Symptom dimensions in obsessive-compulsive disorder: factor analysis on a clinician-rated scale and a self-report measure

A closer look to neural pathways and psychopharmacology of obsessive compulsive disorder

The intricate neural pathways involved in obsessive-compulsive disorder (OCD) affect areas of our brain that control executive functioning, organization, and planning. OCD is a chronic condition that can be debilitating, afflicting millions of people worldwide. The lifetime prevalence of OCD in the US is 2.3%. OCD is predominantly characterized by obsessions consisting of intrusive and unwanted thoughts, often with impulses that are strongly associated with anxiety. Compulsions with OCD encompass repetitive behaviors or mental acts to satisfy their afflicted obsessions or impulses. While these factors can be unique to each individual, it has been widely established that the etiology of OCD is complex as it relates to neuronal pathways, psychopharmacology, and brain chemistry involved and warrants further exploration.

Early maladaptive schemas and obsessive-compulsive disorder: A systematic review and meta-analysis

BACKGROUND

Obsessive-compulsive disorder (OCD) is a condition with poor treatment outcomes. Improved understanding of the aetiology can inform prevention and treatment approaches; hence several studies have assessed early maladaptive schemas (EMSs) in OCD. This systematic review and meta-analysis aimed to synthesise the evidence on relationships between the 18 EMSs and OCD.

METHODS

The study was conducted according to PRISMA guidelines and registered on PROSPERO (CRD42022329337). A systematic search of PubMed, PsycINFO, and CINAHL Complete was conducted on 4 June 2022. Studies in peer-reviewed journal articles were included if they assessed EMSs and OCD (diagnosis or symptom severity) in adults with a mean age of 18 years or older. Studies were excluded if they were not in English, did not include original quantitative data, or reported on case studies. Study details were tabulated and the meta-analysis findings were presented using forest plots. Methodological quality was assessed using the Appraisal tool for Cross-Sectional Studies (AXIS).

RESULTS

Based on 22 studies (pooled N = 3699), all 18 EMSs were positively correlated with OCD. The largest associations were with the dependence/incompetence (r = 0.40 95 % CI [0.32, 0.47]), vulnerability to harm or illness (r = 0.40 95 % CI [0.32, 0.48]), and negativity/pessimism schemas (r = 0.42 95 % CI [0.22, 0.58]).

LIMITATIONS

Several meta-analyses showed considerable heterogeneity and publication bias.

CONCLUSIONS

The findings suggest all EMSs, particularly those relating to disproportionate negative expectations and a perceived inability to cope, are implicated in OCD. Psychological prevention and treatment for OCD may benefit from targeting these schemas.

The global assessment of OCD

Obsessive Compulsive Disorder (OCD) is a common mental disorder that often causes great sufferance, with substantial impairment in social functioning and quality of life and affects family and significant relationships. Notwithstanding its severity, OCD is often not adequately diagnosed, or it is diagnosed with delay, leading often to a long latency between onset of the OCD symptoms and the start of adequate treatments. Several factors contribute to the complexity of OCD's clinical picture: early age of onset, chronic course, heterogeneity of symptoms, high rate of comorbidity with other psychiatric disorders, slow or partial response to therapy. Therefore, it is of primary importance for clinicians involved in diagnosing OCD, to assess all aspects of the disorder. This narrative review focuses on the global assessment of OCD, highlighting crucial areas to explore, pointing out the clinical features which are relevant for the treatment of the disorder, and giving an overview of the psychometric tools that can be useful during the screening procedure.

Bodily obsessions: intrusiveness of organs in somatic obsessive-compulsive disorder

In this paper, I will provide a phenomenological analysis of somatic obsessions at times present in obsessive-compulsive disorder. I will compare two different types of bodily obsessions, which have a different neurological-physiological underpinning: anguishing awareness of one's own heartbeat and of one's own breathing. In addition, I will contrast these two with how one experiences one's own liver. I will use the concepts "tactility obsessions" and "motility obsessions", which I have coined for the purpose of this comparison. In other words, these are obsessions concerning the felt sense of one's autonomous organs and obsessions concerning one's ability to voluntarily move. Ultimately, I claim that the core lived experience in somatic obsessive-compulsive disorder should not only be understood as having to do with intruding and "distorted thoughts" concerning bodily processes, but could also be understood as having to do with a felt sense of our organs interrupting and intruding our daily lives.

Dimensions of interoception in obsessive-compulsive disorder

Interoceptive sensibility (IS) refers to the subjective experience of perceiving and being aware of one's internal body sensations, and is typically evaluated using self-report questionnaires or confidence ratings. Here we evaluated IS in 81 patients with OCD and 76 controls using the Multidimensional Scale of Interoceptive Awareness (MAIA), which contains 8 subscales assessing adaptive and maladaptive responses to sensation. Compared to controls, OCD patients showed hyperawareness of body sensations. Patients also demonstrated a more maladaptive profile of IS characterized by greater distraction from and worry about unpleasant sensations, and reduced tendency to experience the body as safe and trustworthy. These findings were independent of medication status and comorbidities in the patient group. Correlational analyses showed that subscales of the MAIA were differentially associated with OCD symptom dimensions. These findings indicate that patients with OCD show abnormality of IS that is independent of confounding factors related to medication and comorbidities and associated with different OCD symptom dimensions. Future work would benefit from examining neural correlates of these effects and evaluating whether dimensions of IS are impacted by treatments for the disorder.

