Psychosis in epilepsy: Frequency and risk factors

Psychoses are widely accepted as complications of epilepsy. Psychopathology and relation to the seizure disorder may vary considerably. Largely due to differences in selection criteria, clinical studies have often resulted in apparently contradictory hypotheses with regard to frequency, etiology, risk factors, and relation to type of epilepsy. Thorough controlled epidemiological studies are few, and results are inconsistent. We investigated the frequency of different types of psychoses and their correlation with epilepsy variables in a large series of consecutive outpatient referrals with epilepsy. Psychoses were reported in 28 of 697 patients (4%) and were evident both in patients with generalized epilepsies and in those with focal epilepsies. Severity of epilepsy and the occurrence of minor seizures with impairment of consciousness (absences or complex focal seizures) were associated with the presence of psychosis. The existence of brain damage and localization or lateralization of epileptogenic foci were not. We suggest that the frequency of psychosis in epilepsy in general may be overestimated and that psychoses in epilepsy are linked to functional disturbance rather than to localized structural lesions.