Serum oxytocin levels are elevated in body dysmorphic disorder and related to severity of psychopathology

A systematic review of neurocognition and social cognition in body dysmorphic disorder

OBJECTIVE

Neurocognitive underpinnings are implicated in the aetiology and maintenance of body dysmorphic disorder (BDD); however, inconsistent findings across a range of neurocognitive domains suggest that a comprehensive synthesis of the literature using a hierarchical framework of neurocognition is needed.

METHODS

A final search across OVID Medline, PsycNET, Scopus and Web of Science databases was conducted on 20 June 2024 to identify research that examined performance on behavioural tasks of objective neurocognition in BDD. Risk of bias was assessed using the Newcastle-Ottawa Scale. Fifty-four studies aligned with the following inclusion criteria: (1) full-text; (2) peer-reviewed; (3) published in English; (4) employed a neurocognitive task with an objective outcome and (5) involved a case-controlled paradigm consisting of BDD and healthy control samples. Findings were synthesised according to neurocognitive sub-domains viewed as a hierarchy from basic to higher-level domains.

RESULTS

Neurocognitive differences in BDD relative to controls were identified at almost all levels of the hierarchy, most consistently in the upper domains of executive function and social cognition. Vulnerabilities were also demonstrated in the sub-domains of visual perception of faces, Gestalt processing, selective attention to faces and verbal memory. Methodological limitations or the influence of neurocognitive sub-groups may contribute to inconsistencies across the literature.

CONCLUSIONS

Although neurocognitive differences appear central to BDD, a picture of neurocognitive heterogeneity emerged with the salience of stimuli important and a likely bias to local-over-global processing demonstrated across the domains.

A scoping review and hypothetical framework about the interplay between oxytocin and eating disorders

INTRODUCTION

Despite emerging evidence on oxytocin's role in eating disorders,there is a need for a comprehensive review to integrate findings across neurobiological, genetic, hormonal, and therapeutic dimensions. This scoping review synthesizes existing literature on OXT's role in EDs and proposes a new theoretical perspective based on diverse research findings.

METHODS

In accordance with PRISMA guidelines, we systematically synthesized all peer-reviewed articles indexed on PubMed which focused on both OXT and EDs as of December 2023 (k = 32 studies, n = 1942 participants). After summarizing this literature in tables, we completed the narrative synthesis with a discussion of mechanisms informed by an unstructured literature review.

RESULTS

The existing studies propose a connection between OXT receptor Oxtr polymorphisms and ED diagnoses, severity of symptoms, macronutrient preferences, reward function, and early life stress. In addition, OXT plasma levels normalized with ED symptom reduction. Although some OXT studies have failed to show therapeutic changes in food intake and weight, few have reported ameliorations in brain function, food-related attentional bias, cognition, and emotional regulation. Some data have also suggested a contributory role of the transforming growth factor β (TGFβ) and sterol regulatory element binding proteins (SREBPs) to the etiology of EDs through Oxtr expression.

CONCLUSION

Although the current evidence does not support OXT as a standalone cause of or treatment for EDs, OXT research holds promise as a way of identifying future therapies, and OXT itself may serve as a valuable adjunct.

Body dysmorphic disorder

Body dysmorphic disorder (BDD) is an obsessive-compulsive disorder-related psychiatric condition characterized by an intense preoccupation with perceived physical flaws that are not observable by others. BDD affects ~2% of the adult population but is underdiagnosed, partly owing to limited clinician awareness, and undertreated, partly due to limited access to treatment. Research on the aetiology of BDD is scarce but likely involves an interplay between genetic and environmental factors. A few studies suggest functional and structural brain differences (compared with controls) in the regions involved in visual and emotional processing, although firm conclusions about the pathophysiology of the disorder cannot be made at this stage. Diagnosis requires the presence of repetitive behaviours or mental acts typically aimed at checking, correcting or concealing perceived flaws. The disorder typically has its onset before 18 years of age, with a female preponderance in youth but no major gender disparity in adults. Quality of life is markedly impaired across multiple domains and suicide risk is considerable. Evidence-based treatments include cognitive behavioural therapy and selective serotonin reuptake inhibitors. Future research should focus on understanding the biological and environmental factors that increase the risk of BDD, and on improving access to effective treatments, thereby addressing a critical gap in care for this often misunderstood and overlooked disorder.

Disturbed interoception in body dysmorphic disorder: A framework for future research

Body dysmorphic disorder is a severe psychiatric condition characterised by a preoccupation with a perceived appearance flaw or flaws that are typically not observable to others. Although significant advances in understanding the disorder have been made in the past decade, current explanations focus on cognitive, behavioural and visual perceptual disturbances that contribute to the disorder. Such a focus does not consider how perception of the internal body or interoception may be involved, despite (1) clinical observations of disturbed perception of the body in body dysmorphic disorder and (2) disturbed interoception being increasingly recognised as a transdiagnostic factor underlying a wide range of psychopathologies. In this paper, we use an existing model of hierarchical brain function and neural (predictive) processing to propose that body dysmorphic disorder involves defective interoception, with perceived appearance flaws being the result of 'interoceptive prediction errors' that cause body parts to be experienced as 'not just right'. We aim to provide a framework for interoceptive research into body dysmorphic disorder, and outline areas for future research.