Possible role of neuropeptides in obsessive compulsive disorder

Gender-related romantic attachment and serum oxytocin level difference in adult patients with obsessive compulsive disorder

Background

Given the scarcity of data on gender-related romantic attachment changes and the potential role of oxytocin (OT) in the pathophysiology of obsessive-compulsive illness (OCD), the current study aimed to assess gender-related differences in romantic attachment characteristics and their relationship to serum oxytocin in a set of forty OCD cases compared with a similar group of healthy controls .Simultaneously examining the gender differences in serum oxytocin levels in OCD patients, the diagnosis of OCD patients was determined using DSM-5 criteria, and the severity of OCD was determined using the Y-BOCS rating scale. All of the patients were drug-free and not depressed. The romantic attachment was assessed using the “Experiences in Close Relationship” Questionnaire. Standard ELISA kits were used to assess plasma OT levels.

Results

Regarding romantic attachments, patients with obsessive compulsive disorder scored higher on the anxiety and avoidance domains than controls with no significant gender difference. Serum oxytocin was higher in patients with OCD than in healthy controls, indicating a possible underlying pathophysiology of the illness. Also, there was a significant gender difference, with female patients having higher serum oxytocin and symptoms severity being negatively associated.

Conclusions

Taken together, these findings propose that OT may play a role in OCD pathophysiology with gender specificity. Also, OCD associated with insecure romantic attachment.

Oxytocin Receptor Gene DNA Methylation: A Biomarker of Treatment Response in Obsessive-Compulsive Disorder?

INTRODUCTION

Obsessive-compulsive disorder (OCD) is associated with high chronicity and treatment resistance, indicating the need for early therapy response markers enabling fast and personalized treatment adaptations. Although epigenetic mechanisms such as DNA methylation of the oxytocin receptor (OXTR) gene have previously been linked to OCD pathogenesis, epigenetic markers as predictors of treatment success have not yet been investigated in OCD.

OBJECTIVE

For the first time, this therapyepigenetic study aimed to investigate the role of OXTR methylation as a treatment response marker in OCD.

METHODS

In total, 113 inpatients with OCD (57 females) were compared to 113 age- and sex-matched healthy controls. Patients were investigated over a 10-week course of standardized, OCD-specific cognitive-behavioral psychotherapy. Clinical response was measured using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) at baseline, before in vivo exposure, and after therapy. OXTR exon III methylation was analyzed via direct sequencing of sodium bisulfite-treated DNA extracted from blood cells.

RESULTS

Relative OXTR hypermethylation was observed in OCD patients compared to healthy controls. In OCD, higher baseline OXTR methylation was found to predict impaired treatment response at both categorical (responders vs. nonresponders) and dimensional (relative Y-BOCS reduction) levels, whereas lower baseline methylation was related to treatment response and greater symptom improvements. Analysis of Y-BOCS subdimensions revealed that the association between OXTR hypermethylation with impaired treatment response applied especially to symptoms related to obsessions, but not compulsions.

CONCLUSIONS

OXTR hypermethylation may constitute a predictive marker of impaired treatment response in OCD and thus carries great potential for future personalized treatment efforts in OCD.

Genetic and epigenetic architecture of Obsessive-Compulsive Disorder: In search of possible diagnostic and prognostic biomarkers

Obsessive-Compulsive Disorder (OCD) is a prevalent and severe clinical condition whose hallmarks are excessive, unwanted thoughts (obsessions) and repetitive behaviors (compulsions). The onset of symptoms generally occurs during pre-adult life and typically affects subjects in different aspects of their life's, compromising social and professional relationships. Although robust evidence suggests a genetic component in the etiopathogenesis of OCD, the causes of the disorder are still not completely understood. It is thus of relevance to take into account how genes interact with environmental risk factors, thought to be mediated by epigenetic mechanisms. We here provide an overview of genetic and epigenetic mechanisms of OCD, focusing on the modulation of key central nervous system genes, in the attempt to suggest possible disease biomarkers.

Pharmacotherapeutic Strategies and New Targets in OCD

Effective pharmacological and psychotherapeutic treatments are well established for obsessive-compulsive disorder (OCD). Serotonin reuptake inhibitors (SRIs) are first-line treatment and are of benefit to about half of patients. Augmentation of SRI treatment with low-dose neuroleptics is an evidence-based second-line strategy. Specialty psychotherapy is also used as both first-line and second-line treatment and can benefit many. However, a substantial number of patients do not respond to these treatments. New alternatives are urgently needed. This review summarizes evidence for these established pharmacotherapeutic strategies, and for others that have been investigated in refractory disease but are not supported by the same level of evidence. We focus on three neurotransmitter systems in the brain: serotonin, dopamine, and glutamate. We summarize evidence from genetic, neuroimaging, animal model, and other lines of investigation that probe these three systems in patients with OCD. We also review recent work on predictors of response to current treatments. While many studies suggest abnormalities that may provide insight into the pathophysiology of the disorder, most studies have been small, and non-replication of reported findings has been common. Nevertheless, the gradual accrual of evidence for neurotransmitter dysregulation may in time lead the way to new pharmacological strategies.

