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

The relationship between cognitive phenotypes of compulsivity and impulsivity and clinical variables in obsessive-compulsive disorder: A systematic review and Meta-analysis

BACKGROUND

This systematic review and meta-analysis explored the relationship between cognitive phenotypes of compulsivity and impulsivity and clinical variables in obsessive-compulsive disorder (OCD).

METHODS

We searched Pubmed, Scopus, Cochrane Library and PsychINFO databases until February 2023 for studies comparing patients with OCD and healthy controls on cognitive tests of compulsivity and impulsivity. The study followed PRISMA guidelines and was pre-registered on PROSPERO (CRD42021299017).

RESULTS

Meta-analyses of 112 studies involving 8313 participants (4289 patients with OCD and 4024 healthy controls) identified significant impairments in compulsivity (g = -0.58, [95%CI -0.68, -0.47]; k = 76) and impulsivity (g = -0.48, [95%CI -0.57, -0.38]; k = 63); no significant difference between impairments. Medication use and comorbid psychiatric disorders were not significantly related to impairments. No associations were revealed with OCD severity, depression/anxiety, or illness duration.

CONCLUSION

Cognitive phenotypes of compulsivity and impulsivity in patients with OCD appear to be orthogonal to clinical variables, including severity of OCD symptomatology. Their clinical impact is poorly understood and may require different clinical assessment tools and interventions.

Clinical outcomes of deep brain stimulation for obsessive-compulsive disorder: Insight as a predictor of symptom changes

AIM

Deep brain stimulation (DBS) is a safe and effective treatment option for people with refractory obsessive-compulsive disorder (OCD). Yet our understanding of predictors of response and prognostic factors remains rudimentary, and long-term comprehensive follow-ups are lacking. We aim to investigate the efficacy of DBS therapy for OCD patients, and predictors of clinical response.

METHODS

Eight OCD participants underwent DBS stimulation of the nucleus accumbens (NAc) in an open-label longitudinal trial, duration of follow-up varied between 9 months and 7 years. Post-operative care involved comprehensive fine tuning of stimulation parameters and adjunct multidisciplinary therapy.

RESULTS

Six participants achieved clinical response (35% improvement in obsessions and compulsions on the Yale Brown Obsessive Compulsive Scale (YBOCS)) within 6-9 weeks, response was maintained at last follow up. On average, the YBOCS improved by 45% at last follow up. Mixed linear modeling elucidated directionality of symptom changes: insight into symptoms strongly predicted (P = 0.008) changes in symptom severity during DBS therapy, likely driven by initial changes in depression and anxiety. Precise localization of DBS leads demonstrated that responders most often had their leads (and active contacts) placed dorsal compared to non-responders, relative to the Nac.

CONCLUSION

The clinical efficacy of DBS for OCD is demonstrated, and mediators of changes in symptoms are proposed. The symptom improvements within this cohort should be seen within the context of the adjunct psychological and biopsychosocial care that implemented a shared decision-making approach, with flexible iterative DBS programming. Further research should explore the utility of insight as a clinical correlate of response. The trial was prospectively registered with the ANZCTR (ACTRN12612001142820).

The promise and challenges of transcranial magnetic stimulation and deep brain stimulation as therapeutic options for obsessive-compulsive disorder

INTRODUCTION

Obsessive compulsive disorder (OCD) represents a complex and often difficult to treat disorder. Pharmacological and psychotherapeutic interventions are often associated with sub-optimal outcomes, and 40-60% of patients are resistant to first line therapies and thus left with few treatment options. OCD is underpinned by aberrant neurocircuitry within cortical, striatal, and thalamic brain networks. Considering the neurocircuitry impairments that underlie OCD symptomology, neurostimulation therapies provide an opportunity to modulate psychopathology in a personalized manner. Also, by probing pathological neural networks, enhanced understanding of disease states can be obtained.

AREAS COVERED

This perspective discusses the clinical efficacy of TMS and DBS therapies, treatment access options, and considerations and challenges in managing patients. Recent scientific progress is discussed, with a focus on neurocircuitry and biopsychosocial aspects. Translational recommendations and suggestions for future research are provided.

EXPERT OPINION

There is robust evidence to support TMS and DBS as an efficacious therapy for treatment resistant OCD patients supported by an excellent safety profile and favorable health economic data. Despite a great need for alternative therapies for chronic and severe OCD patients, resistance toward neurostimulation therapies from regulatory bodies and the psychiatric community remains. The authors contend for greater access to TMS and DBS for treatment resistant OCD patients at specialized sites with appropriate clinical resources, particularly considering adjunct and follow-up care. Also, connectome targeting has shown robust predictive ability of symptom improvements and holds potential in advancing personalized neurostimulation therapies.

Chronic Deep Brain Stimulation of the Human Nucleus Accumbens Region Disrupts the Stability of Intertemporal Preferences

When choosing between rewards that differ in temporal proximity (intertemporal choice), human preferences are typically stable, constituting a clinically relevant transdiagnostic trait. Here we show, in female and male human patients undergoing deep brain stimulation (DBS) of the anterior limb of the internal capsule/NAcc region for treatment-resistant obsessive-compulsive disorder, that long-term chronic (but not phasic) DBS disrupts intertemporal preferences. Hierarchical Bayesian modeling accounting for temporal discounting behavior across multiple time points allowed us to assess both short-term and long-term reliability of intertemporal choice. In controls, temporal discounting was highly reliable, both long-term (6 months) and short-term (1 week). In contrast, in patients undergoing DBS, short-term reliability was high, but long-term reliability (6 months) was severely disrupted. Control analyses confirmed that this effect was not because of range restriction, the presence of obsessive-compulsive disorder symptoms or group differences in choice stochasticity. Model-agnostic between- and within-subject analyses confirmed this effect. These findings provide initial evidence for long-term modulation of cognitive function via DBS and highlight a potential contribution of the human NAcc region to intertemporal preference stability over time.SIGNIFICANCE STATEMENT Choosing between rewards that differ in temporal proximity is in part a stable trait with relevance for many mental disorders, and depends on prefrontal regions and regions of the dopamine system. Here we show that chronic deep brain stimulation of the human anterior limb of the internal capsule/NAcc region for treatment-resistant obsessive-compulsive disorder disrupts the stability of intertemporal preferences. These findings show that chronic stimulation of one of the brain's central motivational hubs can disrupt preferences thought to depend on this circuit.

Implication of microbiota gut-brain axis in the manifestation of obsessive-compulsive disorder: Preclinical and clinical evidence

Recent research has highlighted the key role of gut microbiota in the development of psychiatric disorders. The adverse impact of stress, anxiety, and depression has been well documented on the commensal gut microflora. Thus, therapeutic benefits of gut microbiota-based interventions may not be avoided in central nervous system (CNS) disorders. In this review, we outline the current state of knowledge of gut microbiota with respect to obsessive-compulsive disorder (OCD). We discuss how OCD-generated changes corresponding to the key neurotransmitters, hypothalamic-pituitary-adrenal axis, and immunological and inflammatory pathways are connected with the modifications of the microbiota-gut-brain axis. Notably, administration of few probiotics such as Lactobacillus rhamnosus (ATCC 53103), Lactobacillus helveticus R0052, Bifidobacterium longum R0175, Saccharomyces boulardii, and Lactobacillus casei Shirota imparted positive effects in the management of OCD symptoms. Taken together, we suggest that the gut microbiota-directed therapeutics may open new treatment approaches for the management of OCD.

