with diminished adverse effects with well-placed lesions created at lower radiation doses. Advances in neuroimaging technology such as diffusion tensor imaging (DTI) based fiber tracking may provide further insight into precisely targeting of the ventral capsule/striatum based on patient-specific variations in white matter connectivity.

Neuroimaging of psychiatric disorders

Psychiatry remains the only medical specialty where diagnoses are still based on clinical syndromes rather than measurable biological abnormalities. As imaging technology and analytical methods evolve, it is becoming clear that subtle but measurable radiological characteristics exist and can be used to experimentally classify psychiatric disorders, predict response to treatment and, hopefully, develop new, more effective therapies. This review highlights advances in neuroimaging modalities that are now allowing assessment of brain structure, connectivity and neural network function, describes technical aspects of the most promising methods, and summarizes observations made in some frequent psychiatric disorders.

The Evolution of Modern Ablative Surgery for the Treatment of Obsessive-Compulsive and Major Depression Disorders

In this review, we describe the evolution of modern ablative surgery for intractable psychiatric disease, from the original image-guided cingulotomy procedure described by Ballantine, to the current bilateral anterior cingulotomy using MRI-guided stereotactic techniques. Extension of the single lesion bilateral cingulotomy to the extended bilateral cingulotomy and subsequent staged limbic leucotomy (LL) is also discussed. Other ablative surgeries for psychiatric disease including subcaudate tractotomy (SCT) and anterior capsulotomy (AC) using modern MRI-guided ablative techniques, as well as radiosurgical capsulotomy, are described. Finally, the potential emerging role of MR-guided focused ultrasound (MRgFUS) for treating conditions such as major depressive disorder (MDD) and obsessive-compulsive disorder (OCD) is discussed.

Application of a staging model in patients with obsessive-compulsive disorder: cross-sectional and follow-up results

INTRODUCTION

Obsessive-compulsive disorder (OCD) is a prevalent and disabling condition with frequent chronic course. Staging models applied to psychiatric disorders seek to define their extent of progression at a particular time-point and differentiate early, milder clinical phenomena from those characterizing illness progression and chronicity. In OCD patients, a staging model has been recently proposed but not tested yet. This was the aim of the present study.

METHODS

From an overall sample of 198 OCD patients, recruited across two psychiatric clinics in Northern Italy, 70 patients on stable treatment completed a follow-up assessment ranging from 12 to 24 months. At follow-up initiation, patients had been divided into four staging groups, according to the model proposed by Fontenelle and Yucel. At the end of the follow-up, patients were subdivided into three groups (no stage change, improved stage, or worsened stage) compared with statistical analyses.

RESULTS

At the end of the follow-up, 67.1% patients showed no stage changes, 24.3% a stage improvement, and 8.6% a stage progression. Worsened patients showed higher rates of comorbid disorders and higher rates of unfavorable employment characteristics compared to the other subgroups (P < .05). Patients with worsened stage showed higher prevalence of somatic obsessions (P < .05), while patients with improved stage showed higher rates of magical thinking and violence/harm obsessions compared to other groups (P < .05).

DISCUSSION

The present results provide epidemiologic and clinical correlates of the first application of a staging model in a sample of OCD patients, encouraging further studies to assess the utility of this approach in the field.

Patient-specific connectomic models correlate with, but do not reliably predict, outcomes in deep brain stimulation for obsessive-compulsive disorder

