Electroencephalographic correlates of electroconvulsive therapy.

The aim of this investigation was to study the detailed profile and persistence of electroconvulsive therapy (ECT)-induced EEG correlates. Subjects were submitted to a detailed clinical evaluation as well as automated, computerized EEG recordings. Analysis was performed of different frequency bands, mean frequency and total power as well as a detailed study of cortical auditory-evoked responses. Age and sex-matched control subjects comprised a group of comparable patients, none of whom had received ECT, a second control group of healthy volunteers and a third group of amitriptyline-treated patients. No statistically significant EEG changes were found among patients who had been treated with ECT from several months to several years prior to the investigation. During ECT, highly significant cumulative effects were observed in most of the EEG measures, particularly increased slow-wave activity and a corresponding reduction in fast-wave activity. Predictably, significant changes also occurred in mean EEG frequency and total power. No significant changes were observed in the cortical-evoked responses. EEG abnormalities were still significant one week following the completion of a course of ECT, but reverted to baseline levels within four weeks.