The inference-based approach to obsessive-compulsive disorder: A comprehensive review of its etiological model, treatment efficacy, and model of change

The role of feared possible selves in the relationship between inferential confusion and obsessive-compulsive symptoms: A replication and extension in a clinical sample

OBJECTIVES

The feared possible self refers to an imagined version of self that one is afraid of being or becoming. Previous evidence has shown that dysfunctional reasoning (i.e., inferential confusion) is associated with obsessive-compulsive disorder (OCD) symptoms, which is partially mediated by a feared self. However, the evidence is reliant on non-clinical samples and a general measure of the feared self.

METHODS

Using a cross-sectional design, the current study attempted to replicate and extend this literature in a sample clinically diagnosed with OCD (n = 350) to assess the pathway from inferential confusion to OCD symptoms when feared self is accounted for as a mediator, particularly the individual dimensions of feared self (i.e., corrupted, culpable, and malformed feared selves). Participants completed a structured clinical interview for DSM-5, as well as measures of inferential confusion (Dysfunctional Reasoning Processes Task), obsessive beliefs, feared self, OCD symptoms, and psychological distress.

RESULTS

Inferential confusion directly, and indirectly through the feared corrupted self, affected OCD symptoms, even after adjusting for obsessive beliefs, psychological distress, and comorbidity. However, the feared culpable and malformed selves did not play a role in this pathway.

CONCLUSIONS

The study underscores that the feared corrupted self links inferential confusion to OCD symptoms, translating to the need to consider both dysfunctional reasoning processes and this specific feared self in clinical settings when treating OCD. Furthermore, the study provides more support for the inference-based approach (IBA) to OCD.

The COGINS: A New Measure of Cognitive Insight in Obsessive-Compulsive and Related Disorders

Research suggests that individuals with obsessive-compulsive and related disorders (OCRDs) with lower insight show a poorer response to cognitive behavioral therapy and might benefit from alternative treatments. However, there are inconsistencies in the literature regarding the definition and measurement of insight. This study endeavored to evaluate the psychometric properties of the Cognitive Obsessional Insight Scale (COGINS), a novel self-report measure of cognitive insight in OCRDs. The sample comprised 166 participants with a diagnosis of obsessive-compulsive disorder or body dysmorphic disorder enrolled in clinical trials. Participants completed the COGINS and a questionnaire battery at baseline and posttreatment. The COGINS demonstrated good internal consistency, test-rest reliability, convergent validity with other OCRD-specific measures of insight, positive associations with OCRD symptomatology, and had a moderating effect on treatment response. The COGINS is a valid and reliable practical tool to measure cognitive insight in OCRDs and might help toward clarifying the role of cognitive insight in this population.

What makes an obsession? A systematic-review and meta-analysis on the specific characteristics of intrusive cognitions in OCD in comparison with other clinical and non-clinical populations

The Diagnostic and Statistical Manual 5th ed. defines obsessions in obsessive-compulsive disorder (OCD) as frequent, persistent, intrusive, unwanted thoughts that provoke anxiety and distress and lead to attempts to neutralize them with either thoughts or actions. However, no systematic review has yet evaluated characteristics that are specific to obsessions occurring in OCD. The aim of the current systematic review and meta-analysis was to investigate the specific features of obsessions occurring in OCD by comparing them to both obsessionally and non-obsessionally-themed intrusions in non-clinical and other clinical populations. Based on a registered protocol, 832 records were found, of which 15 were included in the systematic review and meta-analysis, with a total of 1891 participants. Obsessionally-themed intrusions that occur among those with OCD caused more distress, guilt, negative emotion and interference as compared to similarly-themed intrusions that occur within the general population. The distinction between obsessionally-themed intrusions among those with OCD as compared to those occurring in anxiety and depressive disorder primarily revolves around a higher level of persistence, pervasiveness and distress associated with their occurrence. Further, unacceptability, uncontrollability, ego-dystonicity, alienness, guilt, the form of the intrusion, association with the self and lack of any basis in reality also differentiates between obsessions and intrusions occurring in other disorders. Obsessions share many characteristics with thoughts occurring in other disorders and can be distinguished using a combination of characteristics specific to individual disorders.