Patient feedback and psychosocial outcomes of deep brain stimulation in people with obsessive-compulsive disorder

Severe and refractory psychiatric patients can experience complex and profound changes in symptomology, functioning and well-being from deep brain stimulation (DBS) therapy. Currently, the efficacy of DBS is assessed by clinician rated scales of primary symptoms, yet this does not capture the multitude of DBS mediated changes or represent the patient perspective. We aimed to elucidate the patient perspective in psychiatric DBS application by investigating 1) symptomatic, and 2) psychosocial changes, 3) therapeutic expectations and satisfaction, 4) decision-making capacity, and 5) clinical care recommendations from treatment refractory obsessive-compulsive disorder (OCD) DBS patients. Participants enrolled in an open label clinical trial of DBS therapy for OCD who had reached clinical response were invited to participate in a follow up survey. Participants completed a 1) feedback survey relating to goals, expectations, and satisfaction of therapy, and 2) self-report questionnaires on psychosocial functioning including quality of life, cognitive insight, locus of control, rumination, cognitive flexibility, impulsivity, affect, and well-being. Greatest change was reported for quality of life, rumination, affect and cognitive flexibility. Participants reported realistic expectations, high satisfaction, adequate pre-operative education and decision-making capacity; and advocated for greater access to DBS care and more widespread support services. This is the first identified investigation on psychiatric patient perspectives of functioning and therapeutic outcomes following DBS. Insights from the study have implications for informing psychoeducation, clinical practices, and neuroethical debates. We encourage a greater patient-centred and biopsychosocial approach in evaluating and managing OCD DBS patients, by considering personally meaningful goals and addressing symptomatic and psychosocial recovery.

Stereotactic neurosurgery as a symptomatic treatment for autism spectrum disorders: A systematic review

Stereotactic neurosurgery has been employed in autism spectrum disorders (ASD). However, its safety and effectiveness remain unclear owing to limited sample size and other methodological limitations. We aimed to systematically investigate the safety and efficacy of stereotactic neurosurgery for ASD. Eleven studies with 36 patients were included. Stereotactic neurosurgery alleviated the obsessive-compulsive disorder and aggressive behavior symptoms in ASD, with a mean improvement of 42.74% and 59.59% in the Yale-Brown Obsessive Compulsive Scale and Overt Aggression Scale scores, respectively. Systematic studies are necessary to explore the role of deep brain stimulation for social and communication difficulties in ASD.

Internal Capsule/Nucleus Accumbens Deep Brain Stimulation Increases Impulsive Decision Making in Obsessive-Compulsive Disorder

BACKGROUND

Deep brain stimulation of the anterior limb of the internal capsule (ALIC)/nucleus accumbens is an effective treatment in patients with obsessive-compulsive disorder but may increase impulsive behavior. We aimed to investigate how active stimulation alters subdomains of impulsive decision making and whether respective effects depend on the location of stimulation sites.

METHODS

We assessed 15 participants with obsessive-compulsive disorder performing the Cambridge Gambling Task during active and inactive ALIC/nucleus accumbens deep brain stimulation. Specifically, we determined stimulation-induced changes in risk adjustment and delay aversion. To characterize underlying neural pathways, we computed probabilistic stimulation maps and applied fiber filtering based on normative structural connectivity data to identify "hot" and "cold" spots/fibers related to changes in impulsive decision making.

RESULTS

Active stimulation significantly reduced risk adjustment while increasing delay aversion, both implying increased impulsive decision making. Changes in risk adjustment were robustly associated with stimulation sites located in the central ALIC and fibers connecting the thalamus and subthalamic nucleus with the medial and lateral prefrontal cortex. Both hot spots and fibers for changes in risk adjustment were robust to leave-one-out cross-validation. Changes in delay aversion were similarly associated with central ALIC stimulation, but validation hereof was nonsignificant.

CONCLUSIONS

Our findings provide experimental evidence that ALIC/nucleus accumbens stimulation increases impulsive decision making in obsessive-compulsive disorder. We show that changes in risk adjustment depend on the location of stimulation volumes and affected fiber bundles. The relationship between impulsive decision making and long-term clinical outcomes requires further investigation.

Nucleus accumbens: a systematic review of neural circuitry and clinical studies in healthy and pathological states

OBJECTIVE

The nucleus accumbens (NAcc) of the ventral striatum is critically involved in goal- and reward-based behavior. Structural and functional abnormalities of the NAcc or its associated neural systems are involved in neurological and psychiatric disorders. Studies of neural circuitry have shed light on the subtleties of the structural and functional derangements of the NAcc across various diseases. In this systematic review, the authors sought to identify human studies involving the NAcc and provide a synthesis of the literature on the known circuity of the NAcc in healthy and diseased states, as well as the clinical outcomes following neuromodulation.

METHODS

A systematic review was conducted using the PubMed, Embase, and Scopus databases. Neuroimaging studies that reported on neural circuitry related to the human NAcc with sample sizes greater than 5 patients were included. Demographic data, aim, design and duration, participants, and clinical and neurocircuitry details and outcomes of the studies were extracted.

RESULTS

Of 3591 resultant articles, 123 were included. The NAcc and its corticolimbic connections to other brain regions, such as the prefrontal cortex, are largely involved in reward and pain processes, with distinct functional circuitry between the shell and core in healthy patients. There is heterogeneity between clinical studies with regard to the NAcc indirect targeting coordinates, methods for postoperative confirmation, and blinded trial design. Neuromodulation studies provided promising clinical results in the context of addiction and substance misuse, obsessive-compulsive disorder, and mood disorders. The most common complications were impaired memory or concentration, and a notable serious complication was hypomania.

CONCLUSIONS

The functional diversity of the NAcc highlights the importance of studying the NAcc in healthy and pathological states. The results of this review suggest that NAcc neuromodulation has been attempted in the management of diverse psychiatric indications. There is promising, emerging evidence that the NAcc may be an effective target for specific reward- or pain-based pathologies with a reasonable risk profile.

Modulating Brain Activity with Invasive Brain-Computer Interface: A Narrative Review

Brain-computer interface (BCI) can be used as a real-time bidirectional information gateway between the brain and machines. In particular, rapid progress in invasive BCI, propelled by recent developments in electrode materials, miniature and power-efficient electronics, and neural signal decoding technologies has attracted wide attention. In this review, we first introduce the concepts of neuronal signal decoding and encoding that are fundamental for information exchanges in BCI. Then, we review the history and recent advances in invasive BCI, particularly through studies using neural signals for controlling external devices on one hand, and modulating brain activity on the other hand. Specifically, regarding modulating brain activity, we focus on two types of techniques, applying electrical stimulation to cortical and deep brain tissues, respectively. Finally, we discuss the related ethical issues concerning the clinical application of this emerging technology.

