Cross-diagnostic cognitive heterogeneity in body dysmorphic disorder and obsessive-compulsive disorder

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Highlights

  • No differences in cognitive function between BDD, OCD and healthy control groups.

  • Cluster analysis showed two cross-diagnostic subgroups within BDD and OCD data.

  • Subgroup profiles characterised by ‘intact’ and ‘broadly impaired’ cognitive function.

  • Indicates that BDD and OCD may involve shared profiles of cognitive heterogeneity.

Abstract

Background and objectives

Previous research has indicated that body dysmorphic disorder (BDD) and obsessive-compulsive disorder (OCD) often demonstrate similar cognitive impairments across multiple domains. However, findings for both disorders have not consistently shown impaired cognition. As such, BDD and OCD might share an overlapping pattern of cognitive heterogeneity, characterised by subgroups with different cognitive profiles.

Methods

To evaluate this possibility, we compared 26 BDD, 24 OCD, and 26 healthy control participants on a comprehensive eight-domain cognitive battery. Then, cluster analysis was performed on the BDD and OCD participants’ combined data to explore for cognitive subgroups.

Results

No significant differences were found between the three groups’ cognitive functioning, except for poorer visual learning in OCD relative to healthy controls. Cluster analysis produced two cognitive subgroups within the combined BDD and OCD data, characterised by intact cognition (52%) and broadly impaired cognition (48%). Each subgroup comprised both BDD and OCD participants, in similar proportions. The subgroups did not differ in clinical or demographic features.

Limitations

Sample sizes were moderate. Future research should investigate clustering patterns both in larger groups and separately in BDD and OCD samples to determine replicability.

Conclusions

These findings suggest that BDD and OCD may involve similar patterns of cognitive heterogeneity, and further imply that individuals with either disorder can show a wide range of cognitive profiles, thus necessitating a nuanced approach to future cognitive research in BDD and OCD.

Introduction

Body dysmorphic disorder (BDD) is a serious psychiatric disorder characterised by a preoccupation with a perceived flaw(s) in physical appearance, and time-consuming or repetitive behaviours that are performed in response to this preoccupation (American Psychiatric Association, 2013). BDD is currently considered to be an obsessive-compulsive related disorder, particularly as numerous clinical similarities to obsessive-compulsive disorder (OCD) have been identified (Malcolm et al., 2018). Impairments in cognitive functions, i.e., the mental abilities involved in the acquisition and manipulation of information and mental reasoning, have additionally been theorised to relate to clinical features of both disorders (Fang & Wilhelm, 2015; Frampton, 2003). For instance, difficulties with response inhibition or flexibility have been proposed to relate to difficulties in disengaging from suststained, urge-driven behaviours, such as mirror checking in BDD or compulsive behaviour in OCD (Jefferies-Sewell, Chamberlain, Fineberg, & Laws, 2017). As such, characterisation of cognitive functions provides an important foundation for refining our understanding of potential aetiological or maintenance mechanisms that may be shared across both disorders. However, possible overlaps in the cognitive profiles of these disorders remain relatively understudied (Malcolm et al., 2018).

