Contamination-based Obsessive-compulsive Disorder Research Articles

Disgust-reduction evaluative conditioning (DREC) and brain stimulation in patients with contamination-based obsessive-compulsive disorder: a protocol for a randomized control trial

BackgroundThe negative emotional valence of a stimulus can be altered if paired with a pleasant stimulus, a phenomenon referred to as evaluative conditioning. Disgust, as a central emotion in obsessive-compulsive disorder (OCD), particularly in the contamination subtype, may be an appropriate target for such a method. We know that disgust processing and OCD pathophysiology share in some brain areas, including the orbitofrontal cortex, as the neuromodulation techniques targeted in this area have been able to decrease OCD symptoms. We aim to conduct a randomized clinical trial to investigate the evaluative conditioning effect on disgust reduction in patients with contamination-based OCD when administered with or without neuromodulation targeted orbitofrontal cortex.MethodIn a single-blind randomized control trial (RCT), 55 patients with contamination-based OCD will be randomly assigned to four arms. In a factorial design, they will receive 10 sessions of evaluative conditioning training (either sham or real) plus cathodal transcranial direct current stimulation (tDCS) over the orbitofrontal cortex (either sham or real). The intensity of disgust experience and clinical symptoms will be investigated as primary outcomes and quantitative electroencephalogram and cognitive functions as secondary outcomes. The data will be collected at three assessment levels: baseline, after completing intervention sessions, and 2-month follow-up.DiscussionThe present RCT is the first study that applies evaluative conditioning training in the OCD clinical sample. It will clarify the effect of the evaluative conditioning method alone and with tDCS on disgust reduction in patients with contamination-based OCD. It will provide initial evidence for such an emotion modulation method in the OCD population. The effect of this emotion-focused protocol on cognitive functions and electroencephalogram components is also of interest.Trial registrationClinicalTrials.gov, NCT05907369. Registered on 16 June 2023. Retrospectively registered.

Anti-Disgust Cognitive Behavioral Therapy for Contamination-Based Obsessive Compulsive Disorder: A Randomized Controlled Clinical Trial.

Background: Disgust is a strong and persistent emotion that frequently occurs during exposure-based treatments for contamination-based obsessive compulsive disorder (C-OCD). This study aimed to examine the efficacy of augmenting cognitive behavioral therapy (CBT) with a novel type of anti-disgust cognitive intervention in reducing the severity of OCD, disgust propensity/sensitivity, and refusal rate of exposure and response prevention, while simultaneously increasing acceptance of disgust. Materials and Methods: Fifty-five individuals with C-OCD (mean age 28.1 years, SD = 3.52; 77% female) were randomly assigned to 15 weekly sessions of anti-disgust plus CBT (AD-CBT) or CBT alone. They were evaluated for outcomes four times (pretreatment, prior to exposure and response prevention (ERP) sessions, posttreatment, and three-month follow-up), and mixed-design ANOVAs were used to analyze the data. Results: The findings indicated that when compared to CBT alone, AD-CBT significantly reduced OCD severity, disgust propensity/sensitivity, and concurrently increased disgust acceptance (p < 0.001). Additionally, engaging in an anti-disgust cognitive intervention was associated with lower ERP refusal rate (4% vs. 16%). The superiority of AD-CBT over CBT persisted through the three-month follow-up period. Conclusions: The current study suggests that supplementing CBT for C-OCD with an anti-disgust cognitive intervention significantly increased acceptance of disgust and decreased the refusal rate of ERP, OCD severity, and disgust-related factors.

A brief course of digitally delivered cognitive behavioural therapy for the treatment of blood contamination-based obsessive-compulsive disorder: a structured case report

Abstract The lifetime prevalence of OCD in the UK is estimated to be between 1 in 100 and 1 in every 50 people. It is therefore necessary to explore innovations in practice to expand the reach of the gold standard therapeutic approaches of exposure with response prevention (ERP) and cognitive behavioural therapy (CBT). The COVID-19 pandemic has facilitated such innovations with several services accommodating changes to routine practice by utilising digital platforms to provide videoconference-delivered therapy. Despite a growing evidence base demonstrating efficacy and scope for the use of videoconference-delivered CBT for obsessive-compulsive disorder (OCD), there remains qualitative research collated from clinicians which suggests that a lack of practitioner confidence and a low belief in positive outcomes are barriers to adopting remote therapy practices for clinicians. Therefore, this structured case report describes the assessment, formulation, intervention and outcome of an 11-week videoconference-delivered therapeutic intervention. Reflections are made regarding the use of the digital platform throughout the intervention, alongside the strengths and difficulties of applying videoconference-delivered CBT for OCD. Key learning aims (1) To illustrate a digital treatment of OCD through flexible application of the current evidence base. (2) To gain an understanding of the strengths and weaknesses of delivering digital out-patient CBT for OCD. (3) To consider the utility of structured case reports in routine practice when delivering digital therapy.