Potential therapeutic mechanism of deep brain stimulation of the nucleus accumbens in obsessive-compulsive disorder

Deep brain stimulation (DBS) of the nucleus accumbens (NAc) (NAc-DBS) is an effective solution to refractory obsessive-compulsive disorder (OCD). However, evidence for the neurobiological mechanisms of OCD and the effect of NAc-DBS is still lacking. One hypothesis is that the electrophysiological activities in the NAc are modulated by DBS, and another hypothesis is that the activities of neurotransmitters in the NAc are influenced by DBS. To investigate these potential alterations, rats with quinpirole (QNP)- induced OCD were treated with DBS of the core part of NAc. Then, extracellular spikes (SPK) and local field potentials (LFP) in the NAc were recorded, and the levels of relevant neurotransmitters and related proteins were measured. Analysis of SPK revealed that the firing rate was decreased and the firing pattern was changed after NAc-DBS, and analysis of LFP showed that overall power spectral density (PSD) levels were reduced after NAc-DBS. Additionally, we found that the relative powers of the theta band, alpha band and beta band were increased in OCD status, while the relative powers of the delta band and gamma band were decreased. This pathological pattern of power distribution was reformed by NAc-DBS. Furthermore, we found that the local levels of monoamines [dopamine (DA) and serotonin (5-HT)] and amino acids [glutamate (Glu) and gamma-aminobutyric acid (GABA)] in the NAc were increased in OCD status, and that the expression of the two types of DA receptors in the NAc exhibited an opposite change. These abnormalities could be reversed by NAc-DBS. These findings provide a more comprehensive understanding about the function of the NAc in the pathophysiology of OCD and provide more detailed evidence for the potential effect of NAc-DBS.

Structural and functional correlates of the response to deep brain stimulation at ventral capsule/ventral striatum region for treatment-resistant depression

BACKGROUND

Though deep brain stimulation (DBS) shows increasing potential in treatment-resistant depression (TRD), the underlying neural mechanisms remain unclear. Here, we investigated functional and structural connectivities related to and predictive of clinical effectiveness of DBS at ventral capsule/ventral striatum region for TRD.

METHODS

Stimulation effects of 71 stimulation settings in 10 TRD patients were assessed. The electric fields were estimated and combined with normative functional and structural connectomes to identify connections as well as fibre tracts beneficial for outcome. We calculated stimulation-dependent optimal connectivity and constructed models to predict outcome. Leave-one-out cross-validation was used to validate the prediction value.

RESULTS

Successful prediction of antidepressant effectiveness in out-of-sample patients was achieved by the optimal connectivity profiles constructed with both the functional connectivity (R=0.49 at p<10-4; deviated by 14.4±10.9% from actual, p<0.001) and structural connectivity (R=0.51 at p<10-5; deviated by 15.2±11.5% from actual, p<10-5). Frontothalamic pathways and cortical projections were delineated for optimal clinical outcome. Similarity estimates between optimal connectivity profile from one modality (functional/structural) and individual brain connectivity in the other modality (structural/functional) significantly cross-predicted the outcome of DBS. The optimal structural and functional connectivity mainly converged at the ventral and dorsal lateral prefrontal cortex and orbitofrontal cortex.

CONCLUSIONS

Connectivity profiles and fibre tracts following frontothalamic streamlines appear to predict outcome of DBS for TRD. The findings shed light on the neural pathways in depression and may be used to guide both presurgical planning and postsurgical programming after further validation.

Efficacy of deep brain stimulation for treatment-resistant obsessive-compulsive disorder: systematic review and meta-analysis

Deep brain stimulation (DBS) is an established and growing intervention for treatment-resistant obsessive-compulsive disorder (TROCD). We assessed current evidence on the efficacy of DBS in alleviating OCD and comorbid depressive symptoms including newly available evidence from recent trials and a deeper risk of bias analysis than previously available. PubMed and EMBASE databases were systematically queried using Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. We included studies reporting primary data on multiple patients who received DBS therapy with outcomes reported through the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). Primary effect measures included Y-BOCS mean difference and per cent reduction as well as responder rate (≥35% Y-BOCS reduction) at last follow-up. Secondary effect measures included standardised depression scale reduction. Risk of bias assessments were performed on randomised controlled (RCTs) and non-randomised trials. Thirty-four studies from 2005 to 2021, 9 RCTs (n=97) and 25 non-RCTs (n=255), were included in systematic review and meta-analysis based on available outcome data. A random-effects model indicated a meta-analytical average 14.3 point or 47% reduction (p<0.01) in Y-BOCS scores without significant difference between RCTs and non-RCTs. At last follow-up, 66% of patients were full responders to DBS therapy. Sensitivity analyses indicated a low likelihood of small study effect bias in reported outcomes. Secondary analysis revealed a 1 standardised effect size (Hedges' g) reduction in depressive scale symptoms. Both RCTs and non-RCTs were determined to have a predominantly low risk of bias. A strong evidence base supports DBS for TROCD in relieving both OCD and comorbid depression symptoms in appropriately selected patients.

A Systematic Review of Treatment Outcome Predictors in Deep Brain Stimulation for Refractory Obsessive-Compulsive Disorder

Obsessive-compulsive disorder (OCD) is a chronic and debilitating mental disorder. Deep brain stimulation (DBS) is a promising approach for refractory OCD patients. Research aiming at treatment outcome prediction is vital to provide optimized treatments for different patients. The primary purpose of this systematic review was to collect and synthesize studies on outcome prediction of OCD patients with DBS implantations in recent years. This systematic review (PROSPERO registration number: CRD42022335585) followed the PRISMA (Preferred Reporting Items for Systematic Review and Meta-analysis) guidelines. The search was conducted using three different databases with the following search terms related to OCD and DBS. We identified a total of 3814 articles, and 17 studies were included in our review. A specific tract confirmed by magnetic resonance imaging (MRI) was predictable for DBS outcome regardless of implant targets, but inconsistencies still exist. Current studies showed various ways of successful treatment prediction. However, considering the heterogeneous results, we hope that future studies will use larger cohorts and more precise approaches for predictors and establish more personalized ways of DBS surgeries.

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.

Psychopathological and neuropsychological outcomes of deep brain stimulation for severe- treatment-resistant obsessive-compulsive disorder: An open-label case series

OBJECTIVE

Deep brain stimulation (DBS) is considered a promising intervention for treatment-resistant obsessive-compulsive disorder (OCD). The present study describes the outcomes of the first DBS procedures for OCD in Iran.

METHODS

Four women patients (age range, 25-35 years) with severe OCD meeting stringent criteria for refractoriness to treatment were selected by Psychosurgery Review Board. DBS electrodes were bilaterally implanted in the internal capsule and nucleus accumbens (NAc). Clinical and neuropsychological assessments were undertaken before and after implantation. The outcomes included Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), Hamilton Anxiety Rating Scale (HAM-A), neuropsychological assessments including the Wisconsin Card Sorting Test, Wechsler Memory Scale, and adverse events.

RESULTS

The baseline mean score of the Y-BOCS and HAM-A was 32 ± 6 and 23 ± 14 respectively and decreased to 26 ± 8 and 17 ± 9 after one-year implantation, showing a 19% improvement. Two patients were responders and showed a notable improvement. One patient's score declined 28%, who was not satisfied with DBS results, and one patient worsened under-stimulation. Improvements in the severity of anxiety and cognitive performance were consistent with OCD improvement, and the successfully treated patients showed improvement in anxiety and cognitive performance. No significant cognitive declines were seen. Two patients' suicidal ideation appeared after DBS as an important adverse event.

CONCLUSION

Bilateral DBS of the internal capsule/NAc may be an effective and safe treatment for treatment-refractory OCD. However, there is a need to consider accessibility, high cost, cost-effectiveness, and standardized methodology in future research.

