Obsessive-comnpulsive disorder and comorbid personality disorders

The present chapter will critically review the available research on the role of Comorbid Personality Disorders (CPDs) in Obsessive-Compulsive Disorder (OCD). The first section will cover evidence on the prevalence of concurrent axis II conditions in OCD. There is a variety among studies in the reported findings on this topic, with some studies indicating such prevalence as high as 88% and other as low as 9% (Black et al., 1993; Pigott et al., 1994). Such inconsistency may be attributed to both theoretical and methodological variations across studies. Many studies differ in terms of theoretical definition of personality psychopathology (focus on personality dimensions vs. CPD diagnoses), instruments for CPD assessment (semi-structured interviews vs. self-report measures), research designs (cross-sectional vs. longitudinal), sample selection (inpatient vs. outpatient samples), focus on specific CPDs rather than number of CPDs. This section will also systematically review research on demographic and clinical features related to OCD with CPDs. For example, consistent findings suggested that OCD patients with CPDs tend to be to a higher extent impaired in overall functioning (Denys et al., 2004). Conversely, contradictory results have been found on the association between OCD severity and CPDs, with some studies showing a significant association (Aubuchon & Malatesta, 1994) and other not (Matsunaga et al., 1998). This section will also focus on moderators of the association between OCD and specific CPDs. For example, a greater rigidity was found to mediate the relation between OCD severity and Obsessive-Compulsive Personality Disorder (OCPD) (Wetterneck et al., 2011). The second section of the chapter will cover research on the prognostic role of CPDs in the outcome of cognitive-behavioural therapy (CBT) for OCD. The role of CPDs in OCD outcome raises questions on the necessity to adapt treatment planning to the comorbid status. A noticeable body of research indicated that the presence of CPDs may be associated with a poorer prognosis for CBT (Keeley et al., 2008). However, not all studies consistently found such association. Variations across studies could explain such inconsistency (Dreessen & Arntz, 1998). Some studies assessed personality psychopathology as traits and other as categorical CPD diagnoses. Moreover, the role of CPDs will be critically reviewed in relation to differences across trials in terms of treatment formats (for example low vs. high intensity treatments) or therapeutic components. Consistently, some evidence showed that OCD patients with CPDs may benefit from augmentation treatments, like a time-intensive CBT format (Dèttore et al., 2013). Personality factors that negatively impact treatment could also be specific to some CPDs. Recent trials focused on specific CPDs or personality traits, with some results indicating OCPD and schizotypal traits as predictors of non-response (Moritz et al., 2004; Pinto et al., 2011). A greater perfectionism and a poorer insight could account for such negative outcome of OCPD and schizotypal personality respectively. These findings may underline symptom patterns that could be targeted by tailored interventions. In conclusion, starting from all the available evidence on CPDs in OCD, implications for clinical practice and directions for future research will be highlighted