Deep brain stimulation (DBS) of the ventral internal capsule/ventral striatum (VCVS) is an emerging treatment for obsessive-compulsive disorder (OCD). Recently, multiple studies using normative connectomes have correlated DBS outcomes to stimulation of specific white matter tracts. Those studies did not test whether these correlations are clinically predictive, and did not apply cross-validation approaches that are necessary for biomarker development. Further, they did not account for the possibility of systematic differences between DBS patients and the non-diagnosed controls used in normative connectomes. To address these gaps, we performed patient-specific diffusion imaging in 8 patients who underwent VCVS DBS for OCD. We delineated tracts connecting thalamus and subthalamic nucleus (STN) to prefrontal cortex via VCVS. We then calculated which tracts were likely activated by individual patients' DBS settings. We fit multiple statistical models to predict both OCD and depression outcomes from tract activation. We further attempted to predict hypomania, a VCVS DBS complication. We assessed all models' performance on held-out test sets. With this best-practices approach, no model predicted OCD response, depression response, or hypomania above chance. Coefficient inspection partly supported prior reports, in that capture of tracts projecting to cingulate cortex was associated with both YBOCS and MADRS response. In contrast to prior reports, however, tracts connected to STN were not reliably correlated with response. Thus, patient-specific imaging and a guideline-adherent analysis were unable to identify a tractographic target with sufficient effect size to drive clinical decision-making or predict individual outcomes. These findings suggest caution in interpreting the results of normative connectome studies.

Neurodegenerative disorders management: state-of-art and prospects of nano-biotechnology

Neurodegenerative disorders (NDs) are highly prevalent among the aging population. It affects primarily the central nervous system (CNS) but the effects are also observed in the peripheral nervous system. Neural degeneration is a progressive loss of structure and function of neurons, which may ultimately involve cell death. Such patients suffer from debilitating memory loss and altered motor coordination which bring up non-affordable and unavoidable socio-economic burdens. Due to the unavailability of specific therapeutics and diagnostics, the necessity to control or manage NDs raised the demand to investigate and develop efficient alternative approaches. Keeping trends and advancements in view, this report describes both state-of-the-art and challenges in nano-biotechnology-based approaches to manage NDs, toward personalized healthcare management. Sincere efforts are being made to customize nano-theragnostics to control: therapeutic cargo packaging, delivery to the brain, nanomedicine of higher efficacy, deep brain stimulation, implanted stimulation, and managing brain cell functioning. These advancements are useful to design future therapy based on the severity of the patient's neurodegenerative disease. However, we observe a lack of knowledge shared among scientists of a variety of expertise to explore this multi-disciplinary research field for NDs management. Consequently, this review will provide a guideline platform that will be useful in developing novel smart nano-therapies by considering the aspects and advantages of nano-biotechnology to manage NDs in a personalized manner. Nano-biotechnology-based approaches have been proposed as effective and affordable alternatives at the clinical level due to recent advancements in nanotechnology-assisted theragnostics, targeted delivery, higher efficacy, and minimal side effects.

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.

Clinical applications of neurochemical and electrophysiological measurements for closed-loop neurostimulation

The development of closed-loop deep brain stimulation (DBS) systems represents a significant opportunity for innovation in the clinical application of neurostimulation therapies. Despite the highly dynamic nature of neurological diseases, open-loop DBS applications are incapable of modifying parameters in real time to react to fluctuations in disease states. Thus, current practice for the designation of stimulation parameters, such as duration, amplitude, and pulse frequency, is an algorithmic process. Ideal stimulation parameters are highly individualized and must reflect both the specific disease presentation and the unique pathophysiology presented by the individual. Stimulation parameters currently require a lengthy trial-and-error process to achieve the maximal therapeutic effect and can only be modified during clinical visits. The major impediment to the development of automated, adaptive closed-loop systems involves the selection of highly specific disease-related biomarkers to provide feedback for the stimulation platform. This review explores the disease relevance of neurochemical and electrophysiological biomarkers for the development of closed-loop neurostimulation technologies. Electrophysiological biomarkers, such as local field potentials, have been used to monitor disease states. Real-time measurement of neurochemical substances may be similarly useful for disease characterization. Thus, the introduction of measurable neurochemical analytes has significantly expanded biomarker options for feedback-sensitive neuromodulation systems. The potential use of biomarker monitoring to advance neurostimulation approaches for treatment of Parkinson's disease, essential tremor, epilepsy, Tourette syndrome, obsessive-compulsive disorder, chronic pain, and depression is examined. Further, challenges and advances in the development of closed-loop neurostimulation technology are reviewed, as well as opportunities for next-generation closed-loop platforms.