The Psychopharmacology of Obsessive-Compulsive Disorder: A Preclinical Roadmap

This review evaluates current knowledge about obsessive-compulsive disorder (OCD), with the goal of providing a roadmap for future directions in research on the psychopharmacology of the disorder. It first addresses issues in the description and diagnosis of OCD, including the structure, measurement, and appropriate description of the disorder and issues of differential diagnosis. Current pharmacotherapies for OCD are then reviewed, including monotherapy with serotonin reuptake inhibitors and augmentation with antipsychotic medication and with psychologic treatment. Neuromodulatory therapies for OCD are also described, including psychosurgery, deep brain stimulation, and noninvasive brain stimulation. Psychotherapies for OCD are then reviewed, focusing on behavior therapy, including exposure and response prevention and cognitive therapy, and the efficacy of these interventions is discussed, touching on issues such as the timing of sessions, the adjunctive role of pharmacotherapy, and the underlying mechanisms. Next, current research on the neurobiology of OCD is examined, including work probing the role of various neurotransmitters and other endogenous processes and etiology as clues to the neurobiological fault that may underlie OCD. A new perspective on preclinical research is advanced, using the Research Domain Criteria to propose an adaptationist viewpoint that regards OCD as the dysfunction of a normal motivational system. A systems-design approach introduces the security motivation system (SMS) theory of OCD as a framework for research. Finally, a new perspective on psychopharmacological research for OCD is advanced, exploring three approaches: boosting infrastructure facilities of the brain, facilitating psychotherapeutic relearning, and targeting specific pathways of the SMS network to fix deficient SMS shut-down processes. SIGNIFICANCE STATEMENT: A significant proportion of patients with obsessive-compulsive disorder (OCD) do not achieve remission with current treatments, indicating the need for innovations in psychopharmacology for the disorder. OCD may be conceptualized as the dysfunction of a normal, special motivation system that evolved to manage the prospect of potential danger. This perspective, together with a wide-ranging review of the literature, suggests novel directions for psychopharmacological research, including boosting support systems of the brain, facilitating relearning that occurs in psychotherapy, and targeting specific pathways in the brain that provide deficient stopping processes in OCD.

Integrative analysis of shared genetic pathogenesis by obsessive‑compulsive and eating disorders

A number of common pathological features have been observed in obsessive‑compulsive disorder (OCD) and eating disorders (EDs). The present study examined the association between OCD and EDs at the genetic level in order to gain an improved understanding of the shared genetic basis of the diseases and identify novel potential risk genes for the two diseases. An integrated analysis using large‑scale disease‑gene association data and gene expression data was conducted. Disease‑gene association data were acquired from the Pathway Studio Mammalian database. Gene expression data were acquired from samples of 133 subjects, including 15 ED cases, 16 OCD cases and 102 normal controls. Genes associated with OCD and ED presented significant overlap (21 genes, P=6.70x10‑34), serving roles within multiple common genetic pathways (top 10 pathway enrichment P<4.30x10‑7) that were implicated in the two diseases. A genetic network of 17 genes was constructed, through which OCD and ED were observed to influence each other. Expression analysis revealed four novel common significant genes for OCD and ED (oxytocin receptor, glutamate decarboxylase 2, neuropeptide Y and glutamate ionotropic receptor kainate type subunit 3). These genes demonstrated a strong functional association with the two diseases. The results of the present study supported the presence of complex genetic associations between OCD and ED. Genes associated with one disease are worthy of further investigation as potential risk factors for the other. The findings of the present study may provide novel insights into the understanding of the pathogenesis of OCD and ED.

Maternal programming: Application of a developmental psychopathology perspective

The fetal phase of life has long been recognized as a sensitive period of development. Here we posit that pregnancy represents a simultaneous sensitive period for the adult female with broad and persisting consequences for her health and development, including risk for psychopathology. In this review, we examine the transition to motherhood through the lens of developmental psychopathology. Specifically, we summarize the typical and atypical changes in brain and behavior that characterize the perinatal period. We highlight how the exceptional neuroplasticity exhibited by women during this life phase may account for increased vulnerability for psychopathology. Further, we discuss several modes of signaling that are available to the fetus to affect maternal phenotypes (hormones, motor activity, and gene transfer) and also illustrate how evolutionary perspectives can help explain how and why fetal functions may contribute to maternal psychopathology. The developmental psychopathology perspective has spurred advances in understanding risk and resilience for mental health in many domains. As such, it is surprising that this major epoch in the female life span has yet to benefit fully from similar applications.

Pharmacotherapy for obsessive—compulsive disorder

We present a narrative review of evidence-based treatment for obsessive–compulsive disorder (OCD), covering first-line pharmacological treatment, augmentation strategies, approaches for treatment-refractory OCD and the management of OCD in special populations (children and adolescents, pregnant and breast-feeding women, and elderly people).

Oxytocin receptor gene polymorphisms exert a modulating effect on the onset age in patients with obsessive-compulsive disorder

The oxytocin receptor (OXTR) is a potential candidate in the pathophysiology of obsessive-compulsive disorder (OCD). The present study investigated the association between common single-nucleotide polymorphism (SNPs) of the OXTR gene and the affected status of OCD or distinct clinical subtypes of OCD including the age at onset and symptom dimensions. Ten SNPs of OXTR were examined in 615 patients with OCD and 581 healthy controls. Single-marker and haplotype-based association analyses were conducted. While OXTR variants were not associated with the affected status of OCD or its clinical symptom dimensions, rs2268493 (p=0.00185) and rs13316193 (p=0.00461) of the OXTR gene were associated with the age at onset in patients with OCD. In addition, in haplotype-based association analyses, there was a significant association between the OXTR gene and the onset age in patients with OCD. In particular, the G-C-G haplotype of rs2268493-rs2254298-rs11316193 and the T-G-A haplotype of rs237887-rs2268490-rs4686301 were positively associated with late-onset OCD. Our results suggest that common variants of OXTR may exert a modulating effect on the onset age in OCD pathophysiology. The potential involvement of the oxytocin system in the development and expression of OCD warrants further longitudinal research.

Glutamate-Modulating Drugs as a Potential Therapeutic Strategy in Obsessive-Compulsive Disorder

OBJECTIVE

Obsessive-compulsive disorder (OCD) is a mental disease commonly associated with severe distress and impairment of social functioning. Serotonin reuptake inhibitors and/or cognitive behavioural therapy are the therapy of choice, however up to 40% of patients do not respond to treatment. Glutamatergic signalling has also been implicated in OCD. The aim of the current study was to review the clinical evidence for therapeutic utility of glutamate-modulating drugs as an augmentation or monotherapy in OCD patients.

METHODS

We conducted a search of the MEDLINE database for clinical studies evaluating the effect of glutamate-modulating drugs in OCD.

RESULTS

Memantine is the compound most consistently showing a positive effect as an augmentation therapy in OCD. Anti-convulsant drugs (lamotrigine, topiramate) and riluzole may also provide therapeutic benefit to some OCD patients. Finally, ketamine may be of interest due to its potential for a rapid onset of action.

