Mechanisms of action of ECT: schizophrenia and schizoaffective disorder.

A variety of neurophysiological mechanisms have been suggested to explain the therapeutic action of electroconvulsive therapy (ECT). Processes of kindling, resolution of hemispheric dysfunctions, anticonvulsant effects, and diencephalic stimulation all have been proposed to account for the beneficial effects of ECT. To investigate these, we analyzed clinical, neuropsychological, and electroencephalographic (EEG) data from 110 ECT-treated patients with schizophrenia and schizoaffective disorders, comparing responders with nonresponders. Fifty-four percent of all the patients were rated as very much or much improved. Mechanisms of kindling or anticonvulsant effects were not supported by the data. Dominant hemispheric dysfunctions in schizophrenics were suggested by the neuropsychological test data. There was tenuous support for the sensitization theory and both the neuropsychological and EEG data contradicted the dominant accentuation theory. Taken together with our previous report on ECT-treated patients with affective disorders, we propose that ECT might act by restoration of equilibrium between the hemispheres.