Universal personality dimensions and dysfunctional obsessional beliefs in the DSM-5's OCD and related disorders (OCRDs).

This study aimed to determine the extent to which personality and cognitive factors contribute to the identification of shared associations between the DSM-5's OCD and Related Disorders (OCRDs). Participants (n = 239) were treatment-seeking outpatients with a principal diagnosis of obsessive-compulsive disorder (OCD), body dysmorphic disorder (BDD), hoarding disorder (HD), trichotillomania (TTM), or excoriation disorder (EXC), as compared to healthy community controls (n = 100). Analyses examined the relationships between diagnostic group, personality dimensions, and obsessive beliefs. Results demonstrated that compared to non-clinical controls, all diagnostic groups scored significantly higher on neuroticism and lower on extraversion and conscientiousness. Few significant differences were found across diagnostic groups: extraversion was higher in the TTM group (vs. all OCRDs), conscientiousness was lower in the HD group (vs. OCD, TTM, EXC), and openness to experience was higher in the TTM and EXC groups (vs. OCD, HD). Obsessional beliefs were significantly elevated in all clinical conditions (vs. controls) except for beliefs surrounding responsibility and threat estimation, which were only significantly higher in OCD and BDD groups. These results highlight shared personality and cognitive vulnerability in the OCRDs as well as unique disorder-specific vulnerabilities related to OCD.