Neurobiology of the obsessive-compulsive spectrum disorders

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.

Do housing-induced changes in brain activity cause stereotypic behaviours in laboratory mice?

Abnormal repetitive stereotypic behaviours (SBs) (e.g. pacing, body-rocking) are common in animals with poor welfare (e.g. socially isolated/in barren housing). But how (or even whether) poor housing alters animals' brains to induce SBs remains uncertain. To date, there is little evidence for environmental effects on the brain that also correlate with individual SB performance. Using female mice from two strains (SB-prone DBA/2s; SB-resistant C57/BL/6s), displaying two forms of SB (route-tracing; bar-mouthing), we investigated how housing (conventional laboratory conditions vs. well-resourced 'enriched' cages) affects long-term neuronal activity as assessed via cytochrome oxidase histochemistry in 13 regions of interest (across cortex, striatum, basal ganglia and thalamus). Conventional housing reduced activity in the cortex and striatum. However, DBA mice had no cortical or striatal differences from C57 mice (just greater basal ganglia output activity, independent of housing). Neural correlates for individual levels of bar-mouthing (positive correlations in the substantia nigra and thalamus) were also independent of housing; while route-tracing levels had no clear neural correlates at all. Thus conventional laboratory housing can suppress cortico-striatal activity, but such changes are unrelated to SB (since not mirrored by congruent individual and strain differences). Furthermore, the neural correlates of SB at individual and strain levels seem to reflect underlying predispositions, not housing-mediated changes. To aid further work, hypothesis-generating model fit analyses highlighted this unexplained housing effect, and also suggested several regions of interest across cortex, striatum, thalamus and substantia nigra for future investigation (ideally with improved power to reduce risks of Type II error).

Aberrant cortico-striatal white matter connectivity and associated subregional microstructure of the striatum in obsessive-compulsive disorder

The striatum and its cortical circuits play central roles in the pathophysiology of obsessive-compulsive disorder (OCD). The striatum is subdivided by cortical connections and functions; however, the anatomical aberrations in different cortico-striatal connections and coexisting microstructural anomalies in striatal subregions of OCD patients are poorly understood. Thus, we aimed to elucidate the aberrations in cortico-striatal white matter (WM) connectivity and the associated subregional microstructure of the striatum in patients with OCD. From diffusion tensor/kurtosis imaging of 107 unmedicated OCD patients and 110 matched healthy controls (HCs), we calculated the cortico-striatal WM connectivity and segmented the striatum using probabilistic tractography. For the segmented striatal subregions, we measured average diffusion kurtosis values, which represent microstructural complexity. Connectivity and mean kurtosis values in each cortical target and associated striatal subregions were compared between groups. We identified significantly reduced orbitofrontal WM connectivity with its associated striatal subregion in patients with OCD compared to that in HCs. However, OCD patients exhibited significantly increased caudal-motor and parietal connectivity with the associated striatal subregions. The mean kurtosis values of the striatal subregions connected to the caudal-motor and parietal cortex were significantly decreased in OCD patients. Our results highlighted contrasting patterns of striatal WM connections with the orbitofrontal and caudal-motor/parietal cortices, thus supporting the cortico-striatal circuitry imbalance model of OCD. We suggest that aberrations in WM connections and the microstructure of their downstream regions in the caudal-motor-/parietal-striatal circuits may underlie OCD pathophysiology and further provide potential neuromodulation targets for the treatment of OCD.

Penile Dysmorphophobia With Recurrent Koro: A Case Report

A case of penile dysmorphophobia with recurrent Koro is presented. Different clinical and diagnostic issues relating to the interrelationship of obsessive-compulsive disorder-spectrum, body-dysmorphic disorders, and Koro are discussed.

Relating Compulsivity and Impulsivity With Severity of Behavioral Addictions: A Dynamic Interpretation of Large-Scale Cross-Sectional Findings

BACKGROUND AND AIM

Impulsivity and compulsivity are two key temperament traits involved in behavior regulation. The aim of this study was to test several existing theories in explaining the role of impulsivity and compulsivity in symptom severity in various behavioral addictions.

METHODS

Data were collected from a (representative) general population sample (N = 2,710, mean age:39.8 years (SD:13.6), 51% woman), and from people who are at increased risk of having a behavioral addiction (N = 9,528 in total, mean age: 28.11 (SD:8.3), 34.3% woman), including people with problematic gaming and internet use, pathological gambling, exercise dependence, compulsive buying and work addiction. Symptom severity, reward driven impulsivity and relief driven compulsivity were assessed.

RESULTS

For non-problematic groups, impulsivity is present to about the same extent as compulsivity, whereas for problematic groups, compulsivity dominates over impulsivity in all groups (except for gambling). The strength of the correlation between impulsivity and compulsivity is higher in more severe forms of the disorders (from r = 0.18 to r = 0.59 in the representative population).

DISCUSSION

Based on these data, it appears that relief-driven behavior (negative reinforcement) dominates over reward-driven behavior (positive reinforcement) in more severe cases of a behavioral addiction.

CONCLUSION

This is the first large-scale study to find empirical support for the neuroscientific theory on the dominance of compulsivity ("needing") over impulsivity ("wanting") in more severe cases of a behavioral addiction. Although longitudinal research is needed, a possible shift from impulsivity to compulsivity takes place, similar to substance use addictions, which maintains the circle of addiction.

Evaluation of hemodynamic changes using near-infrared spectroscopy in patients with tic-related obsessive-compulsive disorder

AIM

A tic-related specifier is included in the DSM-5 diagnostic criteria to identify a clinically specific obsessive-compulsive disorder (OCD) subtype. The current study sought to evaluate hemodynamic changes during executive function tasks among OCD patients with and without a lifetime history of tic disorder (TD) and healthy controls, and to investigate the relation between brain activation and clinical variables in each group using structured equation modeling.

METHODS

Twenty-nine OCD patients diagnosed according to the DSM-IV-TR and 15 healthy controls were recruited. Patients were divided into two groups according to the presence or absence of a lifetime history of TD (TD+, n = 11; TD-, n = 18). Prefrontal hemodynamic changes were measured using multi-channel near-infrared spectroscopy during the Verbal Fluency Task, Trail-Making Task, and Tower of London (ToL) Task.

