Current and up-and-coming pharmacotherapy for obsessive-compulsive disorder in adults

Human microbiota from drug-naive patients with obsessive-compulsive disorder drives behavioral symptoms and neuroinflammation via succinic acid in mice

Emerging evidence suggests that the gut microbiota is closely related to psychiatric disorders. However, little is known about the role of the gut microbiota in the development of obsessive-compulsive disorder (OCD). Here, to investigate the contribution of gut microbiota to the pathogenesis of OCD, we transplanted fecal microbiota from first-episode, drug-naive OCD patients or demographically matched healthy individuals into antibiotic-treated specific pathogen-free (SPF) mice and showed that colonization with OCD microbiota is sufficient to induce core behavioral deficits, including abnormal anxiety-like and compulsive-like behaviors. The fecal microbiota was analyzed using 16 S rRNA full-length sequencing, and the results demonstrated a clear separation of the fecal microbiota of mice colonized with OCD and control microbiota. Notably, microbiota from OCD-colonized mice resulted in injured neuronal morphology and function in the mPFC, with inflammation in the mPFC and colon. Unbiased metabolomic analyses of the serum and mPFC region revealed the accumulation of succinic acid (SA) in OCD-colonized mice. SA impeded neuronal activity and induced an inflammatory response in both the colon and mPFC, impacting intestinal permeability and brain function, which act as vital signal mediators in gut microbiota-brain-immune crosstalk. Manipulations of dimethyl malonate (DM) have been reported to exert neuroprotective effects by suppressing the oxidation of accumulated succinic acid, attenuating the downstream inflammatory response and neuronal damage, and can help to partly improve abnormal behavior and reduce neuroinflammation and intestinal inflammation in OCD-colonized mice. We propose that the gut microbiota likely regulates brain function and behaviors in mice via succinic acid signaling, which contributes to the pathophysiology of OCD through gut-brain crosstalk and may provide new insights into the treatment of this disorder.

Will Transcranial Magnetic Stimulation Improve the Treatment of Obsessive-Compulsive Disorder? A Systematic Review and Meta-Analysis of Current Targets and Clinical Evidence

BACKGROUND

Although in 2017 a repetitive transcranial magnetic stimulation (rTMS) protocol received Food and Drug Administration approval for the first time for the treatment of obsessive-compulsive disorder (OCD), which neural target and which protocol should be used for OCD are still debated. The aim of the present study was to perform a systematic review and meta-analysis of the available open and sham-controlled trials.

METHODS

The primary analysis included a pairwise meta-analysis (over 31 trials), and then subgroup analyses were performed for each targeted brain area. Meta-regression analyses explored the possible moderators of effect size.

RESULTS

The pairwise meta-analysis showed a significant reduction in OCD symptoms following active rTMS (g = -0.45 [95%CI: -0.62, -0.29]) with moderate heterogeneity (I² = 34.9%). Subgroup analyses showed a significant effect of rTMS over the bilateral pre-SMA (supplementary motor area), the DLPFC (dorsolateral prefrontal cortex), the ACC/mPFC (anterior cingulate cortex and medial prefrontal cortex), and the OFC (orbitofrontal cortex). No moderators of the effect size emerged.

CONCLUSIONS

TMS of several brain targets represents a safe and effective treatment option for OCD patients. Further studies are needed to help clinicians to individualize TMS protocols and targets for each patient.

EPD1504: a novel μ-opioid receptor partial agonist attenuates obsessive-compulsive disorder (OCD)-like behaviors

Low doses of μ-opioid receptor (MOR) agonists rapidly ameliorate symptoms in treatment-resistant obsessive-compulsive disorder (OCD) patients (10-50% of OCD patients). However, the utility of MOR agonists is limited by their safety liabilities. We developed a novel MOR partial agonist (EPD1540) that has an improved respiratory safety profile when compared to buprenorphine. Buprenorphine is a MOR partial agonist primarily used in the treatment of opiate-use disorder, which in investigator-led trials, has been shown to rapidly ameliorate symptoms in treatment-resistant OCD patients. In this study, we show that doses of EPD1504 and buprenorphine that occupy small fractions of MORs in the CNS (approximately 20%) are as effective as fluoxetine at ameliorating OCD-like behaviors in two different rat models (an operant probabilistic reversal task and marble burying). Importantly, effective doses of EPD1504 did not impair either locomotor activity, or respiration under normoxic or hypercapnic conditions. Additionally, EPD1504 had effects comparable to buprenorphine in the conditioned place preference assay. These results indicate that EPD1504 may provide a safer alternative to buprenorphine for the treatment of OCD patients.