Distribution of electric field in patients with obsessive compulsive disorder treated with deep brain stimulation of the bed nucleus of stria terminalis

Background

Deep brain stimulation (DBS) is being investigated as a treatment for therapy-refractory obsessive compulsive disorder (OCD). Many different brain targets are being trialled. Several of these targets such as the ventral striatum (including the nucleus accumbens (NAc)), the ventral capsule, the inferior thalamic peduncle, and the bed nucleus of stria terminalis (BNST)) belong to the same network, are anatomically very close to one another, or even overlap. Data is still missing on how various stimulation parameters in a given target will affect surrounding anatomical areas and impact the clinical outcome of DBS.

Methods

In a pilot study of eleven participants with DBS of the BNST, we investigate through patient-specific simulation of electric field, which anatomical areas are affected by the electric field, and if this can be related to the clinical results. Our study combined individual patient’s stimulation parameters at 12- and 24-month follow-up with image data from the preoperative MRI and postoperative CT. These data were used to calculate the distribution of electric field and create individual anatomical models of the field of stimulation.

Results

The individual electric stimulation fields by stimulation in the BNST were similar at both the 12- and 24-month follow-up, involving mainly anterior limb of the internal capsule (ALIC), genu of the internal capsule (IC), BNST, fornix, anteromedial globus pallidus externa (GPe), and the anterior commissure. A statistical significant correlation (p < 0.05) between clinical effect measured by the Yale-Brown Obsessive Compulsive Scale and stimulation was found at the 12-month follow-up in the ventral ALIC and anteromedial GPe.

Conclusions

Many of the targets under investigation for OCD are in anatomical proximity. As seen in our study, off-target effects are overlapping. Therefore, DBS in the region of ALIC, NAc, and BNST may perhaps be considered to be stimulation of the same target.

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.

A Unified Functional Network Target for Deep Brain Stimulation in Obsessive-Compulsive Disorder

BACKGROUND

Multiple deep brain stimulation (DBS) targets have been proposed for treating intractable obsessive-compulsive disorder (OCD). Here, we investigated whether stimulation effects of different target sites would be mediated by one common or several segregated functional brain networks.

METHODS

First, seeding from active electrodes of 4 OCD patient cohorts (N = 50) receiving DBS to anterior limb of the internal capsule or subthalamic nucleus zones, optimal functional connectivity profiles for maximal Yale-Brown Obsessive Compulsive Scale improvements were calculated and cross-validated in leave-one-cohort-out and leave-one-patient-out designs. Second, we derived optimal target-specific connectivity patterns to determine brain regions mutually predictive of clinical outcome for both targets and others predictive for either target alone. Functional connectivity was defined using resting-state functional magnetic resonance imaging data acquired in 1000 healthy participants.

RESULTS

While optimal functional connectivity profiles showed both commonalities and differences between target sites, robust cross-predictions of clinical improvements across OCD cohorts and targets suggested a shared network. Connectivity to the anterior cingulate cortex, insula, and precuneus, among other regions, was predictive regardless of stimulation target. Regions with maximal connectivity to these commonly predictive areas included the insula, superior frontal gyrus, anterior cingulate cortex, and anterior thalamus, as well as the original stereotactic targets.

CONCLUSIONS

Pinpointing the network modulated by DBS for OCD from different target sites identified a set of brain regions to which DBS electrodes associated with optimal outcomes were functionally connected-regardless of target choice. On these grounds, we establish potential brain areas that could prospectively inform additional or alternative neuromodulation targets for obsessive-compulsive disorder.

Cognitive Outcome After Deep Brain Stimulation for Refractory Obsessive-Compulsive Disorder: A Systematic Review

INTRODUCTION

Deep brain stimulation (DBS) is an effective treatment for refractory obsessive-compulsive disorder (OCD). Neuropsychological assessment contributes to DBS treatment in several ways: it monitors the cognitive safety of the treatment, identifies beneficial or detrimental cognitive side effects and it could aid to explain variability in treatment outcome, and possibly the treatment's working mechanism(s).

BACKGROUND

This systematic review assessed the cognitive safety of DBS for OCD and explored whether changes in cognitive function may help explain its working mechanism(s).

MATERIALS AND METHODS

EMBASE, PubMed/Medline, Psycinfo, and the Cochrane Library were systematically searched for studies reporting cognitive outcomes following DBS for OCD. Searches were completed in November 2020. Included studies were appraised for study design and quality according to National Heart, Lung and Blood Institute (NHLBI) quality assessment tools.

RESULTS

Five randomized controlled trials and ten observational studies comprising a total of 178 patients were analyzed collectively. Variable outcomes of DBS were observed in the domains of attention, memory, executive functioning, and in particular cognitive flexibility.

CONCLUSION

Although individual studies generally do not report cognitive deterioration after DBS for OCD, the variability of study designs and the multitude of cognitive measures used, precluded a meta-analysis to confirm its safety, and recognition of a cognitive pattern through which the efficacy of DBS for OCD might be explained. In future, prospective studies should preferably include a standardized neuropsychological assessment battery specifically addressing executive functioning and have a longer-term follow-up in order to demonstrate the cognitive safety of the procedure. Such prospective and more uniform data collection may also contribute to our understanding of the working mechanisms of DBS in OCD.

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.

Delayed Sleep Timing in Obsessive-Compulsive Disorder Is Associated With Diminished Response to Exposure and Ritual Prevention

Exposure and ritual prevention (ERP) and pharmacotherapy are typically associated with significant symptom reductions for individuals with obsessive-compulsive disorder (OCD). However, many patients are left with residual symptoms and other patients do not respond. There is increasing evidence that delays in sleep timing/circadian rhythms are associated with OCD but the potential effects of delays in sleep timing on ERP warrant attention. This paper presents data from 31 outpatients with OCD who participated in ERP. Results showed that delayed sleep timing was common and that individuals with delayed bedtimes benefited significantly less from treatment and were significantly more likely to be nonresponders compared to individuals with earlier bedtimes. Further, the effects of sleep timing remained statistically significant even after controlling for global sleep quality, negative affect, and several other variables. These findings add to a growing literature suggesting the utility of better understanding the role of disruptions in the timing of sleep in OCD.

Deep Brain Stimulation Reduces Conflict-Related Theta and Error-Related Negativity in Patients With Obsessive-Compulsive Disorder

OBJECTIVES

Obsessive-compulsive disorder (OCD) is a psychiatric disorder with alterations of cortico-striato-thalamo-cortical loops and impaired performance monitoring. Electrophysiological markers such as conflict-related medial frontal theta (MFT) and error-related negativity (ERN) may be altered by clinically effective deep brain stimulation (DBS) of the anterior limb of the internal capsule and nucleus accumbens (ALIC/NAc). We hypothesized that ALIC/NAc DBS modulates electrophysiological performance monitoring markers.

MATERIALS AND METHODS

Fifteen patients (six male) with otherwise treatment-refractory OCD receiving ALIC/NAc DBS performed a flanker task with EEG recordings at three sessions: presurgery, and at follow-up with DBS on and off. We examined MFT, ERN, and task performance. Furthermore, we investigated interrelations with clinical efficacy and the explored the influence of the location of individual stimulation volumes on EEG modulations.

RESULTS

MFT and ERN were significantly attenuated by DBS with differences most pronounced between presurgery and DBS-on states. Also, we observed reaction time slowing for erroneous responses during DBS-off. Larger presurgery ERN amplitudes were associated with decreased clinical efficacy. Exploratory anatomical analyses suggested that stimulation volumes encompassing the NAc were associated with MFT modulation, whereas ALIC stimulation was associated with modulation of the ERN and clinical efficacy.

