Epilepsy has significant effects on the behavior of most people who have it. In some cases the seizure activity itself is manifested as a brief change or interruption in behavior that might appear unusual to the casual observer. Evidence also suggests that epilepsy can affect behavior when seizures are not occurring. Descriptions of interictal (between-seizure) behavior in people with epilepsy have a long and controversial history. Through the ages, those with epilepsy have been thought to be either blessed with divine powers or marked by evil. Through the 19th century, many considered them insane or thought they had reduced mental and moral powers. The level of public misconception has decreased over time, but many biases about epilepsy and its resulting behavior continue to this day.

Through the 20th century, many writings in the field of psychiatry referred to "the epileptic personality," an interictal syndrome thought to include explosive impulsivity, affective viscosity (the tendency to prolong interactions with others), and egocentricity (overriding concern with the self). Some thought that this syndrome was the result of underlying neurologic factors, but others felt that these personality traits represented a distinct form of epilepsy in themselves. At the time, it was felt that intensive psychoanalytic therapy was the most appropriate treatment for this condition.

More recently, Dr. Norman Geschwind introduced the characteristics of the "interictal personality disorder" to the neurological community. He felt that a number of specific personality characteristics were frequently seen in patients with temporal lobe epilepsy and that they were characteristic of such patients. These traits included deepened emotions, circumstantial thought (overly detailed, with delay in getting to the point), increasing concern with philosophical or religious beliefs, and a change in sexual behavior. Dr. Geschwind and a colleague published these observations in a major journal in 1975.(1)

Bear and Fedio(2) extended Geschwind's observations to include a total of 18 behavioral features:

     Emotionality

     Viscosity

Temporal lobe epilepsy was thought to be responsible for all these characteristics. Bear proposed that interictal electrical activity in the brain caused an overactivity of the limbic regions, which are involved in emotional response and modulation. In the late 1970s, Bear and Fedio developed a structured questionnaire to formally assess symptoms of the interictal personality disorder. Their initial studies found that a significant number of patients with temporal lobe epilepsy exhibited a range of these features, but these results were seldom supported in later studies. Most researchers found that many of the same features could be found in groups with other psychiatric conditions. Other studies focused on flaws in the methods of the original study, including how patients were selected and the characteristics of the questionnaire itself.

The interictal personality disorder has generated a great deal of controversy.(3) There has been little evidence of any specific link between these behavioral features and epilepsy itself. Many feel that these features could be just generalized features of personality changes associated with any form of medical or neurological illness. Some have felt that these features are a reasonable way to characterize the behavior of a number of patients with temporal lobe epilepsy, but others believe that they are far too generalized. Although various individuals may exhibit any of the 18 elements listed, very few people with epilepsy exhibit a majority of them. People working in epilepsy centers have noted that they are aware of a handful of patients who meet some of these criteria -- but they also know other people with some of these features who do not have epilepsy!

In the end, it appears that the full range of behavioral features of the interictal personality disorder or "epileptic personality" is very rarely seen in a single individual. The link between this syndrome and epilepsy is strongly questioned.

References

1. Waxman SG and Geschwind N. The interictal behavior syndrome in temporal lobe epilepsy. Archives of General Psychiatry 1975; 32, 1580-1586. PMID: 1200777.

2. Bear DM and Fedio P. Quantitative analysis of interictal behavior in temporal lobe epilepsy. Archives of Neurology 1977; 34, pp 454-467. PMID: 889477.

3. Benson DF. The Geschwind Syndrome. Advances in Neurology 1991; 55, 411-421. PMID: 2003418.

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