Effects of electroconvulsive therapy on EEG and cerebral blood flow in depression.

Changes in global EEG and global cerebral blood flow (CBF) and their relationship following electroconvulsive therapy (ECT) were studied in 21 depressed in-patients, examined before and after treatment during an ECT series and at follow-up. Two patterns of ECT action could be discerned: acute changes related to single ECT's. The effects on CBF were more marked at the beginning of the ECT series, while the EEG slowing became more pronounced towards the end; non-acute accumulating ECT effects which were insignificant for CBF, whereas the EEG slowing increased progressively during the ECT series. Thus acute and non-acute effects of ECT on EEG and CBF follow different patterns indicating independent seizure effects. They showed a different time course and few correlations were found, suggesting that CBF is more linked to cortical changes while EEG is probably more related to activity in deeper, subcortical structures.