Depression is one of the most debilitating and widespread illnesses affecting up to 20% of individuals in their lifetime. However, the current antidepressant agents take weeks to work, and fail to help at least 40% of depressed patients. Electroconvulsive therapy (ECT) is a remarkably effective treatment for depression, but its use is limited by cognitive dysfunction.~As a result, it is becoming a clinical problem which need to be settled urgently. Previous clinical study showed that subanesthetic dose of ketamine could play a role in antidepressant effects with safety and minimal positive psychotic symptoms.The investigators also found that subanesthetic dose of ketamine combined with other anesthetics could improve cognitive function in depressive rats receiving electroconvulsive shock (a model for analogy with ECT). Few clinical researches concerned the effects of subanesthetic dose of ketamine combined with propofol anesthesia on cognitive function in patients after ECT, therefore the investigators conduct this randomized controlled double-blind trial. In this study, cognitive function will be rated by Mini-Mental State examination score.
Electroconvulsive therapy (ECT) is an effective treatment for depression compared with the current antidepressant agents，but the most important side effect is cognitive dysfunction. The purpose of this study is to determine whether subanesthetic dose of ketamine combined with propofol is superior to propofol anesthesia alone in improving cognitive function in depressive patients undergoing ECT.