RESULTS

There were significant brain activation differences in the frontopolar cortex between OCD patients with and without TD during Verbal Fluency Task and ToL performance. Brain activation in the dorsolateral prefrontal cortex (DLPFC) during the ToL Task in OCD patients with TD exerted a direct causal effect on the severity of compulsions. In addition, we detected a direct causal effect of the severity of obsessions in OCD patients without TD on brain activation in the DLPFC during the ToL Task.

CONCLUSION

Brain activation in the frontopolar cortex exhibits different hemodynamics depending on the task, and DLPFC function may play a different role in the neural basis of developing OCD symptoms between OCD patients with and without TD.

Multi-level assessment of obsessive-compulsive disorder (OCD) reveals relations between neural and neurochemical levels

BACKGROUND

While considerable progress has been made in exploring the psychological, the neural, and the neurochemical dimensions of OCD separately, their interplay is still an open question, especially their changes during psychotherapy.

METHODS

Seventeen patients were assessed at these three levels by psychological questionnaires, fMRI, and venipuncture before and after inpatient psychotherapy. Seventeen controls were scanned at comparable time intervals. First, pre/post treatment changes were investigated for all three levels separately: symptom severity, whole-brain and regional activity, and the concentrations of cortisol, serotonin, dopamine, brain-derived neurotrophic factor (BDNF), and immunological parameters (IL-6, IL-10, TNFα). Second, stepwise linear modeling was used to find relations between the variables of the levels.

RESULTS

The obsessive-compulsive, depressive, and overall symptom severity was significantly reduced after psychotherapy. At the neural level, the activity in the anterior cingulate cortex (ACC), in frontal regions, in the precuneus, and in the putamen had significantly decreased. No significant changes were found on the neurochemical level. When connecting the levels, a highly significant model was found that explains the decrease in neural activity of the putamen by increases of the concentrations of cortisol, IL-6, and dopamine.

CONCLUSION

Multivariate approaches offer insight on the influences that the different levels of the psychiatric disorder OCD have on each other. More research and adapted models are needed.

Central norepinephrine transmission is required for stress-induced repetitive behavior in two rodent models of obsessive-compulsive disorder

RATIONALE

Obsessive-compulsive disorder (OCD) is characterized by repetitive behaviors exacerbated by stress. Many OCD patients do not respond to available pharmacotherapies, but neurosurgical ablation of the anterior cingulate cortex (ACC) can provide symptomatic relief. Although the ACC receives noradrenergic innervation and expresses adrenergic receptors (ARs), the involvement of norepinephrine (NE) in OCD has not been investigated.

OBJECTIVE

To determine the effects of genetic or pharmacological disruption of NE neurotransmission on marble burying (MB) and nestlet shredding (NS), two animal models of OCD.

METHODS

We assessed NE-deficient (Dbh -/-) mice and NE-competent (Dbh +/-) controls in MB and NS tasks. We also measured the effects of anti-adrenergic drugs on NS and MB in control mice and the effects of pharmacological restoration of central NE in Dbh -/- mice. Finally, we compared c-fos induction in the locus coeruleus (LC) and ACC of Dbh -/- and control mice following both tasks.

RESULTS

Dbh -/- mice virtually lacked MB and NS behaviors seen in control mice but did not differ in the elevated zero maze (EZM) model of general anxiety-like behavior. Pharmacological restoration of central NE synthesis in Dbh -/- mice completely rescued NS behavior, while NS and MB were suppressed in control mice by anti-adrenergic drugs. Expression of c-fos in the ACC was attenuated in Dbh -/- mice after MB and NS.

CONCLUSION

These findings support a role for NE transmission to the ACC in the expression of stress-induced compulsive behaviors and suggest further evaluation of anti-adrenergic drugs for OCD is warranted.

Attention-Deficit Hyperactivity and Obsessive-Compulsive Symptoms in Adult Patients With Primary Restless Legs Syndrome: Different Phenotypes of the Same Disease?

OBJECTIVES

To investigate the prevalence of attention deficit hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD) symptoms in adult patients with primary restless legs syndrome (RLS) and to determine the iron biological correlates of these comorbidities.

PARTICIPANTS AND METHODS

We obtained demographic and clinical data from consecutive 105 outpatients with idiopathic RLS who answered validated questionnaires designed to assess the presence of ADHD and OCD symptoms. In these patients, iron blood parameters were routinely checked.

RESULTS

Of the total sample, 42.86% of the patients with RLS showed symptoms reminiscent either of ADHD or OCD. Prevalence of ADHD and OCD symptoms was 27.62% and 7.62%, respectively. Compared to other groups, a significantly higher percentage of RLS patients with ADHD symptoms was on antidepressant (p = 0.012); and women with ADHD symptoms, either alone or combined with OCD symptoms, showed significant reduced ferritin concentrations compared to men with either isolated ADHD symptoms or with combined ADHD and OCD symptoms (p = 0.028 and p = 0.025, respectively).

CONCLUSIONS

Our findings highlight the high prevalence of ADHD and OCD symptoms in adult patients with primary RLS and independently of serum iron stores decrease, except for women with ADHD symptoms either alone or in combination with OCD symptoms. This may suggest an overlapping neurobiological dopaminergic and serotoninergic dysfunction in ADHD, OCD, and RLS, and question the expression of different RLS phenotypes. The efficacy of dopamine agonists in these groups of patients should be questioned in future studies.

Abnormal repetitive behaviors in zebrafish and their relevance to human brain disorders

Abnormal repetitive behaviors (ARBs) are a prominent symptom of numerous human brain disorders and are commonly seen in rodent models as well. While rodent studies of ARBs continue to dominate the field, mounting evidence suggests that zebrafish (Danio rerio) also display ARB-like phenotypes and may therefore be a novel model organism for ARB research. In addition to clear practical research advantages as a model species, zebrafish share high genetic and physiological homology to humans and rodents, including multiple ARB-related genes and robust behaviors relevant to ARB. Here, we discuss a wide spectrum of stereotypic repetitive behaviors in zebrafish, data on their genetic and pharmacological modulation, and the overall translational relevance of fish ARBs to modeling human brain disorders. Overall, the zebrafish is rapidly emerging as a new promising model to study ARBs and their underlying mechanisms.

