Empirical Evidence for Cognitive Subgroups in Body Dysmorphic Disorder

Objective Current understanding of cognitive functioning in body dysmorphic disorder (BDD) is limited, owing to few studies, small sample sizes, and assessment across only limited cognitive domains. Existing research has also shown inconsistent findings, with both intact and impaired cognition reported in BDD, which might point toward cognitive heterogeneity in the disorder. This study aimed to examine the cognitive profile of BDD in a large sample across eight cognitive domains, and to explore whether cognitive subgroups might be identified within BDD. Methods Cognitive domains of inhibition/flexibility, working memory, speed of processing, reasoning and problem-solving, visual and verbal learning, attention/vigilance and social cognition were assessed and compared between 65 BDD patients and 70 healthy controls. Then, hierarchical clustering analysis was conducted on the BDD group’s cognitive data. Results Group-average comparisons demonstrated significantly poorer cognitive functioning in BDD than healthy controls in all domains except for attention/vigilance and social cognition. Cluster analysis identified two divergent cognitive subgroups within our BDD cohort characterised by i ) broadly intact cognitive function with mild selective impairments (72.3%), and ii) broadly impaired cognitive function (27.7%). However, the clusters did not significantly differ on clinical parameters or most sociodemographic characteristics. Conclusion Cognitively diverse subgroups were identified within BDD, yet these were obscured in group-average comparisons. However, subgroup profiles of cognitive functioning seem unrelated to the clinical presentation of BDD. Further research into the underlying mechanisms of cognition in BDD is warranted. Significant Outcomes Cognitive function varies widely among people with body dysmorphic disorder (BDD) and includes subgroups characterised by broadly intact or broadly impaired cognitive profiles. However, reduced performances in visual learning and working memory as relative to healthy participants were identified across both BDD cognitive subgroups to differing degrees. Clinical characteristics were not significantly different among the two BDD cognitive subgroups; what role cognitive functioning may play in the aetiology or presentation of BDD remains unclear. Limitations The output of clustering analysis is sensitive to the choice of variables entered and requires replication with analogous measures of cognition. Psychiatric comorbidities and medications could have impacted cognitive performances in the BDD group in an unaccounted-for manner. Data availability statement Author elects to not share data.