Obsessive-compulsive disorder (OCD) is a type of anxiety disorder in which a person repeatedly dwells on unwanted ideas or feels compelled to perform rituals to relieve tension, to such an extent that the person's life is disrupted. (Well-known examples of such rituals include continually washing one's hands or checking dozens of times to see if the door is locked before leaving home.)

Obsessive-compulsive symptoms occur in a wide range of neurological and medical disorders other than epilepsy. It may appear in patients with a variety of diseases affecting the basal ganglia, such as Parkinson's disease, Tourette's syndrome, and Huntington's disease. It may occur after some kinds of head injury or may be part of some illnesses that cause progressive dementia.

OCD is uncommon (some would say rare) in people with epilepsy, but there does seem to be a connection. OCD is seen most often in those with complex partial seizures originating in the temporal or frontal lobe, or seizures originating in the anterior cingulate gyrus, near the corpus callosum.

Although it is unclear why OCD tends to occur with epilepsy, evidence of the association is quite convincing. Early studies suggested that epilepsy caused certain personality characteristics to develop, including obsessional traits. Some evidence suggested an increased likelihood of a general personality disorder in epilepsy. Others found that different types of epilepsy may be associated with different forms of abnormal thinking or behavior. A well-known article by Waxman and Geschwind (1975) suggested that temporal lobe epilepsy could be linked to a specific behavioral syndrome. Obsessional traits were described as an additional component of this syndrome. Many have felt that symptoms of OCD might occur as a result of generalized personality factors associated with epilepsy.

A number of studies published in the 1980s and 1990s reported a more specific association between OCD and epilepsy. Most of the evidence linking OCD with epilepsy has come from case studies and clinical observations, however, rather than from studies of large groups. In most cases, the patients did not show obsessive-compulsive symptoms before the onset of seizures. Some have suggested that in some people with epilepsy, OCD may be a form of "forced thinking," new thoughts that intrude into the patient's awareness at the onset of a seizure. This behavior may also occur without seizure activity.

Some investigators have tried to use the connection of OCD with epilepsy to look for information about the mechanisms underlying each disorder. The most widely proposed theories suggest a kindling effect, in which seizures localized to one area of the brain stimulate another area (such as the limbic region), leading to the emergence of obsessive-compulsive behavior. Some have documented that epileptic discharges from frontal and limbic brain regions make patients particularly susceptible to this type of behavior. Some have noted symptoms occurring solely after areas of the brain have been removed in epilepsy surgery. Others have seen a link between OCD and seizures originating from the left cerebral hemisphere. Evidence supporting these theories is mainly speculative at this time, however.

Keren L. Isaacs, M.Phil.
George Washington University

Reference
Waxman SG, Geschwind N. The interictal behavior syndrome in temporal lobe epilepsy. Arch Gen Psychiatry 32:1580-1586, 1975. PMID: 1200777

Topic Editor: Andres M. Kanner, M.D.
Last Reviewed:11/13/03