CONCLUSION

ALIC/NAc DBS diminished MFT and ERN, demonstrating modulation of the medial frontal performance monitoring system in OCD. Furthermore, our findings encourage further studies to explore the ERN as a potential predictor for clinical efficacy.

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.

Influence of Simulated Deep Brain Stimulation on the Expression of Inflammatory Mediators by Human Central Nervous System Cells In Vitro

Deep brain stimulation (DBS) seems to modulate inflammatory processes. Whether this modulation leads to an induction or suppression of inflammatory mediators is still controversially discussed. Most studies of the influence of electrical stimulation on inflammation were conducted in rodent models with direct current stimulation and/or long impulses, both of which differ from the pattern in DBS. This makes comparisons with the clinical condition difficult. We established an in-vitro model that simulated clinical stimulation patterns to investigate the influence of electrical stimulation on proliferation and survival of human astroglial cells, microglia, and differentiated neurons. We also examined its influence on the expression of the inflammatory mediators C-X-C motif chemokine (CXCL)12, CXCL16, CC-chemokin-ligand-2 (CCL)2, CCL20, and interleukin (IL)-1β and IL-6 by these cells using quantitative polymerase chain reaction. In addition, protein expression was assessed by immunofluorescence double staining. In our model, electrical stimulation did not affect proliferation or survival of the examined cell lines. There was a significant upregulation of CXCL12 in the astrocyte cell line SVGA, and of IL-1β in differentiated SH-SY5Y neuronal cells at both messenger RNA and protein levels. Our model allowed a valid examination of chemokines and cytokines associated with inflammation in human brain cells. With it, we detected the induction of inflammatory mediators by electrical stimulation in astrocytes and neurons.

Performance monitoring in obsessive-compulsive disorder: Insights from internal capsule/nucleus accumbens deep brain stimulation

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Theta phase coherence is increased following negative performance feedback.

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Deep brain stimulation globally modulates theta phase coherence.

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Fronto-striatal connectivity is related to OCD symptom severity.

Background

Symptoms of obsessive–compulsive disorder (OCD) are partly related to impaired cognitive control processes and theta modulations constitute an important electrophysiological marker for cognitive control processes such as signaling negative performance feedback in a fronto-striatal network. Deep brain stimulation (DBS) targeting the anterior limb of the internal capsule (ALIC)/nucleus accumbens (NAc) shows clinical efficacy in OCD, while the exact influence on the performance monitoring system remains largely unknown.

Methods

Seventeen patients with treatment-refractory OCD performed a probabilistic reinforcement learning task. Analyses were focused on 4–8 Hz (theta) power, intertrial phase coherence (ITPC) and debiased weighted Phase-Lag Index (dwPLI) in response to negative performance feedback. Combined EEG and local field potential (LFP) recordings were obtained shortly after DBS electrode implantation to investigate fronto-striatal network modulations. To assess the impact of clinically effective DBS on negative performance feedback modulations, EEG recordings were obtained pre-surgery and at follow-up with DBS on and off.

Results

Medial frontal cortex ITPC, striatal ITPC and striato-frontal dwPLI were increased following negative performance feedback. Decreased right-lateralized dwPLI was associated with pre-surgery symptom severity. ITPC was globally decreased during DBS-off.

Conclusion

We observed a theta phase coherence mediated fronto-striatal performance monitoring network. Within this network, decreased connectivity was related to increased OCD symptomatology, consistent with the idea of impaired cognitive control in OCD. While ALIC/NAc DBS decreased theta network activity globally, this effect was unrelated to clinical efficacy and performance monitoring.

Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines for Deep Brain Stimulations for Obsessive-Compulsive Disorder: Update of the 2014 Guidelines

BACKGROUND

In 2020, the Guidelines Task Force conducted another systematic review of the relevant literature on deep brain stimulation (DBS) for obsessive-compulsive disorder (OCD) to update the original 2014 guidelines to ensure timeliness and accuracy for clinical practice.

OBJECTIVE

To conduct a systematic review of the literature and update the evidence-based guidelines on DBS for OCD.

METHODS

The Guidelines Task Force conducted another systematic review of the relevant literature, using the same search terms and strategies as used to search PubMed and Embase for relevant literature. The updated search included studies published between 1966 and December 2019. The same inclusion/exclusion criteria as the original guideline were also applied. Abstracts were reviewed and relevant full-text articles were retrieved and graded. Of 864 articles, 10 were retrieved for full-text review and analysis. Recommendations were updated according to new evidence yielded by this update.

RESULTS

Seven studies were included in the original guideline, reporting the use of bilateral DBS as more effective in improving OCD symptoms than sham treatment. An additional 10 studies were included in this update: 1 class II and 9 class III.

CONCLUSION

Based on the data published in the literature, the following recommendations can be made: (1) It is recommended that clinicians utilize bilateral subthalamic nucleus DBS over best medical management for the treatment of patients with medically refractory OCD (level I). (2) Clinicians may use bilateral nucleus accumbens or bed nucleus of stria terminalis DBS for the treatment of patients with medically refractory OCD (level II). There is insufficient evidence to make a recommendation for the identification of the most effective target.The full guidelines can be accessed at https://www.cns.org/guidelines/browse-guidelines-detail/deep-brain-stimulation-obsessive-compulsive-disord.

Deep brain stimulation versus ablative surgery for treatment-refractory obsessive-compulsive disorder: A meta-analysis

OBJECTIVE

Ablative surgery (ABL) and deep brain stimulation (DBS) are last-resort treatment options for patients suffering from treatment-refractory obsessive-compulsive disorder (OCD). The aim of this study was to conduct an updated meta-analysis comparing the clinical outcomes of the ablative procedures capsulotomy and cingulotomy and deep brain stimulation.

METHODS

We conducted a PubMed search to identify all clinical trials on capsulotomy, cingulotomy, and DBS. Random effects meta-analyses were performed on 38 articles with a primary focus on efficacy in reducing OCD symptoms as measured by a reduction in the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) score and the responder rate (≥35% reduction in Y-BOCS score).

RESULTS

With responder rates of 48% and 53% after 12-16 months and 56% and 57% at last follow-up for ABL and DBS, respectively, and large effect sizes in the reduction in Y-BOCS scores, both surgical modalities show effectiveness in treating refractory OCD. Meta-regression did not show a statistically significant difference between ABL and DBS regarding these outcomes. Regarding adverse events, a statistically significant higher rate of impulsivity is reported in studies on DBS.

CONCLUSION

This meta-analysis shows equal efficacy of ABL and DBS in the treatment of refractory OCD. For now, the choice of intervention should, therefore, rely on factors such as risk of developing impulsivity, patient preferences, and experiences of psychiatrist and neurosurgeon. Future research should provide more insight regarding differences between ABL and DBS and response prediction following direct comparisons between the surgical modalities, to enable personalized and legitimate choices between ABL and DBS.

Neuroimaging evaluation of deep brain stimulation in the treatment of representative neurodegenerative and neuropsychiatric disorders

Brain stimulation technology has become a viable modality of reversible interventions in the effective treatment of many neurological and psychiatric disorders. It is aimed to restore brain dysfunction by the targeted delivery of specific electronic signal within or outside the brain to modulate neural activity on local and circuit levels. Development of therapeutic approaches with brain stimulation goes in tandem with the use of neuroimaging methodology in every step of the way. Indeed, multimodality neuroimaging tools have played important roles in target identification, neurosurgical planning, placement of stimulators and post-operative confirmation. They have also been indispensable in pre-treatment screen to identify potential responders and in post-treatment to assess the modulation of brain circuitry in relation to clinical outcome measures. Studies in patients to date have elucidated novel neurobiological mechanisms underlying the neuropathogenesis, action of stimulations, brain responses and therapeutic efficacy. In this article, we review some applications of deep brain stimulation for the treatment of several diseases in the field of neurology and psychiatry. We highlight how the synergistic combination of brain stimulation and neuroimaging technology is posed to accelerate the development of symptomatic therapies and bring revolutionary advances in the domain of bioelectronic medicine.

