Symptom dimensions in OCD: item-level factor analysis and heritability estimates

Defining repetitive behaviours in frontotemporal dementia

Repetitive behaviours are common manifestations of frontotemporal dementia (FTD). Patients with FTD exhibit various types of repetitive behaviours with unique behavioural and cognitive substrates, including compulsivity, lack of impulse control, stereotypy and hoarding. Other sources of repetitive behaviours, such as restrictive interests and insistence on sameness, may also be seen in FTD. Although repetitive behaviours are highly prevalent and potentially discriminatory in this population, their expression varies widely between patients, and the field lacks consensus about the classification of these behaviours. Terms used to describe repetitive behaviours in FTD are highly heterogeneous and may lack precise definitions. This lack of harmonization of the definitions for distinct forms of repetitive behaviour limits the ability to differentiate between pathological behaviours and impedes understanding of their underlying mechanisms. This review examines established definitions of well-characterized repetitive behaviours in other neuropsychiatric disorders and proposes operational definitions applicable to patients with FTD. Building on extant models of repetitive behaviours in non-human and lesion work and models of social behavioural changes in FTD, we describe the potential neurocognitive bases for the emergence of different types of repetitive behaviours in FTD and their potential perpetuation by a predisposition towards habit formation. Finally, examples of distinct therapeutic approaches for different forms of repetitive behaviours are highlighted, along with future directions to accurately classify, measure and treat these symptoms when they impair quality of life.

Early-onset obsessive-compulsive disorder: Sociodemographic and clinical characterization of a large outpatient cohort

INTRODUCTION

Obsessive-compulsive disorder (OCD) is a prevalent and disabling condition characterized by a wide variety of phenotypic expressions. Several studies have reinforced the hypothesis of OCD heterogeneity by proposing subtypes based on predominant symptomatology, course, and comorbidities. Early-onset OCD (EO) could be considered a neurodevelopmental subtype of OCD, with evidence of distinct neurocircuits supporting disease progression. To deepen the heterogeneous nature of the disorder, we analyzed sociodemographic and clinical differences between the EO and late-onset (LO) subtypes in a large outpatient cohort.

METHODS

Two hundred and eighty-four patients diagnosed with OCD were consecutively recruited from the OCD Tertiary Clinic at Luigi Sacco University Hospital in Milan. Sociodemographic and clinical variables were analyzed for the entire sample and compared between the two subgroups (EO, age <18 years [n = 117,41.2 %]; LO: late-onset, age ≥18 years [n = 167, 58.8 %]).

RESULTS

The EO group showed a higher frequency of male gender (65 % vs 42.5 %, p < .001), and a higher prevalence of Tic and Tourette disorders (9.4 % vs 0 %, p < .001) compared to the LO group. Additionally, in the EO subgroup, a longer duration of untreated illness was observed (9.01 ± 9.88 vs 4.81 ± 7.12; p < .001), along with a lower presence of insight (13.8 % vs. 7.5 %, p < .05).

CONCLUSIONS

The early-onset OCD subtype highlights a more severe clinical profile compared to the LO group. Exploring distinct manifestations and developmental trajectories of OCD can contribute to a better definition of homogeneous subtypes, useful for defining targeted therapeutic strategies for treatment.

Revisiting deficits in threat and safety appraisal in obsessive-compulsive disorder

Current behavioural treatment of obsessive-compulsive disorder (OCD) is informed by fear conditioning and involves iteratively re-evaluating previously threatening stimuli as safe. However, there is limited research investigating the neurobiological response to conditioning and reversal of threatening stimuli in individuals with OCD. A clinical sample of individuals with OCD (N = 45) and matched healthy controls (N = 45) underwent functional magnetic resonance imaging. While in the scanner, participants completed a well-validated fear reversal task and a resting-state scan. We found no evidence for group differences in task-evoked brain activation or functional connectivity in OCD. Multivariate analyses encompassing all participants in the clinical and control groups suggested that subjective appraisal of threatening and safe stimuli were associated with a larger difference in brain activity than the contribution of OCD symptoms. In particular, we observed a brain-behaviour continuum whereby heightened affective appraisal was related to increased bilateral insula activation during the task (r = 0.39, pFWE  = .001). These findings suggest that changes in conditioned threat-related processes may not be a core neurobiological feature of OCD and encourage further research on the role of subjective experience in fear conditioning.

Co-occurring depression and obsessive-compulsive disorder: A dimensional network approach

BACKGROUND

Depressive and obsessive-compulsive (OCD) symptoms often co-occur and a number of possible explanations for this co-occurrence have been explored, including shared biological and psychosocial risk factors. Network approaches have offered a novel hypothesis for the link between depression and OCD: functional inter-relationships across the symptoms of these conditions. The few network studies in this area have relied largely on item, rather than process-level constructs, and have not examined relationships dimensionally.

METHODS

Network analytic methods were applied to data from 463 treatment-seeking adults with OCD. Patients completed self-report measures of OCD and depression. Factor analysis was used to derive processes (i.e., nodes) to include in the network. Networks were computed, and centrality, bridge, and stability statistics examined.

RESULTS

Networks showed positive relations among specific OCD and depressive symptoms. Obsessions (particularly repugnant thoughts), negative affectivity, and cognitive-somatic changes (e.g., difficulty concentrating) were central to the network. Unique relations were observed between symmetry OCD symptoms and cognitive-somatic changes. No direct link between harm-related OCD symptoms and depression was observed.

CONCLUSIONS

Our results bring together prior findings, suggesting that both negative affective and psychomotor changes are important to consider in examining the relationship between OCD and depression. Increased consideration of heterogeneity in the content of OCD symptoms is key to improving clinical conceptualizations, particularly when considering the co-occurrence of OCD with other disorders.

Co-occurring Obsessive-Compulsive Disorder and Hoarding Disorder: A Review of the Current Literature

Current research suggests obsessive-compulsive disorder (OCD) co-occurs in around 20% of people with hoarding disorder (HD). The article discusses the theoretical conceptualization of co-occurring HD and OCD (HD+OCD), highlighting similarities between the disorders that may contribute to comorbidity, such as potentially overlapping etiological factors, comorbidity profiles, and phenomenological aspects; and differences that are important to consider in differential diagnosis and conceptualization, such as belief patterns, ego-syntonicty/dystonicity, and trajectory. The combination of HD+OCD versus either disorder alone appears to be associated with a profile characterized by higher nonhoarding OCD symptoms, anxiety symptoms, depression, and tic disorders, and which may be more treatment-refractory. The authors discuss some commonly used measures to assess hoarding that may be relevant in the context of OCD, as differential diagnosis of hoarding behaviors is often difficult, and hoarding may be difficult to detect in patients with OCD, especially in children. The article ends with a discussion on considerations for the treatment of HD+OCD with cognitive-behavioral therapy, as hoarding symptoms are less likely to respond to gold-standard exposure and response prevention, and there are no established treatment protocols that are designed to treat co-occurring HD and OCD.

Towards a definitive symptom structure of obsessive-compulsive disorder: a factor and network analysis of 87 distinct symptoms in 1366 individuals

BACKGROUND

The symptoms of obsessive-compulsive disorder (OCD) are highly heterogeneous and it is unclear what is the optimal way to conceptualize this heterogeneity. This study aimed to establish a comprehensive symptom structure model of OCD across the lifespan using factor and network analytic techniques.

METHODS

A large multinational cohort of well-characterized children, adolescents, and adults diagnosed with OCD (N = 1366) participated in the study. All completed the Dimensional Yale-Brown Obsessive-Compulsive Scale, which contains an expanded checklist of 87 distinct OCD symptoms. Exploratory and confirmatory factor analysis were used to outline empirically supported symptom dimensions, and interconnections among the resulting dimensions were established using network analysis. Associations between dimensions and sociodemographic and clinical variables were explored using structural equation modeling (SEM).

RESULTS

Thirteen first-order symptom dimensions emerged that could be parsimoniously reduced to eight broad dimensions, which were valid across the lifespan: Disturbing Thoughts, Incompleteness, Contamination, Hoarding, Transformation, Body Focus, Superstition, and Loss/Separation. A general OCD factor could be included in the final factor model without a significant decline in model fit according to most fit indices. Network analysis showed that Incompleteness and Disturbing Thoughts were most central (i.e. had most unique interconnections with other dimensions). SEM showed that the eight broad dimensions were differentially related to sociodemographic and clinical variables.

