Abstract
Objective: This study aims to explore the internal and external boundaries of obsessive–compulsive disorder (OCD).
Method: Selected literature is reviewed.
Results: Prevalence and incidence estimates for OCD vary markedly according to diagnostic criteria applied. External boundaries of the disorder are permeable, with a large degree of overlap with other psychiatric disorders, and an association with certain neurological disorders. Some cases of OCD appear to have a neurodevelopmental origin.
Conclusions: Further delineation of disorders characterised by obsessional and compulsive symptoms can inform models of aetiology, pathophysiology and treatment.