LSD1-BDNF activity in lateral hypothalamus-medial forebrain bundle area is essential for reward seeking behavior

Reward induces activity-dependant gene expression and synaptic plasticity-related changes. Lysine-specific histone demethylase 1 (LSD1), a key enzyme driving histone modifications, regulates transcription in neural circuits of memory and emotional behavior. Herein, we focus on the role of LSD1 in modulating the expression of brain derived neurotrophic factor (BDNF), the master regulator of synaptic plasticity, in the lateral hypothalamus-medial forebrain bundle (LH-MFB) circuit during positive reinforcement. Rats, trained for intracranial self-stimulation (ICSS) via an electrode-cannula assembly in the LH-MFB area, were assayed for lever press activity, epigenetic parameters and dendritic sprouting. LSD1 expression and markers of synaptic plasticity like BDNF and dendritic arborization in the LH, showed distinct increase in conditioned animals. H3K4me2 levels at Bdnf IV and Bdnf IX promoters were increased in ICSS-conditioned rats, but H3K9me2 was decreased. While intra LH-MFB treatment with pan Lsd1 siRNA inhibited lever press activity, analyses of LH tissue showed reduction in BDNF expression and levels of H3K4me2 and H3K9me2. However, co-administration of BDNF peptide restored lever press activity mitigated by Lsd1 siRNA. BDNF expression in LH, driven by LSD1 via histone demethylation, may play an important role in reshaping the reward pathway and hold the key to decode the molecular basis of addiction.

The Decline of Deep Brain Stimulation for Obsessive-Compulsive Disorder Following FDA Humanitarian Device Exemption Approval

Background: In February 2009, the US Food and Drug Administration (FDA) granted Humanitarian Device Exemption (HDE) for deep brain stimulation (DBS) in the anterior limb of the internal capsule (ALIC) for the treatment of severely debilitating, treatment refractory obsessive–compulsive disorder (OCD). Despite its promise as a life altering treatment for patients with otherwise refractory, severely debilitating OCD, the use of DBS for the treatment of OCD has diminished since the FDA HDE endorsement and is now rarely performed even at busy referral centers. We sought to identify factors hindering OCD patients from receiving DBS therapy.

Materials and Methods: University of Florida (UF) clinical research databases were queried to identify patients evaluated as potential candidates for OCD DBS from January 1, 2002 to July 30, 2020. A retrospective review of these patients' medical records was performed to obtain demographic information, data related to their OCD, and details relevant to payment such as third-party payer, study participation, evaluation prior to or after HDE approval, and any stated factors prohibiting surgical intervention.

Results: Out of 25 patients with severe OCD identified as candidates for DBS surgery during the past 18 years, 15 underwent surgery. Prior to FDA HDE approval, 6 out of 7 identified candidates were treated. After the HDE, only 9 out of 18 identified candidates were treated. Seven of the 9 were funded by Medicare, 1 paid out of pocket, and 1 had “pre-authorization” from her private insurer who ultimately refused to pay after the procedure. Among the 10 identified OCD DBS candidates who were ultimately not treated, 7 patients—all with private health insurance—were approved for surgery by the interdisciplinary team but were unable to proceed with surgery due to lack of insurance coverage, 1 decided against surgical intervention, 1 was excluded due to medical comorbidities and excessive perceived surgical risk, and no clear reason was identified for 1 patient evaluated in 2004 during our initial NIH OCD DBS trial.

Conclusion: Based on compelling evidence that DBS provides substantial improvement of OCD symptoms and markedly improved functional capacity in 2 out of 3 patients with severely debilitating, treatment refractory OCD, the FDA approved this procedure under a Humanitarian Device Exemption in 2009, offering new hope to this unfortunate patient population. A careful review of our experience with OCD DBS at the University of Florida shows that since the HDE approval, only 50% of the severe OCD patients (9 of 18) identified as candidates for this potentially life altering treatment have been able to access the therapy. We found the most common limiting factor to be failure of private insurance policies to cover DBS for OCD, despite readily covering DBS for Parkinson's disease, essential tremor, and even dystonia—another HDE approved indication for DBS. We have identified an inherent discrimination in the US healthcare system against patients with medication-refractory OCD who are economically challenged and do not qualify for Medicare. We urge policy makers, insurance companies, and hospital administrations to recognize this health care disparity and seek to rectify it.