Exposure therapy in a virtual environment: Validation in obsessive compulsive disorder

Exposure and response prevention (ERP) is the current first-line psychological treatment for Obsessive-compulsive disorder (OCD). However, substantial inter-individual variability exists in treatment outcomes, including inadequate symptom improvements, and notable refusal and attrition rates. These are driven, in part, by impracticalities in simulating intrusive thoughts within clinical settings. Virtual reality (VR) offers the potential of overcoming these limitations in a manner that allows for finely controlled anxiety-provoking scenarios to be created within supportive clinical settings. To validate the potential of VR for treating contamination-based OCD, 22 patients undertook a VR ERP session and a matched session of the current gold-standard of in vivo ERP. In VR, patients were immersed within a contamination environment that permitted flexible delivery of customisable, graded exposure tasks. The VR environment utilised HTC Vive hardware, to allow for patients to both interact with, and physically move through the environment. Subjective and objective measures of distress were recorded, including heart and respiration rates. These measures indicate virtual and in vivo ERP sessions provoke consistent anxiety profiles across an exposure hierarchy. Virtual exposure was advantageous for engagement and adherence to tasks, and the therapeutic alliance was upheld. VR is a promising mechanism for ERP in contamination OCD.

Evaluating the mediating effects of perceived vulnerability to disease in the relation between disgust and contamination-based OCD

Contamination-based obsessive-compulsive disorder (OCD) is thought to develop and be maintained by excessive propensity to experience disgust, particularly in response to perceived contaminants, and dysfunctional threat appraisals pertaining to illness. The present studies attempted to integrate these lines of research by testing the degree to which contamination-based OCD is associated with individual differences in disgust propensity and sensitivity, affective distress in response to perceived contaminants, and perceived threat of illness. In Study 1, a convenience sample of 185 adults completed self-report scales assessing obsessive-compulsive symptoms, disgust propensity and sensitivity, germ aversion, and perceived infectability. Multivariate regression showed that disgust propensity and germ aversion were the only significant predictors of contamination-based obsessions and compulsions. Exploratory analyses suggested that there was a significant indirect effect of disgust propensity on contamination-based obsessions and compulsions via germ aversion. Findings from Study 1 were replicated using a sample of twenty-six obsessive-compulsive participants. Despite the substantially smaller sample, the proportion of the total effects attributable to the mediating effect of germ aversion was comparable, consistent with a significant partial mediation in both samples. These results together suggest that contamination-based OCD symptoms are likely maintained and motivated by basic affective processes.

The Role of Disgust and Threat in Contamination-Related Obsessive–Compulsive Disorder

AbstractTheoretical models suggest that the emotion disgust or threat overestimates are important in the aetiology and maintenance of contamination-based obsessive–compulsive disorder. In the current study, both threat and disgust were manipulated and 115 non-clinical participants (mean age 20.46 years, 94 females) were randomly allocated to one of four conditions: high-disgust/low-threat (n = 29), high-disgust/high-threat (n = 29), low-disgust/low-threat (n = 27), and low-disgust/high-threat (n = 30). Participants completed a hierarchical Behavioural Avoidance Task (BAT). Those in the high-threat and high-disgust conditions completed less BAT steps and showed more latency to begin each step than those in the low-threat and low-disgust conditions. A significant interaction effect was observed for the high-disgust/high-threat condition as significantly more task avoidance was found. However, handwashing duration was not significantly different between the high and low-disgust conditions or the high and low-threat conditions. The overall low mean washing duration of 30 s possibly due to the testing conditions and/or the ethnic heterogeneity of the sample may account for these results. There were also no significant differences in the level of anxiety for participants in the high-threat compared with the low-threat conditions. It is possible that anxiety remained relatively low across conditions as a result of the graduated BAT. Future research and theoretical and clinical implications are discussed.

