Heterogeneity and comorbidity of obsessive-compulsive disorder

Although the DSM-IV-TR suggests that obsessive-compulsive disorder (OCD) is a coherent syndrome, scientific evidence offers a compelling case that OCD is highly heterogeneous and possibly composed of many different subtypes. OCD can display completely distinct symptom patterns thus making it difficult to identify a single "textbook" profile of OCD. The present state of research concerning subtyping is presented. There is a high comorbidity with depression and anxiety disorders, but all together data concerning OCD comorbidity are still not convincing. Currently obsessive-compulsive spectrum disorders (OCS) are described as a set of disorders lying on a continuum from compulsive to impulsive, with the unifying feature being an inability to regulate behaviour as a consequence of defects in inhibition. OCS disorders fall into three major clusters: impulsive disorders, disorders associated with appearance in bodily sensations, and neurological disorders characterized by repetitive behaviour. How these putative OCS disorders overlap with and are independent from obsessive-compulsive disorder itself is thoroughly discussed.