Optimizing Deep Brain Stimulation Parameters in Obsessive-Compulsive Disorder

OBJECTIVES

Deep brain stimulation (DBS) is an innovative and effective treatment for patients with therapy-refractory obsessive-compulsive disorder (OCD). DBS offers unique opportunities for personalized care, but no guidelines on how to choose effective and safe stimulation parameters in patients with OCD are available. Our group gained relevant practical knowledge on DBS optimization by treating more than 80 OCD patients since 2005, the world's largest cohort. The article's objective is to share this experience.

MATERIALS AND METHODS

We provide guiding principles for optimizing DBS stimulation parameters in OCD and discuss the neurobiological and clinical basis.

RESULTS

Adjustments in stimulation parameters are performed in a fixed order. First, electrode contact activation is determined by the position of the electrodes on postoperative imaging. Second, voltage and pulse width are increased stepwise, enlarging both the chance of symptom reduction and of inducing side effects. Clinical evaluation of adjustments in stimulation parameters needs to take into account: 1) the particular temporal sequence in which the various OCD symptoms and DBS side-effects change; 2) the lack of robust response predictors; 3) the limited sensitivity of the Yale-Brown Obsessive-Compulsive Scale to assess DBS-induced changes in OCD symptoms; and 4) a patient's fitness for additional cognitive-behavioral therapy (CBT).

CONCLUSIONS

Decision-making in stimulation parameter optimization needs to be sensitive to the particular time-courses on which various symptoms and side effects change.

Neurocircuitry of Deep Brain Stimulation for Obsessive-Compulsive Disorder as Revealed by Tractography: A Systematic Review

Objective: Deep brain stimulation (DBS) was proposed in 1999 to treat refractory obsessive-compulsive disorder (OCD). Despite the accumulated experience over more than two decades, 30-40% of patients fail to respond to this procedure. One potential reason to explain why some patients do not improve in the postoperative period is that DBS might not have engaged structural therapeutic networks that are crucial to a favorable outcome in non-responders. This article reviews magnetic resonance imaging diffusion studies (DTI-MRI), analyzing neural networks likely modulated by DBS in OCD patients and their corresponding clinical outcome. Methods: We used a systematic review process to search for studies published from 2005 to 2020 in six electronic databases. Search terms included obsessive-compulsive disorder, deep brain stimulation, diffusion-weighted imaging, diffusion tensor imaging, diffusion tractography, tractography, connectome, diffusion analyses, and white matter. No restriction was made concerning the surgical target, DTI-MRI technique and the method of data processing. Results: Eight studies published in the last 15 years were fully assessed. Most of them used 3 Tesla DTI-MRI, and different methods of data acquisition and processing. There was no consensus on potential structures and networks underlying DBS effects. Most studies stimulated the ventral anterior limb of the internal capsule (ALIC)/nucleus accumbens. However, the contribution of different white matter pathways that run through the ALIC for the effects of DBS remains elusive. Moreover, the improvement of cognitive and affective symptoms in OCD patients probably relies on electric modulation of distinct networks. Conclusion: Though, tractography is a valuable tool to understand neural circuits, the effects of modulating different fiber tracts in OCD are still unclear. Future advances on image acquisition and data processing and a larger number of studies are still required for the understanding of the role of tractography-based targeting and to clarify the importance of different tracts for the mechanisms of DBS.

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.