Indices of change in exposure and response prevention for contamination-based OCD

Few studies have examined indices of change in treatment for obsessive compulsive disorder (OCD). The current study evaluated within- and between-session trajectories of fear, disgust, and urge to wash in exposure and response prevention (ERP) for contamination-based OCD and tested whether change in these indices were associated with treatment outcomes. Forty-one participants (75.6% female) engaged in three sessions of ERP for contamination OCD. Participants provided ratings of fear, disgust, and urge to wash during each session, and contamination symptoms were assessed at pre- and post-treatment and two-week follow-up. Fear, disgust, and urge to wash all significantly decreased both within and between sessions. Both fear and disgust declined significantly faster than urge to wash within session, though declines in fear and disgust did not significantly differ from each other. Within-session changes in fear were significantly associated with reduced symptoms at post-treatment, whereas within-session changes in disgust were associated with symptoms at two-week follow-up. The current study highlights the roles of fear and disgust in the context of ERP as unique indicators of treatment outcome for contamination-based OCD. Only within-session fear was uniquely associated with treatment outcome at post, while within-session disgust predicted outcome at follow-up. Theoretical and clinical implications are discussed.

The Mediational Roles of Law of Contagion and Threat Estimations in the Relation Between Disgust and Contamination-based OCD Symptoms

Objectives: The law of contagion is one of the sympathetic of magic principles and is a cognitive distortion related to disgust. To explain how disgust can lead to contamination Obsessive-Compulsive Disorder (OCD) symptoms, this study assumes that the emotion of disgust can activate the law of contagion, which in turn may motivate threat estimations that finally results in OCD symptoms. Methods: This study has a correlational research design. Participants were 495 students (59% women) from Olum Tahghighat University that recruited through convenience sampling. All the participants completed all the questionnaires in the same order: Threat estimation scenarios, the Vancouver Obsessional Compulsive Inventory Contamination Scale (VOCI-C), negative-spiritual contagion subscale from Contagion Sensitivity Scale (CSS), and core disgust subscale from Disgust Scale (DS). This model was examined through Structural Equation Modeling (SEM). Results: The finding revealed that the proposed model had a good fit based on reported indices: χ2, CMIN/DF, GFI, CFI, AGFI, RMSEA. Conclusion: There are mediational roles for the law of contagion and threat estimations in the relation between disgust and OCD symptoms. The proposed psychopathological model can help to promote the disgust theory in OCD and may have implications for cognitive behavioral therapy.

Interpretation bias and contamination-based obsessive-compulsive symptoms influence emotional intensity related to disgust and fear.

Biased processing of disgust-related stimuli is increasingly discussed in addition to fear-related processing as a maintenance factor for contamination-based obsessive-compulsive disorder (C-OCD). However, the differential impact of fear and disgust on biased processing in C-OCD is not yet completely understood. Because it is difficult to distinguish the two emotions in self-report assessment by directly addressing the specific emotions, a text paragraph-based interpretation bias paradigm was applied to more implicitly assess emotions. For the text-based interpretation bias paradigm, disgust-related, fear-related, disgust-fear-ambiguous and neutral text paragraphs describing everyday life situations were developed and validated in a pre-study (N = 205). Fifty-nine healthy participants watched either disgust- or fear-inducing movies and afterwards rated their experienced emotional response to the text paragraphs. The results show that fear and disgust components of an emotional response to mixed-emotional situations are strongly influenced by the situational context, and across the levels of trait contamination fear people did not differ in their fear experiences to everyday situations (which was overall strong), but in their disgust experiences. These findings highlight the strength of situational context on interpretation bias for mixed-emotional disorders and the important role of disgust for C-OCD.

