To date, electroconvulsive therapy (ECT) is the most potent treatment in severe depression. Although ECT has been successfully applied in clinical practice for over 70 years, the underlying mechanisms of action remain unclear. We used functional MRI and a unique data-driven analysis approach to examine functional connectivity in the brain before and after ECT treatment. Our results show that ECT has lasting effects on the functional architecture of the brain. A comparison of pre-and posttreatment functional connectivity data in a group of nine patients revealed a significant cluster of voxels in and around the left dorsolateral prefrontal cortical region (Brodmann areas 44, 45, and 46), where the average global functional connectivity was considerably decreased after ECT treatment (P < 0.05, family-wise error-corrected). This decrease in functional connectivity was accompanied by a significant improvement (P < 0.001) in depressive symptoms; the patients' mean scores on the Montgomery Asberg Depression Rating Scale pre-and posttreatment were 36.4 (SD = 4.9) and 10.7 (SD = 9.6), respectively. The findings reported here add weight to the emerging "hyperconnectivity hypothesis" in depression and support the proposal that increased connectivity may constitute both a biomarker for mood disorder and a potential therapeutic target. T he treatment of depressive disorder is one of the most pressing issues in contemporary medical practice: The illness is a leading cause of significant disability worldwide (1). Current therapeutic strategies are imperfect, and there is an urgent need to develop more consistently effective and rapidly acting treatment solutions. Unfortunately, our understanding of the etiopathology of mood disorder is incomplete. As a result, the elucidation of the mechanisms of action of effective treatment has necessarily been less than secure and advance has been slow. Available treatments (e.g., chemical antidepressant therapy) were discovered serendipitously rather than designed, and insight into the biology of depressive disorder by study of antidepressant actions has been limited. In particular, the effectiveness of electroconvulsive therapy (ECT), the most potent and rapidly acting of all antidepressant agents (2), has eluded a coherent explanatory framework despite its regular use for more than 70 years. However, if the effects of ECT could be reproduced in a less invasive way, and with a more benign side-effect profile, the treatment of severe depression would be significantly enhanced. To achieve this, we need first to understand better how ECT influences brain function. Here, we show that ECT alters the functional architecture of frontal systems by strongly down-regulating connectivity in key circuits implicated in mood disorder.Efforts to delineate the neural substrate of mood disorder using functional brain imaging technology have generally identified abnormal frontal cortical and limbic activity in depressed patients (3-9). Although such regional findings tend to correspond anatomically to tho...

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The CANTAB SRM task revealed reversible cognitive deficiencies relative to a pre-ECT baseline for at least 3 months following ECT, while MMSE score and patients' subjective reports showed only improvement. Visuospatial memory scores eventually exceeded baseline 6 months post-ECT.

BackgroundKetamine has recently become an agent of interest as an acute treatment for severe depression and as the anaesthetic for electroconvulsive therapy (ECT). Subanaesthetic doses result in an acute reduction in depression severity while evidence is equivocal for this antidepressant effect with anaesthetic or adjuvant doses. Recent systematic reviews call for high-quality evidence from further randomised controlled trials (RCTs).AimsTo establish if ketamine as the anaesthetic for ECT results in fewer ECT treatments, improvements in depression severity ratings and less memory impairment than the standard anaesthetic.MethodDouble-blind, parallel-design, RCT of intravenous ketamine (up to 2 mg/kg) with an active comparator, intravenous propofol (up to 2.5 mg/kg), as the anaesthetic for ECT in patients receiving ECT for major depression on an informal basis. (Trial registration: European Clinical Trials Database (EudraCT): 2011-000396-14 and : NCT01306760.)ResultsNo significant differences were found on any outcome measure during, at the end of or 1 month following the ECT course.ConclusionsKetamine as an anaesthetic does not enhance the efficacy of ECT.