CONCLUSIONS

Future research will need to establish if this expanded hierarchical and multidimensional model can help improve our understanding of the etiology, neurobiology and treatment of OCD.

Exam-related unwanted intrusive thoughts and related neutralizing behaviors: Analogues to obsessions and compulsions

Exam-related unwanted intrusive thoughts (UITs) and related neutralizing behaviors are common experiences among students. The present study investigated in what ways these UITs and behaviors are analogues to clinical obsessions and compulsions. Twenty-nine students completed three ecological momentary assessment surveys per day over 7 consecutive days, assessing the severity of exam-related UITs and related neutralizing behaviors, obsessive-compulsive (OC) symptoms, anxiety, distress, urge to neutralize, depressed mood, and stress in the week immediately before an exam period. Multilevel analysis demonstrated that the severity of exam-related UITs and related neutralizing behaviors was positively associated with OC symptoms, anxiety, distress, urge to neutralize, and stress but was not related to depressed mood. During the study period, the exam-related UITs occurred on average 7 times, and the related neutralizing behaviors on average 6 times. Overall, they were experienced with mild severity, low distress, and low urge to neutralize. Findings indicate that some aspects of exam-related UITs and related neutralizing behaviors (e.g., association with distress and urge to neutralize) might be analogous to OC symptoms but not all (e.g., no relation to depressed mood). We discuss how research on obsessive-compulsive disorder could benefit from considering exam-related UITs and related behaviors.

Obsessive-Compulsive Disorders

PURPOSE OF REVIEW

This article describes the phenomenology and clinical presentation of obsessive-compulsive disorder (OCD), a common but underdiagnosed psychiatric disorder. Guidance for effectively identifying obsessive-compulsive symptoms is provided, and treatment options, including psychotherapy, pharmacologic management, and neuromodulation approaches for treatment-resistant OCD, are discussed.

RECENT FINDINGS

OCD affects 2% to 3% of adults worldwide and is associated with substantial individual disability and societal costs. Lack of recognition of common OCD symptom types, in addition to shame and fear of stigma on the part of patients, has created an average delay in diagnosis by almost 10 years and a delay in effective treatment (ie, a treatment gap) of nearly 2 years. Cognitive-behavioral therapy (CBT), specifically a form of CBT that includes a type of behavioral intervention called exposure and response prevention, remains the most effective form of treatment for OCD. If CBT is not effective or not available, pharmacologic treatment with selective serotonin reuptake inhibitors (SSRIs) or clomipramine, a nonselective serotonin reuptake inhibitor, can also be of benefit. Neuromodulation approaches such as deep brain stimulation and transcranial magnetic stimulation are rapidly emerging as effective treatments for OCD, particularly for patients who have not experienced an adequate response to psychotherapy or pharmacologic management.

SUMMARY

OCD affects more than one in every 50 adults in the United States but is recognized and adequately treated in fewer than half of those affected. Early intervention and appropriate treatment can substantially reduce OCD symptom severity, improve quality of life, and minimize the functional disability associated with this chronic and often debilitating illness.

Genetics of obsessive-compulsive disorder

BACKGROUND

Obsessive-compulsive disorder (OCD) is a psychiatric disorder with multiple symptom dimensions (e.g. contamination, symmetry). OCD clusters in families and decades of twin studies clearly demonstrate an important role for genetics in the etiology of the disorder.

METHODS

In this review, we summarize the genetic epidemiology and molecular genetic studies of OCD and obsessive-compulsive symptoms.

RESULTS

OCD is a heritable, polygenic disorder with contributions from both common and rare variants, including de novo deleterious variations. Multiple studies have provided reliable support for a large additive genetic contribution to liability to OCD, with discrete OCD symptom dimensions having both shared and unique genetic risks. Genome-wide association studies have not produced significant results yet, likely because of small sample sizes, but larger meta-analyses are forthcoming. Both twin and genome-wide studies show that OCD shares genetic risk with its comorbid conditions (e.g. Tourette syndrome and anorexia nervosa).

CONCLUSIONS

Despite significant efforts to uncover the genetic basis of OCD, the mechanistic understanding of how genetic and environmental risk factors interact and converge at the molecular level to result in OCD's heterogeneous phenotype is still mostly unknown. Future investigations should increase ancestral genetic diversity, explore age and/or sex differences in genetic risk for OCD and expand the study of pharmacogenetics, gene expression, gene × environment interactions and epigenetic mechanisms for OCD.

Core Motivations of Childhood Obsessive-Compulsive Disorder: The Role of Harm Avoidance and Incompleteness

In an effort to improve patient conceptualization and targeted treatment, researchers have sought to accurately classify OCD subtypes. To date, the most common form of OCD classification has used the content of symptom topography as opposed to functional links between symptoms to categorize OCD. The aim of the current study was to explore the associations between these two forms of OCD classification. Participant topographical symptoms were self-reported using the Obsessive-Compulsive Inventory-Child Version (OCI-CV). Clinicians assessed whether participant symptoms were motivated by harm avoidance and/or incompleteness. Structural equation modeling was employed to explore the associations between harm avoidance and incompleteness and symptom dimensions in youth with OCD. Results showed that harm avoidance was significantly associated with doubting/checking, obsessing, and neutralizing symptoms, whereas incompleteness was associated with doubting/checking, ordering, and neutralizing symptoms. Findings are consistent with child and adult literature and highlight the importance of assessing the underlying function of OC behaviors.

Polygenic risk for obsessive-compulsive disorder (OCD) predicts brain response during working memory task in OCD, unaffected relatives, and healthy controls

Alterations in frontal and parietal neural activations during working memory task performance have been suggested as a candidate endophenotype of obsessive-compulsive disorder (OCD) in studies involving first-degree relatives. However, the direct link between genetic risk for OCD and neuro-functional alterations during working memory performance has not been investigated to date. Thus, the aim of the current functional magnetic resonance imaging (fMRI) study was to test the direct association between polygenic risk for OCD and neural activity during the performance of a numeric n-back task with four working memory load conditions in 128 participants, including patients with OCD, unaffected first-degree relatives of OCD patients, and healthy controls. Behavioral results show a significant performance deficit at high working memory load in both patients with OCD and first-degree relatives (p < 0.05). A whole-brain analysis of the fMRI data indicated decreased neural activity in bilateral inferior parietal lobule and dorsolateral prefrontal cortex in both patients and relatives. Most importantly, OCD polygenic risk scores predicted neural activity in orbitofrontal cortex. Results indicate that genetic risk for OCD can partly explain alterations in brain response during working memory performance, supporting the notion of a neuro-functional endophenotype for OCD.

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

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

A dimensional perspective on the genetics of obsessive-compulsive disorder

This review covers recent findings in the genomics of obsessive-compulsive disorder (OCD), obsessive-compulsive symptoms, and related traits from a dimensional perspective. We focus on discoveries stemming from technical and methodological advances of the past five years and present a synthesis of human genomics research on OCD. On balance, reviewed studies demonstrate that OCD is a dimensional trait with a highly polygenic architecture and genetic correlations to multiple, often comorbid psychiatric phenotypes. We discuss the phenotypic and genetic findings of these studies in the context of the dimensional framework, relying on a continuous phenotype definition, and contrast these observations with discoveries based on a categorical diagnostic framework, relying on a dichotomous case/control definition. Finally, we highlight gaps in knowledge and new directions for OCD genetics research.

An association of Myelin Oligodendrocyte Glycoprotein (MOG) gene variants with white matter volume in pediatric obsessive-compulsive disorder

An increasing number of neuroimaging studies have implicated alterations of white matter in obsessive-compulsive disorder (OCD). The myelin oligodendrocyte glycoprotein (MOG) gene plays a major role in myelination, and has previously demonstrated significant association with this disorder, thus variations in this gene may contribute to observed white matter alterations. The purpose of this study is to examine the relationship between white matter volume in OCD and genetic variations in the MOG gene. Two polymorphisms in the MOG gene, MOG(C1334T) and MOG(C10991T), were investigated for association with total white matter volume as measured using volumetric magnetic resonance imaging in 37 pediatric OCD patients. We compared white matter volumes between allele and genotype groups for each polymorphism using ANCOVA. A significant relationship was detected between genotype C/C of MOG(C10991T) and decreased total white matter volume (P = 0.016). Our results showed an association between a MOG genetic variant and white matter volume. This finding is intriguing in light of the posited role of white matter alteration in the etiology of at least some cases of childhood-onset OCD. Further investigation with larger samples and sub-regional white matter volume phenotypes is warranted.

