Clinical Outcome and Mechanisms of Deep Brain Stimulation for Obsessive-Compulsive Disorder

Neuronavigated Right Orbitofrontal 20 Hz Theta Burst Transcranial Magnetic Stimulation Augmentation for Obsessive-Compulsive Disorder with Comorbid Depression and Anxiety Disorders: An Open-Label Study

BACKGROUND

Despite the availability of pharmacotherapy and psychotherapy for treating obsessive-compulsive disorder (OCD), alternative approaches need to be explored due to the high likelihood of treatment resistance. Neuronavigated 20 Hz theta burst stimulation (TBS-20 Hz), targeting the bilateral dorsolateral prefrontal cortex (DLPFC) augmented with the right orbitofrontal cortex (ROFC), was tested for treating OCD comorbid with depression and anxiety disorders.

METHODS

A retrospective chart review was performed on fourteen patients treated for moderate-to-severe OCD in a private outpatient clinic. Twelve patients had comorbid major depressive disorder (MDD), and thirteen patients had either generalized anxiety disorder (GAD) or panic disorder (PD). Patients completed the Y-BOCS-SR, BDI-II, and BAI rating scales weekly, which were used to measure the changes in OCD, depression, and anxiety symptoms, respectively.

RESULTS

Neuronavigated TBS-20 Hz was sequentially applied to the right DLPFC (RDLPFC), left DLPFC (LDLPFC), and ROFC. A total of 64% (9/14) of patients achieved remission from OCD (Y-BOCS-SR ≤ 14) in an average of 6.1 weeks of treatment (SD = 4.0). A total of 58% (7/12) of patients remitted from MDD (BDI < 13) in an average of 4.1 weeks (SD = 2.8), and 62% (8/13) of patients remitted from GAD/PD (BAI < 8) in an average of 4.3 weeks (SD = 2.5).

CONCLUSIONS

The neuronavigated TBS-20 Hz sequential stimulation of RDLPFC and LDLPFC, followed by ROFC, significantly reduced OCD, MDD, and GAD/PD symptoms. Randomized sham controls are warranted to validate these results.

Deep Brain Stimulation for the Management of Refractory Neurological Disorders: A Comprehensive Review

In recent decades, deep brain stimulation (DBS) has been extensively studied due to its reversibility and significantly fewer side effects. DBS is mainly a symptomatic therapy, but the stimulation of subcortical areas by DBS is believed to affect the cytoarchitecture of the brain, leading to adaptability and neurogenesis. The neurological disorders most commonly studied with DBS were Parkinson's disease, essential tremor, obsessive-compulsive disorder, and major depressive disorder. The most precise approach to evaluating the location of the leads still relies on the stimulus-induced side effects reported by the patients. Moreover, the adequate voltage and DBS current field could correlate with the patient's symptoms. Implantable pulse generators are the main parts of the DBS, and their main characteristics, such as rechargeable capability, magnetic resonance imaging (MRI) safety, and device size, should always be discussed with patients. The safety of MRI will depend on several parameters: the part of the body where the device is implanted, the part of the body scanned, and the MRI-tesla magnetic field. It is worth mentioning that drug-resistant individuals may have different pathophysiological explanations for their resistance to medications, which could affect the efficacy of DBS therapy. Therefore, this could explain the significant difference in the outcomes of studies with DBS in individuals with drug-resistant neurological conditions.

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.

The Efficacy and Safety of Deep Brain Stimulation of Combined Anterior Limb of Internal Capsule and Nucleus Accumbens (ALIC/NAcc-DBS) for Treatment-Refractory Obsessive-Compulsive Disorder: Protocol of a Multicenter, Randomized, and Double-Blinded Study

Backgrounds: Deep brain stimulation (DBS) is an emerging and promising therapeutic approach for treatment-refractory obsessive-compulsive disorder (OCD). The most common DBS targets include the anterior limb of internal capsule (ALIC) and nucleus accumbens (NAcc). This protocol aims to explore the efficacy and safety of the combined ALIC- and NAcc-DBS for treatment-refractory OCD. Methods: We will recruit 64 patients with refractory OCD from six centers, randomly allocate them to active and sham-stimulation groups through a three-month double-blind phase, then enter a three-month open-label phase. In the open-label stage, both groups experience real stimulation. Outcome measures: The primary outcome will be the efficacy and safety of combined ALIC- and NAcc-DBS, determined by treatment response rate between the active and sham-stimulation groups at the double-blind stage and spontaneously reported adverse events. The secondary outcomes are comparisons of change in Y–BOCS, CGI, HAMD, and HAMA scores at the third and sixth months compared to baseline between the active and sham-control groups, as well as the scores of the third month minus the sixth month between the two groups.

Neural Processing Dysfunctions During Fear Learning but Not Reward-Related Processing Characterize Depressed Individuals With High Levels of Repetitive Negative Thinking

BACKGROUND

Repetitive negative thinking (RNT) is a symptom dimension of depression that is associated with a poorer prognosis in terms of higher recurrence, treatment resistance, residual symptoms, and disability. This investigation examined whether RNT is associated with aberrant reward processing and fear learning.

METHODS

Very high RNT (VH-RNT) (n = 60) and high RNT (H-RNT) (n = 60) propensity-matched individuals with depression (age, sex, race/ethnicity, income/employment, body mass index, depressive and anxiety symptom severity) participated in this study along with matched healthy comparison volunteers (n = 30). This propensity-matched sample was selected from the larger Tulsa 1000 study. Participants performed two functional magnetic resonance imaging tasks: the monetary incentive delay task probing reward processing and the fear conditioning task probing aversive learning and extinction.