Review of source-monitoring processes in obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a severe mental illness characterized by persistent, intrusive and distressing obsessions and/or compulsions. Such symptoms have been conceptualized as resulting from a failure in source-monitoring processes, suggesting that patients with OCD fail to distinguish actions they perform from those they just imagine doing. In this study, we aimed to provide an updated and exhaustive review of the literature examining the relationship between source-monitoring and OCD. A systematic search in the literature through January 2019 allowed us to identify 13 relevant publications investigating source-monitoring abilities in patients with OCD or participants with subclinical compulsive symptoms. Most of the retrieved studies did not report any source-monitoring deficits in clinical and subclinical subjects compared with healthy volunteers. However, most of the studies reported that patients with OCD and subclinical subjects displayed reduced confidence in source-monitoring judgments or global cognitive confidence compared to controls. The present review highlighted some methodological and statistical limitations. Consequently, further studies are needed to explore source monitoring with regard to the subcategories of OCD symptoms (i.e., symmetry-ordering, contamination-washing, hoarding, aggressive obsession-checking, sexual-religious thoughts) and to clarify the relationship between source-monitoring subtypes (i.e., reality or internal source-monitoring) and confidence in these populations.

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.

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.

Symptom subtype and quality of life in obsessive-compulsive disorder

Quality of life (QoL) is significantly impaired in OCD across several facets of life, such as social, occupational, and family functioning, subjective sense of well-being, and enjoyment of leisure activities. The present study examined the relationship between 5 symptom subtypes of OCD (contamination, symmetry, hoarding, overresponsibility for harm, and taboo) and QoL. Participants were 325 adults with OCD enrolled in the Brown Longitudinal Obsessive Compulsive Study. Hierarchical linear regression analyses indicated hoarding, contamination, symmetry, and overresponsibility for harm were associated with impairment in household functioning, enjoyment of leisure activities, social relationships, and physical health. The implications of these findings are discussed.

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.

An empirical investigation of incompleteness in a large clinical sample of obsessive compulsive disorder

Obsessive Compulsive Disorder (OCD) is a disorder with heterogeneous clinical presentations. To advance our understanding of this heterogeneity we investigated the prevalence and clinical features associated with incompleteness (INC), a putative underlying core feature of OCD. We predicted INC would be prominent in individuals with OCD and associated with greater severity and impairment. We examined the impact of INC in 307 adults with primary OCD. Participants with clinically significant INC (22.8% of the sample) had significantly greater OCD severity, greater rates of comorbidity, poorer ratings of functioning, lower quality of life, and higher rates of unemployment and disability. Participants with clinically significant INC were also more likely to be diagnosed with OCPD and to endorse symmetry/exactness obsessions and ordering/arranging compulsions than those who reported low INC. Our findings provide evidence that INC is associated with greater severity, comorbidity, and impairment, highlighting the need for improved assessment and treatment of INC in OCD.

Dimensions of control and their relation to disordered eating behaviours and obsessive-compulsive symptoms

BACKGROUND

Issues of personal control have been proposed to play a central role in the aetiology and maintenance of eating disorders. Empirical evidence supporting this relationship is inconsistent, partly due to the multiplicity of constructs used to define "control". This study compares six commonly used measures of control with the aim of determining which operationalisation of control is most centrally relevant to eating pathology. Given the high level of comorbidity between eating disorders and obsessive-compulsive disorder and the potentially common risk/maintenance factors for the two disorders, we also examine the relationship between control and obsessive-compulsive symptomatology.

METHODS

Female community participants (N = 175) completed self-report measures of control, eating disorder pathology and obsessive-compulsive symptoms.

RESULTS

Multivariate analyses of variance indicated significant differences between individuals with high vs. low levels of psychopathology on most of the measures of control. Using regression analyses, we found that a sense of ineffectiveness and fear of losing self-control were the only significant independent predictors of eating pathology, and fear of losing self-control was the most significant predictor of obsessive-compulsive symptoms.

CONCLUSIONS

This study highlights the importance of issues of control, particularly feelings of ineffectiveness and fear of losing self-control, in eating disorder symptoms. Furthermore, our findings suggest that there may be a similar underlying fear of losing self-control among individuals who engage in disordered eating and obsessive-compulsive behaviours. Thus, ineffectiveness and fear of losing self-control are two dimensions that are important to consider in maintenance and treatment models of disordered eating behaviours.

Differences in duration of untreated illness, duration, and severity of illness among clinical phenotypes of obsessive-compulsive disorder

INTRODUCTION

Obsessive-compulsive disorder (OCD) is a prevalent, disabling, and comorbid condition that is frequently under-recognized and poorly treated. OCD phenotypes may differ in terms of clinical presentation and severity. However, few studies have investigated whether clinical phenotypes differ in terms of latency to treatment (ie, duration of untreated illness[DUI]), duration, and severity of illness. The present study was aimed to quantify the aforementioned variables in a sample of OCD patients.