A population-based family clustering study of tic-related obsessive-compulsive disorder

In the latest edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), obsessive-compulsive disorder (OCD) included a new "tic-related" specifier. However, strong evidence supporting tic-related OCD as a distinct subtype of OCD is lacking. This study investigated whether, at the population level, tic-related OCD has a stronger familial load than non-tic-related OCD. From a cohort of individuals born in Sweden between 1967 and 2007 (n = 4,085,367; 1257 with tic-related OCD and 20,975 with non-tic-related OCD), we identified all twins, full siblings, maternal and paternal half siblings, and cousins. Sex- and birth year-adjusted hazard ratios (aHR) were calculated to estimate the risk of OCD in relatives of individuals with OCD with and without comorbid tics, compared with relatives of unaffected individuals. We found that OCD is a familial disorder, regardless of comorbid tic disorder status. However, the risk of OCD in relatives of individuals with tic-related OCD was considerably greater than the risk of OCD in relatives of individuals with non-tic-related OCD (e.g., risk for full siblings: aHR = 10.63 [95% CI, 7.92-14.27] and aHR = 4.52 [95% CI, 4.06-5.02], respectively; p value for the difference < 0.0001). These differences remained when the groups were matched by age at first OCD diagnosis and after various sensitivity analyses. The observed familial patterns of OCD in relation to tics were not seen in relation to other neuropsychiatric comorbidities. Tic-related OCD is a particularly familial subtype of OCD. The results have important implications for ongoing gene-searching efforts.

Are There Familial Patterns of Symptom Dimensions in Obsessive-Compulsive Disorder?

Background: Obsessive-compulsive disorder (OCD) is a heterogeneous illness, and emerging evidence suggests that different symptom dimensions may have distinct underlying neurobiological mechanisms. We aimed to look for familial patterns in the occurrence of these symptom dimensions in a sample of families with at least two individuals affected with OCD. Methods: Data from 153 families (total number of individuals diagnosed with DSM-5 OCD = 330) recruited as part of the Accelerator Program for Discovery in Brain Disorders using Stem Cells (ADBS) was used for the current analysis. Multidimensional Item Response Theory (IRT) was used to extract dimensional scores from the Yale-Brown Obsessive-Compulsive Scale (YBOCS) checklist data. Using linear mixed-effects regression models, intra-class correlation coefficients (ICC), for each symptom dimension, and within each relationship type were estimated. Results: IRT yielded a four-factor solution with Factor 1 (Sexual/Religious/Aggressive), Factor 2 (Doubts/Checking), Factor 3 (Symmetry/Arranging), and Factor 4 (Contamination/Washing). All except for Factor 1 were found to have significant ICCs, highest for Factor 3 (0.41) followed by Factor 4 (0.29) and then Factor 2 (0.27). Sex-concordant dyads were found to have higher ICC values than discordant ones, for all the symptom dimensions. No major differences in the ICC values between parent-offspring and sib-pairs were seen. Conclusions: Our findings indicate that there is a high concordance of OCD symptom dimensions within multiplex families. Symptom dimensions of OCD might thus have significant heritability. In view of this, future genetic and neurobiological studies in OCD should include symptom dimensions as a key parameter in their analyses.

Gray matter volume abnormalities and clinical correlates in OCD with exclusive washing dimension

OBJECTIVE

Obsessive compulsive disorder (OCD) is increasingly being recognized as a heterogeneous disorder with various symptom dimensions. In order to understand the neurobiology of obsessive-compulsive disorder (OCD), it is important to understand the brain basis of homogeneous symptom groups. In this study we investigated the gray matter (GM) changes and correlates of an exclusively homogenous sample of OCD patients (washers with no other obsessive compulsive symptoms).

METHOD

We compared the structural MRI scans (3T) using voxel-based morphometry (VBM) of washers (N = 35) with matched healthy controls (HC) (N = 39).

RESULTS

We found volume deficits corresponding to right inferior frontal gyrus, parahippocampal gyrus and right anterior lobe of cerebellum among washers compared to HC. Among the washers, GM volume of right inferior frontal gyrus, right uncus of the limbic lobe, left cuneus and left superior temporal lobe had significant negative correlation with the illness severity score.

CONCLUSION

Examining homogenous sub-groups of OCD patients may help us further our understanding of neurobiology of OCD.

Trait specific modulatory effects of caffeine exposure on compulsive-like behaviors in a spontaneous mouse model of obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a psychiatric disorder characterized by recurring intrusive thoughts and repetitive compulsive behaviors, ultimately interfering with their quality of life. The complex heterogeneity of symptom dimensions across OCD patient subgroups impedes diagnosis and treatment. The core and comorbid symptomologies of OCD are thought to be modulated by common environmental exposures such as consumption of the psychostimulant caffeine. The effect of caffeine on the expression of obsessions and compulsions are unexplored. The current study utilized mouse strains (HA) with a spontaneous, predictable, and stable compulsive-like phenotype that have face, predictive, and construct validity for OCD. We demonstrate that an acute high dose (25 mg/kg) of caffeine decreased compulsive-like nest-building behavior in the HA strains in the first hour after injection. However, nest-building scores increased in hours 3, 4, and 5 after administration finally decreasing over a 24 h period. In contrast, a high dose of chronic caffeine (25 mg/kg/d) increased nest-building behavior. Interestingly for compulsive-like digging behavior, acute exposure to a high dose of caffeine decreased the number of marbles buried, while chronic exposure had little effect. An acute high dose of caffeine decreased anxiety-like and motor activity in open field behaviors whereas chronic caffeine administration did not have any overall effect on open field activity. The results, therefore, suggest a complex role of caffeine on compulsive-like, anxiety-like, and locomotor behaviors that is dependent on the duration of exposure.

Looking into the genetic bases of OCD dimensions: a pilot genome-wide association study

The multidimensional nature of obsessive-compulsive disorder (OCD) has been consistently reported. Clinical and biological characteristics have been associated with OCD dimensions in different ways. Studies suggest the existence of specific genetic bases for the different OCD dimensions. In this study, we analyze the genomic markers, genes, gene ontology and biological pathways associated with the presence of aggressive/checking, symmetry/order, contamination/cleaning, hoarding, and sexual/religious symptoms, as assessed via the Dimensional Yale-Brown Obsessive Compulsive Scale (DY-BOCS) in 399 probands. Logistic regression analyses were performed at the single-nucleotide polymorphism (SNP) level. Gene-based and enrichment analyses were carried out for common (SNPs) and rare variants. No SNP was associated with any dimension at a genome-wide level (p < 5 × 10^-8). Gene-based analyses showed one gene to be associated with hoarding (SETD3, p = 1.89 × 10^-08); a gene highly expressed in the brain and which plays a role in apoptotic processes and transcriptomic changes, and another gene associated with aggressive symptoms (CPE; p = 4.42 × 10^-6), which is involved in neurotrophic functions and the synthesis of peptide hormones and neurotransmitters. Different pathways or biological processes were represented by genes associated with aggressive (zinc ion response and lipid metabolism), order (lipid metabolism), sexual/religious (G protein-mediated processes) and hoarding (metabolic processes and anion transport) symptoms after FDR correction; while no pathway was associated with contamination. Specific genomic bases were found for each dimension assessed, especially in the enrichment analyses. Further research with larger samples and different techniques, such as next-generation sequencing, are needed to better understand the differential genetics of OCD dimensions.

Functional connectivity within the salience network differentiates autogenous- from reactive-type obsessive-compulsive disorder

BACKGROUND

Obsessive-compulsive disorder (OCD) is a clinically heterogeneous condition. To better understand and treat patients, symptomatology of OCD has been categorized into more homogenous symptom dimensions. The autogenous-reactive classification model has proven helpful in the elucidation of the neurobiological substrates for clinical heterogeneity in OCD. The purpose of the current study was to systematically compare regional and network functional alterations between OCD subtypes based on the autogenous-reactive model.

