1. What is the short-term efficacy? The UK ECT Review Working Group (2003) included six studies comparing the efficacy of ECT with pseudo-ECT for depression and showed that the former was more effective than the latter, with an overall effect size of 0.91. A pooled analysis of data from 18 studies showed that despite the small sample size of some of the studies, ECT was definitely more effective than medication, with an effect size of 0.80. The US Food and Drug The FDA also obtained broadly similar results (2011): five studies showed that a course of ECT was significantly more effective than pseudo-ECT, with 7.1 more points subtracted from the Hamilton Depression Rating Scale (HDRS) than the latter; eight studies showed that ECT was also more effective than drug treatment, with 5.0 more points subtracted from the HDRS than the latter. 2. What are the long-term effects? In its review, the FDA noted that long-term follow-up data for ECT are lacking: studies of ECT regression rarely have follow-up periods longer than 4 weeks. A recent Meta-analysis included 32 relevant studies with a maximum follow-up period of 2 years. For all RCTs, antidepressant treatment halved the relapse rate in the first 6 months compared with placebo (number needed to treat [NNT] = 3). Even with continued pharmacologic maintenance treatment, 51% of patients relapsed within 12 months, with the majority (38%) relapsing within 6 months; the relapse rate at 6 months was similar with maintenance treatment with ECT (37%). In older patients, evidence suggests that pharmacologic maintenance therapy is effective in preventing relapse; a systematic review similarly concluded that ECT maintenance therapy is as effective as pharmacologic maintenance therapy in older patients with major depression, but many of these studies had methodological problems. One study found that optimized antidepressant therapy + group CBT was more effective than medication alone or medication + ultrashort pulse ECT maintenance in preventing depression relapse after ECT: sustained response rates were 77%, 44%, and 40% at 6 months, and 65%, 33%, and 28% at 12 months, respectively. 3. What is the effect of different electrode placement methods on the efficacy? Meta-analysis of earlier studies conducted by the UK ECT Review Working Group showed that bilateral ECT was slightly more effective against depression compared to unilateral ECT (22 studies, effect size 0.32). The FDA similarly found that bilateral ECT was more effective than unilateral ECT, with the advantage reflected in a score of approximately 4 in the HDRS. However, a newer randomized controlled study showed that treatment response rates for bifrontal, bitemporal (bilateral) and right unilateral ECT were similar overall, but the rate of improvement was faster for bilateral ECT. 4. How many times per week is the most appropriate time to perform ECT? A retrospective study that included 7 studies with 214 patients compared the efficacy of ECT twice a week with ECT three times a week. The results showed that there was no significant difference in efficacy between 2 times a week and 3 times a week, but the efficacy of 3 times a week ECT was significantly better than 1 time a week. Therefore, 2 times a week ECT is more appropriate. 5. What is the most appropriate current dose for ECT? The UK ECT Review Working Group noted that high power had a moderate advantage over low power in terms of efficacy (7 studies, effect size 0.58). However, there is insufficient evidence to draw firm conclusions about the risk/benefit ratio of high and low power treatment. The NICE Guidelines Group updated its guidelines based on an analysis by the UK ECT Review Working Group, which was unable to obtain information on the effect of power and electrode placement on efficacy, and concluded that although unilateral ECT with high power was slightly better than bilateral ECT with low power, the difference was not clinically significant. 6. What are the perceived side effects of ECT? One of the most frequently reported adverse effects of ECT is memory impairment, particularly autobiographical memory impairment during the treatment period; some patients may experience longer-term memory problems lasting 3-6 months. Factors associated with more severe cognitive impairment include: sinusoidal stimulation; bilateral electrode placement; older age; female gender; and lower pre-morbid intellectual functioning. The UK ECT Review Working Group corroborated these findings, while confirming that high power was associated with more severe cognitive impairment. There is also evidence that there is no significant difference in the effect of bifrontal, bitemporal (bilateral) and unilateral right-sided electrode placement on cognitive function. A Meta-analysis that included 84 studies with 2981 patients for 24 cognitive variables showed that 72% of the cognitive variables showed significant decreases after 0-3 days of ECT treatment (effect values 1.1-0.21); however, only one variable remained impaired after 4-15 days of ECT treatment, while impairment was no longer detectable after 15 days. In fact, 57% of the cognitive variables, including processing speed, working memory, paracrine memory and some aspects of executive function, improved compared to pre-ECT (effect values 0.35-0.75). The above status underscores the difficulty of identifying the cognitive effects of ECT versus depression, both in the acute and follow-up periods. 7. Summary Despite the proven side effects of ECT, clinicians should be aware that we still have insufficient evidence on treatment for those patients who do not respond well to 2-4 antidepressants, and that ECT has certain advantages. It is important to note that ECT may be a faster-acting treatment option for patients who are severely ill and in poor condition (e.g., persistent suicidal ideation, psychomotor retardation, psychotic symptoms, and/or inadequate fluid intake) and require urgent intervention.