CONCLUSION

Further randomized placebo-controlled trials in larger study populations are necessary in order to draw definitive conclusions on the utility of glutamate-modulating drugs in OCD. Furthermore, genetic and epigenetic factors, clinical symptoms and subtypes predicting treatment response to glutamate-modulating drugs need to be investigated systematically.

Plasma Oxytocin Levels in Untreated Adult Obsessive-Compulsive Disorder Patients

BACKGROUND AND AIM

Given the paucity of information on the possible role of oxytocin (OT) in the pathophysiology of obsessive-compulsive disorder (OCD), our study aimed at evaluating plasma OT levels in a group of 44 OCD outpatients, as compared with a similar group of healthy control subjects. At the same time, the relationships between OT and clinical features and romantic attachment characteristics were examined as well.

METHODS

Diagnosis was assessed according to DSM-IV-TR criteria, while the OCD severity was measured by means of the Y-BOCS rating scale. All patients were drug free and not depressed. The romantic attachment was assessed by means of the Italian version of the 'Experiences in Close Relationships' questionnaire. Plasma OT levels were evaluated by means of a standard RIA kit.

RESULTS

The main findings of our study showed that OT levels were increased in OCD patients, as compared with healthy subjects, and negatively related to symptom severity. Positive relationships were detected between OT levels and the fearful-avoidant and dismissing styles of romantic attachments, but only in male OCD patients.

CONCLUSION

Taken together, these findings suggest that OT may play a role in OCD pathophysiology and also in the romantic attachment of patients with gender specificity.

Transcutaneous electrical acupoint stimulation as an adjunct therapy for obsessive-compulsive disorder: A randomized controlled study

BACKGROUND

Transcutaneous electrical acupoint stimulation (TEAS) is thought to have potential to treat obsessive-compulsive disorder (OCD).

OBJECTIVE

The purpose of this study was to determine whether adding TEAS to cognitive behavioral therapy (CBT) and clomipramine would improve the efficacy of these conventional treatments in OCD.

METHODS

In this randomized controlled trial, 360 OCD patients were assigned to receive TEAS combined with CBT plus clomipramine (Group A, n = 120), TEAS combined with CBT plus placebo (Group B, n = 120), and simulated (placebo) TEAS combined with CBT plus clomipramine (Group C, n = 120) for 12 weeks. The primary outcome was measured using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS).

RESULTS

OCD symptoms in all patients reduced over time, however Groups A and B had a significantly greater reduction in Y-BOCS total score and the subscale for obsession and compulsion between week 2 and week 12 compared to Group C. Groups A and B had similar scores on these measures. Both groups had significantly higher rates of clinical response than Group C (88.3% and 81.7% vs. 67.5%, respectively, p < 0.001); and higher rates of remission (30.0% and 22.5% vs. 9.2%, respectively, p < 0.001). Group B experienced fewer adverse events than the other two groups.

CONCLUSIONS

TEAS enhances the efficacy of conventional OCD interventions and avoids the adverse effects associated with conventional pharmacological treatment. It can be considered as an effective adjunct intervention for OCD.

An autistic dimension

This article focuses on the possibility that autism spectrum disorder (ASD: Asperger syndrome, autism and atypical autism) in its milder forms may be clinically important among a substantial proportion of patients with obsessive-compulsive disorder (OCD), and discusses OCD subtypes based on this proposition. The hypothesis derives from extensive clinical experience of OCD and ASD, and literature searches on MEDLINE. Neuropsychological deficits are more common in OCD than in panic disorder and depression. Moreover, obsessive-compulsive and schizotypal personality disorders are over-represented in OCD. These may constitute misperceived clinical manifestations of ASD. Furthermore, repetitive behaviours and hoarding are common in Asperger syndrome. It is suggested that the comorbidity results in a more severe and treatment resistant form of OCD. OCD with comorbid ASD should be recognized as a valid OCD subtype, analogous to OCD with comorbid tics. An odd personality, with paranoid, schizotypal, avoidant or obsessive-compulsive traits, may indicate these autistic dimensions in OCD patients.

From Autism to Eating Disorders and More: The Role of Oxytocin in Neuropsychiatric Disorders

Oxytocin (oxy) is a pituitary neuropeptide hormone synthesized from the paraventricular and supraoptic nuclei within the hypothalamus. Like other neuropeptides, oxy can modulate a wide range of neurotransmitter and neuromodulator activities. Additionally, through the neurohypophysis, oxy is secreted into the systemic circulation to act as a hormone, thereby influencing several body functions. Oxy plays a pivotal role in parturition, milk let-down and maternal behavior and has been demonstrated to be important in the formation of pair bonding between mother and infants as well as in mating pairs. Furthermore, oxy has been proven to play a key role in the regulation of several behaviors associated with neuropsychiatric disorders, including social interactions, social memory response to social stimuli, decision-making in the context of social interactions, feeding behavior, emotional reactivity, etc. An increasing body of evidence suggests that deregulations of the oxytocinergic system might be involved in the pathophysiology of certain neuropsychiatric disorders such as autism, eating disorders, schizophrenia, mood, and anxiety disorders. The potential use of oxy in these mental health disorders is attracting growing interest since numerous beneficial properties are ascribed to this neuropeptide. The present manuscript will review the existing findings on the role played by oxy in a variety of distinct physiological and behavioral functions (Figure 1) and on its role and impact in different psychiatric disorders. The aim of this review is to highlight the need of further investigations on this target that might contribute to the development of novel more efficacious therapies. Figure 1

Rats with differential self-grooming expression in the elevated plus-maze do not differ in anxiety-related behaviors