Case Report of Dual-Site Neurostimulation and Chronic Recording of Cortico-Striatal Circuitry in a Patient With Treatment Refractory Obsessive Compulsive Disorder

Psychiatric disorders are increasingly understood as dysfunctions of hyper- or hypoconnectivity in distributed brain circuits. A prototypical example is obsessive compulsive disorder (OCD), which has been repeatedly linked to hyper-connectivity of cortico-striatal-thalamo-cortical (CSTC) loops. Deep brain stimulation (DBS) and lesions of CSTC structures have shown promise for treating both OCD and related disorders involving over-expression of automatic/habitual behaviors. Physiologically, we propose that this CSTC hyper-connectivity may be reflected in high synchrony of neural firing between loop structures, which could be measured as coherent oscillations in the local field potential (LFP). Here we report the results from the pilot patient in an Early Feasibility study (https://clinicaltrials.gov/ct2/show/NCT03184454) in which we use the Medtronic Activa PC+ S device to simultaneously record and stimulate in the supplementary motor area (SMA) and ventral capsule/ventral striatum (VC/VS). We hypothesized that frequency-mismatched stimulation should disrupt coherence and reduce compulsive symptoms. The patient reported subjective improvement in OCD symptoms and showed evidence of improved cognitive control with the addition of cortical stimulation, but these changes were not reflected in primary rating scales specific to OCD and depression, or during blinded cortical stimulation. This subjective improvement was correlated with increased SMA and VC/VS coherence in the alpha, beta, and gamma bands, signals which persisted after correcting for stimulation artifacts. We discuss the implications of this research, and propose future directions for research in network modulation in OCD and more broadly across psychiatric disorders.

Deep Brain Stimulation for Major Depression and Obsessive-Compulsive Disorder—Discontinuation of Ongoing Stimulation

Deep brain stimulation (DBS) is currently under research for the treatment of psychiatric disorders, e.g., obsessive-compulsive disorder (OCD) and treatment-resistant depression (TRD). Since the application of DBS in psychiatry has been in use for about 20 years, it is necessary to evaluate its long-term use now. A main issue in the long-term treatment of DBS concerns the effects of a discontinuation of stimulation due to intended as well as unintended reasons. In this contribution, the literature describing discontinuation effects following DBS in OCD and TRD is reviewed. Furthermore, a patient is reported in depth who experienced an unintended discontinuation of supero-lateral medial forebrain bundle (slMFB) DBS for TRD. In this case, the battery was fully depleted without the patient noticing. DBS had led to a sustained response for seven years before discontinuation of stimulation for just several weeks caused a progressive worsening of depression. Altogether, the rapid occurrence of symptom worsening, the absence of a notification about the stimulation status and the difficulties to recapture antidepressant response represent important safety aspects. For a further understanding of the described effects, time courses until worsening of depression as well as biological mechanisms need to be investigated in double-blind controlled trials.

Brain Stimulation in Eating Disorders: State of the Art and Future Perspectives

The management of eating disorders (EDs) is still difficult and few treatments are effective. Recently, several studies have described the important contribution of non-invasive brain stimulation (repetitive transcranial magnetic stimulation, transcranial direct current stimulation, and electroconvulsive therapy) and invasive brain stimulation (deep brain stimulation and vagal nerve stimulation) for ED management. This review summarizes the available evidence supporting the use of brain stimulation in ED. All published studies on brain stimulation in ED as well as ongoing trials registered at clinicaltrials.gov were examined. Articles on neuromodulation research and perspective articles were also included. This analysis indicates that brain stimulation in EDs is still in its infancy. Literature data consist mainly of case reports, cases series, open studies, and only a few randomized controlled trials. Consequently, the evidence supporting the use of brain stimulation in EDs remains weak. Finally, this review discusses future directions in this research domain (e.g., sites of modulation, how to enhance neuromodulation efficacy, personalized protocols).

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.