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.

Oscillatory activity in the BNST/ALIC and the frontal cortex in OCD: acute effects of DBS

Deep brain stimulation (DBS) of the bed nucleus of the stria terminalis/anterior limb of the internal capsule (BNST/ALIC) is successfully used for treatment of patients with obsessive-compulsive disorder (OCD). Clinical and experimental studies have suggested that enhanced network synchronization in the theta band is correlated with severity of symptoms. The mechanisms of action of DBS remain unclear in OCD. We here investigate the effect of acute stimulation of the BNCT/ALIC on oscillatory neuronal activity in patients with OCD implanted with DBS electrodes. We recorded the oscillatory activity of local field potentials (LFPs) from DBS electrodes (contact + 0/- 3; bipolar configuration; both hemispheres) from the BNST/ALIC parallel with frontal cortical electroencephalogram (EEG) one day after DBS surgery in four patients with OCD. BNST/ALIC and frontal EEG oscillatory activities were analysed before stimulation as baseline, and after three periods of stimulation with different voltage amplitudes (1 V, 2 V and 3.5 V) at 130 Hz. Overall, acute high frequency DBS reduced oscillatory theta band (4-8 Hz; p < 0.01) but increased other frequency bands in BNST/ALIC and the frontal cortex (p < 0.01). We show that stimulation of the BNST/ALIC in OCD modulates oscillatory activity in brain regions that are involved in the pathomechanisms of OCD. Our findings confirm and extend the findings that enhanced theta oscillatory activity in neuronal networks may be a biomarker for OCD.

Error-Related Activity in Striatal Local Field Potentials and Medial Frontal Cortex: Evidence From Patients With Severe Opioid Abuse Disorder

For successful goal-directed behavior, a performance monitoring system is essential. It detects behavioral errors and initiates behavioral adaptations to improve performance. Two electrophysiological potentials are known to follow errors in reaction time tasks: the error-related negativity (ERN), which is linked to error processing, and the error positivity (Pe), which is associated with subjective error awareness. Furthermore, the correct-related negativity (CRN) is linked to uncertainty about the response outcome. Here we attempted to identify the involvement of the nucleus accumbens (NAc) in the aforementioned performance monitoring processes. To this end, we simultaneously recorded cortical activity (EEG) and local field potentials (LFP) during a flanker task performed by four patients with severe opioid abuse disorder who underwent electrode implantation in the NAc for deep brain stimulation. We observed significant accuracy-related modulations in the LFPs at the time of the ERN/CRN in two patients and at the time of Pe in three patients. These modulations correlated with the ERN in 2/8, with CRN in 5/8 and with Pe in 6/8, recorded channels, respectively. Our results demonstrate the functional interrelation of striatal and cortical processes in performance monitoring specifically related to error processing and subjective error awareness.

Deep Brain Stimulation in the Bed Nucleus of Stria Terminalis in Obsessive-Compulsive Disorder-1-Year Follow-up

BACKGROUND

Deep brain stimulation (DBS) is under investigation as a treatment for therapy-refractory obsessive-compulsive disorder (OCD). As a crucial part of the anxiety circuit, the bed nucleus of stria terminalis (BNST) has been proposed as a target for DBS in OCD. Here, we investigate clinical outcomes and safety of DBS in the BNST in a series of 11 participants with severe therapy-refractory OCD.

METHODS

Eleven consecutive participants diagnosed with refractory OCD were treated with BNST DBS and completed follow-up. The primary outcome was a change in scores of the Yale Brown Obsessive Compulsive Scale (YBOCS) at 1 year after surgery. Secondary outcomes included changes in scores of the Montgomery-Åsberg Depression Rating Scale (MADRS) and the Global Assessment of Functioning.

RESULTS

At baseline, the mean ± SD YBOCS score was 33 ± 3.0, MADRS score was 29 ± 4.5, and GAF score was 49 ± 5.4. One year after DBS, mean ± SD YBOCS score was 20 ± 4.8 (38% improvement (range 10%-60%) P < 0.01), MADRS score was 21 ± 5.8 (27% improvement, range 4%-74%, P < 0.01), and Global Assessment of Functioning score was 55 ± 6.5 (12% improvement, range 4%-29%, P < 0.05). Of the 11 participants, 6 were considered responders (decrease in YBOCS ≥35%) and 4 partial responders (decrease in YBOCS 25%-34%). Surgical adverse events included 1 case of skin infection leading to reimplantation. The most common transient stimulation-related side effects were anxiety and insomnia.

CONCLUSIONS

BNST DBS is a promising therapy in severe therapy-refractory OCD. Our results are in line with previous publications regarding effect and safety profile. Nevertheless, DBS for OCD remains an investigational therapy and should therefore be performed in multidisciplinary clinical studies.

Invasive and Non-invasive Neurostimulation for OCD

It becomes increasingly clear that (non-)invasive neurostimulation is an effective treatment for obsessive-compulsive disorder (OCD). In this chapter we review the available evidence on techniques and targets, clinical results including a meta-analysis, mechanisms of action, and animal research. We focus on deep brain stimulation (DBS), but also cover non-invasive neurostimulation including transcranial magnetic stimulation (TMS). Data shows that most DBS studies target the ventral capsule/ventral striatum (VC/VS), with an overall 76% response rate in treatment-refractory OCD. Also TMS holds clinical promise. Increased insight in the normalizing effects of neurostimulation on cortico-striatal-thalamic-cortical (CSTC) loops - through neuroimaging and animal research - provides novel opportunities to further optimize treatment strategies. Advancing clinical implementation of neurostimulation techniques is essential to ameliorate the lives of the many treatment-refractory OCD patients.

Deep brain stimulation modulates directional limbic connectivity in obsessive-compulsive disorder

Deep brain stimulation is effective for patients with treatment-refractory obsessive-compulsive disorder. Deep brain stimulation of the ventral anterior limb of the internal capsule rapidly improves mood and anxiety with optimal stimulation parameters. To understand these rapid effects, we studied functional interactions within the affective amygdala circuit. We compared resting state functional MRI data during chronic stimulation versus 1 week of stimulation discontinuation in patients, and obtained two resting state scans from matched healthy volunteers to account for test-retest effects. Imaging data were analysed using functional connectivity analysis and dynamic causal modelling. Improvement in mood and anxiety following deep brain stimulation was associated with reduced amygdala-insula functional connectivity. Directional connectivity analysis revealed that deep brain stimulation increased the impact of the ventromedial prefrontal cortex on the amygdala, and decreased the impact of the amygdala on the insula. These results highlight the importance of the amygdala circuit in the pathophysiology of obsessive-compulsive disorder, and suggest a neural systems model through which negative mood and anxiety are modulated by stimulation of the ventral anterior limb of the internal capsule for obsessive-compulsive disorder and possibly other psychiatric disorders.