RESULTS

Both VH-RNT and H-RNT groups showed lower neural activity than healthy comparison subjects in reward circuitry, including the inferior frontal gyrus (VH-RNT: β = -1.24, H-RNT: β = -1.28) and the cerebellum (VH-RNT: β = -0.93, H-RNT: β = -1.14). However, individuals with VH-RNT exhibited lower activation than those with H-RNT in central autonomic network components during fear conditioning (β = -0.84) and continued conditioned responses during early extinction in the postcentral cortex (β = 0.71).

CONCLUSIONS

VH-RNT showed aberrant processing in fear conditioning during both learning and extinction phases compared with H-RNT. These findings demonstrate that dysfunctions of negative valence associated with RNT may be domain specific, which should be taken into account for identifying potential specific targets of intervention.

Connectomic Deep Brain Stimulation for Obsessive-Compulsive Disorder

Obsessive-compulsive disorder is among the most disabling psychiatric disorders. Although deep brain stimulation is considered an effective treatment, its use in clinical practice is not fully established. This is, at least in part, due to ambiguity about the best suited target and insufficient knowledge about underlying mechanisms. Recent advances suggest that changes in broader brain networks are responsible for improvement of obsessions and compulsions, rather than local impact at the stimulation site. These findings were fueled by innovative methodological approaches using brain connectivity analyses in combination with neuromodulatory interventions. Such a connectomic approach for neuromodulation constitutes an integrative account that aims to characterize optimal target networks. In this critical review, we integrate findings from connectomic studies and deep brain stimulation interventions to characterize a neural network presumably effective in reducing obsessions and compulsions. To this end, we scrutinize methodologies and seemingly conflicting findings with the aim to merge observations to identify common and diverse pathways for treating obsessive-compulsive disorder. Ultimately, we propose a unified network that-when modulated by means of cortical or subcortical interventions-alleviates obsessive-compulsive symptoms.

Deep brain stimulation for obsessive-compulsive disorder: A systematic review of worldwide experience after 20 years

BACKGROUND

Twenty years after its first use in a patient with obsessive-compulsive disorder (OCD), the results confirm that deep brain stimulation (DBS) is a promising therapy for patients with severe and resistant forms of the disorder. Nevertheless, many unknowns remain, including the optimal anatomical targets, the best stimulation parameters, the long-term (LT) effects of the therapy, and the clinical or biological factors associated with response. This systematic review of the articles published to date on DBS for OCD assesses the short and LT efficacy of the therapy and seeks to identify predictors of response.

AIM

To summarize the existing knowledge on the efficacy and tolerability of DBS in treatment-resistant OCD.

METHODS

A comprehensive search was conducted in the PubMed, Cochrane, Scopus, and ClinicalTrials.gov databases from inception to December 31, 2020, using the following strategy: “(Obsessive-compulsive disorder OR OCD) AND (deep brain stimulation OR DBS).” Clinical trials and observational studies published in English and evaluating the effectiveness of DBS for OCD in humans were included and screened for relevant information using a standardized collection tool. The inclusion criteria were as follows: a main diagnosis of OCD, DBS conducted for therapeutic purposes and variation in symptoms of OCD measured by the Yale-Brown Obsessive-Compulsive scale (Y-BOCS) as primary outcome. Data were analyzed with descriptive statistics.

RESULTS

Forty articles identified by the search strategy met the eligibility criteria. Applying a follow-up threshold of 36 mo, 29 studies (with 230 patients) provided information on short-term (ST) response to DBS in, while 11 (with 155 patients) reported results on LT response. Mean follow-up period was 18.5 ± 8.0 mo for the ST studies and 63.7 ± 20.7 mo for the LT studies. Overall, the percentage of reduction in Y-BOCS scores was similar in ST (47.4%) and LT responses (47.2%) to DBS, but more patients in the LT reports met the criteria for response (defined as a reduction in Y-BOCS scores > 35%: ST, 60.6% vs LT, 70.7%). According to the results, the response in the first year predicts the extent to which an OCD patient will benefit from DBS, since the maximum symptom reduction was achieved in most responders in the first 12-14 mo after implantation. Reports indicate a consistent tendency for this early improvement to be maintained to the mid-term for most patients; but it is still controversial whether this improvement persists, increases or decreases in the long term. Three different patterns of LT response emerged from the analysis: 49.5% of patients had good and sustained response to DBS, 26.6% were non responders, and 22.5% were partial responders, who might improve at some point but experience relapses during follow-up. A significant improvement in depressive symptoms and global functionality was observed in most studies, usually (although not always) in parallel with an improvement in obsessive symptoms. Most adverse effects of DBS were mild and transient and improved after adjusting stimulation parameters; however, some severe adverse events including intracranial hemorrhages and infections were also described. Hypomania was the most frequently reported psychiatric side effect. The relationship between DBS and suicide risk is still controversial and requires further study. Finally, to date, no clear clinical or biological predictors of response can be established, probably because of the differences between studies in terms of the neuroanatomical targets and stimulation protocols assessed.

CONCLUSION

The present review confirms that DBS is a promising therapy for patients with severe resistant OCD, providing both ST and LT evidence of efficacy.