The relevance of dysfunctional reasoning to OCD and its treatment: Further evidence for inferential confusion utilizing a new task-based measure

BACKGROUND AND OBJECTIVES

Previous research has highlighted the role of dysfunctional reasoning processes (i.e. "inferential confusion") in the development and maintenance of Obsessive-Compulsive Disorder (OCD). Inferential confusion has previously been found to be a unique predictor of OC symptoms and has shown specificity for OCD. However, these findings have primarily relied on a single self-report questionnaire, and only a limited number of experimentations have been conducted to establish the specificity of inferential confusion to OCD with alternate measures. The current paper demonstrates the relationship of inferential confusion with OCD symptoms in clinical samples by using a task-based measure of inferential confusion.

METHODS

Sixty-four OCD participants, as well as thirty anxious and thirty-four healthy controls completed the recently developed Dysfunctional Reasoning Processes Task (DRPT) and related measures. Thirty-five OCD participants then completed sixteen sessions of cognitive-behavioural therapy (CBT) and completed the same measures post-treatment.

RESULTS

As predicted, dysfunctional reasoning was significantly more elevated for those with OCD relative to control groups. Reduced levels of dysfunctional reasoning during CBT were significantly associated with successful treatment outcome.

LIMITATIONS

Clinical implications should be interpreted with caution due to the relatively small sample size.

CONCLUSIONS

Our findings support the notion that inferential confusion is an important cognitive factor particularly relevant to OCD that needs to be directly addressed as a mechanism of change in CBT.

Formal vs. intuitive categorization and obsessive-compulsive symptoms

BACKGROUND AND OBJECTIVES

Obsessive-compulsive disorder (OCD) is often characterized by rigidity regarding rules and perfectionism, which suggests a formal reasoning style. However, other characterizations suggest an overreliance on internal cues for behavior termination, which suggests a more intuitive reasoning style. We examine reasoning styles in OCD by assessing categorization preferences traditionally classified to rule-based and family resemblance categorization.

METHOD

An initial study (n = 41) and an online replication (n = 85) were conducted. In both studies, groups scoring high and low on OCD symptoms were compared. Categorization preferences and confidence ratings were examined via a modification of a classic categorization task. The task was administered in three conditions: under time limits, with no time limits, and with explicit explanation of both categorization styles.

RESULTS

Aggregating results from both studies showed that obsessive-compulsive symptoms were associated with a reduced preference for rule-based categorization reflecting a tendency towards a more intuitive, non-formal reasoning style. This preference was apparent even when rules were explicitly described. Group differences regarding confidence were inconclusive.

LIMITATIONS

Generalizing results to the clinical population requires further research, and specificity to OC symptoms should be determined.

CONCLUSIONS

Challenging the expected association between OCD and rigidity and perfectionism, findings support suggestions that OCD reasoning strays from formal reasoning. This may explain some of the subjective and idiosyncratic rules adopted by individuals with OCD.

Evaluation of Inference-Based Cognitive-Behavioral Therapy for Obsessive-Compulsive Disorder: A Multicenter Randomized Controlled Trial with Three Treatment Modalities

INTRODUCTION

Inference-based cognitive-behavioral therapy (I-CBT) is a specialized psychological treatment for obsessive-compulsive disorder (OCD) without deliberate and prolonged exposure and response prevention (ERP) that focuses on strengthening reality-based reasoning and correcting the dysfunctional reasoning giving rise to erroneous obsessional doubts and ideas.

OBJECTIVE

The present study aimed to evaluate the effectiveness of I-CBT through a comparison with appraisal-based cognitive behavioral therapy (A-CBT) and an adapted mindfulness-based stress reduction (MBSR) intervention.

METHODS

This was a two-site, parallel-arm randomized controlled trial (RCT) comparing I-CBT with A-CBT. The MBSR intervention acted as a non-specific active control condition. Following formal evaluation, 111 participants diagnosed with OCD were randomly assigned. The principal outcome measure was the Yale-Brown Obsessive-Compulsive Scale.

RESULTS

All treatments significantly reduced general OCD severity and specific symptom dimensions without a significant difference between treatments. I-CBT was associated with significant reductions in all symptom dimensions at post-test. Also, I-CBT led to significantly greater improvement in overvalued ideation, as well as significantly higher rates of remission as compared to MBSR at mid-test.

CONCLUSIONS

I-CBT and MBSR appear to be effective, alternative treatment options for those with OCD that yield similar outcomes as A-CBT. I-CBT may have an edge in terms of the rapidity by which patients reach remission, its generalizability across symptom dimension, its potentially higher level of acceptability, and effectiveness for overvalued ideation. Future research is needed to assess whether additional alternative treatments options can help to increase the number of people successfully treated.