Of the two published studies that have directly compared cognitive functioning between participants with BDD and OCD, both found similarities between the disorders (Hanes, 1998; Toh, Castle, & Rossell, 2015). Hanes (1998) reported significantly poorer planning and inhibition in both participants with BDD (n = 14) and OCD (n = 10) relative to healthy controls (n = 24), though no group differences were detected across tasks of category fluency, visual and verbal learning, or motor function. Toh et al. (2015) found both participants with BDD (n = 21) and OCD (n = 19) exhibited significantly poorer attention, immediate memory and overall cognitive functioning than healthy controls (n = 21), though the groups did not significantly differ in visuospatial construction, language, or delayed memory. Notwithstanding limitations relating to Hanes’ (1998) small sample sizes and potential ceiling effects in the study of Toh et al. (2015), these studies point to similar cognitive functioning between individuals with BDD and OCD. Separate studies examining participants with either BDD or OCD have also reported comparable results across the two disorders, including poor inhibition, planning, working memory, speed of processing, attention, fluency and visual learning relative to healthy controls (Abramovitch, Abramowitz, & Mittelman, 2013; Deckersbach et al., 2000; Dunai, Labuschagne, Castle, Kyrios, & Rossell, 2010; Hanes, 1998; Shin, Lee, Kim, & Kwon, 2014; Snyder, Kaiser, Warren, & Heller, 2015). However, findings in BDD are inconsistent, with some studies reporting impairments relative to healthy controls in the aforementioned domains and others showing no impairments in participants with BDD (Deckersbach et al., 2000; Dunai et al., 2010; Greenberg et al., 2018; Hanes, 1998; Jefferies-Sewell et al., 2017; Rossell, Labuschagne, Dunai, Kyrios, & Castle, 2014; Toh et al., 2015). Though the literature on cognitive functioning in OCD is more extensive than in BDD, findings are similarly inconsistent in demonstrating evidence of both intact and impaired cognition across domains of inhibition, working memory, speed of processing, attention, fluency and visual learning (Abramovitch & Cooperman, 2015).

While inconsistent patterns of cognitive findings for both BDD and OCD might reflect methodological differences across studies (e.g., test selection, sample size, clinical and demographic variability), a parallel possibility is that both BDD and OCD also involve hetereogeneous cognitive functioning. That is, cognitive functioning might range from intact to markedly impaired across subgroups of individuals with the same disorder. Such patterns of cognitive heterogeneity have been robustly established in other mental health disorders such as bipolar disorder and schizophrenia (Burdick et al., 2014; Van Rheenen et al., 2017), and thus may also exist in BDD and OCD. Given the inconsistent cognitive findings for both BDD and OCD, as well as similarities among the disorders when impairments have been reported, BDD and OCD might share overlapping patterns of cognitive heterogeneity. On the other hand, the presence of comorbidity among BDD and OCD could contribute to observations of cognitive similarities between the disorders. Most cognitive studies of participants with BDD have included individuals with current comorbid OCD (in proportions ranging from 10% to 75% of the BDD sample) (Deckersbach et al., 2000; Dunai et al., 2010; Jefferies-Sewell et al., 2017; Rossell et al., 2014; Silverstein et al., 2015; Toh et al., 2015). Other studies did not report participant comorbidities (Greenberg et al., 2018; Hanes, 1998). As such, it is unclear whether apparent similarities in cognitive functioning between the disorders might be unduly influenced by BDD and OCD comorbidity within study samples.

The current study sought to compare and contrast cognitive functioning between individuals with BDD and OCD and explore the potential for a shared pattern of cognitive heterogeneity between the disorders, using a comprehensive cognitive battery and a cluster analysis approach. To this end, individuals with BDD or OCD (with no history of both diagnoses) were firstly compared to each other and against healthy controls in their cognitive performance across eight domains. Then, to explore whether shared cognitive subgroups are present within BDD and OCD, their combined cognitive data were subjected to a hierarchical cluster analysis. We hypothesised that group-level comparisons would demonstrate poorer overall cognitive functioning in both participants with BDD and OCD relative to controls. However, based on previous research suggesting cognitive similarities between BDD and OCD and evidence of inconsistencies across findings (i.e., showing intact and impaired cognition in both disorders), we anticipated that at least two distinct cognitive subgroups would emerge from the combined data of participants with BDD and OCD, ranging from intact to markedly impaired. Our cluster analyses was exploratory and thus no further hypotheses were formed. However, we did anticipate that if shared patterns of cognitive heterogeneity among participants with BDD and OCD exist, we would see a mixture of both participants with BDD and OCD within any subgroups that may emerge from the combined data. Conversely, if BDD and OCD entail markedly divergent rather than shared cognitive profiles, we expected to see subgroups comprised of only individuals with BDD, or individuals with OCD, emerge from the data.

