Proposal for a new five-axis classification scheme for psychoses of epilepsy

Based on an overview of the literature and a multicenter study in Japan, we propose a new five-axis classification scheme for psychoses of epilepsy: (1) epilepsy variables, (2) psychopathology variables, (3) ictus/EEG variables, (4) precipitating factors of psychoses, (5) organic background. A total of 128 patients, 63 males and 65 females, with epilepsy and psychoses were recruited from five treatment centers. A wide heterogeneity of psychoses of epilepsy was demonstrated and categorization by a single axis was shown to be inadequate. Cluster analysis revealed four subgroups characterized by their psychopathology, temporal relationship to seizure occurrence, and EEG changes during psychoses. By comparing with the control epileptic group without psychoses, higher rates of mild intelligence disturbance and abnormal findings by brain imaging were proven among the psychotic group. The scheme involves a dimensional representation of individual patients to capture the complexity of their clinical background and to relay clinical information accurately and systematically. It is believed to hold direct therapeutic implications and to contribute to promoting research by enabling accumulation of a large number of patients on a multicenter basis.