Understanding why people with OCD do what they do, and why other people get involved: supporting people with OCD and loved ones to move from safety-seeking behaviours to approach-supporting behaviours

The distress inherent in obsessive compulsive disorder (OCD) can often lead to partners, family members and friends becoming entangled with the OCD in terms of being drawn into performing certain behaviours to try and reduce the distress of their loved one. In the past this has often been referred to somewhat pejoratively as collusion, or more neutrally as accommodation. In this paper we emphasise that this is usually a natural human response to seeing a loved one in distress and wanting to help. This paper provides detailed clinical guidance on how to understand this involvement and how to include others in the treatment of OCD along with practical tips and hints around potential blocks that may require troubleshooting. It also details the relatively recently introduced concept of approach-supporting behaviours, and provides guidance on how to distinguish these from safety-seeking behaviours. The ‘special case’ of reassurance seeking is also discussed.

Key learning aims

(1)

Therapeutic Alliance and Treatment Outcome in Cognitive Behavior Therapy for Obsessive-Compulsive Disorder

OBJECTIVE

Therapeutic alliance has consistently been found to predict treatment outcomes across various psychotherapies and patient diagnosis. However, the relationship between therapeutic alliance and outcome in Cognitive Behavioral Therapy (CBT) has shown mixed results. This study investigated the impact of different aspects of therapeutic alliance in CBT for Obsessive-Compulsive Disorder (OCD).

METHOD

Data from two previously completed randomized controlled trials of 208 patients with OCD and their therapists were analyzed. Therapeutic alliance was assessed at week 4 of treatment with the patient-rated and therapist-rated Working Alliance Inventory (WAI), which includes three subscales to measure alliance domains (Goal, Task and Bond). Higher WAI score reflects a better therapeutic relationship. OCD severity was rated by independent assessors at baseline and post-treatment using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). Linear regression analyses were used to examine the effects of the different aspects of therapeutic alliance on treatment outcome, adjusted for baseline symptom severity.

RESULTS

A higher total WAI score as rated by therapists significantly predicted a lower post-treatment Y-BOCS. Further, higher scores on the Goal and Task subscales of the WAI were associated with lower post-treatment severity. However, these significant outcomes reflected only small effect sizes.

CONCLUSIONS

In the treatment of OCD, the strength of the therapeutic alliance contributes to outcomes, though to a limited extent. Effective OCD treatment involves the delivery of specific therapy interventions, in the context of a strong therapeutic alliance.

Knowledge and competency standards for specialized cognitive behavior therapy for adult obsessive-compulsive disorder

Obsessive-Compulsive Disorder (OCD) is a leading cause of disability world-wide (World Health Organization, 2008). Treatment of OCD is a specialized field whose aim is recovery from illness for as many patients as possible. The evidence-based psychotherapeutic treatment for OCD is specialized cognitive behavior therapy (CBT, NICE, 2005, Koran and Simpson, 2013). However, these treatments are not accessible to many sufferers around the world. Currently available guidelines for care are deemed to be essential but insufficient because of highly variable clinician knowledge and competencies specific to OCD. The phase two mandate of the 14 nation International OCD Accreditation Task Force (ATF) created by the Canadian Institute for Obsessive Compulsive Disorders is development of knowledge and competency standards for specialized treatments for OCD through the lifespan deemed by experts to be foundational to transformative change in this field. This paper presents knowledge and competency standards for specialized CBT for adult OCD developed to inform, advance, and offer a model for clinical practice and training for OCD. During upcoming ATF phases three and four criteria and processes for training in specialized treatments for OCD through the lifespan for certification (individuals) and accreditation (sites) will be developed based on the ATF standards.

Cognitive-behavioural therapy for a variety of conditions: an overview of systematic reviews and panoramic meta-analysis

BACKGROUND

Cognitive-behavioural therapy aims to increase quality of life by changing cognitive and behavioural factors that maintain problematic symptoms. A previous overview of cognitive-behavioural therapy systematic reviews suggested that cognitive-behavioural therapy was effective for many conditions. However, few of the included reviews synthesised randomised controlled trials.

OBJECTIVES

This project was undertaken to map the quality and gaps in the cognitive-behavioural therapy systematic review of randomised controlled trial evidence base. Panoramic meta-analyses were also conducted to identify any across-condition general effects of cognitive-behavioural therapy.