Specifics of Experimental Modeling 8-OH-DPAT-Induced Perseverative Behavior in Mice

The effect of 5-HT_1A receptor agonist 8-OH-DPAT (intraperitoneal injection in doses of 1, 2, and 4 mg/kg) on spontaneous alternation behavior of mice in Y-maze was studied without and with habituation procedure and food reward. In the first case, 8-OH-DPAT administration led to a decrease in spontaneous alternation and locomotor activity in mice. At the same time, 8-OH-DPAT treatment after habituation and food deprivation increased repeated choices of goal arms without affecting locomotor activity, which was consistent with perseverative behavior. 8-OH-DPAT-induced decrease in spontaneous alternation behavior in Y-maze in mice with habituation and food reward is the most suitable procedure for experimental modeling of the perseverative behavior and studying the anticompulsive activity of new substances.

WNT/β-catenin pathway and circadian rhythms in obsessive-compulsive disorder

The neuropsychiatric disease named obsessive-compulsive disorder is composed by obsessions and/or compulsions. Obsessive-compulsive disorder etiologies are undefined. However, numerous mechanisms in several localizations are implicated. Some studies showed that both glutamate, inflammatory factors and oxidative stress could have main functions in obsessive-compulsive disorder. Glycogen synthase kinase-3β, the major negative controller of the WNT/β-catenin pathway is upregulated in obsessive-compulsive disorder. In obsessive-compulsive disorder, some studies presented the actions of the different circadian clock genes. WNT/β-catenin pathway and circadian clock genes appear to be intricate. Thus, this review focuses on the interaction between circadian clock genes and the WNT/β-catenin pathway in obsessive-compulsive disorder.

Quantification of Metabotropic Glutamate Receptor 5 Availability With Both [11C]ABP688 and [18F]FPEB Positron Emission Tomography in the Sapap3 Knockout Mouse Model for Obsessive-Compulsive-like Behavior

BACKGROUND

This study provides a first direct comparison between positron emission tomography radioligands targeting the allosteric site of the metabotropic glutamate receptor 5 (mGluR5): [¹¹C]ABP688 and [¹⁸F]FPEB. A blocking paradigm was set up to substantiate the common binding site of both radioligands. Second, both radioligands were applied in Sapap3 knockout (KO) mice showing compulsive-like behavior characterized by a lower in vivo mGluR5 availability.

METHODS

First, wild-type mice (n = 7) received four position emission tomography/computed tomography scans: a [¹¹C]ABP688 scan, a [¹⁸F]FPEB scan, and two blocking scans using cold FPEB and cold ABP688, respectively. A second experiment compared both radioligands in wild-type (n = 7) and KO (n = 10) mice. The simplified reference tissue model was used to calculate the nondisplaceable binding potential representing the in vivo availability of mGluR5 in the brain.

RESULTS

Using cold FPEB as a blocking compound for [¹¹C]ABP688 micro-positron emission tomography and vice versa, we observed averaged global reductions in mGluR5 availability of circa 98% for [¹¹C]ABP688 and 82%-96% for [¹⁸F]FPEB. For KOs, the [¹¹C]ABP688 nondisplaceable binding potential was on average 25% lower compared with wild-type control mice (p < .0001-.001), while this was about 17% for [¹⁸F]FPEB (p < .05).

CONCLUSIONS

The current findings substantiate a common binding site and suggest a strong relationship between mGluR5 availability levels measured with both radioligands. In Sapap3 KO mice, a reduced mGluR5 availability could therefore be demonstrated with both radioligands. With [¹¹C]ABP688, higher significance levels were achieved in more brain regions. These findings suggest [¹¹C]ABP688 as a preferable radiotracer to quantify mGluR5 availability, as exemplified here in a model for compulsive-like behavior.

The Chinese version of the family accommodation scale for obsessive-compulsive disorder self-rated: reliability, validity, factor structure, and mediating effect

BACKGROUND

Family accommodation (FA) in obsessive compulsive disorder (OCD) is a common phenomenon. Based on the cost of training interviewers and the time required to administer the scale, the Family Accommodation Scale for Obsessive-Compulsive Disorder Interviewer-Rated (FAS-IR) has been restricted to specific settings. A self-rated version of the family accommodation scale may solve these problems. The aim of this study was to examine the reliability, validity and factor structure of the Family Accommodation Scale Self-rated version (FAS-SR), and the relationship among FA, symptom severity and functional impairment.

