Obsessive-Compulsive Disorder Comorbid with or without Obsessive-Compulsive Personality Disorder: Conceptual Implications, Clinical Correlates and Brain Morphometries.

Background: Obsessive-compulsive disorder (OCD) is often comorbid with obsessive-compulsive personality disorder (OCPD). The relationship between OCD and OCPD is complex, and the impact of comorbid OCPD on OCD remains underexplored, necessitating further research.. This study aims to investigate the clinical correlates and brain morphometries associated with comorbid OCPD in a large sample of unmedicated OCD patients.

Methods: A total of 248 unmedicated patients diagnosed with OCD (45 comorbid with OCPD) were included in this study. All participants were assessed for OCD symptoms, OCPD traits, obsessive beliefs, depression and anxiety. Among them, 145 patients (23 comorbid with OCPD) volunteered to receive magnetic resonance imaging (MRI) brain scans.

Results: Approximately 18% (45/248) of OCD patients were comorbid with OCPD. OCD comorbid with OCPD (OCD+OCPD) exhibited more severe OCD symptoms, obsessive beliefs, depression and anxiety than OCD comorbid without OCPD. Additionally, the severity of OCPD was positively correlated with OCD symptoms and obsessive beliefs. Furthermore, OCD+OCPD patients exhibited increased cortical complexity in the left superior parietal lobule and left precuneus, which mediated the relationship between OCPD and OCD symptoms only in OCD patients comorbid without OCPD.

Conclusions: The co-occurrence of OCPD may contribute to the heightened severity of psychopathological symptoms and associated brain morphological alterations in OCD patients, indicating distinct but interrelated constructs between these two disorders.