METHODS

Autogenous-type OCD patients (OCD-AO, n = 40), reactive-type patients (OCD-RO, n = 42), and healthy controls (HC, n = 70) underwent functional magnetic resonance imaging (fMRI) scans. The amplitude of low-frequency fluctuation (ALFF) and regional homogeneity (ReHo) were compared among subjects. Areas of abnormal local spontaneous brain activity that differentiated OCD-AO and OCD-RO patients were identified and entered as seeds in functional connectivity (FC) analysis.

RESULTS

Compared to OCD-RO patients and HC participants, OCD-AO patients showed increased ALFF in the left anterior insula (AI), increased ReHo in the right AI, and hyperconnectivity between bilateral AI and anterior cingulate cortex (ACC). Both OCD-AO and OCD-RO patients shared regional function deficits in several areas within the prefrontal cortex, and stronger FC between bilateral AI and major nodes of the default mode network (DMN) compared to healthy controls.

CONCLUSION

The current results suggest that aberrant functional interaction between the salience network (SN) and the DMN may represent a common substrate in the pathophysiology of OCD, while impaired functional coupling within the SN is distinct to autogenous-type OCD patients. These findings provide further neurobiological evidence to support the autogenous-reactive classification model and contribute to the understanding of the neurobiological basis for clinical heterogeneity in OCD.

Obsessive-Compulsive Disorder in Singapore: Prevalence, Comorbidity, Quality of Life and Social Support

Introduction: Using data from Singapore Mental Health Study 2016 (SMHS 2016), we examined the prevalence of lifetime and 12-month obsessive-compulsive disorder (OCD),its sociodemographics correlates and association with comorbid psychiatric disorders and physical conditions, perceived social support and quality of life. Materials and Methods: The World Mental Health Composite International Diagnostic Interview (version 3.0) was administered by trained interviewers to 6126 residents aged ≥18 years old to assess OCD prevalence and that of other select psychiatric disorders. Details on sociodemographics, perceived social support and health-related quality of life were obtained. Results: Lifetimeand 12-month prevalence of OCD was 3.6% and 2.9%, respectively. Adjusted regression analysis showed that those with OCD had significantly higher odds of major depressive disorder (odds ratio [OR], 5.4), bipolar disorder (OR, 8.9), generalised anxiety disorder (OR, 7.3) and alcohol abuse (OR, 2.7). OCD was significantly associated with suicidal ideation and suicidality (OR, 5.1). OCD subjects also had higher odds of chronic pain (OR, 2.4) and diabetes (OR, 3.1). Finally, OCD subjects had lower mean mental composite summary scores than controls (respondents without any of the psychiatric disorders and physical conditions included in SMHS 2016) and those with other lifetime psychiatric disorders and physical conditions. Conclusion: OCD prevalence in Singapore is high. Most people with OCD do not seek treatment despite experiencing significant comorbidity and loss of quality of life. Key words: Composite International Diagnostic Interview, Epidemiology, Multi-ethnic, Psychiatric disorder, Survey

Serotonin system genes and obsessive-compulsive trait dimensions in a population-based, pediatric sample: a genetic association study

BACKGROUND

Serotonin system genes are commonly studied in obsessive-compulsive disorder (OCD), but genetic studies to date have produced inconsistent results, possibly because phenotypic heterogeneity has not been adequately accounted for. In this paper, we studied candidate serotonergic genes and homogenous phenotypic subgroups as presented through obsessive-compulsive (OC) trait dimensions in a general population of children and adolescents. We hypothesized that different serotonergic gene variants are associated with different OC trait dimensions and, furthermore, that they vary by sex.

METHODS

Obsessive-compulsive trait dimensions (Cleaning/Contamination, Counting/Checking, Symmetry/Ordering, Superstition, Rumination, and Hoarding) were examined in a total of 5,213 pediatric participants in the community using the Toronto Obsessive-Compulsive Scale (TOCS). We genotyped candidate serotonin genes (directly genotyping the 5-HTTLPR polymorphism in SLC6A4 for 2018 individuals and using single nucleotide polymorphism (SNP) array data for genes SLC6A4, HTR2A, and HTR1B for 4711 individuals). We assessed the association between variants across these genes and each of the OC trait dimensions, within males and females separately. We analyzed OC traits as both (a) dichotomized based on a threshold value and (b) quantitative scores.

RESULTS

The [L_G + S] variant in 5-HTTLPR was significantly associated with hoarding in males (p-value of 0.003 and 0.004 for categorical and continuous analyses, respectively). There were no significant findings for 5-HTTLPR in females. Using SNP array data, there were significant findings for rumination in males for HTR2A SNPs (p-value of 1.04e-6 to 5.20e-6).

CONCLUSIONS

This represents the first genetic association study of OC trait dimensions in a community-based pediatric sample. Our strongest results indicate that hoarding and rumination may be distinct in their association with serotonin gene variants and that serotonin gene variation may be specific to sex. Future genetic association studies in OCD should properly account for heterogeneity, using homogenous subgroups stratified by symptom dimension, sex, and age group.

Obsessive-Compulsive Disorder

PURPOSE OF REVIEW

This article reviews current knowledge regarding diagnosis, pathophysiology, and treatment trends in obsessive-compulsive disorder (OCD), a severe, underrecognized, and chronic condition frequently encountered in neurologic practice.

RECENT FINDINGS

With a lifetime prevalence estimated at 2.5%, OCD is a common condition that can also present comorbidly with neurologic disease. The core symptoms of OCD are obsessions and compulsions. Obsessions are intrusive repetitive thoughts, urges, images, or impulses that trigger anxiety and that the individual is not able to suppress. Compulsions are repetitive behaviors or mental acts occurring in response to an obsession with the intention of reducing the distress caused by obsessions. Neuroimaging, neuropsychological, and pharmacologic studies suggest that the expression of OCD symptoms is associated with dysfunction in a cortico-striato-thalamo-cortical circuit. Evidence-based treatments for OCD comprise pharmacotherapy and cognitive-behavioral therapy. Selective serotonin reuptake inhibitors (SSRIs) are the first-line drugs recommended for OCD, but significant differences exist in their use for OCD compared to their use for other mood and anxiety conditions, including the need for higher dosage, longer trials necessitated by a longer lag for therapeutic response, and typically lower response rates. Cognitive-behavioral therapy, based on the principles of exposure and response prevention, shows results superior to pharmacologic treatments with lower relapse rates on long-term follow-up and thus should be considered in the treatment plan of every patient with OCD.

SUMMARY

OCD and obsessive-compulsive symptoms are frequently encountered in the neurologic clinic setting and require a high index of suspicion to effectively screen for them and an illness-specific therapeutic approach.

A comparison of cluster and factor analytic techniques for identifying symptom-based dimensions of obsessive-compulsive disorder

A growing body of literature suggests that obsessive-compulsive disorder (OCD) is a heterogeneous condition. The studies investigating symptom dimensions have been limited by numerous methodological differences and sample characteristics. The purpose of this study was to compare the two most commonly applied statistical techniques used in addressing this question in the same large cohort of individuals with OCD. Both cluster analysis and factor analysis were used to examine OCD symptom data as measured by the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) Symptom Checklist for 355 individuals with a primary diagnosis of OCD. The factor analysis revealed a three-factor model best described as symmetry obsessions/ordering compulsions, contamination obsessions/cleaning compulsions and aggressive obsessions/checking compulsions. In contrast, the cluster analysis yielded a stable four-cluster solution best described as symmetry obsessions/ordering compulsions, contamination obsessions/cleaning compulsions, aggressive-somatic-religious obsessions/checking compulsions and a mixed symptom profile. Although there was overlap in the models resulting from these two statistical approaches, cluster analysis better captured the dimensional nature of OCD by demonstrating the prevalence of symptom categories in each subgroup. Though both analyses are capable of providing similar outputs, the validity of these results is limited given the input of a priori symptom categories from the Y-BOCS.