Individual differences are important biological predictors for reactivity to stressful stimulation. The extent to which trait differences underlie animal's reactions to conditioned and unconditioned fear stimuli, for example, is still to be clarified. Although grooming behavior has been associated with some aspects of the obsessive-compulsive disorder in humans, its relation with other anxiety disorders is still unknown. Given that grooming behavior could be a component of the whole spectrum of these disorders, in the present study we allocated male Wistar rats in low, intermediate and high self-grooming groups according to the duration of such behavior in the elevated plus-maze (EPM). These groups were then evaluated in unconditioned fear tests, such as the EPM and the open-field, and in conditioned fear tests, such as fear-potentiated startle and fear extinction retention. Additionally, we studied the expression of unconditioned behaviors in marble burying test and the sensorimotor gate function with prepulse inhibition test. Neurochemicals and neuroendocrine parameters were also evaluated, with the quantification of basal corticosterone in the plasma, and dopamine, serotonin and their metabolites in brain structures involved with fear processing. In general, rats classified according to grooming expression showed similar performance in all behavioral tests. Accordingly, corticosterone and monoamine concentrations were similar among groups. Thus, despite grooming expression elicited by different approaches--especially pharmacological ones--has been related with some aspects of anxiety disorders, rats with different expression of spontaneous self-grooming in the EPM do not differ in anxiety-like behaviors nor in neurochemical and neuroendocrine parameters generally associated with anxiety disorders.

Plasma oxytocin changes and anti-obsessive response during serotonin reuptake inhibitor treatment: a placebo controlled study

BACKGROUND

The drug treatments of choice for obsessive-compulsive disorder (OCD) are serotonin reuptake inhibitors (SRIs). However, a correlation between the neuropeptide oxytocin in cerebrospinal fluid and the severity of OCD has previously been shown, and oxytocin and serotonin are interconnected within the brain. Few studies have investigated whether SRIs have any effect on oxytocin; thus, our aim was to explore the possibility that oxytocinergic mechanisms contribute to the anti-obsessive effect of SRIs.

METHOD

In a randomized, double-blind trial, comparing SRIs (clomipramine and paroxetine) with placebo in 36 adults with OCD (characterized for subtypes), plasma oxytocin was measured with radioimmunoassay after plasma extraction, at baseline, after 1 week, and after 4 weeks of treatment, and related to baseline severity and clinical response after 12 weeks, as measured by the Yale-Brown Obsessive Compulsive Scale (Y-BOCS).

RESULTS

Baseline oxytocin levels correlated positively with baseline Y-BOCS ratings, but only among the future SRI responders. Patients with early onset of OCD had higher baseline oxytocin. During treatment, plasma oxytocin did not differ between SRI and placebo treatment. In SRI responders, plasma oxytocin first decreased and then increased; in non-responders (to SRI as well as to placebo), the reverse was the case. After 4 weeks, treatment responders had attained higher oxytocin levels compared to non-responders. The intra-individual range (i.e., the variability) of plasma oxytocin between measurements was the measure that best differentiated responders from non-responders. This range was higher in responders than non-responders, and lower in patients with autistic traits.

CONCLUSIONS

SRIs have highly variable effects on plasma oxytocin between individuals. The associations between baseline oxytocin and OCD severity and between oxytocin changes and treatment response support the notions that oxytocin is involved in OCD pathophysiology, and that the anti-obsessive effects of SRIs are partly exerted through oxytocinergic mechanisms.

Prosocial effects of oxytocin and clinical evidence for its therapeutic potential

There has been unprecedented interest in the prosocial effects of the neuropeptide oxytocin in humans over the last decade. A range of studies has demonstrated correlations between basal oxytocin levels and the strength of social and bonding behaviors both in healthy individuals and in those suffering from psychiatric disorders. Mounting evidence suggests associations between polymorphisms in the oxytocin receptor gene and prosocial behaviors and there may also be important epigenetic effects. Many studies have now reported a plethora of prosocial effects of intranasal application of oxytocin, including the domains of trust, generosity, socially reinforced learning, and emotional empathy. The main focus of this review will be to summarize human preclinical work and particularly the rapidly growing number of clinical studies which have identified important links between oxytocin and a wide range of psychiatric disorders, and have now started to directly assess its therapeutic potential.

Animal models of obsessive-compulsive disorder: exploring pharmacology and neural substrates

During the last 30 years there have been many attempts to develop animal models of obsessive-compulsive disorder (OCD). Most models have not been studied further following the original publication, and in the past few years, most papers present studies employing a few established animal models, exploring the neural basis of compulsive behavior and developing new treatment strategies. Here we summarize findings from the five most studied animal models of OCD: 8-OHDPAT (8-hydroxy-2-(di-n-propylamino)-tetralin hydrobromide) induced decreased alternation, quinpirole-induced compulsive checking, marble burying, signal attenuation and spontaneous stereotypy in deer mice. We evaluate each model's face validity, derived from similarity between the behavior in the model and the specific symptoms of the human condition, predictive validity, derived from similarity in response to treatment (pharmacological or other), and construct validity, derived from similarity in the mechanism (physiological or psychological) that induces behavioral symptoms and in the neural systems involved. We present ideas regarding future clinical research based on each model's findings, and on this basis, also emphasize possible new approaches for the treatment of OCD.

Autism and oxytocin: new developments in translational approaches to therapeutics

Autism is a neurodevelopmental disorder characterized by dysfunction in three core symptom domains: speech and communication deficits, repetitive or compulsive behaviors with restricted interests, and social impairment. The neuropeptide oxytocin, along with the structurally similar peptide arginine vasopressin, may play a role in the etiology of autism, and especially in the social impairment domain. Oxytocin is a nonapeptide (i.e., it has nine amino acids). It is synthesized in magnocellular neurons in the paraventricular nucleus and the supraoptic nucleus of the hypothalamus and is released into the bloodstream by way of axon terminals in the posterior pituitary. Oxytocin is released both peripherally, where it is involved in milk letdown and the facilitation of uterine contractions, and centrally, where it acts as a neuromodulator along with arginine vasopressin. Here, we discuss relevant translational research pertaining to the role of oxytocin in social and repetitive behaviors and consider clinical implications. We also discuss current research limitations, review recent preliminary findings from studies involving oxytocin in autism spectrum disorder patient populations, and point to possible directions for future research.

Postpartum obsessive-compulsive disorder: prevalence and clinical characteristics

OBJECTIVE

The principal aims of this study were to examine the prevalence rate, clinical characteristics, and related factors of postpartum obsessive-compulsive disorder (OCD).