Identification of biomarkers that predict response to subthalamic nucleus deep brain stimulation in resistant obsessive-compulsive disorder: protocol for an open-label follow-up study

INTRODUCTION

Deep brain stimulation (DBS) of bilateral anteromedial subthalamic nucleus (amSTN) has been found to be helpful in a subset of patients with severe, chronic and treatment-refractory obsessive-compulsive disorder (OCD). Biomarkers may aid in patient selection and optimisation of this invasive treatment. In this trial, we intend to evaluate neurocognitive function related to STN and related biosignatures as potential biomarkers for STN DBS in OCD.

METHODS AND ANALYSIS

Twenty-four subjects with treatment-refractory OCD will undergo open-label STN DBS. Structural/functional imaging, electrophysiological recording and neurocognitive assessment would be performed at baseline. The subjects would undergo a structured clinical assessment for 12 months postsurgery. A group of 24 healthy volunteers and 24 subjects with treatment-refractory OCD who receive treatment as usual would be recruited for comparison of biomarkers and treatment response, respectively. Baseline biomarkers would be evaluated as predictors of clinical response. Neuroadaptive changes would be studied through a reassessment of neurocognitive functioning, imaging and electrophysiological activity post DBS.

ETHICS AND DISSEMINATION

The protocol has been approved by the National Institute of Mental Health and Neurosciences Ethics Committee. The study findings will be disseminated through peer-reviewed scientific journals and scientific meetings.

A prospective international multi-center study on safety and efficacy of deep brain stimulation for resistant obsessive-compulsive disorder

Deep brain stimulation (DBS) has been proposed for severe, chronic, treatment-refractory obsessive-compulsive disorder (OCD) patients. Although serious adverse events can occur, only a few studies report on the safety profile of DBS for psychiatric disorders. In a prospective, open-label, interventional multi-center study, we examined the safety and efficacy of electrical stimulation in 30 patients with DBS electrodes bilaterally implanted in the anterior limb of the internal capsule. Safety, efficacy, and functionality assessments were performed at 3, 6, and 12 months post implant. An independent Clinical Events Committee classified and coded all adverse events (AEs) according to EN ISO14155:2011. All patients experienced AEs (195 in total), with the majority of these being mild (52% of all AEs) or moderate (37%). Median time to resolution was 22 days for all AEs and the etiology with the highest AE incidence was 'programming/stimulation' (in 26 patients), followed by 'New illness, injury, condition' (13 patients) and 'pre-existing condition, worsening or exacerbation' (11 patients). Sixteen patients reported a total of 36 serious AEs (eight of them in one single patient), mainly transient anxiety and affective symptoms worsening (20 SAEs). Regarding efficacy measures, Y-BOCS reduction was 42% at 12 months and the responder rate was 60%. Improvements in GAF, CGI, and EuroQol-5D index scores were also observed. In sum, although some severe AEs occurred, most AEs were mild or moderate, transient and related to programming/stimulation and tended to resolve by adjustment of stimulation. In a severely treatment-resistant population, this open-label study supports that the potential benefits outweigh the potential risks of DBS.

Integrative and Network-Specific Connectivity of the Basal Ganglia and Thalamus Defined in Individuals

The basal ganglia, thalamus, and cerebral cortex form an interconnected network implicated in many neurological and psychiatric illnesses. A better understanding of cortico-subcortical circuits in individuals will aid in development of personalized treatments. Using precision functional mapping-individual-specific analysis of highly sampled human participants-we investigated individual-specific functional connectivity between subcortical structures and cortical functional networks. This approach revealed distinct subcortical zones of network specificity and multi-network integration. Integration zones were systematic, with convergence of cingulo-opercular control and somatomotor networks in the ventral intermediate thalamus (motor integration zones), dorsal attention and visual networks in the pulvinar, and default mode and multiple control networks in the caudate nucleus. The motor integration zones were present in every individual and correspond to consistently successful sites of deep brain stimulation (DBS; essential tremor). Individually variable subcortical zones correspond to DBS sites with less consistent treatment effects, highlighting the importance of PFM for neurosurgery, neurology, and psychiatry.

Tractographic description of major subcortical projection pathways passing the anterior limb of the internal capsule. Corticopetal organization of networks relevant for psychiatric disorders

BACKGROUND

Major depression (MD) and obsessive-compulsive disorder (OCD) are psychiatric diseases with a huge impact on individual well-being. Despite optimal treatment regiments a subgroup of patients remains treatment resistant and stereotactic surgery (stereotactic lesion surgery, SLS or Deep Brain Stimulation, DBS) might be an option. Recent research has described four networks related to MD and OCD (affect, reward, cognitive control, default network) but only on a cortical and the adjacent sub-cortical level. Despite the enormous impact of comparative neuroanatomy, animal science and stereotactic approaches a holistic theory of subcortical and cortical network interactions is elusive. Because of the dominant hierarchical rank of the neocortex, corticofugal approaches have been used to identify connections in subcortical anatomy without anatomical priors and in part confusing results. We here propose a different corticopetal approach by identifying subcortical networks and search for neocortical convergences thereby following the principle of phylogenetic and ontogenetic network development.