Specificity of Disgust in the Prediction of Behavioral Avoidance of Possible Contaminants

Individual differences related to disgust have been implicated in a host of psychiatric disorders, including obsessive–compulsive disorder (OCD). Theory suggests that individual differences in disgust propensity and, perhaps, sensitivity, make individuals more prone to experience disgust when confronted with potential contaminants, which then motivates avoidance of possible contaminants or safety behaviors aimed at removing contaminants when avoidance is not possible. However, no study has concurrently examined the relations of disgust propensity and state disgust with avoidance of contaminant-based stimuli. The present study recruited a sample of 90 undergraduate participants and utilized a multimodal assessment (including self-reported disgust and a behavioral approach task using possible contaminants) to examine the direct and indirect effects of disgust propensity, disgust sensitivity, trait anxiety, state disgust, and state anxiety on avoidance of the stimuli. Results suggested disgust propensity was the only individual difference variable to significantly correlate with avoidance. Although state disgust and state anxiety were significantly correlated with disgust propensity and avoidance, only state disgust significantly mediated the effects of disgust propensity on avoidance. These findings suggest that disgust propensity and state disgust may lead to avoidance of possible contaminants, thereby perpetuating contamination fears and aversions. As such, these results have implications for the etiology of contamination-based OCD. Additional research with clinical samples and more objective measures of state emotional experiences are needed.

Prospective associations between disgust proneness and OCD symptoms: Specificity to excessive washing compulsions

Although considerable evidence has linked disgust proneness (DP) to obsessive-compulsive disorder (OCD), few studies have examined the extent to which DP predicts OCD symptoms over time. Further, it remains unclear if DP is a risk factor for the contamination subtype of OCD specifically or if it is prospectively associated with other OCD symptom subtypes. The present study sought to address these gaps in the literature with a large sample of unselected community participants (n = 497) that completed measures of DP and OCD symptoms monthly over a 6-month period. Latent growth analysis revealed that initial levels of DP were associated with higher initial level of total OCD symptoms when controlling for depression, but not the slope of change in total OCD symptoms over time. Initial levels of total OCD symptoms were also associated with higher initial levels of DP when controlling depression, but not the slope of change in DP over time. Examination of symptom specificity revealed that initial levels of DP were associated with initial levels of washing, neutralizing, obsessing, ordering, and hoarding symptoms. However, initial levels of DP were associated only with the slope of change in the washing subtype when controlling for depression such that high initial levels of DP were associated with steeper increases in washing symptoms of OCD over the 6-month period. These findings suggest that although DP may have concurrent associations with symptoms of OCD more broadly, prospective associations are specific to the contamination/washing subtype of OCD. The implications of these findings for the etiology and treatment of contamination-based OCD are discussed.

A multi-method analysis of incompleteness in behavioral treatment of contamination-based OCD

Contamination fear and washing compulsions are among the most common symptoms of obsessive compulsive disorder (OCD). Though these symptoms have traditionally been viewed as being driven by a desire to avoid harm, recent research has highlighted the importance of feelings of incompleteness (INC) or not-just right experiences (NJREs) in this symptom dimension. However, no study to date has examined the extent to which INC/NJREs may be associated with treatment response for contamination symptoms. The current study used a multi-method approach to examine the role of INC/NJREs in treatment of contamination symptoms. Participants (n = 88) with elevated contamination symptoms, half of whom met for an OCD diagnosis, engaged in three sessions of exposure and response prevention (ERP) targeting contamination fears, and completed self-report and in vivo measures of INC/NJRES and contamination symptoms. ERP was associated with significant reductions in INC/NJREs. Further, changes in INC were associated with changes in contamination symptoms, independent of changes in harm avoidance. Greater discomfort in response to an in vivo NJRE task at pre-treatment predicted poor treatment response, though a self-report measure of INC did not predict response. These findings provide novel evidence for the importance of INC/NJREs in contamination-based OCD and its treatment.

Disgust sensitivity mediates the effects of race on contamination aversion

African Americans report greater contamination aversion than European Americans. Few studies have attempted to identify potential causes for this elevated contamination aversion, though existing research and theory suggests this may be partly due to concomitant heightened disgust sensitivity. The present study examined the relations between race, disgust sensitivity, and contamination aversion among African and European Americans. A convenience sample of four-hundred and twenty-nine participants completed the Disgust Scale – Revised (DS-R) and the Padua Inventory – Revised (PI-R). African Americans endorsed greater disgust sensitivity (DS- R total) – particularly on the core and contamination subscales of the DS-R – and scored higher on the contamination subscale of the PI-R (but not on other subscales) than European Americans. Mediational analyses revealed a significant total effect of race on contamination aversion and a significant indirect effect of race on contamination aversion through disgust sensitivity; the direct effect of race on contamination aversion remained significant even after controlling for race. These findings suggest that elevated contamination aversions among African Americans may be partly due to elevated disgust sensitivity. If confirmed with larger and clinical samples, and more robust experimental methods, this relationship may prove to have implications for the treatment of contamination-based obsessive-compulsive disorder (OCD) among African Americans.

