Obsessive–compulsive disorder (OCD) is a mental disorder in which a person feels the need to perform certain routines repeatedly (called “compulsions”), or has certain thoughts repeatedly (called “obsessions”). The person is unable to control either the thoughts or activities for more than a short period of time.
The cause of the disorder has not yet been established.
Data […] suggests that three brain areas are involved with OCD: the orbitofrontal cortex (OFC), the anterior cingulate cortex (ACC), and the head of the caudate nucleus. Several studies have found that in patients with OCD, these areas: (1) are hyperactive at rest relative to healthy control; (2) become increasingly active with symptom provocation; and (3) no longer exhibit hyperactivity following successful treatment with SRI pharmacotherapy or cognitive-based therapy. This understanding is frequently cited as evidence that abnormality in these neuroanatomical regions may cause OCD.