MATERIAL AND METHODS

This work used a diffusion tensor imaging data from a normative cohort (Human Connectome Project, HCP; n = 200) to describe eight subcortical fiber projection pathways (PPs) from subthalamic nucleus (STN), substantia nigra (SNR), red nucleus (RN), ventral tegmental area (VTA), ventrolateral thalamus (VLT) and mediodorsal thalamus (MDT) in a normative space (MNI). Subcortical and cortical convergences were described including an assignment of the specific pathways to MD/OCD-related networks. Volumes of activated tissue for different stereotactic stimulation sites and procedures were simulated to understand the role of the distinct networks, with respect to symptoms and treatment of OCD and MD.

RESULTS

The detailed course of eight subcortical PPs (stnPP, snrPP, rnPP, vlATR, vlATRc, mdATR, mdATRc, vtaPP/slMFB) were described together with their subcortical and cortical convergences. The anterior limb of the internal capsule can be subdivided with respect to network occurrences in ventral-dorsal and medio-lateral gradients. Simulation of stereotactic procedures for OCD and MD showed dominant involvement of mdATR/mdATRc (affect network) and vtaPP/slMFB (reward network).

DISCUSSION

Corticofugal search strategies for the evaluation of stereotactic approaches without anatomical priors often lead to confusing results which do not allow for a clear assignment of a procedure to an involved network. According to our simulation of stereotactic procedures in the treatment of OCD and MD, most of the target regions directly involve the reward (and affect) networks, while side-effects can in part be explained with a co-modulation of the control network.

CONCLUSION

The here proposed corticopetal approach of a hierarchical description of 8 subcortical PPs with subcortical and cortical convergences represents a new systematics of networks found in all different evolutionary and distinct parts of the human brain.

New Directions in the Use of Brain Stimulation Interventions in Patients with Obsessive-Compulsive Disorder

Obsessive-Compulsive Disorder (OCD) is a highly disabling condition with early onset and chronic course in most of the affected patients. In addition, OCD may show high comorbidity and suicide attempt rates, which worsen the overall burden of the disease for patients and their caregivers. First-line treatments for OCD consist of pro-serotonergic compounds and cognitive-behavioral therapy. Nonetheless, many patients show only limited benefit from such interventions and require additional "next-step" interventions, including augmentative antipsychotics and glutamate-modulating agents. Based on the knowledge about altered neurocircuitry in OCD, brain stimulation techniques, including transcranial magnetic and electrical stimulations (TMS and tDCS) and deep brain stimulation (DBS), have been increasingly investigated over the last decade, revealing positive results for otherwise intractable and treatment-refractory patients. Available evidence in the field is in continuous evolution and professionals actively involved in the management of OCD patients, psychiatrists in particular, need to be updated about latest developments. Through the analysis of controlled studies, meta-analyses, and International treatment guidelines, the present article is aimed at providing the state of the art on the use of brain stimulation techniques for the treatment of OCD.

Electrophysiological and imaging evidence of sustained inhibition in limbic and frontal networks following deep brain stimulation for treatment refractory obsessive compulsive disorder

Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder that arises from a complex interaction of environmental and genetic factors. Despite numerous pharmacological and behavioral interventions, approximately 10% of patients remain refractory. High-frequency deep brain stimulation (HF-DBS) has shown promising results for treatment-refractory OCD. We report the follow-up result of up to 6 years of 4 treatment-refractory OCD patients treated by HF-DBS. Targets of stimulation were the anterior limb of the internal capsule (ALIC) in two cases, and the nucleus accumbens (NAc) in the remaining cohort. The clinical profiles were quantified by the Yale-Brown obsessive-compulsive scale (Y-BOCS). Highly significant reductions in Y-BOCS scores were obtained from all patients during the follow-up period. A greater that 90% reduction in Y-BOCS, observed in the most successful case, was achieved with NAc HF-DBS. Y-BOCS scores in the other patients consistently achieved over 50% reductions in OCD symptoms. FDG-PET imaging indicated post-surgical reductions in metabolism, in not only targeted limbic networks, but also other frontal cortical and subcortical regions, suggesting that large-scale network modulation and inhibitions are associated with functional recovery in OCD. This study demonstrates that HF-DBS targeted to the ALIC and NAc is a safe and effective method for ameliorating intractable, treatment-refractory OCD symptoms. The NAc appeared to be the superior target for symptom reduction, and local inhibition of NAc activity and reduced frontal metabolism are key therapeutic indications.

Open-label trial of anterior limb of internal capsule-nucleus accumbens deep brain stimulation for obsessive-compulsive disorder: insights gained

BACKGROUND

For more than 15 years, deep brain stimulation (DBS) has served as a last-resort treatment for severe treatment-resistant obsessive-compulsive disorder (OCD).

METHODS

From 2010 to 2016, 20 patients with OCD (10 men/10 women) were included in a single-centre trial with a naturalistic open-label design over 1 year to evaluate the effects of DBS in the anterior limb of the internal capsule and nucleus accumbens region (ALIC-NAcc) on OCD symptoms, executive functions, and personality traits.

RESULTS

ALIC-NAcc-DBS significantly decreased OCD symptoms (mean Yale-Brown Obsessive Compulsive Scale reduction 33%, 40% full responders) and improves global functioning without loss of efficacy over 1 year. No significant changes were found in depressive or anxiety symptoms. Our study did not show any effect of ALIC-NAcc-DBS on personality traits or executive functions, and no potential outcome predictors were identified in a post hoc analysis. Other than several individual minor adverse events, ALIC-NAcc-DBS has been shown to be safe, but 35% of patients reported a sudden increase in anxiety and anhedonia after acute cessation of stimulation.