A comparison of symptom dimensions for obsessive compulsive disorder and obsessive compulsive-related disorders

Objective

In this study, it is aimed to determine obsessive compulsive-related disorders (OCRDs) comorbidity among the patients with obsessive compulsive disorder (OCD) and compare patients with OCD with or without comorbid OCRDs in terms of the severity of their OCD symptoms, symptom dimensions, and comorbidity with other axis I disorders.

Methods

The study included 90 patients diagnosed as having OCD according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR). The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) diagnostic criteria for OCRDs were used to determine the presence of OCRDs. In order to determine the symptom dimensions and severity of these individuals’ OCD symptoms, we administered the Dimensional Obsessive Compulsive Scale (DOCS) and The Yale-Brown Obsessive Compulsive Scale (Y-BOCS).

Results

In our study, 20% of the patients with OCD simultaneously met the criteria for at least one OCRD, we also found that a significantly greater proportion of this group were men. None of the mentioned disorders was associated with any symptom dimensions we evaluated using DOCS. In addition, no differences were found in the severity of OCD symptoms and comorbid axis I disorders between the group with comorbid OCRDs and the group without comorbid OCRDs.

Discussion

There was no significant relationship between the symptom dimensions of OCD and OCRDs. It is found that OCRD comorbidity does not increase the severity of OCD symptoms and the prevalence of an axis I diagnosis.

Co-occurrence of Sensory Overresponsivity with Obsessive-Compulsive Symptoms in Childhood and Early Adolescence

OBJECTIVE

Sensory overresponsivity (SOR) is characterized by challenges in integrating and responding to everyday sensory experiences. Obsessive-compulsive disorder (OCD) is characterized by intrusive thoughts, ritualistic behaviors, and sensory phenomena. There is some evidence that individuals with co-occurring symptoms of SOR and OCD experience more severe anxiety than those with symptoms of OCD alone, but most studies employed small numbers of participants (typically with an OCD diagnosis) assessed at a single time point. Our 2-fold objective was to replicate previous research showing an association between OCD symptoms and SOR symptoms concurrently and to extend these analyses longitudinally in a large, birth-register-based sample.

METHOD

Twins (N = 1613) and their primary caregivers participated in a multimodal, multimethod, longitudinal study. Primary caregivers completed the SOR inventory for their offspring at the age of 8 years, and twins completed the adult sensory profile at the age of 13 years. Parents completed the OCD module of the Diagnostic Interview Schedule for Children-IV when twins were 8 years; twins completed the same module at 13 years. Linear regression models tested for the concurrent and longitudinal associations between SOR and OCD controlling for socioeconomic status.

RESULTS

Concurrently, participants' likelihood of exhibiting OCD symptoms increased with each symptom of tactile or auditory overresponsivity at 8 years and 13 years (odds ratio = 1.1-2.7). However, SOR measured at age 8 years was unrelated to adolescent OCD symptoms at 13 years and vice versa.

CONCLUSION

SOR symptoms, although significantly related to concurrent OCD symptoms, do not appear to precede OCD symptoms, suggesting that SOR symptoms may reflect another type of OCD sensory phenomenon rather than a comorbid condition.

Corticostriatal-limbic correlates of sub-clinical obsessive-compulsive traits

Obsessive-compulsive (OC) traits such as intrusive worrisome ideas or excessive concerns for threats are frequent in general population (5%-13%). However, the structural neural correlates of the sub-clinical OC traits remain largely unknown. Based on the data of obsessive-compulsive disorder (OCD), we hypothesized that the subcortical and cortical structures, constituting the cortico-striatal-thalamo-cortical circuit (CSTC) and the limbic system, could be associated with OC traits. Here we conducted voxel-based morphometry (VBM) in order to investigate fine grained volume changes of these structures in 49 non-clinical subjects. Analysis of structural covariances of these structures was also conducted. We identified volume changes associated with OC traits in the left putamen and the left amygdala. The results of structural covariance analysis revealed increased covariances in relation to the heightened OC traits between the left putamen to bilateral medial prefrontal cortex and to the left cerebellum, and between the left globus pallidus to the bilateral anterior cingulate cortices. The present finding of volume changes of the corticostriatal-limbic structures may reflect neuroplasticity associated with OC traits. Since the abnormality of these structures were also observed in the clinical OCD, the subclinical subjects with OC traits shared "neuronal obsessive traits" that might precondition OCD at the network level.

Examining the factor structure of the self-report Yale-Brown Obsessive Compulsive Scale Symptom Checklist

Obsessive-compulsive symptom dimensions are important in studies about the pathogenesis and treatment of obsessive-compulsive disorder. More than 30 factor analytic studies using the Yale-Brown Obsessive Compulsive Scale Symptom Checklist (Y-BOCS-SC) interview version have been published. However, a drawback of the Y-BOCS-SC interview is that it is time-consuming for the clinician. Baer's self-report version of the Y-BOCS-SC could be a less time-consuming alternative. The purpose of this study was to examine the factor structure of Baer's self-report Y-BOCS-SC. In a sample of 286 patients, we performed two factor analyses, one using categories and one using items of the Y-BOCS-SC. Using category-level data, we identified four factors; when using items we identified six factors. Symptom dimensions for contamination/cleaning, symmetry/repeating/counting/ordering and hoarding were found in both analyses. The impulsive aggression, pathological doubt, sexual, religious somatic and checking categories formed one factor in the analysis using category-level data and divided into three factors using item-level data. These factors correspond with studies using the interview version and support our hypothesis that the self-report version of the Y-BOCS-SC could be an alternative for the interview version.

Heritability of obsessive-compulsive trait dimensions in youth from the general population

Obsessive-compulsive disorder (OCD) is a heritable childhood-onset psychiatric disorder that may represent the extreme of obsessive-compulsive (OC) traits that are widespread in the general population. We report the heritability of the Toronto Obsessive-Compulsive Scale (TOCS), a new measure designed to assess the complete range of OC traits in youth. We also examined the dimensional nature of the TOCS and the degree to which genetic effects are unique or shared between dimensions. OC traits were measured using the TOCS in 16,718 youth (6-18 years) at a science museum. We conducted a factor analysis to identify OC trait dimensions. We used univariate and multivariate twin models to estimate the heritability of OC trait dimensions in a subset of twins (220 pairs). Six OC dimensions were identified: Cleaning/Contamination, Symmetry/Ordering, Rumination, Superstition, Counting/Checking, and Hoarding. The TOCS total score (74%) and each OC dimension was heritable (30-77%). Hoarding was not highly correlated with other OC dimensions, but did share genetic effects. Shared genetics accounted for most of the shared variance among dimensions, whereas unique environment accounted for the majority of dimension-specific variance. One exception was Hoarding, which had considerable unique genetic factors. A latent trait did not account for the shared variance between dimensions. In conclusion, OC traits and individual OC dimensions were heritable, although the degree of shared and dimension-specific etiological factors varied by dimension. The TOCS may be informative for genetic research of OC traits in youth. Genetic research of OC traits should consider both OC dimension and total trait scores.

Assessing Sexual Orientation Symptoms in Obsessive-Compulsive Disorder: Development and Validation of the Sexual Orientation Obsessions and Reactions Test (SORT)

Obsessive-compulsive disorder (OCD) includes many symptom presentations, which creates unique diagnostic challenges. Fears surrounding one's sexual orientation are common within OCD (also called SO-OCD), but SO-OCD is consistently misdiagnosed by physicians and psychologists. To address this issue, we describe the development of a self-report measure for assessing SO-OCD to help distinguish OCD from distress caused by a sexual orientation identity crisis. The current paper details two studies that established the psychometric properties and clinical utility of this measure. In Study 1, the factor structure, validity, and reliability were examined for the measure's 12 items in a sample of 1,673 university students. The results revealed a two-factor solution for the measure (Factor 1: Transformation Fears; Factor 2: Somatic Checking) and preliminary evidence of validity and reliability. In Study 2, the measure was tested with LGBTQ and heterosexual community samples and clinical samples of individuals with SO-OCD and other types of OCD. The two-factor solution and evidence of validity and reliability were supported in these samples. Cut-off points were established to distinguish between community members and SO-OCD sufferers, as well as between those experiencing SO-OCD and other types of OCD. Limitations and future directions are discussed.