Critical Review of the Use of Second-Generation Antipsychotics in Obsessive-Compulsive and Related Disorders

Currently, all second-generation antipsychotics are approved for schizophrenia. Many are also approved for bipolar disorder, with some also approved as adjunctive treatment for depression and autism-related irritability. Second-generation antipsychotics are increasingly being prescribed for indications other than those approved by the Food and Drug Administration, such as in dementia, anxiety, and post-traumatic stress disorder to name a few. Obsessive-compulsive and related disorders are a group of disorders characterized by preoccupation and repetitive behaviors. According to the latest edition of the Diagnostic and Statistical Manual of Mental Disorders, obsessive-compulsive disorder, body dysmorphic disorder, trichotillomania, hoarding disorder, and excoriation, the latter two being newly designated disorders, fall under obsessive-compulsive and related disorders. Due to a lack of well designed clinical studies specifically addressing the use of second-generation antipsychotics in obsessive-compulsive and related disorders, it is unknown whether these agents are clinically beneficial. Current research describing the pathophysiology of these disorders shows the involvement of similar brain regions and neurotransmitters across the five obsessive-compulsive and related disorders. Despite differences in the receptor binding profiles, second-generation antipsychotics share many common pharmacodynamics properties. This review sought to examine all the published reports of second-generation antipsychotics being used in the management of symptoms of the aforementioned diseases and compile evidence for clinicians who encounter patients who are unresponsive to standard treatment.

Introducing Transthyretin as a Differentially Expressed Protein in Washing Subtype of Obsessive-Compulsive Disorder

Introduction:

Obsessive-Compulsive Disorder (OCD) as one of the important mental problems is valuable topic for proteomic research studies to better understand the underlying mechanisms of this disorder.

Methods:

In this paper, gel-based proteomic was used to investigate the proteome profile of 16 female patients with OCD, washing subtype before and after treatment with fluoxetine and comparing them with 20 healthy female controls.

Results:

One of the abnormally expressed protein spots in this study was introduced and examined for protein-protein interaction network analysis via Cytoscape and its plug-ins. Transthyretin (TTR) protein showed significant expression changes (fold change=1.7, P<0.05). While the expression level of TTR is significantly decreased in OCD patients before any treatments, the trend is partially normalized after treatment with fluoxetine in positive responders. Furthermore, TTR interaction profile shows that the proteins interacting with this protein may get affected as this protein expression trend changes in OCD patients.

Conclusion:

TTR can be considered for further studies to be validated as a potential biomarker for OCD.

Prevalence of Obsessive-Compulsive Spectrum Disorders in Obsessive-Compulsive Disorder

INTRODUCTION

There is growing awareness of the heterogeneity of obsessive-compulsive disorder (OCD) and of the multiple systems involved in its pathogenesis. Identification of obsessive-compulsive spectrum disorders (OCSDs) may have important implications in the management and prognosis of OCD, but there is a paucity of research in the domain of identification of OCSD in probands with OCD. There are few studies that have examined OCSD in the first-degree relatives (FDR) of OCD patients, some of these were not controlled, and these studies have no final agreements over outcomes, and therefore, this area needs to be further explored.

OBJECTIVES

The objective of this study was to assess the prevalence of OCSDs in OCD probands; and its relationship to sociodemographic and clinical variables, comparing each aspect by a control group of schizophrenia probands.

MATERIALS AND METHODS

Sixty patients each of OCD and schizophrenia, diagnosed by the Diagnostic and Statistical Manual of Mental Disorders IV Text Revision,[1] above 18 years of age and giving informed consent, were interviewed using the Structured Clinical Interview for OCSD, Yale-Brown Obsessive-Compulsive Rating Scale, Hamilton Rating Scale for Depression, and Hamilton Rating Scale for Anxiety.

RESULTS

In OCD group, 22 OCSDs were found in 11 subjects whereas in schizophrenia group, 2 OCSDs (self-injury) were found in two probands. When the two groups were compared in terms of individual OCSDs, there was no significant difference between them. However, when the comparison was made taking into account all OCSDs taken together, it was significantly higher (P = 0.016) in the OCD group compared to the schizophrenia group.

CONCLUSION

OCSDs were significantly more in OCD probands as compared to schizophrenia probands. This suggests a familial aggregation of these disorders.

Adolescents newly diagnosed with eating disorders have structural differences in brain regions linked with eating disorder symptoms

BACKGROUND

Adults with eating disorders (ED) show brain volume reductions in the frontal, insular, cingulate, and parietal cortices, as well as differences in subcortical regions associated with reward processing. However, little is known about the structural differences in adolescents with behavioural indications of early stage ED.

AIM

This is the first study to investigate structural brain changes in adolescents newly diagnosed with ED compared to healthy controls (HC), and to study whether ED cognitions correlate with structural changes in adolescents with ED of short duration.

METHODS

Fifteen adolescent females recently diagnosed with ED, and 28 age-matched HC individuals, were scanned with structural magnetic resonance imaging (MRI). Whole-brain and region-of-interest analyses were conducted using voxel-based morphometry (VBM). ED cognitions were measured with self-report questionnaires and working memory performance was measured with a neuropsychological computerized test.

RESULTS AND CONCLUSIONS

The left superior temporal gyrus had a smaller volume in adolescents with ED than in HC, which correlated with ED cognitions (concerns about eating, weight, and shape). Working memory reaction time correlated positively with insula volumes in ED participants, but not HC. In ED, measurements of restraint and obsession was negatively correlated with temporal gyrus volumes, and positively correlated with cerebellar and striatal volumes. Thus, adolescents with a recent diagnosis of ED had volumetric variations in brain areas linked to ED cognitions, obsessions, and working memory. The findings emphasize the importance of early identification of illness, before potential long-term effects on structure and behaviour occur.