METHODS

One hundred fourteen outpatients with a Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision (DSM-IV-TR) diagnosis of OCD were recruited, and their main clinical features were collected. Severity of illness was assessed through the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), and the main phenotypes were identified through the Y-BOCS Symptom Checklist. A one-way analysis of variance (ANOVA) test, followed by a Bonferroni post-hoc test, were performed to compare DUI, duration, and severity of illness across subgroups.

RESULTS

In the whole sample, the mean DUI exceeded 7 years (87.35±11.75 months), accounting for approximately half of the mean duration of illness (172.2±13.36 months). When subjects were categorized into 4 main clinical phenotypes, respectively, aggressive/checking (n=31), contamination/cleaning (n=37), symmetry/ordering (n=32), and multiple phenotypes (n=14), DUI, duration, and severity of illness resulted significantly higher in the aggressive/checking subgroup, compared to other subgroups (F=3.58, p<0.01; F=3.07, p<0.01; F=4.390, p<0.01).

DISCUSSION

In a sample of OCD patients, along with a mean latency to treatment of approximately 7 years, regardless of the phenotype, patients had spent half of their duration of illness (DI) without being treated. DUI, duration, and severity of illness resulted significantly higher in the aggressive/checking subgroup.

Are stressful life events causally related to the severity of obsessive-compulsive symptoms? A monozygotic twin difference study

Traumatic or stressful life events have long been hypothesized to play a role in causing or precipitating obsessive-compulsive symptoms but the impact of these environmental factors has rarely been investigated using genetically informative designs. We tested whether a wide range of retrospectively-reported stressful life events (SLEs) influence the lifetime presence and severity of obsessive-compulsive symptoms (OCS) in a large Swedish population-based cohort of 22,084 twins. Multiple regression models examined whether differences in SLEs within twin pairs were significantly associated with differences in OCS. In the entire sample (i.e., both monozygotic [MZ] and dizygotic twin pairs), two SLEs factors, “abuse and family disruption” and “sexual abuse”, were significantly associated with the severity of OCS even after controlling for depressive symptoms. Other SLEs factors were either not associated with OCS (“loss”, “non-sexual assault”) or were no longer associated with OCS after controlling for depression (“illness/injury”). Within MZ pair analyses, which effectively control for genetic and shared environmental effects, showed that only the “abuse and family disruption” factor remained independently related to within-pair differences in OCS severity, even after controlling for depressive symptoms. Despite being statistically significant, the magnitude of the associations was small; “abuse and family disruption” explained approximately 3% of the variance in OCS severity. We conclude that OCS are selectively associated with certain types of stressful life events. In particular, a history of interpersonal abuse, neglect and family disruption may make a modest but significant contribution to the severity of OCS. Further replication in longitudinal cohorts is essential before causality can be firmly established.

The relationships between obsessive-compulsive symptom dimensions and cognitions in obsessive-compulsive disorder

Several studies have linked obsessive-compulsive symptoms to specific obsessive-compulsive cognitions, however methodologies have varied, and no study has determined obsessive-compulsive symptoms using the most widely used clinician rating scale, the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). Considering that almost all studies that used factor analysis to ascertain OCD symptom dimensions were based on the Y-BOCS and that self-report instruments assessing obsessive-compulsive symptoms correlate poorly with the Y-BOCS, there is a need to use the Y-BOCS to examine the relationship between obsessive-compulsive cognitions and obsessive-compulsive symptom dimensions. This study examined the relationship between five Y-BOCS-derived obsessive-compulsive symptom dimensions and the three obsessive-compulsive cognitive domains identified by the obsessive-beliefs questionnaire (OBQ). The symmetry/ordering symptom dimension was associated with increased perfectionism/intolerance of uncertainty, the unacceptable/taboo thoughts symptom dimension was associated with increased importance/control of thoughts and the doubt/checking symptom dimension was associated with increased responsibility/threat estimation. There was no statistical evidence of an association between any OBQ belief sub-scale and the hoarding symptom dimension nor the contamination/cleaning symptom dimension. The findings encourage symptom-based approaches to cognitive-behavioural therapy for some OCD symptoms and call for further research on cognitions associated with contamination/cleaning symptoms and hoarding.

Further support for five dimensions of obsessive-compulsive symptoms

Attempts to explain the phenotypic heterogeneity of obsessive-compulsive disorder (OCD) have resulted in three to six OCD symptom dimensions. This study aimed to clarify the nature of these symptom dimensions using a self-report instrument (Vancouver Obsessional Compulsive Inventory [VOCI]) in addition to the clinician-rated Yale-Brown Obsessive Compulsive Scale-Symptom Checklist (YBOCS-SC). Participants (N = 154) were recruited to a study designed to specifically assess OCD symptom dimensions. Symptoms assessed via the YBOCS-SC and the VOCI were subjected to principal components analysis (PCA). Linear regression was used to assess the relationship between the YBOCS-SC-derived symptom dimensions and the VOCI symptom subscales. PCA of the YBOCS-SC and the VOCI revealed five OCD symptom dimensions that explained 68% and 60% of the variance, respectively. The results also supported a distinction between the doubt/checking symptom dimension and the unacceptable/taboo thoughts dimension that includes mental rituals. The YBOCS-SC-derived symptom components were predicted by their respective VOCI symptom subscale scores.