CONCLUSIONS

We conclude that ALIC-NAcc-DBS is a well-tolerated and promising last-resort treatment option for OCD. The cause of variability in the outcome remains unclear, and the aspect of reversibility must be examined critically. The present data from one of the largest samples of patients with OCD treated with DBS thus far support the results of previous studies with smaller samples.

Cellular, molecular, and clinical mechanisms of action of deep brain stimulation-a systematic review on established indications and outlook on future developments

Deep brain stimulation (DBS) has been successfully used to treat movement disorders, such as Parkinson's disease, for more than 25 years and heralded the advent of electrical neuromodulation to treat diseases with dysregulated neuronal circuits. DBS is now superseding ablative techniques, such as stereotactic radiofrequency lesions. While serendipity has played a role in developing DBS as a therapy, research during the past two decades has shown that electrical neuromodulation is far more than a functional lesion that can be switched on and off. This understanding broadens the field to enable new types of stimulation, clinical indications, and research. This review highlights the complex effects of DBS from the single cell to the neuronal network. Specifically, we examine the electrical, cellular, molecular, and neurochemical mechanisms of DBS as applied to Parkinson's disease and other emerging applications.

Transcranial direct current stimulation for the treatment of obsessive-compulsive disorder? A qualitative review of safety and efficacy

Obsessive-compulsive disorder (OCD) is a highly disabling psychiatric disorder characterized by recurrent obsessions and compulsions. It has a lifetime prevalence of 1-3% in the general population and commonly has a chronic course. First-line treatments consist of selective serotonin reuptake inhibitors and cognitive-behavioral therapy but up to 60% of patients respond partially or not at all to these treatments. This paper reviewed the literature on the safety and efficacy of transcranial direct current stimulation (tDCS) for the treatment of obsessive-compulsive disorder and discussed future directions for research and clinical application. Criteria for inclusion were open or controlled studies on tDCS and OCD that used validated rating scales along with well-described stimulus parameters. In the majority of the limited number of published studies, most patients with treatment-resistant obsessive-compulsive disorder had either moderate or marked benefit with this technique different stimulation targets, sometimes sustained for many months. This technique might be efficacious in the treatment of obsessive-compulsive disorder, although it is difficult to draw definitive conclusions about its efficacy, future well-designed sham-controlled studies are needed to confirm the safety and efficacy of tDCS for the treatment of this condition.

Altered Cortico-Striatal Functional Connectivity During Resting State in Obsessive-Compulsive Disorder

Background: Neuroimaging studies show that obsessive-compulsive disorder (OCD) is characterized by an alteration of the cortico-striato-thalamo-cortical (CSTC) system in terms of an imbalance of activity between the direct and the indirect loop of the CSTC. As resting-state functional connectivity (FC) studies investigated only specific parts of the CSTC in patients with OCD up to now, the present study aimed at exploring FC in the CSTC as a whole. Methods: We investigated potential alterations in resting-state FC within the CSTC system in 44 OCD patients and 40 healthy controls by taking into consideration all relevant nodes of the direct and indirect CSTC loop. Results: Compared to healthy controls, OCD patients showed an increased FC between the left subthalamic nucleus (STN) and the left external globus pallidus (GPe), as well as an increased FC between the left GPe and the left internal globus pallidus (GPi). Conclusion: These findings may contribute to a better understanding of the OCD pathophysiology by providing further information on the connectivity alterations within specific regions of the CSTC system. In particular, increased FC between the STN and the left GPe may play a major role in OCD pathology. This assumption is consistent with the fact that these regions are also the main target sites of therapeutic deep brain stimulation in OCD.

Personalized striatal targets for deep brain stimulation in obsessive-compulsive disorder

BACKGROUND

Psychiatric conditions currently treated with deep brain stimulation (DBS), such as obsessive-compulsive disorder (OCD), are heterogeneous diseases with different symptomatic dimensions, indicating that fixed neuroanatomical DBS targets for all OCD cases may not be efficacious.

OBJECTIVE/HYPOTHESIS

We tested whether the optimal DBS target for OCD is fixed for all patients or whether it is individualized and related to each patient's symptomatic content. Further, we explored if the optimal target can be predicted by combining functional neuroimaging and structural connectivity.

METHODS

In a prospective, randomized, double-blinded study in 7 OCD patients, symptomatic content was characterized pre-operatively by clinical interview and OCD symptom-provocation during functional MRI. DBS electrode implantation followed a trajectory placing 4 contacts along a striatal axis (nucleus accumbens to caudate). Patients underwent three-month stimulation periods for each contact (and sham), followed by clinical evaluation. Probabilistic tractography, applied to diffusion-weighted images acquired pre-operatively, was used to study the overlap between projections from the prefrontal areas activated during symptom provocation and the volume of activated tissue of each electrode contact.

RESULTS

Six patients were classified responders, with median symptomatic reduction of 50% achieved from each patient's best contact. This was located at the caudate in 4 cases and at the accumbens in 2. Critically, the anatomical locus of the best contact (accumbens or caudate) was related to an index derived by combining functional MRI responses to prevailing symptom provocation and prefronto-cortico-striatal projections defined by probabilistic tractography.

CONCLUSION

Our results therefore represent a step towards personalized, content-specific DBS targets for OCD.