Successful Treatment of Psychiatric Symptoms after Traumatic Brain Injury Using Deep Brain Stimulation to the Anterior Limb of Internal Capsule-Nucleus Accumbens

Psychiatric symptoms are common after traumatic brain injury (TBI), and some patients have poor drug therapeutic efficacy. We report a successfully treated case of psychiatric symptoms after TBI using deep brain stimulation (DBS) to the anterior limb of internal capsule (ALIC)-nucleus accumbens (NAc) in a 76-year-old woman. The patient suffered from auditory hallucination, mood changes, and insomnia caused by TBI. Psychological test assessment showed the scores of Hamilton Anxiety Scale, Hamilton Depression Scale and Positive and Negative Syndrome Scale were 30, 35, and 96 respectively. Head magnetic resonance imaging scan showed right temporal lobe encephalomalacia. Head magnetic resonance spectroscopy (MRS) showed bilateral basal ganglia choline increased relatively. After DBS to the ALIC-NAc, the target parameters were adjusted. The psychiatric symptoms were completely improved and the result of head MRS was normal in the end. The current report declares that DBS is reversible, adjustable and safe in the treatment of psychiatric symptoms caused by TBI. DBS to the ALIC-NAc should be considered as a possible treatment choice once a patient showed psychiatric symptoms after TBI.

Deep brain stimulation and sensorimotor gating in tourette syndrome and obsessive-compulsive disorder

Recent translational data suggest that deep brain stimulation (DBS) of the cortico-striato-thalamo-cortical (CSTC) loops improves sensorimotor gating in psychiatric disorders that show deficient prepulse inhibition (PPI), a robust operational measure of sensorimotor gating. To our knowledge we are the first to investigate this effect in patients with Tourette syndrome (TS). We measured PPI of the acoustic startle reflex in patients with TS (N = 10) or Obsessive-Compulsive Disorder (OCD) (N = 8) treated with DBS of the centromedian and ventro-oral internal thalamic nucleus and the anterior limb of internal capsule-nucleus accumbens area respectively, and aged- and gender-matched healthy controls (HC). PPI of the DBS groups was measured in randomized order in the ON and OFF stimulation condition. Statistical analysis revealed no significant difference in PPI (%) of patients with TS between ON (M = 20.5, SD = 14.9) and OFF (M = 25.2, SD = 29.7) condition. There were significantly reduced PPI levels in patients with TS in the ON condition compared to HC (M = 49.2, SD = 10.7), but no significant difference in PPI between TS in the OFF condition and HC. Furthermore, we found no significant stimulation or group effect for OCD and HC (OCD ON: M = 57.0, SD = 8.3; OCD OFF: 67.8, SD = 19.6; HC: M = 63.0, SD = 24.3). Our study has a number of limitations. Sample sizes are small due to the restricted patient collective. The study was not controlled for use of psychoactive medication or nicotine. Furthermore, we were not able to assess presurgical PPI measurements. In conclusion, we were able to show that PPI is impaired in patients with TS. This finding is in line with recent translational work. With respect to the OCD cohort we were not able to replicate our previously published data. A disability in sensorimotor gating plays a pivotal role in many psychiatric disorders therefore more research should be conducted to disentangle the potential and limitations of modulating sensorimotor gating via brain stimulation techniques.

Normative vs. patient-specific brain connectivity in deep brain stimulation

Brain connectivity profiles seeding from deep brain stimulation (DBS) electrodes have emerged as informative tools to estimate outcome variability across DBS patients. Given the limitations of acquiring and processing patient-specific diffusion-weighted imaging data, a number of studies have employed normative atlases of the human connectome. To date, it remains unclear whether patient-specific connectivity information would strengthen the accuracy of such analyses. Here, we compared similarities and differences between patient-specific, disease-matched and normative structural connectivity data and their ability to predict clinical improvement. Data from 33 patients suffering from Parkinson's Disease who underwent surgery at three different centers were retrospectively collected. Stimulation-dependent connectivity profiles seeding from active contacts were estimated using three modalities, namely patient-specific diffusion-MRI data, age- and disease-matched or normative group connectome data (acquired in healthy young subjects). Based on these profiles, models of optimal connectivity were calculated and used to estimate clinical improvement in out of sample data. All three modalities resulted in highly similar optimal connectivity profiles that could largely reproduce findings from prior research based on this present novel multi-center cohort. In a data-driven approach that estimated optimal whole-brain connectivity profiles, out-of-sample predictions of clinical improvements were calculated. Using either patient-specific connectivity (R = 0.43 at p = 0.001), an age- and disease-matched group connectome (R = 0.25, p = 0.048) and a normative connectome based on healthy/young subjects (R = 0.31 at p = 0.028), significant predictions could be made. Our results of patient-specific connectivity and normative connectomes lead to similar main conclusions about which brain areas are associated with clinical improvement. Still, although results were not significantly different, they hint at the fact that patient-specific connectivity may bear the potential of explaining slightly more variance than group connectomes. Furthermore, use of normative connectomes involves datasets with high signal-to-noise acquired on specialized MRI hardware, while clinical datasets as the ones used here may not exactly match their quality. Our findings support the role of DBS electrode connectivity profiles as a promising method to investigate DBS effects and to potentially guide DBS programming.

Long-Term Deep Brain Stimulation in Treatment-Resistant Obsessive-Compulsive Disorder: Outcome and Quality of Life at Four to Eight Years Follow-Up

BACKGROUND

Obsessive compulsive disorder (OCD) is a severe disabling disease, and around 10% of patients are considered to be treatment-resistant (tr) in spite of guideline-based therapy. Deep brain stimulation (DBS) has been proposed as a promising treatment for patients with trOCD. However, the optimal site for stimulation is still a matter of debate, and clinical long-term follow-up observations including data on quality of life are sparse. We here present six trOCD patients who underwent DBS with electrodes placed in the bed nucleus of the stria terminalis/anterior limb of the internal capsule (BNST/ALIC), followed for four to eight years after lead implantation.

MATERIALS AND METHODS

In this prospective observational study, six patients (four men, two women) aged 32-51 years and suffering from severe to extreme trOCD underwent DBS of the BNST/ALIC. Symptom severity was assessed using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), and quality of life using the World Health Organization Quality of Life assessment scale (WHO-QoL BREF). Follow-up was obtained at least for four years in all patients.

RESULTS

With chronic DBS for four to eight years, four of the six patients had sustained improvement. Two patients remitted and two patients responded (defined as >35% symptom reduction), while the other two patients were considered nonresponders on long-term. Quality of life markedly improved in remitters and responders. We did not observe peri-interventional side effects or adverse effects of chronic stimulation.

CONCLUSIONS

Chronic DBS of ALIC provides long-term benefit up to four to eight years in trOCD, although not all patients take profit. Targeting the BNST was not particularly relevant since no patient appeared to benefit from direct stimulation of the BNST. Quality of life improved in DBS responders, documented by improved QoL scores and, even more important, by regaining of autonomy and improving psychosocial functioning.

