EEG abnormalities in clozapine-treated schizophrenic patients.

A prospective study of EEG findings and occurrence of seizures in patients with refractory schizophrenia treated with clozapine has been conducted. Pretrial EEG and EEG under treatment at a fixed dose of clozapine 300 mg/day were performed. Fifteen patients entered the study, four patients were withdrawn because of side effects or poor compliance. EEG abnormalities appeared in seven of the 11 patients who completed the study (64%): generalized slowing in six of them and epileptic activity in two (one patient had both types of change). None of the patients developed clinical seizures. EEG abnormalities were more frequently observed in those with better clinical response to clozapine and/or shorter duration of disease, although these findings were not statistically significant. We conclude that EEG abnormalities occur frequently (64%) in schizophrenic patients who receive clozapine. However, the EEG changes do not necessarily predict the occurrence of convulsions.