Seizure threshold rise during electroconvulsive therapy in schizophrenic patients.

A rise in seizure threshold during a course of electroconvulsive therapy (ECT) has been demonstrated in patients with depression and mania, but no information has been available as to whether the same result occurs in schizophrenia. Ninety-three patients with schizophrenia underwent estimation of the seizure threshold by the dose-titration method, at the first and second, seventh, fourteenth, and twentieth treatments over an index ECT course. The 3-week stabilization period was used as a response criterion. Eighty-six patients (92%) showed a rise in threshold. The magnitude of increment was 269+/-244%. The rise in seizure threshold could be predicted by the number of treatments, initial seizure threshold and EEG seizure duration, and these factors explained 42% of the variance.