Cluster analysis of obsessive-compulsive symptomatology: Identifying obsessive-compulsive disorder subtypes

Background: There is increasing evidence that obsessive-compulsive disorder (OCD) is a heterogeneous disorder. Different clinical subtypes may be characterized by differing pathophysiological mechanisms and treatment outcomes. Methods: A cluster analysis was performed on 45 items of the Yale-Brown Obsessive-Compulsive Symptoms Checklist (YBOCS-CL) for 261 patients with OCD. Cluster solutions emerging at different linkage distance levels, and the associations of identified clusters with demographic, clinical and relevant genetic variables, were investigated. Results: A 6-cluster solution emerged at a linkage distance level of 1.5, and a 3-cluster solution emerged at a linkage distance level of 2.1. The 3 clusters in the latter solution were labeled I) Contamination/ washing, II) Hoarding/ symmetry/ ordering, and III) Obsessional/ checking. Increased Cluster III scores were associated with earlier age of OCD onset and the Met/Met (LIL) genotype of the COMT Val158Met polymorphism. Conclusion: The data here are consistent with previous work delineating the different symptom subtypes of OCD, also with previous work suggesting that the Met/Met (L/L) genotype of the COMT Val158Met polymorphism may be associated with anxiety symptoms, as well as with previous work suggesting that dopaminergic genes may be particularly important in early-onset OCD.