Obsessive-Compulsive Symptoms in an Adolescent Appearing after Cerebellar Vermian Mass Resection

Obsessive compulsive symptoms have been reported in frontal lobe tumours and basal ganglia lesions. We report herewith a case of an adolescent who had a vermian cystic mass for which he underwent excision surgery. Three months postsurgery family members noticed that he started with repeated hand washing and abnormal walking pattern. Also, he developed bedwetting in sleep at night. He was given clinical diagnosis of Obsessive-Compulsive Disorder (OCD) and Nocturnal enuresis following a cerebellar mass removal which improved with fluoxetine and impiramine respectively.

Neuropsychological, electrophysiological and neurological impairments in patients with obsessive compulsive disorder, their healthy siblings and healthy controls: Identifying potential endophenotype(s)

The etiology of obsessive-compulsive disorder (OCD) has not been clarified. This study aimed to investigate the cognitive, neurological, electrophysiological functions which are reflected in executive functions, memory, visuospatial integration; neurological examination and auditory event related potentials (AERP) (N100, N200, P200 and P300) in patients with OCD, their siblings, and control subjects and to determine potential endophenotypic markers. Thirty-three patients with OCD, 18 siblings and 21 controls; matched for age, gender and years of education were included. Yale Brown Obsessive Compulsive Symptoms Checklist Scale, Hamilton Depression-Rating Scale, an exhaustive neuropscyhological test battery and Neurological Evaluation Scale were administered. Their AERP recordings were obtained. Executive functions and visuospatial integration were highly impaired in patients and slightly in their siblings compared to controls. P200 amplitude was sorted as siblings>patients>controls. P300 amplitude was sorted as patients<siblings<controls. Neurological Evaluation Scale scores were lower in patients compared to siblings and controls. The logistic regression analysis showed that, higher P300 amplitude, better performance on block design test and faster completion of Stroop test would predict being in the control group, whereas higher P200 amplitude would predict being in the case (patient and sibling) groups. We suggest that these seem to be the potential endophenotypes of OCD.

Is disorder X in category or spectrum Y? General considerations and application to the relationship between obsessive-compulsive disorder and anxiety disorders

Is obsessive-compulsive disorder (OCD) best categorized as an anxiety disorder? This question has been raised previously, but advances in the psychobiology of OCD and the anxiety disorders, and preparations for Diagnostic and Statistical Manual of Mental Disorders-V and International Classification of Diseases-11, make reconsideration timely. The debate in turn raises the more general issue of how best to address any question of the form "is disorder x in category or spectrum y?" Such questions are related to a number of key debates in philosophy of science and language and have also increasingly been addressed by the cognitive-affective neuroscience of categorization. Here, we review this background debate and use OCD as a relevant exemplar.

Compulsivity and Impulsivity in Pathological Gambling: Does a Dimensional-Transdiagnostic Approach Add Clinical Utility to DSM-5 Classification?

Although the phenomenology of Pathological Gambling (PG) is clearly characterized by impulsive features, some of the Diagnostic and Statistical Manual of Mental Disorder (DSM-5) criteria for PG are similar to those of Obsessive Compulsive Disorder (OCD). Therefore, the compulsive-impulsive spectrum model may be a better (or complementary) fit with PG phenomenology. The present exploratory research was designed to further investigate the compulsive and impulsive features characterizing PG, by comparing PG individuals, alcohol dependents (ADs), OCD patients, and healthy controls (HCs) on both self-report and cognitive measures of compulsivity and impulsivity. A better understanding of the shared psychological and cognitive mechanisms underlying differently categorized compulsive and impulsive disorders may significantly impact on both clinical assessment and treatment strategies for PG patients. With respect to self-report measures, PG individuals reported more compulsive and impulsive features than did HCs. As regards motor inhibition ability indices, PG individuals and HCs performed similarly on the Go/No-go task and better than AD individuals and OCD patients. Results from the Iowa Gambling Task highlighted that PG, AD, and OCD participants performed worse than did HCs. An in-depth analysis of each group's learning profile revealed similar patterns of impairment between PG and AD individuals in decision-making processes. Current findings support the utility of adopting a dimensional-transdiagnostic approach to complement the DSM-5 classification when working with PG individuals in clinical practice. Indeed, clinicians are encouraged to assess both compulsivity and impulsivity to provide individualized case conceptualizations and treatment plans focusing on the specific phenomenological features characterizing each PG patient.

The classification of Obsessive-Compulsive and Related Disorders in the ICD-11

BACKGROUND

To present the rationale for the new Obsessive-Compulsive and Related Disorders (OCRD) grouping in the Mental and Behavioural Disorders chapter of the Eleventh Revision of the World Health Organization's International Classification of Diseases and Related Health Problems (ICD-11), including the conceptualization and essential features of disorders in this grouping.

METHODS

Review of the recommendations of the ICD-11 Working Group on the Classification for OCRD. These sought to maximize clinical utility, global applicability, and scientific validity.

RESULTS

The rationale for the grouping is based on common clinical features of included disorders including repetitive unwanted thoughts and associated behaviours, and is supported by emerging evidence from imaging, neurochemical, and genetic studies. The proposed grouping includes obsessive-compulsive disorder, body dysmorphic disorder, hypochondriasis, olfactory reference disorder, and hoarding disorder. Body-focused repetitive behaviour disorders, including trichotillomania and excoriation disorder are also included. Tourette disorder, a neurological disorder in ICD-11, and personality disorder with anankastic features, a personality disorder in ICD-11, are recommended for cross-referencing.

LIMITATIONS

Alternative nosological conceptualizations have been described in the literature and have some merit and empirical basis. Further work is needed to determine whether the proposed ICD-11 OCRD grouping and diagnostic guidelines are mostly likely to achieve the goals of maximizing clinical utility and global applicability.

CONCLUSION

It is anticipated that creation of an OCRD grouping will contribute to accurate identification and appropriate treatment of affected patients as well as research efforts aimed at improving our understanding of the prevalence, assessment, and management of its constituent disorders.