METHODS

In total, 171 patients with OCD and 145 paired relatives participated in this study. The Sheehan Disability Scale (SDS), Obsessive-Compulsive Inventory Revised (OCI-R), Zung Self-Rating Depression Scale (Zung-SDS), 12-item Family Assessment Devices (FAD-12), Clinical Global Impression of Severity Scale (CGI-S), Global Assessment of Functioning (GAF), and Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) were used as tools for patients. The FAS-SR, FAS-IR, FAD-12, and the patients' symptom severity of Y-BOCS compulsion were used as tools for relatives. The psychometric properties of the FAS-SR were evaluated using Cronbach's alpha coefficient, test-retest reliability and validity. Mediation analysis was used to determine the relationship among FA, symptom severity and functional impairment.

RESULTS

A total of 97.9% of relatives of OCD patients reported at least one kind of FA behavior, and 56.6% of participants engaged in FA every day in the past week. The FAS-SR includes a three-factor structure: (1) providing reassurance and participation; (2) facilitation; and (3) modification. The scale's Cronbach's alpha and test-retest coefficients were 0.875 and 0.970, respectively. The total FAS-SR score was significantly positively associated with the Y-BOCS, FAD-12, CGI-S, FAS-IR, and SDS scores, and negatively associated with the total GAF score. FA partially mediated the relationship between symptom severity and functional impairment.

CONCLUSION

The FAS-SR was proven to have satisfactory psychometric properties, and can play an important role in the evaluation and early intervention of OCD. This result indicates the importance of assessing symptom severity in conjunction with FA when evaluating OCD patients' functional impairment.

Possible actions of cannabidiol in obsessive-compulsive disorder by targeting the WNT/β-catenin pathway

Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder characterized by recurrent and distinctive obsessions and/or compulsions. The etiologies remain unclear. Recent findings have shown that oxidative stress, inflammation, and glutamatergic pathways play key roles in the causes of OCD. However, first-line therapies include cognitive-behavioral therapy but only 40% of the patients respond to this first-line therapy. Research for new treatment is mandatory. This review focuses on the potential effects of cannabidiol (CBD), as a potential therapeutic strategy, on OCD and some of the presumed mechanisms by which CBD provides its benefit properties. CBD medication downregulates GSK-3β, the main inhibitor of the WNT/β-catenin pathway. The activation of the WNT/β-catenin could be associated with the control of oxidative stress, inflammation, and glutamatergic pathway and circadian rhythms dysregulation in OCD. Future prospective clinical trials could focus on CBD and its different and multiple interactions in OCD.

Bidirectional Behavioral Selection in Mice: A Novel Pre-clinical Approach to Examining Compulsivity

Obsessive-compulsive disorder (OCD) and related disorders (OCRD) is one of the most prevalent neuropsychiatric disorders with no definitive etiology. The pathophysiological attributes of OCD are driven by a multitude of factors that involve polygenic mechanisms, gender, neurochemistry, physiological status, environmental exposures and complex interactions among these factors. Such complex intertwining of contributing factors imparts clinical heterogeneity to the disorder making it challenging for therapeutic intervention. Mouse strains selected for excessive levels of nest- building behavior exhibit a spontaneous, stable and predictable compulsive-like behavioral phenotype. These compulsive-like mice exhibit heterogeneity in expression of compulsive-like and other adjunct behaviors that might serve as a valuable animal equivalent for examining the interactions of genetics, sex and environmental factors in influencing the pathophysiology of OCD. The current review summarizes the existing findings on the compulsive-like mice that bolster their face, construct and predictive validity for studying various dimensions of compulsive and associated behaviors often reported in clinical OCD and OCRD.

Focused ultrasound for functional neurosurgery

INTRODUCTION

Brain lesioning is a fundamental technique in the functional neurosurgery world. It has been investigated for decades and presented promising results long before novel pharmacological agents were introduced to treat movement disorders, psychiatric disorders, pain, and epilepsy. Ablative procedures were replaced by effective drugs during the 1950s and by Deep Brain Stimulation (DBS) in the 1990s as a reversible neuromodulation technique. In the last decade, however, the popularity of brain lesioning has increased again with the introduction of magnetic resonance-guided focused ultrasound (MRgFUS).

OBJECTIVE

In this review, we will cover the current and emerging role of MRgFUS in functional neurosurgery.

METHODS

Literature review from PubMed and compilation.