DATA SOURCES

The overview was designed with cognitive-behavioural therapy patients, clinicians and researchers. The Cochrane Library, MEDLINE, EMBASE, PsycINFO, Cumulative Index to Nursing and Allied Health Literature, Child Development & Adolescent Studies, Database of Abstracts of Reviews of Effects and OpenGrey databases were searched from 1992 to January 2019.

REVIEW METHODS

Study inclusion criteria were as follows: (1) fulfil the Centre for Reviews and Dissemination criteria; (2) intervention reported as cognitive-behavioural therapy or including one cognitive and one behavioural element; (3) include a synthesis of cognitive-behavioural therapy trials; (4) include either health-related quality of life, depression, anxiety or pain outcome; and (5) available in English. Review quality was assessed with A MeaSurement Tool to Assess systematic Reviews (AMSTAR)-2. Reviews were quality assessed and data were extracted in duplicate by two independent researchers, and then mapped according to condition, population, context and quality. The effects from high-quality reviews were pooled within condition groups, using a random-effect panoramic meta-analysis. If the across-condition heterogeneity was I2 < 75%, we pooled across conditions. Subgroup analyses were conducted for age, delivery format, comparator type and length of follow-up, and a sensitivity analysis was performed for quality.

RESULTS

A total of 494 reviews were mapped, representing 68% (27/40) of the categories of the International Classification of Diseases, Eleventh Revision, Mortality and Morbidity Statistics. Most reviews (71%, 351/494) were of lower quality. Research on older adults, using cognitive-behavioural therapy preventatively, ethnic minorities and people living outside Europe, North America or Australasia was limited. Out of 494 reviews, 71 were included in the primary panoramic meta-analyses. A modest effect was found in favour of cognitive-behavioural therapy for health-related quality of life (standardised mean difference 0.23, 95% confidence interval 0.05 to 0.41, prediction interval -0.05 to 0.50, I2 = 32%), anxiety (standardised mean difference 0.30, 95% confidence interval 0.18 to 0.43, prediction interval -0.28 to 0.88, I2 = 62%) and pain (standardised mean difference 0.23, 95% confidence interval 0.05 to 0.41, prediction interval -0.28 to 0.74, I2 = 64%) outcomes. All condition, subgroup and sensitivity effect estimates remained consistent with the general effect. A statistically significant interaction effect was evident between the active and non-active comparator groups for the health-related quality-of-life outcome. A general effect for depression outcomes was not produced as a result of considerable heterogeneity across reviews and conditions.

LIMITATIONS

Data extraction and analysis were conducted at the review level, rather than returning to the individual trial data. This meant that the risk of bias of the individual trials could not be accounted for, but only the quality of the systematic reviews that synthesised them.

CONCLUSION

Owing to the consistency and homogeneity of the highest-quality evidence, it is proposed that cognitive-behavioural therapy can produce a modest general, across-condition benefit in health-related quality-of-life, anxiety and pain outcomes.

FUTURE WORK

Future research should focus on how the modest effect sizes seen with cognitive-behavioural therapy can be increased, for example identifying alternative delivery formats to increase adherence and reduce dropout, and pursuing novel methods to assess intervention fidelity and quality.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42017078690.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 9. See the NIHR Journals Library website for further project information.

COVID-19, obsessive-compulsive disorder and invisible life forms that threaten the self

This communication explores unique characteristics of obsessive-compulsive disorder (OCD) in the context of the current coronavirus pandemic. When do irrational fears of contamination as seen in OCD start to diverge from rational fears and behaviors? The current paper argues that the personal meaning attributed to viruses and germs, including their personification as entities that possess human-like characteristics, allows them to threaten and violate an individual's identity. Specifically, it suggests that fears of contamination become obsessional when the threat of viruses and germs becomes personal, not solely in terms of its objective outcomes, but in how these life forms are able to threaten the self as the result of a fear of inner corruption characterizing those with OCD. The person with OCD may act as if, or believe that they are acting upon reality when they fear contagion, but are in effect only acting upon an underlying fear of inner corruption that is confused with reality itself. The current paper concludes with some clinical recommendations on how to treat obsessional fears of contamination in the context of the current pandemic.

