In recent years there has been a dramatic revolution in our conceptualization of obsessive–compulsive disorder (OCD). OCD has long been considered a prototypical psychogenic condition, one that allowed an important window onto the workings of the unconscious mind. The disorder was thought to be relatively uncommon and refractory to treatment. In the last decade or so, however, advances in the neurobiology of OCD have led to a view that this disorder is best understood as one of the neuropsychiatric disorders, with specific brain dysfunction underlying complex behavioural symptoms. Furthermore, OCD is now recognized to be one of the most common psychiatric disorders (Karno et al., 1984; Weissman et al., 1994), and the introduction of novel pharmacotherapeutic and psychotherapeutic interventions has significantly improved its outcome (Baer and Minichiello, 1990; Jenike, 1992).

One of the most interesting aspects of current research on OCD is the new perspective that is being brought to questions about brain–behaviour relationships. Clearly, patients with OCD suffer from psychological symptoms, with anxiety-provoking intrusive thoughts (obsessions) leading to repetitive and ritualistic responses (compulsions). Functional imaging studies, however, demonstrate that these symptoms are mediated by specific dysfunctional brain circuits. Of significant interest is that both medication and psychotherapy lead to normalization of these circuits. Thus, while OCD may involve brain dysfunction, a comprehensive understanding of the condition also requires attention to brain-based emergent psychological structures and processes (Stein and Hollander, 1992).

In order to think about and further study this kind of integration of biological and behavioural data, clinicians and researchers may find it useful to draw on the theoretical constructs and empirical methods of cognitive science.