RESULTS

Investigated since 1930, MRgFUS is a technology enabling targeted energy delivery at the convergence of mechanical sound waves. Based on technological advancements in phased array ultrasound transducers, algorithms accounting for skull penetration by sound waves, and MR imaging for targeting and thermometry, MRgFUS is capable of brain lesioning with sub-millimeter precision and can be used in a variety of clinical indications.

CONCLUSION

MRgFUS is a promising technology evolving as a dominant tool in different functional neurosurgery procedures in movement disorders, psychiatric disorders, epilepsy, among others.

Lithium: a potential therapeutic strategy in obsessive-compulsive disorder by targeting the canonical WNT/β pathway

Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder characterized b-y recurrent and distinctive obsessions and/or compulsions. The etiologies remain unclear. Recent findings have shown that oxidative stress, inflammation, and the glutamatergic pathway play key roles in the causes of OCD. However, first-line therapies include cognitive-behavioral therapy but only 40% of the patients respond to this first-line therapy. Research for a new treatment is mandatory. This review focuses on the potential effects of lithium, as a potential therapeutic strategy, on OCD and some of the presumed mechanisms by which lithium provides its benefit properties. Lithium medication downregulates GSK-3β, the main inhibitor of the WNT/β-catenin pathway. The activation of the WNT/β-catenin could be associated with the control of oxidative stress, inflammation, and glutamatergic pathway. Future prospective clinical trials could focus on lithium and its different and multiple interactions in OCD.

Early onset obsessive-compulsive disorder: the biological and clinical phenotype

Moving from a behavioral-based to a biological-based classification of mental disorders is a crucial step toward a precision-medicine approach in psychiatry. In the last decade, a big effort has been made in order to stratify genetic, immunological, neurobiological, cognitive, and clinical profiles of patients. Making the case of obsessive-compulsive disorder (OCD), a lot have been made in this direction. Indeed, while the Diagnostic and Statistical Manual of Mental Disorders (DSM) diagnosis of OCD aimed to delineate a homogeneous group of patients, it is now clear that OCD is instead an heterogeneous disorders both in terms of neural networks, immunological, genetic, and clinical profiles. In this view, a convergent amount of literature, in the last years, indicated that OCD patients with an early age at onset seem to have a specific clinical and biological profile, suggesting it as a neurodevelopmental disorder. Also, these patients tend to have a worse outcome respect to adult-onset patients and there is growing evidence that early-interventions could potentially improve their prognosis. Therefore, the aim of the present paper is to review the current available genetic, immunological, neurobiological, cognitive, and clinical data in favor of a more biologically precise subtype of OCD: the early-onset subtype. We also briefly resume current available recommendations for the clinical management of this specific population.

Investigational and Experimental Drugs to Treat Obsessive-Compulsive Disorder

Treatment-resistance is a frequent condition for obsessive-compulsive disorder (OCD). Over the past decades, a lot of effort has been made to address this issue, and several augmentation strategies of serotonergic drugs have been investigated. Antidopaminergic drugs are considered the first choice as augmentation strategy for treatment-resistant OCD patients, but they seem to work only for a subset of patients, and none of them have been officially approved for OCD. Recently, the role of glutamate and inflammation in OCD pathophysiology clearly emerged, and this has led to several investigations on glutamatergic and anti-inflammatory agents. Results seem promising but still inconclusive. Probiotic interventions (considered to modulate the immune systems and the brain activity) are gaining attention in several psychiatric fields but are still at their early stages in the OCD field. Research on new treatment approaches for OCD is moving forward, and more than one hundred interventional trials are ongoing around the world. While the vast majority of these trials involve neuromodulation and psychotherapeutic approaches, only a small proportion (around 20%) involve the investigation of new pharmacological approaches (tolcapone, nabilone, psilocybin, troriluzole, nitrous oxide, rituximab, naproxen, and immunoglobulins). Here, we provide a comprehensive review of investigational and experimental drugs to treat OCD.