Validating a dimension of doubt in decision-making: A proposed endophenotype for obsessive-compulsive disorder

Doubt is subjective uncertainty about one's perceptions and recall. It can impair decision-making and is a prominent feature of obsessive-compulsive disorder (OCD). We propose that evaluation of doubt during decision-making provides a useful endophenotype with which to study the underlying pathophysiology of OCD and potentially other psychopathologies. For the current study, we developed a new instrument, the Doubt Questionnaire, to clinically assess doubt. The random dot motion task was used to measure reaction time and subjective certainty, at varying levels of perceptual difficulty, in individuals who scored high and low on doubt, and in individuals with and without OCD. We found that doubt scores were significantly higher in OCD cases than controls. Drift diffusion modeling revealed that high doubt scores predicted slower evidence accumulation than did low doubt scores; and OCD diagnosis lower than controls. At higher levels of dot coherence, OCD participants exhibited significantly slower drift rates than did controls (q<0.05 for 30%, and 45% coherence; q<0.01 for 70% coherence). In addition, at higher levels of coherence, high doubt subjects exhibited even slower drift rates and reaction times than low doubt subjects (q<0.01 for 70% coherence). Moreover, under high coherence conditions, individuals with high doubt scores reported lower certainty in their decisions than did those with low doubt scores. We conclude that the Doubt Questionnaire is a useful instrument for measuring doubt. Compared to those with low doubt, those with high doubt accumulate evidence more slowly and report lower certainty when making decisions under conditions of low uncertainty. High doubt may affect the decision-making process in individuals with OCD. The dimensional doubt measure is a useful endophenotype for OCD research and could enable computationally rigorous and neurally valid understanding of decision-making and its pathological expression in OCD and other disorders.

Inverse reasoning processes in obsessive-compulsive disorder: Replication in a clinical sample

The inference-based approach (IBA) is one cognitive model that aims to explain the aetiology and maintenance of obsessive-compulsive disorder (OCD). IBA theory suggests that certain reasoning processes lead an individual with OCD to confuse imagined possibilities with actual probabilities, a process termed inferential confusion. One such reasoning process is inverse reasoning, where hypothetical causes form the basis of conclusions about reality. Recently, we developed a task-based measure of inverse reasoning. In an online sample, we reported significant and positive associations between endorsement of inverse reasoning on this task and OCD symptomatology. We concluded that there was some support for the role of inverse reasoning in OCD but these results required extension using a between-groups design in a clinical sample. Therefore, the present study compared endorsement in inverse reasoning on this task between individuals diagnosed with OCD, anxiety and/or mood disorder (clinical controls), and healthy individuals (healthy controls). Relative to both control groups, the OCD group demonstrated significantly greater endorsement in inverse reasoning on scenarios where OCD relevant concerns were prompted. When non-OCD relevant concerns were involved, the OCD group only evidenced greater endorsement in inverse reasoning relative to the healthy control group. Implications for IBA theory are discussed.

Inductive and deductive reasoning in obsessive-compulsive disorder

BACKGROUND AND OBJECTIVES

This study examined the hypothesis that participants diagnosed with obsessive-compulsive disorder (OCD) show a selective deficit in inductive reasoning but are equivalent to controls in deductive reasoning.

METHODS

Twenty-five participants with OCD and 25 non-clinical controls made inductive and deductive judgments about a common set of arguments that varied in logical validity and the amount of positive evidence provided (premise sample size). A second inductive reasoning task required participants to make forced-choice decisions and rate the usefulness of diverse evidence or non-diverse evidence for evaluating arguments.

RESULTS

No differences in deductive reasoning were found between participants diagnosed with OCD and control participants. Both groups saw that the amount of positive evidence supporting a conclusion was an important guide for evaluating inductive arguments. However, those with OCD showed less sensitivity to premise diversity in inductive reasoning than controls. The findings were similar for both emotionally neutral and OCD-relevant stimuli.

LIMITATIONS

The absence of a clinical control group means that it is difficult to know whether the deficit in diversity-based reasoning is specific to those with OCD.

CONCLUSIONS

People with OCD are impaired in some forms of inductive reasoning (using diverse evidence) but not others (use of sample size). Deductive reasoning appears intact in those with OCD. Difficulties using evidence diversity when reasoning inductively may maintain OCD symptoms through reduced generalization of learned safety information.

Causal role for inverse reasoning on obsessive-compulsive symptoms: Preliminary evidence from a cognitive bias modification for interpretation bias study

BACKGROUND AND OBJECTIVES

The inference-based approach (IBA) is a cognitive account of the genesis and maintenance of obsessive-compulsive disorder (OCD). According to the IBA, individuals with OCD are prone to using inverse reasoning, in which hypothetical causes form the basis of conclusions about reality. Several studies have provided preliminary support for an association between features of the IBA and OCD symptoms. However, there are currently no studies that have investigated the proposed causal relationship of inverse reasoning in OCD.