Obsessive-compulsive symptoms in children with first degree relatives diagnosed with obsessive-compulsive disorder

Objective:

A first-degree relative affected by obsessive-compulsive disorder (OCD) and obsessive-compulsive symptoms (OCS) in childhood is an important risk factor for developing the disorder in adulthood. The relationship between a family history of OCD and the presence of OCS and its correlates in childhood is not well established.

Methods:

A total of 66 children whose parents or siblings have been diagnosed with OCD were assessed for the presence of OCS and clinical correlates.

Results:

Three children (4.5%) were reported to have received an OCD diagnosis and another 26 (39.4%) were identified as having OCS. Children with OCS had higher rates of coercive behavior and came from families with lower socioeconomic status. Contamination/cleaning dimension symptoms in the proband were associated with OCS in the assessed children.

Conclusion:

OCS are frequent among family members of individuals with OCD and are associated with socioeconomic status, coercive behaviors and proband contamination/cleaning symptoms. Future longitudinal studies should test the risk of developing OCD in association with these characteristics.

Activation of cortical and striatal regions during the expression of a naturalistic compulsive-like behavior in the rabbit

Nest building behavior in the pregnant rabbit (Oryctolagus cuniculus) can serve as a model for compulsions in obsessive compulsive disorder (OCD). Previous work showed that the "straw carrying" phase of nest building (during which the rabbit repeatedly collects straw in its mouth, carries it into the nest box and deposits it there, and then returns to collect more) is associated with increased c-FOS expression (a marker of neuronal activity) in the orbitofrontal, anterior cingulate, and piriform cortices. In the present study, we quantified c-FOS expression in the caudate and putamen, as well as in the primary motor, somatosensory, and prefrontal cortices of: (1) pregnant rabbits given straw (PREG + STRAW); pregnant rabbits not given straw (PREG); (3) estrous rabbits given straw (ESTROUS + STRAW); and (4) estrous rabbits not given straw (ESTROUS). We found that straw carrying was associated with increased c-FOS expression in the dorsal putamen, ventral caudate, primary motor cortex, and somatosensory cortex. Additionally, a correlational analysis of PREG + STRAW animals revealed that these regions, along with the premotor and prelimbic cortices, were significantly intercorrelated with respect to c-FOS expression, suggesting their "coactivation" during repetitive straw carrying. By contrast, behavioral interactions of non-pregnant (ESTROUS) rabbits with straw (e.g., sniffing, nibbling it) were associated with a distinct pattern of c-FOS expression that included the medial and ventral putamen. c-FOS expression in PREG + STRAW rabbits is similar to patterns of regional brain activity in OCD patients exposed to obsession-provoking stimuli, as well as to those observed in healthy human mothers responding to infant-associated stimuli.

Getting it just right: A reevaluation of OCD symptom dimensions integrating traditional and Bayesian approaches

Previous research using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) suggests that the heterogeneous symptoms of obsessive-compulsive disorder (OCD) may reflect four underlying dimensions. However, past results vary substantially, which may be due to (a) the reliance on aggregated scores, (b) the common use of exploratory factor analyses, and (c) the exclusion of several symptoms. The present study tested the homogeneity of the original Y-BOCS categories using confirmatory factor analysis and modified categories where necessary. To test multidimensional models, data were further analyzed with Bayesian structural equation models, which better capture item heterogeneity in contrast to ordinary factor analysis. All analyses were run with two samples of patients with OCD allowing for cross-validation. Only a minority of the original Y-BOCS categories proved to be homogeneous. Modification yielded 10 homogeneous first-order factors, which can be reduced to four second-order factors: Incompleteness, Taboo Thoughts, Responsibility, and Contamination. This two-level factor model outperformed competing factor structures. The results corroborate the notion of four broader symptom dimensions in OCD, although the specific factor structure deviates from previous research. Differences presumably derive from using the full range of OCD symptoms and the combined exploratory and confirmatory approach with BSEM as a theoretically more appropriate analytical framework.

Factor analysis of symptom profile in early onset and late onset OCD

This study aimed to assess the factor structure of early and late onset OCD. Additionally, cluster analysis was conducted in the same sample to assess the applicability of the factors. 345 participants were assessed with Yale Brown Obsessive Compulsive Scale symptom checklist. Patients were classified as early onset (onset of symptoms at age ≤ 18 years) and late onset (onset at age > 18 years) OCD depending upon the age of onset of the symptoms. Factor analysis and cluster analysis of early-onset and late-onset OCD was conducted. The study sample comprised of 91 early onset and 245 late onset OCD subjects. Males were more common in the early onset group. Differences in the frequency of phenomenology related to contamination related, checking, repeating, counting and ordering/arranging compulsions were present across the early and late onset groups. Factor analysis of YBOCS revealed a 3 factor solution for both the groups, which largely concurred with each other. These factors were named as hoarding and symmetry (factor-1), contamination (factor-2) and aggressive, sexual and religious factor (factor-3). To conclude this study shows that factor structure of symptoms of OCD seems to be similar between early-onset and late-onset OCD.

White matter alterations associate with onset symptom dimension in obsessive-compulsive disorder

AIM

The high heterogeneity of obsessive-compulsive disorder (OCD) is best described by a multidimensional model involving symptom dimensions. We aimed to investigate white matter alterations associated with OCD, focusing on the impact of long-lasting effect of symptom dimensions assessed at onset of illness. Furthermore, we investigated white matter alterations associated with this disorder, controlling for the impact of medications and for the prevailing current symptom dimension.

METHODS

We studied 58 patients affected by OCD and 58 age- and sex-matched healthy controls. We divided patients according to symptom dimension at onset of illness, assessed with the five-factor model. T-tests were performed in order to investigate differences between subgroups. Similar analyses were performed considering the prevailing current symptom dimension. Analyses were conducted with tract-based spatial statistics on diffusion tensor imaging.

RESULTS

Doubt/checking and rituals/superstition symptom dimensions at onset and symmetry/perfectionism current symptom dimensions were characterized by significant alterations in diffusion tensor imaging measures. An association of white matter alterations and symmetry/perfectionism current dimension was found only when controlling for the effect of doubt/checking dimension at onset. Finally, results pointed out that the observed differences between patients and healthy controls were carried by the effect of previous and current medications.

CONCLUSION

Our findings evidenced that onset symptom dimensions are associated with enduring alterations of white matter microstructure. Onset symptom dimensions may reflect underlying endophenotypes. In addition, present results confirm the effect of medications on white matter in OCD, showing a large effect of current treatment on myelination.

Genetic and phenotypic overlap of specific obsessive-compulsive and attention-deficit/hyperactive subtypes with Tourette syndrome

BACKGROUND

The unique phenotypic and genetic aspects of obsessive-compulsive (OCD) and attention-deficit/hyperactivity disorder (ADHD) among individuals with Tourette syndrome (TS) are not well characterized. Here, we examine symptom patterns and heritability of OCD and ADHD in TS families.

METHOD

OCD and ADHD symptom patterns were examined in TS patients and their family members (N = 3494) using exploratory factor analyses (EFA) for OCD and ADHD symptoms separately, followed by latent class analyses (LCA) of the resulting OCD and ADHD factor sum scores jointly; heritability and clinical relevance of the resulting factors and classes were assessed.

RESULTS

EFA yielded a 2-factor model for ADHD and an 8-factor model for OCD. Both ADHD factors (inattentive and hyperactive/impulsive symptoms) were genetically related to TS, ADHD, and OCD. The doubts, contamination, need for sameness, and superstitions factors were genetically related to OCD, but not ADHD or TS; symmetry/exactness and fear-of-harm were associated with TS and OCD while hoarding was associated with ADHD and OCD. In contrast, aggressive urges were genetically associated with TS, OCD, and ADHD. LCA revealed a three-class solution: few OCD/ADHD symptoms (LC1), OCD & ADHD symptoms (LC2), and symmetry/exactness, hoarding, and ADHD symptoms (LC3). LC2 had the highest psychiatric comorbidity rates (⩾50% for all disorders).

CONCLUSIONS

Symmetry/exactness, aggressive urges, fear-of-harm, and hoarding show complex genetic relationships with TS, OCD, and ADHD, and, rather than being specific subtypes of OCD, transcend traditional diagnostic boundaries, perhaps representing an underlying vulnerability (e.g. failure of top-down cognitive control) common to all three disorders.