Symptom dimensions in obsessive-compulsive disorder: phenomenology and treatment outcomes with exposure and ritual prevention

BACKGROUND

Obsessive-compulsive disorder (OCD) is a severe condition with varied symptom presentations. Currently, the cognitive-behavioral treatment with the most empirical support is exposure and ritual prevention (EX/RP); however, clinical impression and some empirical data suggest that certain OCD symptoms are more responsive to treatment than others.

METHODS

Prior work identifying symptom dimensions within OCD is discussed, including epidemiological findings, factor analytic studies, and biological findings. Symptom dimensions most reliably identified include contamination/cleaning, doubt about harm/checking, symmetry/ordering, and unacceptable thoughts/mental rituals. The phenomenology of each of these subtypes is described and research literature is summarized, emphasizing the differential effects of EX/RP and its variants on each of these primary symptom dimensions.

RESULTS

To date it appears that EX/RP is an effective treatment for the various OCD dimensions, although not all dimensions have been adequately studied (i.e. symmetry and ordering).

CONCLUSIONS

Modifications to treatment may be warranted for some types of symptoms. Clinical implications and directions for future research are discussed.

Symptom Dimensions in Two Samples of Africans Americans with Obsessive-Compulsive Disorder

Obsessive-compulsive disorder (OCD) is a leading cause of disability worldwide, however, there is a lack of research that includes African Americans, thus it is unclear whether findings about symptom dimensions can be generalized to this population. A sample of adult African Americans with OCD (N=74) was recruited at the University of Pennsylvania (Penn) and administered the Yale Brown Obsessive-Compulsive checklist (YBOCS) to better understand the phenomenology of OCD in African Americans. Frequencies of symptoms are reported and compared to findings from the National Survey of American Life (NSAL; N=54). A principal components analysis of YBOCS categories and items was performed on the Penn sample. A six-component solution was found, that included Contamination & Washing, Hoarding, Sexual Obsessions & Reassurance, Aggression & Mental Compulsions, Symmetry & Perfectionism, and Doubt & Checking, explaining 59.1% of the variance. Factors identified were similar to those of previous studies in primarily white samples. African Americans with OCD reported more contamination symptoms and were twice as likely to report excessive concerns with animals as European Americans with OCD. The results indicate the presence of cultural differences, which is consistent with findings among non-clinical samples. Implications of these findings are discussed.

Distinct neuropsychological profiles of three major symptom dimensions in obsessive-compulsive disorder

Recent neuroimaging studies have suggested that different symptom dimensions are mediated by partially distinct neural systems in obsessive-compulsive disorder (OCD). However, the correlations between neuropsychological profiles and symptom dimensions in OCD are unknown. The aim of this study was to examine the extent to which OCD symptom dimensions were associated with episodic memory and attention and executive functions. The symptom dimensions of 63 patients with OCD were assessed using both the Padua Inventory and the Y-BOCS symptom checklist. Then, we administered the Logical Memory (LM) subset of the Wechsler Memory Scale-Revised (WMR-R) test and evaluated inhibition (Stroop test, Trail Making test) and cognitive flexibility (Digit Symbol test, Letter Fluency, and Category Fluency). While associations were observed between scores on the contamination/cleaning dimension and better performances on the LM and Trail Making tests, associations were also observed between scores on the aggressive/checking dimension and poorer performances on the Trail Making test. In addition, we found that scores on the symmetry/ordering dimension were associated with poorer performances on the LM and Trail Making tests. Our results support the hypothesis that different symptoms may represent distinct and partially overlapping neurocognitive networks in OCD patients.

Latent class analysis of the Yale-Brown Obsessive-Compulsive Scale symptoms in obsessive-compulsive disorder

OBJECTIVE

Obsessive-compulsive disorder (OCD) is phenomenologically heterogeneous, and findings of underlying structure classification based on symptom grouping have been ambiguous to date. Variable-centered approaches, primarily factor analysis, have been used to identify homogeneous groups of symptoms; but person-centered latent methods have seen little use. This study was designed to uncover sets of homogeneous groupings within 1611 individuals with OCD based on symptoms.

METHOD

Latent class analysis models using 61 obsessive-compulsive symptoms collected from the Yale-Brown Obsessive-Compulsive Scale were fit. Relationships between latent class membership and treatment response, sex, symptom severity, and comorbid tic disorders were tested for relationship to class membership.

RESULTS

Latent class analysis models of best fit yielded 3 classes. Classes differed only in frequency of symptom endorsement. Classes with higher symptom endorsement were associated with earlier age of onset, being male, higher Yale-Brown Obsessive-Compulsive Scale symptom severity scores, and comorbid tic disorders. There were no differences in treatment response between classes.

CONCLUSIONS

These results provide support for the validity of a single underlying latent OCD construct, in addition to the distinct symptom factors identified previously via factor analyses.