Deep Brain Stimulation Modified Autism-Like Deficits via the Serotonin System in a Valproic Acid-Induced Rat Model

Deep brain stimulation (DBS) is known to be a promising treatment for resistant depression, which acts via the serotonin (5-hydroxytryptamine, 5-HT) system in the infralimbic prefrontal cortex (ILPFC). Previous study revealed that dysfunction of brain 5-HT homeostasis is related to a valproate (VPA)-induced rat autism spectrum disorder (ASD) model. Whether ILPFC DBS rescues deficits in VPA-induced offspring through the 5-HT system is not known. Using VPA-induced offspring, we therefore explored the effect of DBS in autistic phenotypes and further investigated the underlying mechanism. Using combined behavioral and molecular approaches, we observed that applying DBS and 5-HT_1A receptor agonist treatment with 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) reversed sociability deficits, anxiety and hyperactivity in the VPA-exposed offspring. We then administered the selective 5-HT_1A receptor antagonist N-[2-[4-(2-Methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinylcyclohexanecarboxamide maleate (WAY 100635), following which the effect of DBS in terms of improving autistic behaviors was blocked in the VPA-exposed offspring. Furthermore, we found that both 8-OH-DPAT and DBS treatment rescued autistic behaviors by decreasing the expressions of NR2B subunit of N-methyl-D-aspartate receptors (NMDARs) and the β₃ subunit of γ-aminobutyric acid type A receptors (GABA_AR) in the PFC region. These results provided the first evidence of characteristic behavioral changes in VPA-induced offspring caused by DBS via the 5-HT system in the ILPFC.

Deep Brain Stimulation for Intractable Obsessive-compulsive Disorder: The International and Japanese Situation/Scenario

Deep brain stimulation (DBS) is used to treat symptoms by modulating the cortico-striato-thalamo-cortical (CSTC) loop in the central nervous system (CNS), and attempts to research loop circuit disorders have been globally initiated among the intractable neurological and psychiatric disorders. DBS treatment has been evaluated for all these newly found CNS loop circuit disorders. In 2011, neurosurgical treatments for psychiatric disorders were renamed from “psychosurgery” to “neurosurgery for psychiatric disorders (NPD)” by the World Society for Stereotactic and Functional Neurosurgery (WSSFN). Moreover, in 2014, “Consensus on guidelines for stereotactic neurosurgery for psychiatric disorders” was published by the WSSFN to address the differences in correspondence of stereotactic NPD. Globally, two multicenter prospective randomized control trials regarding DBS of the subcallosal cingulated gyrus and ventral anterior internal capsule/ventral striatum for intractable depression have been terminated after futility analysis. However, DBS for intractable obsessive-compulsive disorder (OCD), unlike for intractable depression, is showing steady development. In Japan, NPDs have not been performed since 1975 following the adoption of “Resolution of total denial for psychosurgery” by the Japanese Society of Psychiatry and Neurology. Nevertheless, a trend to adopt new neuro-modulation techniques for psychiatric disorders, including DBS, are emerging. We have created a clinical research protocol for the use of DBS in intractable OCD, which has been approved by the ethical committee of Hamamatsu University School of Medicine, with the hope of commencing DBS treatment for intractable OCD patients in the near future.

Neural correlates of affective and non-affective cognition in obsessive compulsive disorder: A meta-analysis of functional imaging studies

Obsessive compulsive disorder (OCD) is characterized by intrusive thoughts and repetitive ritualistic behaviors and has been associated with diverse functional brain abnormalities. We sought to synthesize current evidence from functional magnetic resonance imaging (fMRI) studies and examine their alignment to pathogenetic models of OCD. Following systematic review, we identified 54 task-fMRI studies published in the last decade comparing adults with OCD (n=1186) to healthy adults (n=1159) using tasks of affective and non-affective cognition. We used voxel-based quantitative meta-analytic methods to combine primary data on anatomical coordinates of case-control differences, separately for affective and non-affective tasks. We found that functional abnormalities in OCD cluster within cortico-striatal thalamic circuits. Within these circuits, the abnormalities identified showed significant dependence on the affective or non-affective nature of the tasks employed as circuit probes. In studies using affective tasks, patients overactivated regions involved in salience, arousal and habitual responding (anterior cingulate cortex, insula, caudate head and putamen) and underactivated regions implicated in cognitive and behavioral control (medial prefrontal cortex, posterior caudate). In studies using non-affective cognitive tasks, patients overactivated regions involved in self-referential processing (precuneus, posterior cingulate cortex) and underactivated subcortical regions that support goal-directed cognition and motor control (pallidum, ventral anterior thalamus, posterior caudate). The overall pattern suggests that OCD-related brain dysfunction involves increased affective and self-referential processing, enhanced habitual responding and blunted cognitive control.

The application of deep brain stimulation in the treatment of psychiatric disorders

Deep brain stimulation (DBS) is a last-resort treatment for neurological and psychiatric disorders that are refractory to standard treatment. Over the last decades, the progress of DBS in psychiatry has been slower than in neurology, in part owing to the heterogenic symptomatology and complex neuroanatomy of psychiatric disorders. However, for obsessive-compulsive disorder (OCD) DBS is now an accepted treatment. This study first reviews clinical outcomes and mechanisms of DBS for OCD, and then discusses these results in an overview of current and future psychiatric applications, including DBS for mood disorders, Tourette's syndrome, addiction, anorexia nervosa, autism, schizophrenia, and anxiety disorders. In addition, it will focus on novel techniques that may enhance the application of DBS in psychiatry.