Neural correlates of working memory deficits and associations to response inhibition in obsessive compulsive disorder

Previous research in patients with obsessive-compulsive disorder (OCD) has indicated performance decrements in working memory (WM) and response inhibition. However, underlying neural mechanisms of WM deficits are not well understood to date, and empirical evidence for a proposed conceptual link to inhibition deficits is missing.

We investigated WM performance in a numeric n-back task with four WM load conditions during functional Magnetic Resonance Imaging (fMRI) in 51 patients with OCD and 49 healthy control participants who were matched for age, sex, and education. Additionally, a stop signal task was performed outside the MRI scanner in a subsample.

On the behavioral level, a significant WM load by group interaction was found for both accuracy (p < 0.02) and reaction time measures (p < 0.03), indicating increased reaction times as well as reduced accuracy specifically at high WM load (3-back) in patients with OCD. Whole-brain analyses of fMRI-data identified neural correlates of a load-dependent WM decrement in OCD in the supplementary motor area (SMA) and the inferior parietal lobule (IPL). Within the OCD sample, SMA-activity as well as n-back performance were correlated with stop signal task performance.

Results from behavioral and fMRI-analyses indicate a reduced WM load-dependent modulation of neural activity in OCD and suggest a common neural mechanism for inhibitory dysfunction and WM decrements in OCD.

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Numeric working memory was tested in 51 OCD patients during fMRI for the first time.

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OCD show increased neural activity at low and decreased activity at high load.

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BOLD signal in supplementary motor area predicts symptoms and response inhibition.

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Study shows first evidence for neural alterations in numeric working memory in OCD.

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Study suggests common neural mechanism for inhibitory and working memory dysfunction.

Quantifying dimensional severity of obsessive-compulsive disorder for neurobiological research

Current research to explore genetic susceptibility factors in obsessive-compulsive disorder (OCD) has resulted in the tentative identification of a small number of genes. However, findings have not been readily replicated. It is now broadly accepted that a major limitation to this work is the heterogeneous nature of this disorder, and that an approach incorporating OCD symptom dimensions in a quantitative manner may be more successful in identifying both common as well as dimension-specific vulnerability genetic factors. As most existing genetic datasets did not collect specific dimensional severity ratings, a specific method to reliably extract dimensional ratings from the most widely used severity rating scale, the Yale-Brown Obsessive Compulsive Scale (YBOCS), for OCD is needed. This project aims to develop and validate a novel algorithm to extrapolate specific dimensional symptom severity ratings in OCD from the existing YBOCS for use in genetics and other neurobiological research. To accomplish this goal, we used a large data set comprising adult subjects from three independent sites: the Brazilian OCD Consortium, the Sunnybrook Health Sciences Centre in Toronto, Canada and the Hospital of Bellvitge, in Barcelona, Spain. A multinomial logistic regression was proposed to model and predict the quantitative phenotype [i.e., the severity of each of the five homogeneous symptom dimensions of the Dimensional YBOCS (DYBOCS)] in subjects who have only YBOCS (categorical) data. YBOCS and DYBOCS data obtained from 1183 subjects were used to build the model, which was tested with the leave-one-out cross-validation method. The model's goodness of fit, accepting a deviation of up to three points in the predicted DYBOCS score, varied from 78% (symmetry/order) to 84% (cleaning/contamination and hoarding dimensions). These results suggest that this algorithm may be a valuable tool for extracting dimensional phenotypic data for neurobiological studies in OCD.

Discrimination and symptoms of obsessive-compulsive disorder among African Americans

This study examined symptoms of obsessive-compulsive disorder (OCD) in a nationally representative sample of African American adults (n = 3,570) and correlations between OCD symptom dimensions and experiences of discrimination. Two categories of discrimination were examined, everyday racial discrimination and everyday nonracial discrimination (e.g., because of gender, age, and weight), to determine if racial discrimination had a unique impact on OCD symptoms. Results indicated that everyday racial discrimination was related to both categories of obsessions and all 4 categories of compulsions. Everyday nonracial discrimination, however, was not related to any of the categories of obsessions or compulsions. This indicates that racial discrimination is uniquely related to obsessions and compulsions for African Americans. The implications of these findings are discussed. (PsycINFO Database Record

A critical appraisal of heterogeneity in Obsessive-Compulsive Disorder using symptom-based clustering analysis

Obsessive-compulsive disorder (OCD) encompasses a broad range of symptoms and is commonly considered a heterogeneous condition. Attempts were made to define discrete OCD subtypes using a range of symptom-based methods including factor and cluster analyses. The present study aims to find the most appropriate clustering model based on Yale-Brown obsessive-compulsive scale (YBOCS) checklist explaining OCD heterogeneity. Five different clustering algorithms (FCM, K-means, Ward, Ward+K-means and Complete) applied on YBOCS symptoms of 216 patients with OCD. Data studied as four different sets including item-level raw data, item-based factor scores, category-level raw data and category-based factor scores and clustering results for 2 to 6 cluster solutions evaluated by four clustering indices (Davies-Bouldin, Calinski-Harabasz, Silhouettes and Dunn indices). Two-cluster solution was detected as the most appropriate model for item and category-based clustering analyses of YBOCS checklist symptoms. Patients in each cluster were characterized based on their clinical and demographic properties and results showed that they had similar patterns of symptoms but in different severities. Heterogenity of OCD based on the YBOCS-symptoms has been challenged as OCD patients were classified based on their symptom severity not their symptom patterns. More investigations need to find appropriate measures explaining OCD heterogeneity with clinical importance.

Demographic and health-related correlates of obsessive-compulsive symptoms among African Americans

This study examined the correlates of the symptoms of obsessive-compulsive disorder (OCD) among a nationally-representative sample of African American adults (n = 3,570). Demographic and several self-rated health variables were examined. Although only 1.6% of the sample met DSM-IV diagnostic criteria for OCD, a sizeable proportion of the sample reported compulsions (12.5%) and obsessions (15.3%). Material hardship was positively associated with nearly all measured symptoms of OCD and fewer years of educational attainment was related to greater compulsive symptoms. Self-rated mental health was related to both compulsions and obsessions, and self-rated physical health was associated with counting and repeating compulsions. Implications and areas for further research with African Americans are discussed, including improving access to care for those most in need of services.

Polygenic risk score and heritability estimates reveals a genetic relationship between ASD and OCD

Obsessive-compulsive disorder (OCD) and Autism spectrum disorder (ASD) are both highly heritable neurodevelopmental disorders that conceivably share genetic risk factors. However, the underlying genetic determinants remain largely unknown. In this work, the authors describe a combined genome-wide association study (GWAS) of ASD and OCD. The OCD dataset includes 2998 individuals in nuclear families. The ASD dataset includes 6898 individuals in case-parents trios. GWAS summary statistics were examined for potential enrichment of functional variants associated with gene expression levels in brain regions. The top ranked SNP is rs4785741 (chromosome 16) with P value=6.9×10^-7 in our re-analysis. Polygenic risk score analyses were conducted to investigate the genetic relationship within and across the two disorders. These analyses identified a significant polygenic component of ASD, predicting 0.11% of the phenotypic variance in an independent OCD data set. In addition, we examined the genomic architecture of ASD and OCD by estimating heritability on different chromosomes and different allele frequencies, analyzing genome-wide common variant data by using the Genome-wide Complex Trait Analysis (GCTA) program. The estimated global heritability of OCD is 0.427 (se=0.093) and 0.174 (se=0.053) for ASD in these imputed data.

Identification of Two Heritable Cross-Disorder Endophenotypes for Tourette Syndrome

OBJECTIVE

Phenotypic heterogeneity in Tourette syndrome is partly due to complex genetic relationships among Tourette syndrome, obsessive-compulsive disorder (OCD), and attention deficit hyperactivity disorder (ADHD). Identifying symptom-based endophenotypes across diagnoses may aid gene-finding efforts.

METHOD

Assessments for Tourette syndrome, OCD, and ADHD symptoms were conducted in a discovery sample of 3,494 individuals recruited for genetic studies. Symptom-level factor and latent class analyses were conducted in Tourette syndrome families and replicated in an independent sample of 882 individuals. Classes were characterized by comorbidity rates and proportion of parents included. Heritability and polygenic load associated with Tourette syndrome, OCD, and ADHD were estimated.