Altered serotonin transporter binding potential in patients with obsessive-compulsive disorder under escitalopram treatment: [11C]DASB PET study

BACKGROUND

Obsessive-compulsive disorder (OCD) is a chronic, relapsing mental illness. Selective serotonin reuptake inhibitors block serotonin transporters (SERTs) and are the mainstay of treatment for OCD. SERT abnormalities are reported in drug-free patients with OCD, but it is not known what happens to SERT levels during treatment. This is important as alterations in SERT levels in patients under treatment could underlie poor response, or relapse during or after treatment. The aim of the present study was first to validate a novel approach to measuring SERT levels in people taking treatment and then to investigate SERT binding potential (BP) using [11C]DASB PET in patients with OCD currently treated with escitalopram in comparison with healthy controls.

METHOD

Twelve patients and age- and sex-matched healthy controls were enrolled. The patients and healthy controls underwent serial PET scans after administration of escitalopram and blood samples for drug concentrations were collected simultaneously with the scans. Drug-free BPs were obtained by using an inhibitory E max model we developed previously.

RESULTS

The inhibitory E max model was able to accurately predict drug-free SERT BP in people taking drug treatment. The drug-free BP in patients with OCD currently treated with escitalopram was significantly different from those in healthy volunteers [Cohen's d = 0.03 (caudate), 1.16 (putamen), 1.46 (thalamus), -5.67 (dorsal raphe nucleus)].

CONCLUSIONS

This result extends previous findings showing SERT abnormalities in drug-free patients with OCD by indicating that altered SERT availability is seen in OCD despite treatment. This could account for poor response and the high risk of relapse in OCD.

An interrogation of cognitive findings in pediatric obsessive-compulsive and related disorders

Current findings in the field of psychology have led to increased interest and a new conceptualization of disorders characterized by repetitive behaviors, namely the obsessive compulsive and related disorders (OCRDs). Scant research, however, has sought to collect and categorize the extant research on pediatric OCRDs. Particularly, no adequate review of the pediatric cognitive literature existed until now, despite the clear implication of abnormalities in neuroanatomical structures and cognitive functioning in adult samples. While evidence for cognitive dysfunction in pediatric samples is presented, this paper also suggests that differences in cognitive dysfunction may indeed exist between adults and youth with OCRDs. Specifically, those irregularities present in said youth at varying developmental stages may impact the origination and maintenance of OCRDs across time. Finally, this paper seeks to formulate potential future goals for the research field, particularly through transdiagnostic approaches to processes linked with symptom presentations. This is of particular importance as an improved understanding of the interaction of cognitive function and growth is key to further comprehension of the OCRDs.

Signal attenuation as a rat model of obsessive compulsive disorder

In the signal attenuation rat model of obsessive-compulsive disorder (OCD), lever-pressing for food is followed by the presentation of a compound stimulus which serves as a feedback cue. This feedback is later attenuated by repeated presentations of the stimulus without food (without the rat emitting the lever-press response). In the next stage, lever-pressing is assessed under extinction conditions (i.e., no food is delivered). At this stage rats display two types of lever-presses, those that are followed by an attempt to collect a reward, and those that are not. The latter are the measure of compulsive-like behavior in the model. A control procedure in which rats do not experience the attenuation of the feedback cue serves to distinguish between the effects of signal attenuation and of extinction. The signal attenuation model is a highly validated model of OCD and differentiates between compulsive-like behaviors and behaviors that are repetitive but not compulsive. In addition the measures collected during the procedure eliminate alternative explanations for differences between the groups being tested, and are quantitative, unbiased and unaffected by inter-experimenter variability. The major disadvantages of this model are the costly equipment, the fact that it requires some technical know-how and the fact that it is time-consuming compared to other models of OCD (11 days). The model may be used for detecting the anti- or pro-compulsive effects of pharmacological and non-pharmacological manipulations and for studying the neural substrate of compulsive behavior.

Adenylyl cyclase-5 in the dorsal striatum function as a molecular switch for the generation of behavioral preferences for cue-directed food choices

Background

Behavioral choices in habits and innate behaviors occur automatically in the absence of conscious selection. These behaviors are not easily modified by learning. Similar types of behaviors also occur in various mental illnesses including drug addiction, obsessive-compulsive disorder, schizophrenia, and autism. However, underlying mechanisms are not clearly understood. In the present study, we investigated the molecular mechanisms regulating unconditioned preferred behaviors in food-choices.

Results

Mice lacking adenylyl cyclase-5 (AC5 KO mice), which is preferentially expressed in the dorsal striatum, consumed food pellets nearly one after another in cages. AC5 KO mice showed aversive behaviors to bitter tasting quinine, but they compulsively chose quinine-containing AC5 KO-pellets over fresh pellets. The unusual food-choice behaviors in AC5 KO mice were due to the gain of behavioral preferences for food pellets containing an olfactory cue, which wild-type mice normally ignored. Such food-choice behaviors in AC5 KO mice disappeared when whiskers were trimmed. Conversely, whisker trimming in wildtype mice induced behavioral preferences for AC5 KO food pellets, indicating that preferred food-choices were not learned through prior experience. Both AC5 KO mice and wildtype mice with trimmed whiskers had increased glutamatergic input from the barrel cortex into the dorsal striatum, resulting in an increase in the mGluR1-dependent signaling cascade. The siRNA-mediated inhibition of mGluR1 in the dorsal striatum in AC5 KO mice and wildtype mice with trimmed whiskers abolished preferred choices for AC5 KO food pellets, whereas siRNA-mediated inhibition of mGluR3 glutamate receptors in the dorsal striatum in wildtype mice induced behavioral preferences for AC5 KO food pellets, thus mimicking AC5 KO phenotypes.

Conclusions

Our results show that the gain and loss of behavioral preferences for a specific cue-directed option were regulated by specific cellular factors in the dorsal striatum, such that the preferred food choices were switched on when either the mGluR3-AC5 pathway was inactive or the mGluR1 pathway was active, whereas the preferred food-choices were switched off when mGluR1 or its downstream pathway was suppressed. These results identify the AC5 and mGluR system in the dorsal striatum as molecular on/off switches to direct decisions on behavioral preferences for cue-oriented options.

