On heterogeneity of the obsessive-compulsive disorder: a review

Abstract

Although obsessive-compulsive disorder (OCD) has been traditionally considered a homogeneous disorder, there is a growing number of studies as to its heterogeneity. In this article, we review the main theoretical and empirical classifications as found in the literature on OCD, with a special eye on those that focus on grouping together obsessive-compulsive symptoms. These studies comprise two different methodological approaches: the dimensional (using factorial-analytic methods) and the cate-gorical (using cluster analyses). The first approach has been used to study both the intrusive thoughts analogous to obsessions as experienced by non-clinical participants, as well as the clinical obsessions in OCD patients. The main part of these studies was found to cluster a number of factors (groups of symptoms) between four and six. From a categorical perspective only OCD patients were studied and - though less consistent - the results point at a range between three and five clusters or groups of patients. These results, as well as the advantages and limitations of the methodological and concep-tual approaches encountered, are examined and evaluated with special emphasis on their respective contributions to the understanding of OCD.