Schizophrenia in epilepsy: seizure and psychosis variables.

Prior studies have incompletely established a relationship between epilepsy and schizophrenia, primarily because of methodological difficulties. We undertook a two-part retrospective investigation of neurology clinic patients with epilepsy and schizophrenia. Part I: Interictal schizophrenic disorders occurred in 149 (9.25%) of 1,611 epileptic outpatients, compared with only 23 (1.06%) of 2,167 migraine outpatients. Part II: Among age- and sex-matched groups, we compared 62 epilepsy-with-schizophrenia patients with 62 epilepsy patients on six seizure variables, and we compared them with 62 schizophrenia patients on 10 psychosis variables. The epilepsy-with-schizophrenia group had a later epilepsy age of onset with more complex partial seizures, more patients with auras, and fewer patients with generalized epilepsy. Except for increased suicidal behavior, epileptic patients did not differ from controls on psychosis variables; however, psychotic symptoms often emerged with increased seizure activity. Together these results support a distinct association of schizophrenic disorders with epilepsy, particularly with seizures emanating from the temporal limbic system.