METHOD

The subjects were a nonclinical sample of 400 postpartum women. They were interviewed from the 2nd up to the 26th week after birth. The Mini International Neuropsychiatric Interview was used for diagnosis of OCD, the Yale-Brown Obsessive-Compulsive Symptom Checklist was used to determine the types of obsessions and compulsions, and the Structured Clinical Interview for DSM-IV Axis I Disorders was used to diagnose comorbid depressive episode.

RESULTS

Thirty-six (9%) of the sample met the diagnostic criteria for OCD according to the Mini International Neuropsychiatric Interview, and 9 (2.3%) reported postpartum onset OCD. Obsessive-compulsive disorder was more frequent in mothers with personal history of previous psychiatric disorder, somatic disease, or obstetric complication in pregnancy/birth, and who were multiparous. The most common obsessions were aggressive, contamination and miscellaneous, and compulsion for washing/cleaning and checking, and 38.9% have a comorbid depressive episode.

CONCLUSION

Women have increased risk of OCD or obsessive-compulsive symptoms in the postpartum period. For this reason, all women, particularly women with previous psychiatric history, somatic disease, or with complications in pregnancy or at the birth should be carefully screened for OCD in the postpartum period.

Adenylate-cyclase activity in platelets of patients with obsessive-compulsive disorder

Although the main biological hypothesis on the pathophysiology of obsessive-compulsive disorder (OCD) is centered on the serotonin system, indications are available that other neurotransmitters, and even second messengers, particularly the cyclic adenosine monophosphate (cAMP) signaling, may be involved, though effective data are few. Therefore, the aim of the present study was to evaluate and compare the basal and isoprenaline (ISO)-stimulated velocity of adenylate-cyclase (AC) in human platelet membranes of patients with OCD and healthy control subjects. The results showed that the basal and ISO-stimulated AC activity, as well as the dose-response curves of ISO by using agonist concentrations ranging between 0.1 nM and 10 muM, were not different in the two groups. However, OCD patients showed lower EC(50) and higher E(max) values than healthy subjects. These findings suggest the presence of supersensitive beta-adrenergic receptors in platelets of OCD patients.

Naltrexone augmentation in OCD: a double-blind placebo-controlled cross-over study

Current treatments for Obsessive Compulsive Disorder (OCD) rely primarily on serotonergic mechanisms. However, approximately 30% of patients do not respond to serotonin reuptake inhibitors and remain chronically ill. Given the behavioral similarities between some of the compulsive behaviors in OCD and addiction, we hypothesized that the opioid antagonist naltrexone might attenuate compulsions in OCD as well. The effect of naltrexone augmentation to SRI was compared to placebo in 10 OCD outpatients who had not responded to an adequate dose of SSRI or clomipramine for at least 2 months. Participants underwent 5 weeks of treatment with naltrexone or placebo (and 1 week of tapering) in a randomized, double-blind, cross-over design. Patients were evaluated weekly using the Y-BOCS, CGI, HAM-A, and MADRS scales. A two-way repeated measures MANOVA revealed no significant effect for Y-BOCS. However, while receiving naltrexone, patients had significantly higher scores on CGI, MADRS and HAM-A as compared to placebo. The lack of significant findings on OC symptoms could be due to either ceiling effect or alternatively, due to a non-specific exacerbation on anxiety and depression but not on OC symptoms.

Novel mutations of the extraneuronal monoamine transporter gene in children and adolescents with obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a disease of complex aetiology with a marked genetic component. Impact of the serotonergic system has been reported but the contribution of additional transmitter systems to the pathogenesis seems likely. The extraneuronal monoamine transporter, EMT (SLC22A3), is implicated in non-neuronal termination of noradrenergic signalling in the central nervous system and a candidate gene for a variety of neuropsychiatric disorders. We conducted a case-control study of 84 Caucasian children and adolescents with OCD according to DSM-IV criteria, and healthy adults by comprehensive sequencing of the EMT gene. Additionally, targeted genotype analysis was done with patient-parent trios. Known polymorphisms and frequent haplotypes were not associated with OCD in the present sample. Transmission disequilibrium test was negative for the presumptive cryptic splice site 1233G>A polymorphism. However, we identified two novel independent mutations exclusively in affected patients. A thus far unknown -106/107delAG mutation was detected in three male patients of unaffected parents but was not prevalent in 204 healthy subjects (p=0.024). In a luciferase reporter assay the mutant allele conferred increased promoter activity by 36%. Furthermore, we describe the first non-synonymous substitution in the EMT gene, Met370Ile, in a family of affected female members that co-segregated with the disease. The residue exhibits a high degree of inter-species conservation. Heterologous expression of mutant cDNA revealed a 40% decline of transport capacity for norepinephrine. Rare mutations in the EMT gene suggest a causative or modulating role in genetic subtypes of OCD.

Neuroanatomical and cellular substrates of hypergrooming induced by microinjection of oxytocin in central nucleus of amygdala, an experimental model of compulsive behavior

Oxytocin (OT) is a neurosecretory nonapeptide synthesized in hypothalamic cells that project to the neurohypophysis as well as to widely distributed sites in the central nervous system. Central OT microinjections induce a variety of cognitive, sexual, reproductive, grooming and affiliative behaviors in animals. Obsessive-compulsive disorder (OCD) includes a range of cognitive and behavioral symptoms that bear some relationship with OT. Here, we study the neuroanatomical and cellular substrates of the hypergrooming induced by administration of OT in the central nucleus of amygdala (CeA). In this context, this hypergrooming is considered as a model of compulsive behavior. Our data suggest a link between the CeA and the hypothalamic grooming area (HGA). The HGA includes parts of the paraventricular nucleus and the dorsal hypothalamic area. Our data on colocalization of OT (immunohistochemistry for peptide), OT receptor (binding assay) and its retrogradely labeled cells after Fluoro-Gold injection in the CeA suggest that CeA and connections are important substrates of the circuit underlying this OT-dependent compulsive behavioral pattern.

