The obsessive-compulsive dimension

Abstract Obsessive-compulsive disorder (OCD) is a clinical syndrome characterised by recurrent intrusive thoughts (obsessions) and repetitive mental or behavioural acts (compulsions), typically performed in response to obsessions or related anxiety. OCD generally has a stable symptom pattern throughout life, but nevertheless is well known for its heterogeneity, as symptomatic presentations and comorbidity patterns differ widely among patients. A number of other psychiatric and neurological disorders may share similar phenomenological characteristics with OCD or are sometimes conceptualised as atypical OCDs. These heterogeneous aspects of the disorder have led to a search for OCD subtypes that might be associated with different etiologies or treatment responses. In the past few decades, the predominant models of OCD pathophysiology have focused on cortico-striatal circuitry, but more recent neuroimaging studies implicate involvement of the lateral and medial orbitofrontal cortices, the dorsal anterior cingulate cortex, and amygdalo-cortical circuitry, in addition to cortico-striatal circuitry, in the pathophysiology of this disorder. In this chapter, we have highlighted how a dimensional approach can offer opportunities for better assessment and more effective treatment than categorical diagnosis. The usefulness of this approach is based on the fact that the obsessive psychopathological dimension can be found in a number of syndromes, and that treatment can be provided for it independently of the baseline disorder. For this purpose, our patients have been assessed with the SVARAD and treated accordingly, taking into account the particulars of each individual case.