RESULTS

The authors identified two cross-disorder symptom-based phenotypes across analyses: symmetry (symmetry, evening up, checking obsessions; ordering, arranging, counting, writing-rewriting compulsions, repetitive writing tics) and disinhibition (uttering syllables/words, echolalia/palilalia, coprolalia/copropraxia, and obsessive urges to offend/mutilate/be destructive). Heritability estimates for both endophenotypes were high and statistically significant (disinhibition factor=0.35, SE=0.03; symmetry factor=0.39, SE=0.03; symmetry class=0.38, SE=0.10). Mothers of Tourette syndrome probands had high rates of symmetry (49%) but not disinhibition (5%). Polygenic risk scores derived from a Tourette syndrome genome-wide association study (GWAS) were significantly associated with symmetry, while risk scores derived from an OCD GWAS were not. OCD polygenic risk scores were significantly associated with disinhibition, while Tourette syndrome and ADHD risk scores were not.

CONCLUSIONS

The analyses identified two heritable endophenotypes related to Tourette syndrome that cross traditional diagnostic boundaries. The symmetry phenotype correlated with Tourette syndrome polygenic load and was present in otherwise Tourette-unaffected mothers, suggesting that this phenotype may reflect additional Tourette syndrome (rather than OCD) genetic liability that is not captured by traditional DSM-based diagnoses.

Relationships between neuropsychological variables and factor-analysed symptom dimensions in obsessive compulsive disorder

Despite mounting evidence for the distinctiveness of symptom dimensions in obsessive-compulsive disorder, neuropsychological studies have been few, focused on small samples, and relying on classification of participants based on mutually exclusive symptom categories, resulting in lack of concordance across neuropsychological and imaging studies. Neuropsychological assessment was undertaken with 150 individuals with DSM IV OCD, and neuropsychological variables were analysed in relation to symptom dimension scores derived from factor analysis. Five dimensions were derived from principal components analysis with varimax rotation - contamination/washing, doubts/checking, symmetry/ordering, forbidden thoughts, and hoarding. After controlling for severity of depression and OCD, antipsychotic and benzodiazepine use, and all other symptom dimensions, washing was associated with poorer attention/working memory, visuo-spatial construction and better planning time; checking was related to poorer alternation learning; symmetry linked with poorer verbal fluency; forbidden thoughts with better visuospatial scanning and working memory; hoarding with poorer immediate verbal recall and better visuospatial working memory. The neuropsychological associations are explained in the context of existing neuroimaging evidence, and the clinical picture of each symptom dimension. The use of factor-analysed symptom dimensions and a large sample of individuals with OCD are strengths of the study.

Age-Specific Prevalence of Hoarding and Obsessive Compulsive Disorder: A Population-Based Study

OBJECTIVE

Little is known about the age-specific prevalence of hoarding and obsessive compulsive symptoms (OCS), particularly in older age groups. The objectives of this study were to estimate the age-specific prevalence, severity, and relationships between hoarding and OCS in males and females using a large population-based sample.

METHODS

We assessed the age-specific prevalence rates of hoarding disorder (HD) and OC disorder (OCD) in males and females (at various age ranges between 15 and 97 years) from the Netherlands Twins Register (N = 15,194). Provisional HD and OCD diagnoses were made according to Diagnostic and Statistical Manual of Mental Health Disorders, 5th Edition, criteria using self-report measures. We also assessed hoarding and OCS severity in the various age groups and explored specific hoarding and OCS patterns (e.g., difficulty discarding, excessive acquisition, clutter, checking, washing, perfectionism, and obsessions) with age.

RESULTS

Prevalence of provisional HD diagnoses (2.12%) increased linearly by 20% with every 5 years of age (z = 13.8, p < 0.0001) and did not differ between males and females. Provisional OCD diagnoses were most common in younger individuals and in individuals over age 65. Co-occurring OCD increased hoarding symptom severity (coefficient: 4.5; SE: 0.2; 95% CI: 4.1-4.9; t = 22.0, p < 0.0001). Difficulty discarding for HD and checking behaviors for OCD appeared to drive most increases in these diagnoses in older ages.

CONCLUSION

Increased prevalence and severity of HD with age appears to be primarily driven by difficulties with discarding. Increases in OCD prevalence with older age were unexpected and of potential clinical relevance.

Structure and clinical correlates of obsessive-compulsive symptoms in a large sample of children and adolescents: a factor analytic study across five nations

The underlying structure of obsessive-compulsive disorder (OCD) remains to be confirmed in child and adolescent populations. In this paper we report the first factor analytic study of individual OCD items from Children's Yale-Brown Obsessive Compulsive Scale (CY-BOCS). OCD symptoms were assessed using the CY-BOCS symptom checklist in a sample of 854 patients with OCD (7-18 years of age) recruited from clinics in five countries. Pooled data were subjected to exploratory and confirmatory factor analysis (CFA) to identify the optimal factor structure. Various models were tested for age and gender subgroups. Also, the invariance of the solution across age and gender was tested and associations with demographic and clinical factors were explored. A three-factor model provided the best-fit solution. It consisted of the following factors: (1) harm/sexual, (2) symmetry/hoarding, (3) contamination/cleaning. The factor structure was invariant for age and gender across subgroups. Factor one was significantly correlated with anxiety, and factor two with depression and anxiety. Factor three was negatively correlated with tic disorder and attention-deficit/hyperactivity disorder (ADHD). Females had higher scores on factor two than males. The OCD symptom structure in children and adolescents is consistent across age and gender and similar to results from recent child and adolescents although hoarding may not be a separate factor. Our three-factor structure is almost identical to that seen in early studies on adults. Common mental disorders had specific patterns of associations with the different factors.

Exploring yale-brown obsessive-compulsive scale symptom structure in Iranian OCD patients using item-based factor analysis

Obsessive compulsive disorder (OCD) is a heterogeneous psychiatric disorder. This study aimed to reach a comprehensive perspective of OCD symptoms in Iranian patients. Item-based factor analysis of Y-BOCS checklist from 216 outpatients resulted in five factors including aggression/checking, contamination/cleaning, symmetry/ordering/repeating/counting/hoarding, sexual and somatic. Regression analyses showed that miscellaneous items can be predicted by these factors. Results showed that OCD subtypes in Iranian patients resemble to those of other nations except the aggressive, sexual and religious obsessions; demonstrating the influence of the culture on obsession manifestation. The correlation analyses of factors and clinical characteristics demonstrated that aggression/checking was associated with high obsession scores and more avoidance. Contamination/cleaning was correlated with higher compulsion score. Patients with higher scores on symmetry/ordering/counting/repeating/hoarding had familial OCD pattern with earlier age of onset, lower age at assessment, higher obsession and more avoidance. Sexual factor was associated with less compulsion scores and somatic factor was associated with higher obsessions and compulsions as well as less familial history and more avoidance. These findings provide a comprehensive view of OCD symptom structure in Iranian OCD patients and will be of value to studies using symptom factor to lead investigation of its causes, correlates and treatment strategies considering cross-cultural differences.

"Not Just Right Experiences" as a psychological endophenotype for obsessive-compulsive disorder: Evidence from an Italian family study

The heart of the obsessional process may be considered the subject's underlying impression that "something is wrong" or "that something is not just as it should be". This phenomenon, labeled "not just right experiences" (NJREs), has increasingly been receiving attention as a possible marker of obsessive-compulsive disorder (OCD). The present study sought to add to the evidence that NJREs may be a putative endophenotype of obsessional symptoms. To this aim, measures of NJREs, obsessive-compulsive (OC) symptoms and psychological distress were compared in offspring of parents with and without OC symptoms. The offspring of parents with OC symptoms (N=120) reported higher frequency and severity of NJREs compared to offspring of parents without OC symptoms (N=106). Such differences remained significant for NJREs frequency and close to significance for NJREs severity, when general distress (i.e., anxiety and depression) was controlled. The possible role of NJREs as an endophenotype for OCD is discussed in reference to Gottesman and Gould criteria and the National Institute of Mental Health RDoC initiative.