Brain activation during cognitive planning in twins discordant or concordant for obsessive-compulsive symptoms

Neuroimaging studies have indicated abnormalities in cortico-striatal-thalamo-cortical circuits in patients with obsessive–compulsive disorder compared with controls. However, there are inconsistencies between studies regarding the exact set of brain structures involved and the direction of anatomical and functional changes. These inconsistencies may reflect the differential impact of environmental and genetic risk factors for obsessive–compulsive disorder on different parts of the brain. To distinguish between functional brain changes underlying environmentally and genetically mediated obsessive–compulsive disorder, we compared task performance and brain activation during a Tower of London planning paradigm in monozygotic twins discordant (n = 38) or concordant (n = 100) for obsessive–compulsive symptoms. Twins who score high on obsessive–compulsive symptoms can be considered at high risk for obsessive–compulsive disorder. We found that subjects at high risk for obsessive–compulsive disorder did not differ from the low-risk subjects behaviourally, but we obtained evidence that the high-risk subjects differed from the low-risk subjects in the patterns of brain activation accompanying task execution. These regions can be separated into those that were affected by mainly environmental risk (dorsolateral prefrontal cortex and lingual cortex), genetic risk (frontopolar cortex, inferior frontal cortex, globus pallidus and caudate nucleus) and regions affected by both environmental and genetic risk factors (cingulate cortex, premotor cortex and parts of the parietal cortex). Our results suggest that neurobiological changes related to obsessive–compulsive symptoms induced by environmental factors involve primarily the dorsolateral prefrontal cortex, whereas neurobiological changes induced by genetic factors involve orbitofrontal–basal ganglia structures. Regions showing similar changes in high-risk twins from discordant and concordant pairs may be part of compensatory networks that keep planning performance intact, in spite of cortico-striatal-thalamo-cortical deficits.

Sensory gating and sensorimotor gating in medication-free obsessive-compulsive disorder patients

Obsessive-compulsive disorder (OCD) is associated with deficits in inhibition mechanisms. This is reflected in reports showing impaired sensorimotor and sensory gating in OCD patients, as measured with prepulse inhibition (PPI) of the startle reflex and P50 suppression paradigms. However, most of the patients in these studies used medication and the results were not controlled for menstrual cycle phase in women. In this study PPI and P50 suppression were tested in 25 medication-free OCD patients and 25 healthy controls, using auditory stimuli and controlling for menstrual cycle effects. Subgroups were established, based on clinical variables (e.g. 'washers' and 'checkers'). No impairments in PPI or P50 suppression were found in the OCD group when compared with healthy controls. However, a subgroup of OCD patients ('checkers', n=12) showed increased P50 suppression. It was concluded that sensorimotor and sensory gating is not impaired in drug-free OCD patients, taking into account the menstrual cycle effects in women. These results do not support hypotheses linking deficits in these inhibition paradigms and the pathogenesis of OCD. The finding of an increased P50 suppression in the subgroup of 'checkers' deserves further investigation and underlines the value of studying subgroups of OCD.

Dimensional predictors of response to SRI pharmacotherapy in obsessive-compulsive disorder

BACKGROUND

Obsessive-compulsive disorder (OCD) is clinically heterogeneous. Previous studies have reported different patterns of treatment response to serotonin reuptake inhibitors (SRI) based on symptom dimension. Our objective was to replicate these results in OCD patients who participated in one of four randomized, placebo-controlled, clinical trials (RCT).

METHODS

A total of 165 adult OCD subjects participated in one or more eight-week RCT with clomipramine, fluvoxamine, or fluoxetine. All subjects were classified as having major or minor symptoms in four specific OC symptom dimensions that were derived in a previous factor analytic study involving many of these same patients. Ordinal logistic regression was used to test the association between OC symptom dimensions and SRI response.

RESULTS

We found a significant association between the symptom dimension involving sexual, religious and harm-related obsessions as well as checking compulsions (AGG/SR) and improved SRI response. This increased rate of SRI response was experienced primarily by individuals with harm-related obsessions. Over 60% of patients with AGG/SR OCD symptoms were rated as very much improved after SRI treatment.

LIMITATIONS

As some of the RCTs included were conducted prior to the development of the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), improvement in OCD severity was assessed using the Clinical Global Improvement (CGI) Scale. Data from the double-blind and open-label continuation phases of these trials was collapsed together to increase statistical power.

CONCLUSIONS

Patients with OCD vary in their response to SRIs. The presence of AGG/SR symptoms is associated with an initial positive response to SRIs. These data add to the growing body of work linking central serotonin systems with aggressive behavior.

Endophenotypes of obsessive-compulsive disorder: rationale, evidence and future potential

Obsessive-compulsive disorder (OCD) is a heritable and debilitating neuropsychiatric condition. Attempts to delineate genetic contributions have met with limited success, and there is an ongoing search for intermediate trait or vulnerability markers rooted in the neurosciences. Such markers would be valuable for detecting people at risk of developing the condition, clarifying etiological factors and targeting novel treatments. This review begins with brief coverage of the epidemiology of OCD, and presents a hierarchical model of the condition. The advantages of neuropsychological assessment and neuroimaging as objective measures of brain integrity and function are discussed. We describe the concept of endophenotypes and examples of their successful use in medicine and psychiatry. Key areas of focus in the search for OCD endophenotypes are identified, such as measures of inhibitory control and probes of the integrity of orbitofrontal and posterior parietal cortices. Finally, we discuss exciting findings in unaffected first-degree relatives of patients with OCD that have led to the identification of several candidate endophenotypes of the disorder, with important implications for neurobiological understanding and treatment of this and related conditions.