A Preliminary Examination of Acceptance and Commitment Therapy Versus Exposure and Response Prevention for Patients with Obsessive-Compulsive Disorder on an Optimal Dose of SSRIs: A Randomized Controlled Trial in Iran

This study compared the effects of adding acceptance and commitment therapy (ACT) or exposure and response prevention (ERP) to adults diagnosed with obsessive compulsive disorder (OCD) already on an optimal and stable dose of selective serotonin reuptake inhibitors (SSRIs). Forty adults on SSRIs who were diagnosed with OCD participated in a randomized controlled trial in Iran of 12 individual weekly sessions of either ACT+SSRI, ERP+SSRI, or continued SSRI only. The results showed significant reductions in OCD symptom severity in ACT+SSRI and ERP+SSRI conditions at posttreatment with significantly greater reductions in both conditions compared to SSRI-only at follow-up. Additionally, psychological inflexibility and use of thought control strategies significantly decreased in the ACT+SSRI condition at posttreatment and follow-up compared to the ERP+SSRI and SSRI conditions. Both conditions led to decreases in perceived importance of stop signals. Results provide cross-cultural support for the treatment of OCD using ACT and ERP as adjuncts to SSRI and modest process of change differences between ACT and ERP. Future directions and study limitations are discussed.

Metacognitive beliefs predict early response to pharmacological treatment in patients with obsessive-compulsive disorder

RATIONALE

Metacognitions, beliefs that monitor or control thoughts and coping, are considered to be important components for development and maintenance of obsessive-compulsive disorder (OCD).

OBJECTIVES

This study prospectively investigated whether metacognitive beliefs can predict early treatment response after serotonin reuptake inhibitor (SRI) initiation in patients with OCD.

METHODS

Drug-naïve or medication-free patients with OCD (N = 156) were assessed for various characteristics, including metacognitions. In total, 132 patients were followed for 4 weeks, and their clinical responses to pharmacological treatment were assessed using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). Early treatment response was defined as a 20% or greater reduction from the baseline Y-BOCS score at 4 weeks. Logistic and linear regression analyses were performed to identify major determinants for the early treatment outcome.

RESULTS

Among participants with OCD, 53 patients (40.15%) were early responders. The logistic regression model revealed two significant predictors, age (beta = - 0.113, p < 0.001) and "positive beliefs about worry," which refers to metacognitive beliefs concerning the benefits of engaging in worry (beta = - 0.067, p = 0.001), for identifying early responders. Moreover, in the linear regression model, lower "positive beliefs about worry" was also shown as a significant predictor for the degree of better early improvement (beta = - 0.566, p = 0.001).

CONCLUSIONS

These results suggest that lower metacognition of "positive beliefs about worry" predicts improvement of obsessive-compulsive symptoms seen early on in the SRI treatment, and that pathological metacognitive belief would lead to delayed response to SRI treatment in OCD.

Sexual dysfunction and satisfaction in obsessive compulsive disorder: protocol for a systematic review and meta-analysis

BACKGROUND

Obsessive compulsive disorder (OCD) is a chronic mental health condition recognized as one of the most serious causes of disability and impaired quality of life. In the literature, there is no review about sexual dysfunction and satisfaction in OCD. The current paper presents the protocol for a systematic review and meta-analysis aimed to summarize data (1) comparing the presence of sexual dysfunction between groups with OCD and non-clinical groups, (2) investigating prevalence of each one of the sexual dysfunctions in patients with OCD, (3) comparing risk for sexual dysfunction in OCD groups with the prevalence in control groups, (4) comparing sexual satisfaction between OCD groups and non-clinical groups, and (5) investigating moderators of sexual dysfunction in OCD groups as compared with control groups. Gender, age, marital status, OCD symptom severity and subtypes, comorbid depressive disorders, comorbid anxiety disorders, concurrent psychiatric medications, comorbid general medical disease, and study quality will be investigated as moderators.

METHODS

The protocol is reported according to PRISMA-P guidelines. The search will be conducted by independent reviewers during the second week of December 2019 by using electronic databases (Scopus, PubMed, EMBASE, PsycINFO, CINAHL, and the Cochrane Library), by contacting the authors of the included studies to identify further data, by examining the references of the included studies, and by handsearching conference proceedings and theses/doctoral dissertations. The study quality will be independently evaluated using the Newcastle-Ottawa Quality Assessment Scale. Random-effect meta-analyses will be computed. If there is insufficient data for a specific outcome, only a systematic review will be performed.

DISCUSSION

This review may support clinical practice highlighting the importance of the assessment of sexuality in patients with OCD and suggesting the use of therapeutic strategies dedicated to sexuality in this clinical population with the aim of improving patients' quality of life. Potential limitations will regard the heterogeneity of the studies in terms of the instruments used to assess sexual dysfunction/satisfaction and of the definitions used to conceptualize sexual dysfunction.

SYSTEMATIC REVIEW REGISTRATION

Prospero CRD42019132264.