The neuroscience of affiliation: forging links between basic and clinical research on neuropeptides and social behavior

Animal studies point to the role of two neuropeptides-oxytocin and vasopressin-in the regulation of affiliative behaviors including mating, pair-bond formation, maternal/parenting behavior, and attachment. These findings may have important implications for understanding and treating clinical disorders marked by social deficits and/or disrupted attachment. This review focuses on advances made to date in the effort to forge links between basic and clinical research in the area of neuropeptides and social behavior. The literature on oxytocin and its involvement in stress response, affiliation, and prosocial behavior is reviewed, and the implications of these findings for such disorders as autism as well as other social and stress-related disorders including social phobia, post-traumatic stress disorder, and some personality disorders are considered. Finally, unresolved issues and directions for future research are discussed.

Treatment-resistant anxiety disorders

Several epidemiological studies confirmed that Anxiety Disorders as a group are the most prevalent psychiatric conditions in the United States. The importance of these conditions is underlined by the fact that they cause significant disability, poor quality of life, alcohol and drug abuse. Anxiety disorders are treatable conditions and respond to the front-line interventions such as serotonin reuptake inhibitors and cognitive behavioral therapy. However, only about 60% of patients respond to those treatments to any significant degree. Many still have residual symptoms or stay treatment refractory. The group of anxiety patients that is resistant to the treatment has been shown to have very poor quality of life and have highest rate of suicidal attempts than any other disorders. Many biological, treatment specific and social factors are affecting treatment resistance. In this paper, we are attempting to review reasons for the treatment resistance. In addition, we would like to review current strategies that could be helpful in reducing treatment resistance and aiding people chronically suffering from these severe and disabling conditions.

Animal models of obsessive-compulsive disorder: rationale to understanding psychobiology and pharmacology

Animal models have shown progressive development and have undoubtedly proven their supportive value in OCD research. Thus, various animal models have confirmed the importance of the 5-HT [72-74] and dopamine systems [104,111] in the neurobiology and treatment of OCD. Given the neurochemical, emotional, and cognitive complexity of the disorder, how-ever, animal models are being used to investigate more and more complicated neurochemical and behavioral theories purported to underlie OCD. The lever-press model, for example, has implicated deficient response feed-back in a neural system that regulates operant behavior [74]. Studies on stereotypic movement disorder [89] have opened a new avenue of investigation into the neurobiology of stereotypy that may be applicable to more complex syndromes such as OCD. Models that have focused on specific neuropsychologic aspects of OCD such as reward [74], displacement behavior[63,101], perseveration and indecisiveness [73,102], and spontaneous stereotypy [90,94] are important in their attempt to unify the diverse behavioral manifestations of this disorder. It is clear that for a deeper, more holistic understanding of OCD, multiple animal models will be needed to allow investigation of the various aspects of the disorder and to provide convergent validation of the research findings. The heterogeneous nature of OCD, the various subtypes that exist within the disorder, and the range of obsessive-compulsive spectrum disorders suggest that particular questions regarding OCD may be addressed best by us-ing a particular ethologic model, whereas other questions might require a pharmacologic model or a combination of both for meaningful results[62,115]. Genetic models will be extremely useful for studying the genetics of pathologic behavior and for relating these findings to neuroanatomic and neurochemical changes in the model (eg, DICT-7 mice as a model for Tourette's syndrome and OCD). Neither ethologic nor pharmacologic models, however, can assess whether the "compulsive" behavior is a response to an "obsessive" anxiety or fear. Perhaps the symptoms seen in patients who have OCD, which may be exacerbated by everyday stress, are analogous to displacement behaviors in animals and also reflect some form of anxiety or stress [98]. In this regard, the bank vole model [116]has provided evidence that previously developed stereotypies increase markedly after acute stress and argues that healthy individuals "habituate" to everyday stress, whereas patients who have OCD do not. Interindividual variation in behavioral response and attempts to replicate studies in different laboratories often is the nemesis of the behavioral scientist. Small within- and between-subject variability is usually desirable, how-ever, because there are cases in which the study of the variability of the model could lead to a better understanding of the disorder. Variability can-not always be considered an error; it is possible that previously disregarded neuronal systems may have a place in the observed variation and, indeed, in the pathophysiology of OCD. In this regard, SRIs are not always effective for OCD [6,29,30] such that a lack of effect in a model may reflect an un-known neurobiological basis for compulsive behavior in a sub-group of SRI refractory patients. Similarly, separating the afflicted (ie, working with animals that show greater behavioral change in a model and/or after drug treatment) would have distinct benefits. To increase successful implementation of an ethologic animal model, especially when reinforcement models or signal attenuation models are used,the laboratory must be equipped with the essential behavioral testing apparatus as well as the operant chambers/rooms in which to conduct the train-ing and data collection. Quantification of certain stereotypy behaviors also requires experienced or trained observers. An illustration of the difficulty in measuring behavioral changes is that in the rewarded alternation model,a good response to behavioral treatment (alternation training) may lead to a floor effect [73] which, after successful drug treatment of the animal,produces no residual persistence (ie, measurable behavioral change) on which a drug treatment can be tested. Clearly, the choice of ethologic, pharmacologic, or genetic models should be considered carefully. A well-validated model may quell many of the limitations and considerations described previously. Noninvasive neuroimaging(eg, the use of small-animal single-photon emission CT) to explore the neuroanatomic basis of OCD offers an exciting future challenge, especially if combined with pharmacologic or ethologic models, and could confirm or ex-tend knowledge of the neuroanatomy of OCD. Although studies to investigate further the interactive role of 5-HT, dopamine, GABA, and glutamate are still needed, the role of neuroactive peptides such as cholecystokinin, corticotrophin-releasing factor, neuropeptide Y, tachykinins (ie, substance P),and natriuretic peptides in OCD should also be considered. Genetically engineered animal models will become increasingly valuable in combination with new technologies such as gene-chip microarrays, RNA interference, and advanced proteomics that will help further the understanding of OCD. Animal models of OCD are poised to play a vital role in extending the knowledge of the disorder now and in the future.

Is obsessive-compulsive disorder an anxiety disorder?