Measuring obsessive-compulsive symptoms: Padua Inventory-Revised vs. Yale-Brown Obsessive Compulsive Scale

Although the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) and the Padua Inventory-Revised (PI-R) are the most widely used instruments for assessing presence and severity of symptoms in obsessive-compulsive disorder (OCD), the correlation between the two instruments is surprisingly low. The aim of the present investigation was to test two possible explanations for the discrepancy between these instruments by comparing both scales in 120 OCD patients. The tested hypotheses included: (1) differences in the way the measures are administered, i.e. observer-rated vs. self-rated; and (2) differences in the way severity is calculated, i.e. the PI-R measures severity by aggregating symptoms, while the Y-BOCS measures severity unrelated to the number of symptoms. Results indicated that neither hypothesis satisfactorily explains the differences between the measures. The investigation concludes that the Y-BOCS and PI-R measure relatively unrelated features of OCD, and the combined use of multiple measures is recommended to assess the complexity of OCD phenomena.

Meta-analysis of the symptom structure of obsessive-compulsive disorder

OBJECTIVE

OCD is a clinically heterogeneous condition. This heterogeneity has the potential to reduce power in genetic, neuroimaging, and clinical trials. Despite a mounting number of studies, there remains debate regarding the exact factor structure of OCD symptoms. The authors conducted a meta-analysis to determine the factor structure of the Yale-Brown Obsessive Compulsive Scale Symptom Checklist.

METHOD

Studies were included if they involved subjects with OCD and included an exploratory factor analysis of the 13 Yale-Brown Obsessive Compulsive Scale Symptom Checklist categories or the items therein. A varimax-rotation was conducted in SAS 9.1 using the PROC FACTOR CORR to extract factors from sample-size weighted co-occurrence matrices. Stratified meta-analysis was conducted to determine the factor structure of OCD in studies involving children and adults separately.

RESULTS

Twenty-one studies involving 5,124 participants were included. The four factors generated were 1) symmetry: symmetry obsessions and repeating, ordering, and counting compulsions; 2) forbidden thoughts: aggression, sexual, religious, and somatic obsessions and checking compulsions, 3) cleaning: cleaning and contamination, and 4) hoarding: hoarding obsessions and compulsions. Factor analysis of studies including adults yielded an identical factor structure compared to the overall meta-analysis. Factor analysis of child-only studies differed in that checking loaded highest on the symmetry factor and somatic obsessions, on the cleaning factor.

CONCLUSIONS

A four-factor structure explained a large proportion of the heterogeneity in the clinical symptoms of OCD. Further item-level factor analyses are needed to determine the appropriate placement of miscellaneous somatic and checking OCD symptoms.

Evidence for a heritable unidimensional symptom factor underlying obsessionality

The division of obsessive-compulsive symptoms (OCS) into specific factors is now widely accepted. However, the utility of these categories for genetic studies remains unclear, as studies examining their heritability have been inconsistent. Less attention has been paid to the possibility that clinically significant obsessionality is primarily determined by a "core" group of OCS that crosses the boundaries between symptom subgroups. The aim of this study is to determine whether such a core group exists, and to compare its heritability to that of the more traditionally derived symptom factors. We examined the properties and heritability of obsessive-compulsive symptoms in college students, medical students, and obsessive-compulsive disorder (OCD) families using the Leyton Obsessional Inventory. In each of the three samples, we identified a core group of symptoms that comprised a single unique construct and accounted for over 90% of the variation of the four more traditional symptom factors. This core construct was highly correlated with OCD in our families and had a heritability estimate of 0.19 when OCD was not included as a covariate and 0.49 when OCD was included as a covariate. In contrast, the four symptom factors were not heritable. There appears to be an underlying unidimensional component to obsessionality, both in non-clinical and clinical samples. This component, which is heritable, accounts for the majority of the variation of the more traditionally derived symptom factors in our sample, and is composed of OCS that are not specific to any of the symptom subgroups.

Symptom subtypes of obsessive-compulsive disorder: are they relevant for treatment?

Several symptom subtypes of obsessive-compulsive disorder (OCD) have been identified on the basis of the predominant obsessions and compulsions. The objectives of the present article were to review the literature on the relationship between OCD symptom subtypes and treatment response and to suggest strategies that might assist with the choice of treatment and improve treatment outcome in patients with various subtypes. An extensive literature search was performed, relevant studies were identified, and their results reported. Overt compulsions were generally associated with a relatively good response to the behaviour therapy technique of exposure and response prevention (ERP) and with poorer response to serotonin re-uptake inhibitors (SRIs). Washing/cleaning and checking compulsions tend to respond well to ERP, whereas the majority of studies show that washing/cleaning compulsions are associated with a poorer response to SRIs. Most studies suggest that patients with the symmetry, ordering and arranging subtype do not fare worse with ERP and SRIs than patients with other symptom subtypes. Some studies suggested that obsessions might respond to SRIs somewhat better than to ERP. In the majority of the studies, hoarding and the subtype characterized by sexual or religious obsessions and absence of overt compulsions ('pure obsessions') have been associated with poor response to ERP and SRIs. It was concluded that treatment strategies cannot be precisely tailored to OCD symptom subtypes. Many other factors influence the outcome of treatment and need to be considered along with the symptom subtypes when making decisions about treatment. While ERP and SRIs remain the mainstay of treatment regardless of the symptom subtype, the addition of cognitive therapy techniques and/or antipsychotic medications may enhance treatment response in the presence of certain features discussed in the article.