Section snippets

Participants

Participants were 26 individuals with BDD, 24 with OCD, and 26 healthy controls, recruited through public advertisements and community and outpatient psychiatric services between August 2017 and March 2020. Primary diagnoses were confirmed using the BDD Diagnostic Module for the DSM-5 (Phillips, 2017) and the OCD module of the Mini International Neuropsychiatric Interview (MINI) 7.0.2 for the DSM-5 (Sheehan, 2016). Individuals who met criteria for both BDD and OCD or who reported having been

Demographic and clinical characteristics

As shown in Table 1, the three groups were similar in sex distribution, mean age, estimated IQ, educational attainment, and occupational status. Though participants with BDD and OCD displayed similar mean ages of illness onset and illness duration, the participants with BDD demonstrated significantly more severe core symptoms and poorer insight into their illness.

Group-wise cognitive performances

There were no significant differences between participants with BDD, OCD, and the healthy control groups in any of the eight

Discussion

This study represents the first exploratory investigation of cross-diagnostic cognitive heterogeneity across BDD and OCD. At the diagnostic-group level, we found significant differences in visual learning after co-varying for age, driven by significantly poorer visual learning in participants with OCD as compared to controls. Yet, contrary to our hypotheses, no further significant group differences were evident between participants with BDD, with OCD, and healthy control participants across the

Funding

A.M and T.P were supported by Australian Government Research Training Program Scholarships during this research. S.L.R holds a Senior National Health and Medical Research Council (NHMRC) Fellowship (GNT1154651). This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Author contributions: CRediT roles

Amy Malcolm: Conceptualisation, Project administration, Methodology, Investigation, Formal analysis, Writing – Original draft, Writing – Review and editing; Toni D. Pikoos: Investigation, Writing – Review and editing; David J. Castle: Resources (patients), Writing – Review and editing; Susan L. Rossell: Supervision, Conceptualisation, Methodology, Project administration, Writing – Review and editing.

Declaration of competing interest

Dr. Castle has received grant monies for research from Eli Lilly, Janssen Cilag, Roche, Allergen, Bristol-Myers Squibb, Pfizer, Lundbeck, Astra Zeneca, Hospira; Travel Support and Honoraria for Talks and Consultancy from Eli Lilly, Bristol-Myers Squibb, Astra Zeneca, Lundbeck, Janssen Cilag, Pfizer, Organon, Sanofi-Aventis, Wyeth, Hospira, Servier, Seqirus; and is a current Advisory Board Member for Lu AA21004: Lundbeck; Varenicline: Pfizer; Asenapine: Lundbeck; Aripiprazole LAI: Lundbeck;

References (37)

  • K. Burdick et al.

    Empirical evidence for discrete neurocognitive subgroups in bipolar disorder: Clinical implications

    Psychological Medicine

    (2014)
  • T. Deckersbach et al.

    Characteristics of memory dysfunction in body dysmorphic disorder

    Journal of the International Neuropsychological Society

    (2000)
  • D.C. Delis et al.

    The delis-kaplan executive function System: Examiner's manual

    (2001)
  • J. Dunai et al.

    Executive function in body dysmorphic disorder

    Psychological Medicine

    (2010)
  • J.L. Eisen et al.

    The Brown assessment of beliefs scale: Reliability and validity

    American Journal of Psychiatry

    (1998)
  • A. Fang et al.

    Clinical features, cognitive biases, and treatment of body dysmorphic disorder

    Annual Review ofClinical Psychology

    (2015)
  • I. Frampton

    Neuropsychological models of obsessive-compulsive disorder

  • W.K. Goodman et al.

    The Yale-Brown obsessive compulsive scale: I. Development, use, and reliability

    Archives of General Psychiatry

    (1989)
  • Cited by (2)

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