Obsessive-compulsive disorder (OCD) is classified as an anxiety disorder in the DSM-IV-TR [American Psychiatric Association, 2000. Diagnostic and statistical manual of mental disorders, Fourth ed., rev. Washington, DC: Author]; however, the notion of a spectrum of obsessive-compulsive (OC) related disorders that is comprised of such disparate disorders as OCD, body dysmorphic disorder, certain eating disorders, pathological gambling, and autism, is gaining acceptance. The fact that these disorders share obsessive-compulsive features and evidence similarities in patient characteristics, course, comorbidity, neurobiology, and treatment response raises the question of whether OCD is best conceptualized as an anxiety or an OC spectrum disorder. This article reviews evidence from comorbidity and family studies, as well as biological evidence related to neurocircuitry, neurotransmitter function, and pharmacologic treatment response that bear on this question. The implications of removing OCD from the anxiety disorders category and moving it to an OC spectrum disorders category, as is being proposed for the DSM-V, is discussed.

Functional mu opioid receptors are expressed in cholinergic interneurons of the rat dorsal striatum: territorial specificity and diurnal variation

Striatal cholinergic interneurons play a crucial role in the control of movement as well as in motivational and learning aspects of behaviour. Neuropeptides regulate striatal cholinergic transmission and particularly activation of mu opioid receptor (MOR) inhibits acetylcholine (ACh) release in the dorsal striatum. In the present study we investigated whether this cholinergic transmission could be modulated by an enkephalin/MOR direct process. We show that mRNA and protein of MORs are expressed by cholinergic interneurons in the limbic/prefrontal territory but not by those in the sensorimotor territory of the dorsal striatum. These MORs are functional because potassium-evoked release of ACh from striatal synaptosomes was dose-dependently reduced by a selective MOR agonist, this effect being suppressed by a MOR antagonist. The MOR regulation of cholinergic interneurons presented a diurnal variation. (i) The percentage of cholinergic interneurons containing MORs that was 32% at the beginning of the light period (morning) increased to 80% in the afternoon. (ii) The MOR-mediated inhibition of synaptosomal ACh release was higher in the afternoon than in the morning. (iii) While preproenkephalin mRNA levels remained stable, enkephalin tissue content was the lowest (-32%) in the afternoon when the spontaneous (+35%) and the N-methyl-d-aspartate-evoked (+140%) releases of enkephalin (from microsuperfused slices) were the highest. Therefore, by acting on MORs present on cholinergic interneurons, endogenously released enkephalin reduces ACh release. This direct enkephalin/MOR regulation of cholinergic transmission that operates only in the limbic/prefrontal territory of the dorsal striatum might contribute to information processing in fronto-cortico-basal ganglia circuits.

Obsessive-compulsive symptoms associated with clozapine and risperidone treatment: three case reports and review of the literature

Treatment-emergent obsessive-compulsive symptoms (OCSs) have raised concern since the widespread introduction of serotonin-dopamine antagonists (SDAs) for the treatment of schizophrenia. Further investigations of SDA-emergent OCSs and their response to anti-obsessional agents will be beneficial for clinicians in helping patients who suffer from this problem. We present three cases of schizophrenia in which distressing OCSs occurred during clozapine or risperidone treatment. OCSs were assessed consecutively using the Yale-Brown Obsessive-Compulsive Scale. The OCSs of these three patients were responsive to anti-obsessional agents, including fluvoxamine, clomipramine, and paroxetine. We also review the current literature and discuss the possible pathophysiology and psychopathology of SDA-emergent OCSs.

Role of oxytocin and vasopressin in the transitions of weaning in the rat

Sucklings (18-day-old) and weanlings (35-day-old) were injected icv with oxytocin or its antagonist (both 0.5 microg/1 microl), or vasopressin (1.0 ng/1 microl) or its antagonist (100 ng/1 microl), prior to 4-min observation in a behavioral maze with a sibling in one box and their anesthetized dam in the other. Oxytocin abolished nipple attachment in sucklings, decreased time spent with the dam, and increased self-grooming. The oxytocin antagonist had little influence on behavior. Vasopressin increased self-grooming while its antagonist reduced passive contact with the dam, increased active contact with her, and increased exploration and activity. We conclude that these neuropeptides have diverse roles during weaning, maintaining sucklings' behavior or promoting weaning, and subserving the transition from attachment to the dam to independence from her. We propose that these neurochemicals, and others, mediate the neural, affiliative, and affective changes of weaning, and that the term "weaning" should be understood to encompass these behavioral transitions.

Anxiety disorders in women

Women have higher overall prevalence rates for anxiety disorders than men. Women are also much more likely than men to meet lifetime criteria for each of the specific anxiety disorders: generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD), social anxiety disorder (SAD), posttraumatic stress disorder (PTSD), simple phobia, panic disorder, and agoraphobia. Considerable evidence suggests that anxiety disorders remain underrecognized and undertreated despite their association with increased morbidity and severe functional impairment. Increasing evidence suggests that the onset, presentation, clinical course, and treatment response of anxiety disorders in women are often distinct from that associated with men. In addition, female reproductive hormone cycle events appear to have a significant influence on anxiety disorder onset, course, and risk of comorbid conditions throughout a woman's life. Further investigations concerning the unique features present in women with anxiety disorders are needed and may represent the best strategy to increase identification and optimize treatment interventions for women afflicted with these long-neglected psychiatric disorders.