White matter structural alterations in pediatric obsessive-compulsive disorder: relation to symptom dimensions

The aims of this study were to identify gray matter (GM) and white matter (WM) volume abnormalities in pediatric obsessive-compulsive patients, to examine their relationship between these abnormalities and the severity of disorder, and to explore whether they could be explained by the different symptom dimensions.

METHODS

62 child and adolescent OCD patients (11-18years old) and 46 healthy subjects of the same gender and similar age and estimated intellectual quotient were assessed by means of psychopathological scales and magnetic resonance imaging (MRI). Axial three-dimensional T1-weighted images were obtained in a 3T scanner and analyzed using optimized voxel-based morphometry (VBM).

RESULTS

Compared with healthy controls, OCD patients showed lower white matter (WM) volume in the left dorsolateral and cingulate regions involving the superior and middle frontal gyri and anterior cingulate gyrus (t=4.35, p=0.049 FWE (family wise error)-corrected). There was no significant correlation between WM and the severity of obsessive-compulsive symptomatology. There were no regions with lower gray matter (GM) volume in OCD patients than in controls. Compared with healthy controls, only the "harm/checking" OCD dimension showed a cluster with a near significant decrease in WM volume in the right superior temporal gyrus extending into the insula (t=5.61, p=.056 FWE-corrected).

CONCLUSION

The evidence suggests that abnormalities in the dorsolateral prefrontal cortex, anterior cingulate cortex, temporal and limbic regions play a central role in the pathophysiology of OCD. Moreover, regional brain volumes in OCD may vary depending on specific OCD symptom dimensions, indicating the clinical heterogeneity of the condition.

Diagnosis, evaluation, and management of trichotillomania

Trichotillomania, or chronic hairpulling, is a common condition that affects primarily women. The disorder can cause significant psychosocial impairment and is associated with elevated rates of psychiatric comorbidity. In this article, the phenomenology, etiology, assessment, and treatment of the disorder are discussed.

Repetitive transcranial magnetic stimulation over the orbitofrontal cortex for obsessive-compulsive disorder: a double-blind, crossover study

This pilot study was designed to assess the efficacy of low-frequency repetitive transcranial magnetic stimulation (rTMS) over the right orbitofrontal cortex (OFC) by means of a double-cone coil in patients suffering from obsessive-compulsive disorder. We hypothesized that low-frequency stimulation of the OFC would lead to a reduction in clinical symptoms, as measured on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). A randomized, double-blind, crossover design was implemented with two 1-week treatment periods (active stimulation versus sham stimulation) separated by a 1-month washout period. Concomitantly, a subgroup of patients underwent a positron emission tomography (PET) scan after each stimulation sequence. Statistical analyses compared the Y-BOCS scores at the end of each period. At day 7, we observed a significant decrease from baseline in the Y-BOCS scores, after both active (P<0.01) and sham stimulation (P=0.02). This decrease tended to be larger after active stimulation than after sham stimulation: -6 (-29, 0) points versus -2 (-20, 4) points (P=0.07). Active versus sham PET scan contrasts showed that stimulation was related to a bilateral decrease in the metabolism of the OFC. The OFC should definitely be regarded as a key neuroanatomical target for rTMS, as it is easier to reach than either the striatum or the subthalamic nucleus, structures favored in neurosurgical approaches.

Dissociative Experiences are Associated with Obsessive-Compulsive Symptoms in a Non-clinical Sample: A Latent Profile Analysis

INTRODUCTION

There has been a burgeoning literature considering the significant associations between obsessive-compulsive symptoms and dissociative experiences. In this study, the relationsips between dissociative symtomotology and dimensions of obsessive-compulsive symptoms were examined in homogeneous sub-groups obtained with latent class algorithm in an undergraduate Turkish sample.

METHOD

Latent profile analysis, a recently developed classification method based on latent class analysis, was applied to the Dissociative Experiences Scale (DES) item-response data from 2976 undergraduates. Differences in severity of obsessive-compulsive symptoms, anxiety and depression across groups were evaluated by running multinomial logistic regression analyses. Associations between latent class probabilities and psychological variables in terms of obsessive-compulsive sub-types, anxiety, and depression were assessed by computing Pearson's product-moment correlation coefficients.

RESULTS

The findings of the latent profile analysis supported further evidence for discontinuity model of dissociative experiences. The analysis empirically justified the distinction among three sub-groups based on the DES items. A marked proportion of the sample (42%) was assigned to the high dissociative class. In the further analyses, all sub-types of obsessive-compulsive symptoms significantly differed across latent classes. Regarding the relationships between obsessive-compulsive symptoms and dissociative symptomatology, low dissociation appeared to be a buffering factor dealing with obsessive-compulsive symptoms; whereas high dissociation appeared to be significantly associated with high levels of obsessive-compulsive symptoms.

CONCLUSION

It is concluded that the concept of dissociation can be best understood in a typological approach that dissociative symptomatology not only exacerbates obsessive-compulsive symptoms but also serves as an adaptive coping mechanism.

Gender differences in obsessive-compulsive disorder: findings from a large Indian sample

AIM

Gender has been considered as one of the possible factors mediating phenotypic expression of obsessive-compulsive disorder (OCD). We examined gender differences in a large sample of subjects with OCD from India with respect to socio-demographic parameters, symptom characteristics, and comorbidity patterns.

METHODS

Consecutive patients (n=545) who consulted a specialty OCD clinic over 5 years at a large psychiatric hospital in India were evaluated.

RESULTS

Men (n=332) compared to women (n=213) with OCD had an earlier onset (p<0.001), higher frequency of sexual (p<0.001) and religious obsessions (p=0.001) pathological doubts (p<0.001) and checking (p<0.001) and repeating compulsions (p<0.001), and a greater tendency to have comorbid social phobia (p=0.006). Women compared to men were more likely to be married, had a higher frequency of fear of contamination (p=0.017), comorbid depression (p=0.014) and greater suicidal risk (p=0.003).