Deep Brain Stimulation of the Nucleus Accumbens Core Affects Trait Impulsivity in a Baseline-Dependent Manner

Deep brain stimulation (DBS) of the nucleus accumbens (NA) is explored as a treatment for refractory psychiatric disorders, such as obsessive-compulsive disorder (OCD), depressive disorder (MDD), and substance use disorder (SUD). A common feature of some of these disorders is pathological impulsivity. Here, the effects of NAcore DBS on impulsive choice and impulsive action, two distinct forms of impulsive behavior, were investigated in translational animal tasks, the delayed reward task (DRT) and five-choice serial reaction time task (5-CSRTT), respectively. In both tasks, the effects of NAcore DBS were negatively correlated with baseline impulsive behavior, with more pronounced effects in the 5-CSRTT. To further examine the effects of DBS on trait impulsive action, rats were screened for high (HI) and low (LI) impulsive responding in the 5-CSRTT. NAcore DBS decreased impulsive, premature responding in HI rats under conventional conditions. However, upon challenged conditions to increase impulsive responding, NAcore DBS did not alter impulsivity. These results strongly suggest a baseline-dependent effect of DBS on impulsivity, which is in line with clinical observations.

Anterior Cingulate Implant for Obsessive-Compulsive Disorder

BACKGROUND

Obsessive-compulsive disorder (OCD) is a brain disorder with a lifetime prevalence of 2.3%, causing severe functional impairment as a result of anxiety and distress, persistent and repetitive, unwanted, intrusive thoughts (obsessions), and repetitive ritualized behavior (compulsions). Approximately 40%-60% of patients with OCD fail to satisfactorily respond to standard treatments. Intractable OCD has been treated by anterior capsulotomy and cingulotomy, but more recently, neurostimulation approaches have become more popular because of their reversibility.

OBJECTIVE

Implants for OCD are commonly being used, targeting the anterior limb of the internal capsula or the nucleus accumbens, but an implant on the anterior cingulate cortex has never been reported.

METHODS

We describe a patient who was primarily treated for alcohol addiction, first with transcranial magnetic stimulation, then by implantation of 2 electrodes overlying the rostrodorsal part of the anterior cingulate cortex bilaterally.

RESULTS

Her alcohol addiction developed as she was relief drinking to self-treat her OCD, anxiety, and depression. After the surgical implant, she underwent placebo stimulation followed by real stimulation of the dorsal anterior cingulate cortex, which dramatically improved her OCD symptoms (decrease of 65.5% on the Yale-Brown Obsessive Compulsive Drinking Scale) as well as her alcohol craving (decrease of 87.5%) after 36 weeks of treatment. Although there were improvements in all the scores, there was only a modest reduction in the patient's weekly alcohol consumption (from 50 units to 32 units).

CONCLUSIONS

Based on these preliminary positive results we propose to further study the possible beneficial effect of anterior cingulate cortex stimulation for intractable OCD.

Effects of Deep Brain Stimulation on Autonomic Function

Over the course of the development of deep brain stimulation (DBS) into a well-established therapy for Parkinson's disease, essential tremor, and dystonia, its utility as a potential treatment for autonomic dysfunction has emerged. Dysfunction of autonomic processes is common in neurological diseases. Depending on the specific target in the brain, DBS has been shown to raise or lower blood pressure, normalize the baroreflex, to alter the caliber of bronchioles, and eliminate hyperhidrosis, all through modulation of the sympathetic nervous system. It has also been shown to improve cortical control of the bladder, directly induce or inhibit the micturition reflex, and to improve deglutition and gastric emptying. In this review, we will attempt to summarize the relevant available studies describing these effects of DBS on autonomic function, which vary greatly in character and magnitude with respect to stimulation target.

Perimovement decrease of alpha/beta oscillations in the human nucleus accumbens

The present work clarifies how the nucleus accumbens contributes to action. This region is often assumed to influence behavior “off-line” by evaluating outcomes. Studying rare recordings of local field potentials from the human nucleus accumbens, we observe a perimovement decrease of alpha and beta oscillations in seven of eight individuals, a signal that, in the motor system, is directly related to action preparation. Our results support the idea of an online role of this region for imminent action.

The human nucleus accumbens is thought to play an important role in guiding future action selection via an evaluation of current action outcomes. Here we provide electrophysiological evidence for a more direct, i.e., online, role during action preparation. We recorded local field potentials from the nucleus accumbens in patients with epilepsy undergoing surgery for deep brain stimulation. We found a consistent decrease in the power of alpha/beta oscillations (10–30 Hz) before and around the time of movements. This perimovement alpha/beta desynchronization was observed in seven of eight patients and was present both before instructed movements in a serial reaction time task as well as before self-paced, deliberate choices in a decision making task. A similar beta decrease over sensorimotor cortex and in the subthalamic nucleus has been directly related to movement preparation and execution. Our results support the idea of a direct role of the human nucleus accumbens in action preparation and execution.