Improving long term patient outcomes from deep brain stimulation for treatment-refractory obsessive-compulsive disorder

Introduction: Deep brain stimulation (DBS) has emerged as an effective treatment for patients with severe treatment-refractory obsessive-compulsive disorder (OCD). Over the past two decades, several clinical trials with multiple years of follow-up have shown that DBS offers long-term symptom relief for individuals with severe OCD, though a portion of patients do not achieve an adequate response.Areas covered: This review sought to summarize the literature on the efficacy and long-term effectiveness of DBS for OCD, and to identify strategies that have the potential to improve treatment outcomes.Expert opinion: Although this literature is just emerging, a small number of DBS enhancement strategies have shown promising initial results. More posterior targets along the striatal axis and at the bed nucleus of the stria terminalis appear to offer greater symptom relief than more anterior targets. Research is also beginning to demonstrate the feasibility of maximizing treatment outcomes with target selection based on neural activation patterns during symptom provocation and clinical presentation. Finally, integrating DBS with post-surgery exposure and response prevention therapy appears to be another promising approach. Definitive conclusions about these strategies are limited by a low number of studies with small sample sizes that will require multi-site replication.

The Use of Neuromodulation for Symptom Management

Pain and other symptoms of autonomic dysregulation such as hypertension, dyspnoea and bladder instability can lead to intractable suffering. Incorporation of neuromodulation into symptom management, including palliative care treatment protocols, is becoming a viable option scientifically, ethically, and economically in order to relieve suffering. It provides further opportunity for symptom control that cannot otherwise be provided by pharmacology and other conventional methods.

Tissue Response to Neural Implants: The Use of Model Systems Toward New Design Solutions of Implantable Microelectrodes

The development of implantable neuroelectrodes is advancing rapidly as these tools are becoming increasingly ubiquitous in clinical practice, especially for the treatment of traumatic and neurodegenerative disorders. Electrodes have been exploited in a wide number of neural interface devices, such as deep brain stimulation, which is one of the most successful therapies with proven efficacy in the treatment of diseases like Parkinson or epilepsy. However, one of the main caveats related to the clinical application of electrodes is the nervous tissue response at the injury site, characterized by a cascade of inflammatory events, which culminate in chronic inflammation, and, in turn, result in the failure of the implant over extended periods of time. To overcome current limitations of the most widespread macroelectrode based systems, new design strategies and the development of innovative materials with superior biocompatibility characteristics are currently being investigated. This review describes the current state of the art of in vitro, ex vivo, and in vivo models available for the study of neural tissue response to implantable microelectrodes. We particularly highlight new models with increased complexity that closely mimic in vivo scenarios and that can serve as promising alternatives to animal studies for investigation of microelectrodes in neural tissues. Additionally, we also express our view on the impact of the progress in the field of neural tissue engineering on neural implant research.

Deep brain stimulation in the treatment of obsessive-compulsive disorder: current perspectives

Deep brain stimulation (DBS) is a neuro-psychosurgical technique widely accepted in movement disorders, such as Parkinson's disease. Since 1999, DBS has been explored for severe, chronic and treatment-refractory psychiatric diseases. Our review focuses on DBS in obsessive-compulsive disorder (OCD), considered as a last treatment resort by most of learned societies in psychiatry. Two main stimulation areas have been studied: the striatal region and the subthalamic nucleus. But, most of the trials are open-labeled, and the rare controlled ones have failed to highlight the most efficient target. The recent perspectives are otherwise encouraging. Indeed, clinicians are currently considering other promising targets. A case series of 2 patients reported a decrease in OCD symptoms after DBS in the medial forebrain bundle and an open-label study is exploring bilateral habenula stimulation. New response criteria are also investigating such as quality of life, or subjective and lived-experience. Moreover, first papers about cost-effectiveness which is an important criterion in decision making, have been published. The effectiveness of tractography-assisted DBS or micro-assisted DBS is studying with the aim to improve targeting precision. In addition, a trial involving rechargeable pacemakers is undergoing because this mechanism could be efficient and have a positive impact on cost-effectiveness. A recent trial has discussed the possibility of using combined cognitive behavioral therapy (CBT) and DBS as an augmentation strategy. Finally, based on RDoc Research, the latest hypotheses about the understanding of cortico-striato-thalamo-cortical circuits could offer new directions including clinical predictors and biomarkers to perform adaptive closed-loop systems in the next future.