Original Article Bipolar obsessive-compulsive disorder and personality disorders Clinical and epidemiological studies in recent years have suggested that comorbidity between obsessive- compulsive disorder (OCD) and bipolar disorder (BD) is highly prevalent. In BD patients, the lifetime rates of comorbid OCD have been reported to range between 3.2% and 35%, depending on the charac- teristics of subjects included (with or without psychotic features, BD type I or II or mixed samples) (1–13). Conversely, the rate of lifetime comorbid BD in clinical samples of OCD patients ranges between 3.8% and 21.5%, with a higher prevalence of BD type II (7.8–17.7%) (14–22). When bipolar comorbidity was dimensionally ex- plored by using soft bipolar spectrum criteria, rates Maina G, Albert U, Pessina E, Bogetto F. Bipolar obsessive-compulsive disorder and personality disorders. Bipolar Disord 2007: 9: 722–729. ª Blackwell Munksgaard, 2007 Objectives: Relatively few systematic data exist on the clinical impact of bipolar comorbidity in obsessive-compulsive disorder (OCD) and no studies have investigated the inﬂuence of such a comorbidity on the prevalence and pattern of Axis II comorbidity. The aim of the present study was to explore the comorbidity of personality disorders in a group of patients with OCD and comorbid bipolar disorder (BD). Methods: The sample consisted of 204 subjects with a principal diagnosis of OCD (DSM-IV) and a Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) score ‡16 recruited from all patients consecutively referred to the Anxiety and Mood Disorders Unit, Department of Neuroscience, University of Turin over a period of 5 years (January 1998–December 2002). Diagnostic evaluation and Axis I comorbidities were collected by means of the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I). Personality status was assessed by using the Structured Clinical Interview for DSM-IV Axis II Disorders (SCID-II). Socio-demographic and clinical features (including Axis II comorbidities) were compared between OCD patients with and without a lifetime comorbidity of BD. Results: A total of 21 patients with OCD (10.3%) met DSM-IV criteria for a lifetime BD diagnosis: 4 (2.0%) with BD type I and 17 (8.3%) with BD type II. Those without a BD diagnosis showed signiﬁcantly higher rates of male gender, sexual and hoarding obsessions, repeating compulsions and lifetime comorbid substance use disorders, when compared with patients with BD/OCD. With regard to personality disorders, those with BD/OCD showed higher prevalence rates of Cluster A (42.9% versus 21.3%; p ¼ 0.027) and Cluster B (57.1% versus 29.0%; p ¼ 0.009) personality disorders. Narcissistic and antisocial personality disorders were more frequent in BD/OCD. Conclusions: Our results point towards clinically relevant eﬀects of comorbid BD on the personality proﬁles of OCD patients, with higher rates of narcissistic and antisocial personality disorders in BD/OCD patients. Giuseppe Maina, Umberto Albert, Enrico Pessina and Filippo Bogetto Department of Neuroscience, Anxiety and Mood Disorders Unit, University of Turin, Turin, Italy Key words: bipolar disorder – comorbidity – obsessive-compulsive disorder – personality disorders Received 13 March 2005, revised and accepted for publication 31 October 2006 Corresponding author: Prof. Giuseppe Maina, Department of Neurosciences, Anxiety and Mood Disorders Unit, University of Turin, Via Cherasco 11, 10126 Turin, Italy. Fax: + 39 011 673473; e-mail: giuseppemaina@hotmail.com The authors of this paper do not have any commercial associations that might pose a conﬂict of interest in connection with this manu- script. Bipolar Disorders 2007: 9: 722–729 Copyright ª Blackwell Munksgaard 2007 BIPOLAR DISORDERS 722