Heritability of obsessive-compulsive symptom dimensions

Recent research has shown that obsessive-compulsive symptoms (OCS) differ remarkably among patients and can be divided into several symptom dimensions. OCS are influenced by genetic components, but it is unknown to what extent these symptom dimensions are heritable. The phenotypic heterogeneity also raises the question to what extent the symptom dimensions are influenced by specific or shared genetic factors. We studied a population sample of 1,383 female twins from the Virginia Twin Registry. OCS was measured by a questionnaire with 20 items from the Padua Inventory. After factor analysis, three reliable OC symptom dimensions were retained: Rumination, Contamination, and Checking. These OC dimensions were analyzed with multivariate genetic models to investigate both the overlap and uniqueness of genetic and environmental contributions underlying OC symptom dimensions. The multivariate common pathway model provided the best description of the data. All symptom dimensions share variation with a latent common factor, that is, OC behavior. Variation in this common factor was explained by both genes (36%) and environmental factors (64%). Only the Contamination dimension was influenced by specific genes and seemed to be a relatively independent dimension. The results suggest that a broad OC behavioral phenotype exists, influenced by both genes and nonshared environment. In addition, we found evidence for specific genetic and environmental factors underlying the Contamination dimension. Use of the Contamination dimension could therefore provide a powerful approach for the detection of genetic susceptibility loci that contribute to OCS.

Environmental factors in obsessive-compulsive behavior: evidence from discordant and concordant monozygotic twins

To investigate environmental factors that protect against or exacerbate obsessive-compulsive (OC) symptoms, we selected 25 monozygotic (MZ) twin pairs discordant, 17 MZ twin pairs concordant high and 34 MZ pairs concordant low on OC symptoms from a large longitudinal Dutch sample of adult twin pairs and their family members, applying stringent criteria for OC symptomatology. Data were collected on psychopathology, family structure, health, lifestyle, birth complications and life events. Unique environmental factors were studied using within-discordant MZ pair comparisons, whereas between-concordant MZ pair comparisons were used to study environmental factors that are shared by the twins of an MZ pair. The high-scoring MZ twins of the discordant group reported more life events (especially sexual abuse) than their low-scoring twin-siblings. The between-pair comparisons showed lower birth weight in the discordant MZ pairs than in the concordant MZ pairs. Further, the concordant high MZ pairs as well as their spouses had a lower educational level than the two other groups. On scale scores of anxious-depression, neuroticism, and somatic complaints, concordant high MZ pairs showed highest scores, and the discordant MZ pairs scored intermediate, except for neuroticism, on which the high-scoring twins of discordant MZ pairs were equal to the concordant high pairs. Discordance on psychological scale scores between the concordant MZ pairs was evident from 1991 onward, and within the discordant MZ pairs from 1997 onward, confirming previous reports of an association of early-onset OC symptoms with higher genetic load. Parent scores of OC symptoms and anxious-depression suggested intermediate genetic load in the discordant MZ group. In conclusion, this study reports on both unique and shared environmental factors associated with OC symptomatology. Whether these factors operate in addition to or in interaction with genetic disposition is to be elucidated in future studies.

A self-report version of the Yale-Brown Obsessive-Compulsive Scale Symptom Checklist: psychometric properties of factor-based scales in three samples

Current research in Obsessive-Compulsive Disorder (OCD) recognizes substantial symptom heterogeneity and emphasizes dimensional assessment of core domains. This study administered a self-report version of the Yale-Brown Obsessive-Compulsive Scale Symptom Checklist to OCD patients (n=53), non-OCD psychiatric patients (n=96), and students (n=419). Factor analyses of category- versus item-level data produced different solutions (4 or 5 vs. 3 factors, respectively), but support a multidimensional framework for OCD symptoms. For between-groups analyses, the two patient groups scored significantly higher than students on nearly all dimensions. However, OCD and non-OCD patients differed significantly only on Symmetry/Ordering symptoms. These findings provide novel data concerning this instrument and suggest that most of its scales may not distinguish OCD patients clearly when administered in this manner. We provide recommendations for improving subsequent self-report versions but caution users not to over-extend its intended use.

Symptom dimensions in obsessive-compulsive disorder: implications for the DSM-V

In the absence of definitive etiological markers of vulnerability or a unitary profile of pathophysiology for obsessive-compulsive disorder (OCD), obsessive-compulsive (OC) symptom dimensions seem to offer a fruitful point of orientation. The complex clinical presentation of OCD can be summarized using a few consistent and temporally stable symptom dimensions. These can be understood as a spectrum of potentially overlapping features that are likely to be continuous with "normal" worries and extend beyond the traditional nosological boundaries of OCD. Although the understanding of the dimensional structure of obsessive-compulsive symptoms (OCS) is still imperfect, this quantitative approach to phenotypic traits has the potential to advance our understanding of OCD and may aid in the identification of more robust endophenotypes. Preliminary data suggest that these dimensional phenotypes may be useful in studies of the natural history, genetics, neurobiology, and treatment outcome of OCD. A dimensional approach is not mutually exclusive of other methods to parse the larger spectrum of disorders related to OCD. Thus far, age-of-onset of OCS and the individual's "tic-related" status seem to be particularly useful categorical distinctions. Finally, existing assessment methods are inadequate and new dimensional scales are needed to take full advantage of a dimensional approach in clinical and population-based studies.