A brief demonstration of frontostriatal connectivity in OCD patients with intracranial electrodes

Closed-loop neuromodulation is presumed to be the logical evolution for improving the effectiveness of deep brain stimulation (DBS) treatment protocols (Widge et al., 2018). Identifying symptom-relevant biomarkers that provide meaningful feedback to stimulator devices is an important initial step in this direction. This report demonstrates a technique for assaying neural circuitry hypothesized to contribute to OCD and DBS treatment outcomes. We computed phase-lag connectivity between LFPs and EEGs in thirteen treatment-refractory OCD patients. Simultaneous recordings from scalp EEG and externalized DBS electrodes in the ventral capsule/ventral striatum (VC/VS) were collected at rest during the perioperative treatment stage. Connectivity strength between midfrontal EEG sensors and VC/VS electrodes correlated with baseline OCD symptoms and 12-month posttreatment OCD symptoms. Results are qualified by a relatively small sample size, and limitations regarding the conclusiveness of VS and mPFC as neural generators given some concerns about volume conduction. Nonetheless, findings are consistent with treatment-relevant tractography findings and theories that link frontostriatal hyperconnectivity to the etiopathogenesis of OCD. Findings support the continued investigation of connectivity-based assays for aiding in determination of optimal stimulation location, and are an initial step towards the identification of biomarkers that can guide closed-loop neuromodulation systems.

A Systematic Review of Deep Brain Stimulation Targets for Obsessive Compulsive Disorder

BACKGROUND

Obsessive compulsive disorder (OCD) is a complex neuropsychiatric disease characterized by obsessions and compulsions. Deep brain stimulation (DBS) has demonstrated efficacy in improving symptoms in medically refractory patients. Multiple targets have been investigated.

OBJECTIVE

To systematically review the current level and quality of evidence supporting OCD-DBS by target region with the goal of establishing a common nomenclature.

METHODS

A systematic literature review was performed using the PubMed database and a patient/problem, intervention, comparison, outcome search with the terms "DBS" and "OCD." Of 86 eligible articles that underwent full-text review, 28 were included for review. Articles were excluded if the target was not specified, the focus on nonclinical outcomes, the follow-up period shorter than 3 mo, or the sample size smaller than 3 subjects. Level of evidence was assigned according to the American Association of Neurological Surgeons/Congress of Neurological Surgeons joint guideline committee recommendations. Quality of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation approach.

RESULTS

Selected publications included 9 randomized controlled trials, 1 cohort study, 1 case-control study, 1 cross-sectional study, and 16 case series. Striatal region targets such as the anterior limb of the internal capsule, ventral capsule/ventral striatum, and nucleus accumbens were identified, but stereotactic coordinates were similar despite differing structural names. Only 15 of 28 articles included coordinates.

CONCLUSION

The striatal area is the most commonly targeted region for OCD-DBS. We recommend a common nomenclature based on this review. To move the field forward to individualized therapy, active contact location relative to stereotactic coordinates and patient specific anatomical and clinical variances need to be reported.

Elucidating neural network changes induced by deep brain stimulation for OCD

This scientific commentary refers to ‘Deep brain stimulation modulates directional limbic connectivity in obsessive-compulsive disorder’, by Fridgeirsson etal. (doi:10.1093/brain/awaa100).

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.

Weight Change after Striatal/Capsule Deep Brain Stimulation Relates to Connectivity to the Bed Nucleus of the Stria Terminalis and Hypothalamus

Weight changes are insufficiently understood adverse events of deep brain stimulation. In this context, exploring neural networks of weight control may inform novel treatment strategies for weight-related disorders. In this study, we investigated weight changes after deep brain stimulation of the ventral striatum/ventral capsule and to what extent changes are associated with connectivity to feeding-related networks. We retrospectively analyzed 25 patients undergoing deep brain stimulation for obsessive-compulsive disorder or substance dependency. Weight changes were assessed preoperatively and six to twelve months after surgery and then matched with individual stimulation sites and stimulation-dependent functional connectivity to a priori defined regions of interest that are involved in food intake. We observed a significant weight gain after six to twelve months of continuous stimulation. Weight increases were associated with medial/apical localization of stimulation sites and with connectivity to hypothalamic areas and the bed nucleus. Thus, deep brain stimulation of the ventral striatum/ventral capsule influences weight depending on localization and connectivity of stimulation sites. Bearing in mind the significance of weight-related disorders, we advocate further prospective studies investigating the neuroanatomical and neuropsychological underpinnings of food intake and their neuromodulatory therapeutic potential.

Local and Global Changes in Brain Metabolism during Deep Brain Stimulation for Obsessive-Compulsive Disorder

Recent approaches have suggested that deep brain stimulation (DBS) for obsessive-compulsive disorder relies on distributed networks rather than local brain modulation. However, there is insufficient data on how DBS affects brain metabolism both locally and globally. We enrolled three patients with treatment-refractory obsessive-compulsive disorder with ongoing DBS of the bilateral ventral capsule/ventral striatum. Patients underwent resting-state ¹⁸F-fluorodeoxyglucose and positron emission tomography in both stimulation ON and OFF conditions. All subjects showed relative hypometabolism in prefronto-basal ganglia-thalamic networks compared to a healthy control cohort when stimulation was switched OFF. Switching the stimulation ON resulted in differential changes in brain metabolism. Locally, volumes of activated tissue at stimulation sites (n = 6) showed a significant increase in metabolism during DBS ON compared to DBS OFF (Mean difference 4.5% ± SD 2.8; p = 0.012). Globally, differential changes were observed across patients encompassing prefrontal increase in metabolism in ON vs. OFF condition. Bearing in mind limitations of the small sample size, we conclude that DBS of the ventral capsule/ventral striatum for obsessive-compulsive disorder increases brain metabolism locally. Across distributed global networks, DBS appears to exert differential effects, possibly depending on localization of stimulation sites and response to the intervention.

Deep Brain Stimulation for Refractory Obsessive-Compulsive Disorder: Towards an Individualized Approach

Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder featuring repetitive intrusive thoughts and behaviors associated with a significant handicap. Of patients, 20% are refractory to medication and cognitive behavioral therapy. Refractory OCD is associated with suicidal behavior and significant degradation of social and professional functioning, with high health costs. Deep brain stimulation (DBS) has been proposed as a reversible and controllable method to treat refractory patients, with meta-analyses showing 60% response rate following DBS, whatever the target: anterior limb of the internal capsule (ALIC), ventral capsule/ventral striatum (VC/VS), nucleus accumbens (NAcc), anteromedial subthalamic nucleus (amSTN), or inferior thalamic peduncle (ITP). But how do we choose the "best" target? Functional neuroimaging studies have shown that ALIC-DBS requires the modulation of the fiber tract within the ventral ALIC via the ventral striatum, bordering the bed nucleus of the stria terminalis and connecting the medial prefrontal cortex with the thalamus to be successful. VC/VS effective sites of stimulation were found within the VC and primarily connected to the medial orbitofrontal cortex (OFC) dorsomedial thalamus, amygdala, and the habenula. NAcc-DBS has been found to reduce OCD symptoms by decreasing excessive fronto-striatal connectivity between NAcc and the lateral and medial prefrontal cortex. The amSTN effective stimulation sites are located at the inferior medial border of the STN, primarily connected to lateral OFC, dorsal anterior cingulate, and dorsolateral prefrontal cortex. Finally, ITP-DBS recruits a bidirectional fiber pathway between the OFC and the thalamus. Thus, these functional connectivity studies show that the various DBS targets lie within the same diseased neural network. They share similar efficacy profiles on OCD symptoms as estimated on the Y-BOCS, the amSTN being the target supported by the strongest evidence in the literature. VC/VS-DBS, amSTN-DBS, and ALIC-DBS were also found to improve mood, behavioral adaptability and potentially both, respectively. Because OCD is such a heterogeneous disease with many different symptom dimensions, the ultimate aim should be to find the most appropriate DBS target for a given refractory patient. This quest will benefit from further investigation and understanding of the individual functional connectivity of OCD patients.