Effects of exposure to erotica on disgust: A preliminary test among contamination-fearful individuals

Disgust has been implicated in the fear of contamination that is commonly observed in obsessive-compulsive disorder (OCD). However, basic and treatment-oriented research has shown that disgust is resistant to extinction among those with a fear of contamination. Consequently, there is growing interest in discovering novel approaches to targeting heightened disgust responding among those with OCD. Recent experimental research suggests that sexual arousal may inhibit disgust responding. Accordingly, the present study examines the effects of exposure to erotica on verbal reports of disgust and behavioral avoidance in a contamination-fearful sample of adults. Participants viewed sexually arousing, positively arousing, or neutral films and participated in a series of sexually relevant and non-sexually relevant behavioral approach tasks. Participants also gave ratings of disgust before and after completing each behavioral task. Although no group differences were observed for the number of steps completed on the behavioral approach tasks, those who viewed sexually arousing films reported significantly less change in disgust throughout the behavioral approach task compared to those who viewed positively arousing and neutral films. The potential clinical implications of the effects of sexual arousal on disgust responding in contamination-based OCD are discussed.

Changing disgust through imagery rescripting and cognitive reappraisal in contamination-based obsessive-compulsive disorder

Contamination-related obsessive-compulsive disorder (C-OCD) is characterized by strongly experienced disgust and fear, in response to potentially contaminating stimuli. Both emotions differ in their susceptibility for change by habituation and extinction, which are important processes for the success of exposure therapy. Even though the response rates for exposure therapy for C-OCD are very good, it seems promising to test additional therapeutic techniques which target disgust more directly. Therefore, imagery rescripting and cognitive reappraisal were evaluated for their potential to change levels of disgust (within-subject), in the two-session laboratory study with 30 participants, with diagnosed C-OCD, and 30 matched, healthy controls (between-subject), presented. The results show that both emotion-regulation strategies reduced disgust better than a non-intervention control task (counting fishes), across all the participants. Therefore, both strategies seem to be applicable and effective for reducing disgust, in the short term, in participants with diagnosed C-OCD. The implications of these findings for the experimental approach and for the clinical treatment of C-OCD, are discussed.

The effects of cognitive reappraisal on conditioned disgust in contamination-based OCD: An analogue study

Experimental research has shown that conditioned disgust is resistant to extinction, which may account for the slower habituation to disgust relative to fear in contamination-based obsessive-compulsive disorder (OCD). However, few studies have examined the efficacy of interventions that may attenuate conditioned disgust responses. Studies of cognitive reappraisal have demonstrated that reinterpreting a stimulus can alter emotional responding. This technique is based on cognitive theories which suggest that anxiety disorders arise from biased cognitions; therefore, changing a person’s thoughts will elicit durable changes in emotional responses. Given the demonstrated effectiveness of cognitive reappraisal, the present study examined whether cognitive reappraisal would attenuate conditioned disgust responses. We conditioned participants high in contamination fear (n=55) using images of neutral food items (conditioned stimuli; CS) paired with videos of individuals vomiting (unconditioned stimuli; US) while we obtained subjective disgust reports. After conditioning, half of the participants were randomly assigned to cognitive reappraisal training aimed at decreasing their emotional response to the US and CS, while the other half received no such training. The findings showed that cognitive reappraisal participants demonstrated a reduction in learned disgust across sessions and further benefited from extinction. These findings suggest that cognitive reappraisal may be an effective strategy for attenuating learned disgust.