What is the optimal way to subdivide obsessive-compulsive disorder?

The clinical presentation of obsessive-compulsive disorder (OCD) varies not only across patients but over the course of the disorder. This diversity indicates that OCD is a heterogeneous disorder, which may have an important impact on psychopathological, longitudinal, genetic, and treatment research. To better understand OCD heterogeneity, more homogeneous phenotypic descriptions are necessary to delimiting clinically meaningful subgroups of patients. Besides phenotypic descriptions, another method of delimiting OCD patient subgroups includes the search for endophenotypes (extended phenotypes) based on neurophysiological, immunological, genetic, neuropsychological, or neuroanatomic (neuroimaging) paradigms. This article will describe some strategies that deal with OCD heterogeneity, including the identification of more homogeneous phenotypical categories, an improved understanding of obsessive-compulsive symptom dimensions and how to use them as quantitative traits, and broadening the diagnostic boundaries of OCD to include other related conditions. The relevance and limitations of each approach are also discussed. Since the etiological mechanisms associated with the expressions of OCD are unknown, there is probably not one but several heuristic strategies to search for more homogeneous OCD subgroup, that combined may provide the most fruitful results.

Symptom dimensions in obsessive-compulsive disorder: prediction of cognitive-behavior therapy outcome

OBJECTIVE

A significant number of patients with obsessive-compulsive disorder (OCD) fail to benefit sufficiently from treatments. This study aimed to evaluate whether certain OCD symptom dimensions were associated with cognitive-behavioral therapy (CBT) outcome.

METHOD

Symptoms of 104 CBT-treated in-patients with OCD were assessed with the clinician-rated Yale-Brown Obsessive-Compulsive Scale symptom checklist. Logistic regression analyses examined outcome predictors.

RESULTS

The most frequent OCD symptoms were aggressive and contamination obsessions, and compulsive checking and cleaning. Patients with hoarding symptoms at baseline (n = 19) were significantly less likely to become treatment responders as compared to patients without these symptoms. Patients with sexual and religious obsessions tended to respond less frequently, although this failed to reach statistical significance (P = 0.07). Regression analyses revealed that higher scores on the hoarding dimension were predictive of non-response, even after controlling for possible confounding variables.

CONCLUSION

Our results strongly indicate that in-patients with obsessive-compulsive hoarding respond poorly to CBT.

Dissociation and symptom dimensions of obsessive-compulsive disorder. A replication study

BACKGROUND

Obsessive-compulsive disorder (OCD) is a phenotypically very heterogeneous disease with high rates of comorbid psychiatric pathology. Previous studies have indicated that OCD is associated with higher levels of dissociation. The aims of the present study were to replicate and extend previous findings of a significant link between certain OCD symptom dimensions and dissociation.

METHODS

The study sample comprised 50 patients with OCD, as confirmed by the Mini International Neuropsychiatric Interview,who had a score of at least 16 on the Yale-Brown Obsessive-Compulsive Scale. All patients were assessed with the short version of the Hamburg Obsessive-Compulsive Inventory and the Dissociative Experience Scale (DES). Correlation analyses and multiple regression analyses were performed to evaluate the relationship between OCD symptom dimensions and dissociation.

RESULTS

The checking dimension was most strongly related to dissociation, followed by the symmetry/ordering and obsessive thoughts dimensions. In contrast, no significant relationship was found between dissociation and the washing/cleaning, counting/touching, and aggressive impulses/fantasies dimensions. Multiple regression analyses revealed that: (1) only the checking dimension showed an independent positive correlation with dissociation, and (2) only higher scores on the DES subscale "amnestic dissociation" were associated with higher scores for checking compulsions.

CONCLUSIONS

Our results suggest that there might be a specific link between checking behavior and dissociation in OCD. Moreover, checking compulsions seem to be particularly associated with amnestic dissociation. Further studies focusing on amnestic dissociation as a potentially important determinant of checking compulsions are warranted.

Deconstructing obsessive-compulsive disorder: a multidimensional perspective

PURPOSE OF REVIEW

The aim of this article is to critically summarize the most promising attempts to split obsessive-compulsive disorder into subgroups based on clinical characteristics (i.e. age of onset, presence of comorbid tics, positive family history) and symptom theme, with particular emphasis on the latter.

RECENT FINDINGS

Attempts to split obsessive-compulsive disorder into mutually exclusive sub-groups based on clinical characteristics have been useful but not exempt of problems. The complex clinical presentation of the condition can be reduced to a few consistent, temporally stable symptom dimensions that can coexist in any given individual. Researchers have begun to investigate the genetics and neural mechanisms of these symptom dimensions and to develop specific assessment and treatment protocols for each particular problem.

SUMMARY

The multidimensional model of obsessive-compulsive disorder proposes a middle ground between the 'lumping' and 'splitting' perspectives. The disorder can be better understood as a spectrum of multiple potentially overlapping syndromes. The most fruitful research strategy will be to examine the common and specific etiological factors implicated in each symptom dimension.