Secondary Analyses Study

Secondary Analyses of Anonymised Data from Four Historical Studies of Electroconvulsive Therapy

Electroconvulsive therapy (ECT) is the most acutely effective treatment for severe, sometimes life-threatening, depression. Nevertheless, its use remains limited due to cognitive side effects, particularly retrograde amnesia for memories of personally experienced past events. Our research group previously conducted the largest European clinical trial to date comparing two types of ECT differing in electrode placement (high-dose right unilateral ECT versus moderate dose bitemporal ECT). This trial (EFFECT-Dep) showed that high-dose unilateral ECT was noninferior to bitemporal ECT in terms of therapeutic response and had fewer cognitive side effects. These findings suggested high-dose unilateral ECT as the preferred ECT option for treating depression and improved the acceptability of this effective treatment.

Data collected by our group as part of the EFFECT-Dep Trial and three other prospective studies (KEEP-WELL, Decision-Making Capacity Study and AMBER-Dep) carried out at St Patrick’s Mental Health Services (SPMHS) between May 2008 and May 2019 provide a rare opportunity to study the patient characteristics governing therapeutic response and cognitive side effects after ECT. By pooling data from these four historical studies, we have assembled one of the largest prospective ECT databases to date containing clinical and demographic characteristics, ECT treatment parameters, and measures of treatment response and cognitive side effects in 232 patients hospitalised with moderate-to-severe depression.

The proposed study is a series of secondary data analyses of this prospective observational database assembled by our group at SPMHS in collaboration with biostatisticians at the Department of Biostatistics, King’s College London. The study aims to explore causal mechanisms of therapeutic response and retrograde amnesia following ECT. If we can understand the mechanisms by which some patients benefit more from ECT, treatment delivery could be targeted to patients most likely to respond and avoid exposing patients unlikely to benefit to the unnecessary risk of cognitive side effects. Furthermore, if baseline or ECT session characteristics predicting retrograde amnesia after ECT can be identified, we may be able to modify ECT delivery to minimise such side effects.

In the interest of transparency, please see a Public Notice regarding this project.