METHODS

In a non-clinical sample (N = 187), we used an interpretive cognitive bias procedure to train a bias towards using inverse reasoning (n = 64), healthy sensory-based reasoning (n = 65), or a control condition (n = 58). Participants were randomly allocated to these training conditions. This manipulation allowed us to assess whether, consistent with the IBA, inverse reasoning training increased compulsive-like behaviours and self-reported OCD symptoms.

RESULTS

Results indicated that compared to a control condition, participants trained in inverse reasoning reported more OCD symptoms and were more avoidant of potentially contaminated objects. Moreover, change in inverse reasoning bias was a small but significant mediator of the relationship between training condition and behavioural avoidance. Conversely, training in a healthy (non-inverse) reasoning style did not have any effect on symptoms or behaviour relative to the control condition.

LIMITATIONS

As this study was conducted in a non-clinical sample, we were unable to generalise our findings to a clinical population.

CONCLUSIONS

Findings generally support the IBA model by providing preliminary evidence of a causal role for inverse reasoning in OCD.

Distrust of the senses and its association with obsessive-compulsive symptoms

BACKGROUND AND OBJECTIVES

Leading cognitive theories of OCD suggests that despite prevalent and persistent doubt, individuals with OCD do not have perceptual deficits. An alternate cognitive theory, the Seeking Proxies for Internal States hypothesis (SPIS), proposes that sensory distrust in OCD stems from actual deficits in accessing internal states. Consistent with the SPIS, previous research has found that high-OC individuals were less accurate than low-OC individuals in producing target levels of muscle tension in a biofeedback task and that OC symptoms were positively associated with reliance on an external proxy.

METHODS

The current study aimed to replicate and extend the SPIS hypothesis in two experiments using a modified version of the biofeedback-aided muscle tensing task using grip strength as the sensory input and a distance perception task. We contrasted the performance of undergraduate students self-reporting high- and low-OC symptoms.

RESULTS

Overall, our findings failed to substantially support the SPIS hypothesis such that OC symptoms were not associated with deficient access to internal states of grip strength and distance perception or increased reliance on feedback.

LIMITATIONS

As this study was conducted in a non-clinical sample, we were unable to generalise our findings to a clinical population.

CONCLUSIONS

Findings are commensurate with the wider OCD literature suggesting the absence of cognitive and perceptual deficits in OCD individuals.

Inverse reasoning processes in obsessive-compulsive disorder

The inference-based approach (IBA) is one cognitive model that aims to explain the aetiology and maintenance of obsessive-compulsive disorder (OCD). The model proposes that certain reasoning processes lead an individual with OCD to confuse an imagined possibility with an actual probability, a state termed inferential confusion. One such reasoning process is inverse reasoning, in which hypothetical causes form the basis of conclusions about reality. Although previous research has found associations between a self-report measure of inferential confusion and OCD symptoms, evidence of a specific association between inverse reasoning and OCD symptoms is lacking. In the present study, we developed a task-based measure of inverse reasoning in order to investigate whether performance on this task is associated with OCD symptoms in an online sample. The results provide some evidence for the IBA assertion: greater endorsement of inverse reasoning was significantly associated with OCD symptoms, even when controlling for general distress and OCD-related beliefs. Future research is needed to replicate this result in a clinical sample and to investigate a potential causal role for inverse reasoning in OCD.

Diet and Doubt: A Clinical Case Study of Inference-Based Therapy for Bulimia Nervosa

There is a recognized overlap between eating disorders (EDs) and obsessive-compulsive disorder (OCD) in terms of diagnosis, phenomenology, epidemiology, and psychological characteristics related to the disorder. In light of these similarities, a cognitive inference-based therapy (IBT) program, shown to be effective in treating OCD, was adapted for EDs. This case study describes the application of IBT treatment for a 35-year-old woman diagnosed with bulimia nervosa who also demonstrated overvalued ideation related to her body weight and shape. Over a 20-week period, the client's ED pathology significantly decreased. Notably, the frequency of binge episodes was reduced by 90% from pre- to posttreatment and by 100% at 6-month follow-up. Significant reductions were also observed in dietary restriction and overvalued ideation. This case study has important implications for the treatment of individuals with both an ED and strong overvalued ideas.