WCA recommendations for the long-term treatment of obsessive-compulsive disorder in adults

What are the latest psychotherapeutic and pharmacotherapeutic treatment recommendations for obsessive-compulsive disorder (OCD)? OCD is a relatively common disorder with a lifetime prevalence of approximately 2% in the general population. It often has an early onset, usually in childhood or adolescence, and frequently becomes chronic and disabling if left untreated. High associated healthcare utilization and costs, and reduced productivity resulting in loss of earning, pose a huge economic burden to OCD patients and their families, employers, and society. OCD is characterized by the presence of obsessions and compulsions that are time-consuming, cause marked distress, or significantly interfere with a person's functioning. Most patients with OCD experience symptoms throughout their lives and benefit from long-term treatment. Both psychotherapy and pharmacotherapy are recommended, either alone or in combination, for the treatment of OCD. Cognitive-behavioral therapy is the psychotherapy of choice. Pharmacologic treatment options include the tricyclic antidepressant clomipramine and the selective serotonin reuptake inhibitors (SSRIs) citalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline. These have all shown benefit in acute treatment trials; clomipramine, fluvoxamine, fluoxetine, and sertraline have also demonstrated benefit in long-term treatment trials (at least 24 weeks), and clomipramine, sertraline, and fluvoxamine have United States Food and Drug Administration approvals for use in children and adolescents. Available treatment guidelines recommend first-line use of an SSRI (ie, fluoxetine, fluvoxamine, paroxetine, sertraline, or citalopram) in preference to clomipramine, due to the latter's less favorable adverse-event profile. Further, pharmacotherapy for a minimum of 1-2 years is recommended before very gradual withdrawal may be considered.

Neuropeptides: general characteristics and neuropharmaceutical potential in treating CNS disorders

The general characteristics of neuropeptides are discussed as a background for the understanding of their role in regulation of physiological systems. The extent of those systems that are crucially affected by neuropeptides is vast and the complexity of their interactions makes the clinical focus on a specific neuropeptide unsatisfactory. The clinical potential of neuropeptides affecting eating disorders, CNS behavioral disorders and the neuroregenerative and neuroprotective action of neuropeptides is discussed. It is probable that successful neuropeptide therapeutics will depend upon the application of translational and combinational research using various ingenious combinations of neuropeptides, their agonists and antagonists, neuropeptide receptor agonists and antagonists, improved methods of delivery and the development of peptides targeted to the genetic profile of individual patients.

Obsessive-compulsive disorder

Obsessive-compulsive disorder is a frequent, chronic, costly, and disabling disorder that presents in several medical settings, but is under-recognised and undertreated. For many years, obsessive-compulsive neurosis was seen as a disorder that provided an important window on the workings of the unconscious mind. Today, obsessive-compulsive disorder is viewed as a good example of a neuropsychiatric disorder, mediated by pathology in specific neuronal circuits, and responsive to specific pharmacotherapeutic and psychotherapeutic interventions. In the future we can expect more precise delineation of the origins of this disorder, with integration of data from neuroanatomical, neurochemical, neuroethological, neurogenetic, and neuroimmunological research.

Effect of nicotine on quinpirole-induced checking behavior in rats: implications for obsessive-compulsive disorder

BACKGROUND

Rats treated chronically in a large, open field with the dopamine D2/D3 receptor agonist quinpirole (QNP) develop compulsive checking behavior as defined by a set of behavioral criteria. This paradigm has been suggested as an animal model of obsessive-compulsive disorder (OCD). Because nicotine blocks various behaviors induced by ontogenetic QNP administration, we asked whether nicotine could attenuate QNP-induced compulsive checking.

METHODS

Adult male Long-Evans rats (n = 14/group) were treated twice weekly with saline (control), or with QNP (0.5 mg/kg) for 14-16 injections. On the last two injections, rats were pretreated in random order with an acute dose of nicotine (0.3 mg/kg base) or saline 10 min before administration of QNP or saline; and the effects on checking behavior was examined. The effects of chronic QNP treatment on nicotinic receptors in discrete brain regions were also determined.

RESULTS

Chronic QNP resulted in compulsive checking and increases in cerebellar alpha4beta2 and alpha7 nicotinic receptor densities. Nicotine pretreatment significantly reduced one of the three measures of compulsive checking behavior.

CONCLUSIONS

Nicotine attenuates some symptoms of compulsive checking in a rat model of OCD; however, the mechanisms of this effect and therapeutic efficacy of nicotinic agonists in OCD require further study.

Neurobiology and clinical pharmacology of obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a brain disorder with recognizable periods of onset, course, familial occurrence, epidemiology, phenomenology, and treatment response. Several manifestations of pathophysiology are beginning to be defined, although they may represent intermediate pathophysiology rather than primary etiology. Positron emission tomography studies have consistently identified hypermetabolism in the orbitofrontal cortex, caudate nucleus, and, sometimes, anterior cingulate cortex. Neuropsychologic testing frequently identifies abnormalities in visuospatial function. Abnormal levels of cerebrospinal fluid neurotransmitters and neuromodulators are identifiable in untreated patients with OCD and return toward normal levels after effective treatment. The most consistent pathophysiologic finding in OCD points toward an abnormality in serotonin neurotransmission. Therapeutic response to selective serotonin reuptake inhibitors and the absence of improvement with norepinephrine reuptake inhibitors and dopamine antagonists argue strongly for a role of serotonin in the pathophysiology and treatment of OCD. Despite this clear indication from treatment trials, probes and manipulations of the serotonin system and its specific receptors have not provided a useful understanding of specific abnormalities. Clomipramine or potent selective serotonin reuptake inhibitors are the pharmacotherapy of choice for OCD, with a more limited role reserved for monoamine oxidase inhibitors. If one selective serotonin reuptake inhibitor is ineffective, others may be beneficial, in addition to the different proserotonergic and nonserotonergic augmentation strategies that could be useful in treatment of resistant OCD patients. Nondrug therapies are also important in OCD: behavioral therapy is frequently helpful and neurosurgery is sometimes helpful when other treatments fail.

The cognitive-affective neuroscience of obsessive-compulsive disorder

There is substantial evidence that obsessive-compulsive disorder (OCD) is mediated by specific cortico-striatal- thalamic-cortical (CTSC) circuits. Here we discuss very recent publications that address the following questions: How does damage to CSTC circuitry come about?; What are the neurochemical systems involved in mediating this circuitry?; and What are the implications of such damage for understanding the pathogenesis and management of OCD? A cognitive-affective neuroscience perspective is helpful in advancing our understanding of the role of these circuits in OCD and the dysfunctional procedural strategies that appear to characterize this disorder. Furthermore, this model is becoming integrated with a range of data including brain imaging, genetic, immunologic, and neurochemical findings.