Electrophysiological correlates of the adverse cognitive effects of electroconvulsive therapy

Resting state, eyes closed, 19-lead EEG recordings were obtained at pre-ECT baseline and just prior to penultimate treatment and during the week follo wing the ECT course in 59 patients with major depression. Patients had been randomized to ECT conditions that varied in electrode placement and stimul us intensity. The EEG data were submitted to power spectral analysis, and g lobal and topographic effects were characterized for the delta and theta fr equency bands. Relations between the EEG changes and scores on three cognit ive measures were examined. The period of disorientation immediately follow ing RUL ECT was associated with an accentuation of delta power in anterior frontal and temporal regions. Across the electrode placements, increased th eta activity in left frontotemporal regions was associated with longer reco very of orientation. Post-ECT decrements in global cognitive status, as ass essed by the modified Mini-Mental Stare exam, were associated with a greate r increase in delta relative to theta power, globally across the cortex. Th e magnitude of retrograde amnesia for autobiographical events correlated wi th increased theta activity in left frontotemporal regions. The findings su ggest that distinct neurophysiological changes subserve the therapeutic and adverse cognitive effects of ECT. Postictal disorientation and post-ECT re trograde amnesia appear to share a common physiological substrate.