CONCLUSIONS

Our study provides further evidence for gender related differences in clinical features of obsessive-compulsive disorder. Our findings are only partly comparable with results from studies across the world possibly due to various biological and cultural factors mediating the phenotypic expression of OCD across the genders. There is a need to examine the biological basis for these gender differences.

Potential implications of research on genetic or heritable contributions to pedophilia for the objectives of criminal law

In recent years, there has been increasing scientific research on possible genetic or heritable influences to the etiology of pedophilia, driven by national and public concerns about better understanding the disorder in order to reduce children's vulnerabilities to pedophilic and child sex offenders. This research has corresponded to growing academic dialogue on how advances in genetic research, especially concerning the causes and development of particular mental disorders or behaviors, may affect traditional practices of criminal law and how the justice system views, manages, and adjudicates different types of criminal behavior and offenders. This paper strives to supplement this dialogue by exploring several of the many possible effects and implications of research surrounding genetic or heritable contributions to pedophilia for the five widely accepted objectives that enforce and regulate the punishment of criminal law. These include retribution, incapacitation, deterrence, rehabilitation, and restoration. Although still currently in early stages, genetic and heritability research on the etiology of pedophilia may have the potential moving forward to influence the current and established punitive methods and strategies of how the justice system perceives, adjudicates, regulates, and punishes pedophilic and sex offenders, as well as how to best prevent sexual offending against children by pedophilic offenders in the future.

Effects of mood stabilizers on marble-burying behavior in mice: involvement of GABAergic system

RATIONALE

Obsessive-compulsive disorder (OCD) is characterized by recurrent unwanted thoughts (obsessions), usually accompanied by repetitive behaviors (compulsions) intended to alleviate anxiety. Marble-burying behavior is a pharmacological model for study of OCD.

OBJECTIVES

In the present study, we examined the effects of mood stabilizers on marble-burying behavior in mice, as well as the role of GABA receptors in this behavior.

METHODS

The effects of treatment with valproate, carbamazepine, lithium carbonate, lamotrigine, muscimol and baclofen on marble-burying behavior in mice were evaluated.

RESULTS

Valproate (10, 30 and 100 mg/kg, i.p.) and carbamazepine (30 and 100 mg/kg, p.o.) significantly reduced marble-burying behavior without affecting total locomotor activity in ICR mice. Lamotrigine (30 mg/kg, i.p.) also significantly reduced marble-burying behavior in ddY mice. On the other hand, lithium carbonate (10, 30 and 100 mg/kg, i.p.) reduced total locomotor activity without affecting marble-burying behavior in ddY mice. The selective GABA(A) receptor agonist muscimol (1 mg/kg) significantly reduced marble-burying behavior without affecting total locomotor activity, whereas the selective GABA(B) receptor agonist baclofen (3 mg/kg) reduced total locomotor activity without affecting marble-burying behavior. Moreover, the selective GABA(A) receptor antagonist bicuculline (3 mg/kg) significantly counteracted the decrease in marble-burying induced by the administration of muscimol (1 mg/kg) and valproate (100 mg/kg).

CONCLUSIONS

These results suggest that GABAergic mechanism is involved in marble-burying behavior, and that valproate, carbamazepine and lamotrigine reduce marble-burying behavior. Moreover, valproate reduces marble-burying behavior via a GABA(A) receptor-dependent mechanism.

The genetic factors influencing the development of trichotillomania

Trichotillomania (TTM), an obsessive-compulsive spectrum disorder (OCSD), is a psychiatric condition characterized by repetitive hair pulling. Evidence from family and twin studies suggest a heritable link of TTM. Functional polymorphisms in genes involved in neuronal pathways might influence the susceptibility to TTM. This review is an attempt to compile the genetic factors reported to modify the development of TTM.

Proton magnetic resonance spectroscopy in pediatric obsessive-compulsive disorder: longitudinal study before and after treatment

Abnormalities in neurochemical compounds in obsessive-compulsive disorder (OCD) may help increase our knowledge of neurobiological abnormalities in the fronto-subcortical circuits. The aims of this exploratory study were to identify with in vivo magnetic resonance spectroscopy ((1)H-MRS) the possible alterations in neurometabolites in a group of drug naïve children and adolescents with OCD in comparison with a control group and to determine whether there was any effect of treatment on the metabolite levels. Eleven OCD children and adolescents (age range 9-17 years; 6 male, 5 female) and twelve healthy subjects with similar age, sex and estimated intellectual quotient were studied. Proton magnetic resonance spectroscopy at 1.5 T was used. We placed 3 voxels, one bilaterally located involving anterior cingulate-medial frontal regions, and one in each striatal region involving the caudate and putaminal regions. Concentrations of creatine (Cr), myo-inositol (mI), total Cho (glycerophosphocholine+phosphocholine), total NAA (N-acetyl aspartate+N-acetyl aspartylglutamate), and total Glx (glutamate+glutamine) were calculated. We found significantly lower concentrations of total Cho in left striatum in OCD patients compared with healthy subjects. The difference in Cho concentrations in left striatum between the two groups did not change over time and persisted at follow-up assessment. Like the control subjects, OCD patients undergoing pharmacological treatment and clinical recovery showed no significant changes in neurometabolic activity between the first and second evaluations.

Obsessive-compulsive symptoms in schizophrenia: prevalence, clinical features and treatment. A literature review

OBJECTIVES

To investigate the prevalence of obsessive-compulsive symptoms in schizophrenia, the clinical features of the sub-group of patients with schizophrenia and obsessive-compulsive symptoms and treatment options for these patients.

METHOD

A literature review of studies investigating the prevalence, clinical features and treatment of patients with schizophrenia and obsessive-compulsive symptoms.

RESULTS

The prevalence of obsessive-compulsive symptoms in schizophrenic patients, while generally found to be higher than in the general population, varies widely between different studies. Differences in symptom severity between schizophrenic patients with obsessive-compulsive symptoms and those without have been found, however findings so far have been inconsistent. A number of case reports have implicated atypical antipsychotic medication in the emergence of obsessive-compulsive symptoms. There is evidence to support a combined treatment with an antipsychotic agent and an anti-obsessional agent.