Role of the dorsal anterior cingulate cortex in obsessive-compulsive disorder: converging evidence from cognitive neuroscience and psychiatric neurosurgery

OBJECTIVE Advances in understanding the neurobiological basis of psychiatric disorders will improve the ability to refine neuromodulatory procedures for treatment-refractory patients. One of the core dysfunctions in obsessive-compulsive disorder (OCD) is a deficit in cognitive control, especially involving the dorsal anterior cingulate cortex (dACC). The authors' aim was to derive a neurobiological understanding of the successful treatment of refractory OCD with psychiatric neurosurgical procedures targeting the dACC. METHODS First, the authors systematically conducted a review of the literature on the role of the dACC in OCD by using the search terms "obsessive compulsive disorder" and "anterior cingulate." The neuroscience literature on cognitive control mechanisms in the dACC was then combined with the literature on psychiatric neurosurgical procedures targeting the dACC for the treatment of refractory OCD. RESULTS The authors reviewed 89 studies covering topics that included structural and functional neuroimaging and electrophysiology. The majority of resting-state functional neuroimaging studies demonstrated dACC hyperactivity in patients with OCD relative to that in controls, while task-based studies were more variable. Electrophysiological studies showed altered dACC-related biomarkers of cognitive control, such as error-related negativity in OCD patients. These studies were combined with the cognitive control neurophysiology literature, including the recently elaborated expected value of control theory of dACC function. The authors suggest that a central feature of OCD pathophysiology involves the generation of mis-specified cognitive control signals by the dACC, and they elaborate on this theory and provide suggestions for further study. CONCLUSIONS Although abnormalities in brain structure and function in OCD are distributed across a wide network, the dACC plays a central role. The authors propose a theory of cognitive control dysfunction in OCD that attempts to explain the therapeutic efficacy of dACC neuromodulation. This theoretical framework should help to guide further research into targeted treatments of OCD and other disorders of cognitive control.

Removing and reimplanting deep brain stimulation therapy devices in resistant OCD (when the patient does not respond): case report

BACKGROUND

Deep brain stimulation (DBS) is emerging as a promising tool in the treatment of refractory obsessive-compulsive disorder (OCD) but the search for the best target still continues. This issue is especially relevant when particularly resistant profiles are observed in some patients, which have been ascribed to individual responses to DBS according to differential patterns of connectivity. As patients have been implanted, new dilemmas have emerged, such as what to do when the patient does not respond to surgery.

CASE PRESENTATION

Here we describe a 22-year-old male with extremely severe OCD who did not respond to treatment with DBS in the nucleus accumbens, but who did respond after explanting and reimplanting leads targeting the ventral capsule-ventral striatum region. Information regarding the position of the electrodes for both surgeries is provided and possible brain structures affected during stimulation are reviewed. To our knowledge this case is the first in the literature reporting the removal and reimplantation of DBS leads for therapeutical benefits in a patient affected by a mental disorder.

CONCLUSION

The capability for explantation and reimplantation of leads should be considered as part of the DBS therapy reversibility profile in resistant mental disorders, as it allows application in cases of non-response to the first surgery.

Effects of Deep Brain Stimulation on the Lived Experience of Obsessive-Compulsive Disorder Patients: In-Depth Interviews with 18 Patients

Deep Brain Stimulation (DBS) is a relatively new, experimental treatment for patients suffering from treatment-refractory Obsessive Compulsive Disorder (OCD). The effects of treatment are typically assessed with psychopathological scales that measure the amount of symptoms. However, clinical experience indicates that the effects of DBS are not limited to symptoms only: patients for instance report changes in perception, feeling stronger and more confident, and doing things unreflectively. Our aim is to get a better overview of the whole variety of changes that OCD patients experience during DBS treatment. For that purpose we conducted in-depth, semi-structured interviews with 18 OCD patients. In this paper, we present the results from this qualitative study. We list the changes grouped in four domains: with regard to (a) person, (b) (social) world, (c) characteristics of person-world interactions, and (d) existential stance. We subsequently provide an interpretation of these results. In particular, we suggest that many of these changes can be seen as different expressions of the same process; namely that the experience of anxiety and tension gives way to an increased basic trust and increased reliance on one's abilities. We then discuss the clinical implications of our findings, especially with regard to properly informing patients of what they can expect from treatment, the usefulness of including CBT in treatment, and the limitations of current measures of treatment success. We end by making several concrete suggestions for further research.

Effects of Deep Brain Stimulation on the Lived Experience of Obsessive-Compulsive Disorder Patients: In-Depth Interviews with 18 Patients

Deep Brain Stimulation (DBS) is a relatively new, experimental treatment for patients suffering from treatment-refractory Obsessive Compulsive Disorder (OCD). The effects of treatment are typically assessed with psychopathological scales that measure the amount of symptoms. However, clinical experience indicates that the effects of DBS are not limited to symptoms only: patients for instance report changes in perception, feeling stronger and more confident, and doing things unreflectively. Our aim is to get a better overview of the whole variety of changes that OCD patients experience during DBS treatment. For that purpose we conducted in-depth, semi-structured interviews with 18 OCD patients. In this paper, we present the results from this qualitative study. We list the changes grouped in four domains: with regard to (a) person, (b) (social) world, (c) characteristics of person-world interactions, and (d) existential stance. We subsequently provide an interpretation of these results. In particular, we suggest that many of these changes can be seen as different expressions of the same process; namely that the experience of anxiety and tension gives way to an increased basic trust and increased reliance on one's abilities. We then discuss the clinical implications of our findings, especially with regard to properly informing patients of what they can expect from treatment, the usefulness of including CBT in treatment, and the limitations of current measures of treatment success. We end by making several concrete suggestions for further research.