Obsessive Compulsive Personality Disorder (OCPD) is a common, highly co-morbid disorder. Subjected to comparatively little research, OCPD shares aspects of phenomenology and neuropsychology with obsessive-compulsive spectrum disorders and neurodevelopmental disorders such as autism spectrum disorder (ASD). A greater understanding of this interrelationship would provide new insights into its diagnostic classification and generate new research and treatment heuristics.

To investigate the distribution of OCPD traits within a cohort of OCD patients. To evaluate the clinical overlap between traits of OCPD, OCD and ASD, as well as level of insight and treatment resistance.

We interviewed 73 consenting patients from a treatment seeking OCD Specialist Service. We evaluated the severity of OCPD traits (Compulsive Personality Assessment Scale; CPAS), OCD symptoms (Yale–Brown Obsessive Compulsive Scale; Y-BOCS), ASD traits (Adult Autism Spectrum Quotient; AQ) and insight (Brown Assessment of Beliefs Scale; BABS).

Out of 67 patients, 24 (36%) met DSM-IV criteria for OCPD, defined using the CPAS. Using Pearson's test, CPAS scores significantly (P<0.01) correlated with total AQ and selected AQ domains but not with BABS. Borderline significant correlation was observed with Y-BOCS (P=0.07). OCPD was not over-represented in a highly resistant OCD subgroup.

Disabling OCPD traits are common in the OCD clinic. They strongly associate with ASD traits, less strongly with OCD severity and do not appear related to poor insight or highly treatment-resistant OCD. The impact of OCPD on OCD treatment outcomes requires further research.