CONCLUSION

Studies investigating the prevalence of obsessive-compulsive symptoms in schizophrenia and their effect on the clinical symptoms have yielded inconsistent results and further studies using larger samples of patients and looking at different subgroups of schizophrenic patients are required. Treatment options need further research to investigate whether the results of relatively small studies can be replicated.

Thought problems from adolescence to adulthood: measurement invariance and longitudinal heritability

This study investigates the longitudinal heritability in Thought Problems (TP) as measured with ten items from the Adult Self Report (ASR). There were ~9,000 twins, ~2,000 siblings and ~3,000 additional family members who participated in the study and who are registered at the Netherlands Twin Register. First an exploratory factor analysis was conducted to examine the underlying factor structure of the TP-scale. Then the TP-scale was tested for measurement invariance (MI) across age and sex. Next, genetic and environmental influences were modeled on the longitudinal development of TP across three age groups (12-18, 19-27 and 28-59 year olds) based on the twin and sibling relationships in the data. An exploratory factor analysis yielded a one-factor solution, and MI analyses indicated that the same TP-construct is assessed across age and sex. Two additive genetic components influenced TP across age: the first influencing TP throughout all age groups, while the second arises during young adulthood and stays significant throughout adulthood. The additive genetic components explained 37% of the variation across all age groups. The remaining variance (63%) was explained by unique environmental influences. The longitudinal phenotypic correlation between these age groups was entirely explained by the additive genetic components. We conclude that the TP-scale measures a single underlying construct across sex and different ages. These symptoms are significantly influenced by additive genetic factors from adolescence to late adulthood.

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.

Can obsessions drive you mad? Longitudinal evidence that obsessive-compulsive symptoms worsen the outcome of early psychotic experiences

OBJECTIVE

Although there is substantial comorbidity between psychotic disorder and obsessive-compulsive disorder (OCD), little is known about how these clinical phenotypes, and their subclinical extended phenotypes, covary and impact on each other over time. This study examined cross-sectional and longitudinal associations between both (extended) phenotypes in the general population.

METHOD

Data were obtained from the three waves of the NEMESIS-study. A representative population sample of 7076 participants were assessed using the composite international diagnostic interview (CIDI) at baseline (T(0)), 1 year later at T(1) and again 2 years later at T(2).

RESULTS

At T(0), a lifetime diagnosis of psychotic disorder was present in 1.5% of the entire sample, in 11.5% of the people with any OC symptom and in 23.0% of individuals diagnosed with OCD. OC symptoms at T(0) predicted incident psychotic symptoms at T(2). Similarly, T(0) psychotic symptoms predicted T(2) OC symptoms. The likelihood of persistence of psychotic symptoms or transition to psychotic disorder was higher if early psychosis was accompanied by co-occurring OC symptoms, but not the other way around.

CONCLUSION

OCD and the psychosis phenotype cluster together and predict each other at (sub)clinical level. The co-occurrence of subclinical OC and psychosis may facilitate the formation of a more 'toxic' form of persistent psychosis.

High but not low frequency stimulation of both the globus pallidus and the entopeduncular nucleus reduces 'compulsive' lever-pressing in rats

The anti-compulsive effects of high and low frequency stimulation (LFS, HFS) of the entopeduncular nucleus and globus pallidus (the rat's equivalent, respectively, of the primate's internal and external segments of the globus pallidus) were assessed in the signal attenuation rat model of obsessive-compulsive disorder (OCD). HFS, but not LFS, of the two nuclei exerted an anti-compulsive effect, suggesting that HFS of either segment of the globus pallidus may provide an additional therapeutic strategy for OCD.

Variations in the shape of the frontobasal brain region in obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) emerges during childhood through young adulthood coinciding with the late phases of postnatal brain development when fine remodeling of brain anatomy takes place. Previous research has suggested the existence of subtle anatomical alterations in OCD involving focal volume variations in different brain regions including the frontal lobes and basal ganglia. We investigated whether anatomical changes might also involve variations in the shape of the frontobasal region. A total of 101 OCD patients and 101 control subjects were examined using magnetic resonance imaging. A cross-sectional image highly representative of frontal-basal ganglia anatomy was selected in each individual and 25 reliable anatomical landmarks were identified to assess shape changes. A pixel-wise morphing approach was also used to dynamically illustrate the findings. We found significant group differences for overall landmark position and for most individual landmarks delimiting the defined frontobasal region. OCD patients showed a deformation pattern involving shortening of the anterior-posterior dimension of the frontal lobes and basal ganglia, and enlargement of cerebrospinal fluid spaces around the frontal opercula. In addition, we observed significant correlation of brain tissue shape variation with frontal sinus size. Identification of a global change in the shape of the frontobasal region may further contribute to characterizing the nature of brain alterations in OCD. The coincidence of brain shape variations with morphological changes in the frontal sinus indicates a potential association of OCD to late development disturbances, as the frontal sinus macroscopically emerges during the transition between childhood and adulthood.

Should an obsessive-compulsive spectrum grouping of disorders be included in DSM-V?

The obsessive-compulsive (OC) spectrum has been discussed in the literature for two decades. Proponents of this concept propose that certain disorders characterized by repetitive thoughts and/or behaviors are related to obsessive-compulsive disorder (OCD), and suggest that such disorders be grouped together in the same category (i.e. grouping, or "chapter") in DSM. This article addresses this topic and presents options and preliminary recommendations to be considered for DSM-V. The article builds upon and extends prior reviews of this topic that were prepared for and discussed at a DSM-V Research Planning Conference on Obsessive-Compulsive Spectrum Disorders held in 2006. Our preliminary recommendation is that an OC-spectrum grouping of disorders be included in DSM-V. Furthermore, we preliminarily recommend that consideration be given to including this group of disorders within a larger supraordinate category of "Anxiety and Obsessive-Compulsive Spectrum Disorders." These preliminary recommendations must be evaluated in light of recommendations for, and constraints upon, the overall structure of DSM-V.