Symptom dimensions in OCD and their association with clinical characteristics and comorbid disorders Lokesh Prabhu, Anish V. Cherian, Biju Viswanath, Thennarasu Kandavel, Suresh Bada Math, Y.C. Janardhan Reddy n Department of Psychiatry, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore 560029, India article info Article history: Received 4 June 2012 Received in revised form 13 October 2012 Accepted 15 October 2012 Available online 26 October 2012 Keywords: Obsessive–compulsive disorder Symptom dimension Dimensional YBOCS Comorbidity Heterogeneity abstract The complex clinical phenotype of obsessive–compulsive disorder (OCD) can be summarized in to a few temporally stable and consistent symptom dimensions that may have distinct clinical and neurobio- logical correlates. We examined the relationship between symptom dimensions and clinical character- istics in 161 consecutive patients with DSM-IV diagnosis of OCD with the Yale–Brown Obsessive– Compulsive Scale severity score of Z20 recruited from a specialty OCD clinic in India. Clinician administered version of the Dimensional-Yale–Brown Obsessive–Compulsive Scale (D-YBOCS) was used to assess symptom dimensions. Earlier age of onset of OCD was associated with sexual/religious, aggression and symmetry dimensions. Fear of contamination was associated with female sex, higher family loading, greater severity of illness, poorer insight, and somewhat poorer functioning and lower physical quality of life. Aggression dimension was associated with presence of anxiety disorders and social phobia in particular. Our study demonstrates relatively specific associations between OCD symptom dimensions and clinical characteristics supporting the view that symptom dimensions could be employed to reduce the heterogeneity of OCD. The study encourages research on neurobiological and genetic underpinnings of symptom dimensions and supports inclusion of symptom dimensions in characterizing OCD in DSM-5 text. & 2012 Elsevier Inc. All rights reserved. 1. Introduction The exact etiology of obsessive–compulsive disorder (OCD) is unknown. Systematic search for the genetic basis of OCD has not yielded any meaningful and replicable findings (Grados, Walkup, & Walford, 2003; Samuels, 2009). This is possibly due to the heterogeneous nature of OCD (Miguel et al., 2005; Samuels, 2009; Stein, 2000). Given this heterogeneity, there have been various attempts to subtype OCD into homogenous entities using clinical phenomenological characteristics such as age at onset of OCD (Hemmings et al., 2004), comorbidity profile (e.g. tic disorders) (Miguel, do Rosario-Campos, Shavitt, Hounie, & Mercadante, 2001), familiality (Viswanath, Narayanaswamy, Cherian, Reddy, & Math, 2011) and recently symptom dimensions (Mataix-Cols, Rosario-Campos, & Leckman, 2005). There is wide variation in the thematic content of obsessions and compulsions. Empirical evidence suggests that the diversity in OCD symptoms can be reduced to a fewer number of symptom dimensions; as a result OCD is increasingly seen as a dimensional disorder (Mataix-Cols et al., 2005). Most widely used approach to reduce the heterogeneity is to generate symptom dimensions based on the factor analysis of the symptoms such as the ones generated by the Yale–Brown Obsessive–Compulsive Scale (YBOCS) symptom checklist (Goodman et al., 1989). A recent meta-analysis of 21 factor analytic studies of the YBOCS symptom checklist involving 5124 participants identified four symptom dimensions: (a) symmetry obsessions; counting, ordering and arranging compulsions; (b) forbidden thoughts (aggressive, sexual, religious and somatic obsessions; and related checking compulsions); (c) contamination/cleaning, and (d) hoarding (Bloch, Landeros-Weisenberger, Rosario, Pittenger, & Leckman, 2008). These symptom dimensions have been reported to be temporally (Mataix-Cols et al., 2002) and cross-culturally stable (Matsunaga et al., 2008), with distinct neural correlates (Mataix-Cols et al., 2004) and comorbidity patterns (Hasler et al., 2005). Brain-imaging and genetic studies have also provided preliminary evidence for the biological validity of these dimen- sions (Gilbert et al., 2008; Hashimoto et al., 2011; van den Heuvel et al., 2009). There is also some evidence that symptom dimensions may have specific relationships with certain clinical characteristics such as age of onset and comorbid patterns. An integration of Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/jocrd Journal of Obsessive-Compulsive and Related Disorders 2211-3649/$ - see front matter & 2012 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jocrd.2012.10.002 n Corresponding author. Tel.: þ91 80 269 95278. E-mail address: ycjreddy@gmail.com (Y.C. Janardhan Reddy). Journal of Obsessive-Compulsive and Related Disorders 2 (2013) 14–21