Pavlovian disgust conditioning as a model for contamination-based OCD: Evidence from an analogue study

Pavlovian fear conditioning provides a model for anxiety-related disorders, including obsessive-compulsive disorder (OCD). However, disgust is the predominant emotional response to contamination, which is a common theme in OCD. The present study sought to identify disgust conditioning abnormalities that may underlie excessive contamination concerns relevant to OCD. Individuals high and low in contamination concern (HCC, n = 32; LCC, n = 30) completed an associative learning task in which one neutral face (conditioned stimulus; CS+) was followed by a disgusting image (unconditioned stimulus; US) and another neutral face (CS–) was unreinforced. Following this acquisition procedure, there was an extinction procedure in which both CSs were presented unreinforced. The groups did not show significant differences in discriminant responding to the CSs following acquisition. However, following extinction, the HCC group reported less reduction in their expectancy of the US following the CS+, and also reported greater disgust to the CS+, compared to the LCC group. Increased disgust to the CS+ following both acquisition and extinction was correlated with increased symptoms of contamination-based OCD and increased disgust sensitivity. Additionally, disgust sensitivity mediated group differences in disgust responding to the CS+ at acquisition and extinction. Also, failure to adjust US expectancy in response to extinction partially mediated group differences in disgust to the CS+ following extinction. Together, these findings suggest that excessive contamination concerns observed in OCD may be related to difficulty inhibiting acquired disgust, possibly due to elevated disgust sensitivity that characterizes the disorder.

Predicting response to cognitive behavioral therapy in contamination-based obsessive–compulsive disorder from functional magnetic resonance imaging

Although cognitive behavioral therapy (CBT) is an effective treatment for obsessive-compulsive disorder (OCD), few reliable predictors of treatment outcome have been identified. The present study examined the neural correlates of symptom improvement with CBT among OCD patients with predominantly contamination obsessions and washing compulsions, the most common OCD symptom dimension. Participants consisted of 12 OCD patients who underwent symptom provocation with contamination-related images during functional magnetic resonance imaging (fMRI) scanning prior to 12 weeks of CBT. Patterns of brain activity during symptom provocation were correlated with a decrease on the Yale-Brown Obsessive Compulsive Scale (YBOCS) after treatment, even when controlling for baseline scores on the YBOCS and the Beck Depression Inventory (BDI) and improvement on the BDI during treatment. Specifically, activation in brain regions involved in emotional processing, such as the anterior temporal pole and amygdala, was most strongly associated with better treatment response. By contrast, activity in areas involved in emotion regulation, such as the dorsolateral prefrontal cortex, correlated negatively with treatment response mainly in the later stages within each block of exposure during symptom provocation. Successful recruitment of limbic regions during exposure to threat cues in patients with contamination-based OCD may facilitate a better response to CBT, whereas excessive activation of dorsolateral prefrontal regions involved in cognitive control may hinder response to treatment. The theoretical implications of the findings and their potential relevance to personalized care approaches are discussed.

Imagery in mental contamination: A questionnaire study

ObjectivesIntrusive imagery is hypothesised to evoke feelings of contamination and urges to wash. This study aimed to (1) develop a questionnaire to assess imagery associated with contamination fears; and (2) compare contamination imagery in a sample of people with contamination based obsessive–compulsive disorder (C-OCD) with a non-clinical student sample. MethodsNon-clinical students (n=45) and people with C-OCD and contamination fears (n=45) completed a self-report questionnaire designed to assess images associated with contamination. ResultsCompared to non-clinical participants, people with C-OCD reported images associated with contamination that were more vivid, harder to dismiss and distressing. Participants with contamination fears reported images that directly evoked feelings of dirtiness and triggered compulsive washing behaviours. A small number of participants reported beneficial images that reduced feelings of contamination. ConclusionsThese preliminary findings indicate that imagery can evoke feelings of contamination. However, future research is needed to establish the nature and causative role of imagery in mental contamination. Questionnaire methods may be useful for clinical assessment of imagery associated with contamination fears.

Disgust and Fear Responding in Contamination-Based Obsessive-Compulsive Disorder During Pictorial Exposure

The emotion of disgust has been implicated in the development and maintenance of contamination-based obsessive-compulsive disorder (OCD). In the present study nonclinical participants with high (n=26) and low (n=28) levels of OCD contamination symptoms were exposed to 2 categories of disgust stimuli (blood injury and body waste) across 4 blocks using standardized disgust images. Self-report disgust and fear were recorded, as well as cardiovascular heart rate. In both groups, an initial primary disgust reaction was observed. Self-report disgust and fear, but not heart rate deceleration, was greater in the high symptom group. The high symptom group showed reductions in heart rate deceleration, whereas the low symptom group did not. Significant differences in self-report changes across time were observed between the groups, with fear increasing to a greater extent for high contamination fearful individuals when viewing body waste images. The implications of these findings for theoretical models and clinical treatment of OCD with prominent contamination symptoms are discussed.