Electroconvulsivetherapy (ECT) is the most acutely effective treatment for severe depression butis limited by cognitive side-effects, to which older adult may be morevulnerable. The most common form of ECTworldwide uses bitemporal (BT) electrode placement which is more powerful thanright unilateral (RUL) placement but is associated with more cognitivedeficits. However, RUL-ECT at higherelectrical doses may be as effective as BT-ECT but with less cognitiveside-effects. The aim of this trial is to compare the effectiveness and cognitiveside-effects of high-dose RUL-ECT with standard BT-ECT.

Wecarried out a pragmatic, two-group, parallel-design, randomised, non-inferiority trial (ISRCTN23577151) of twice-weekly BT-ECT at 1.5 timesseizure threshold versus high-dose RUL-ECT at 6 times seizure threshold forpatients with a major depressive episode. 138 patients (69 per group) were randomised to ensure adequate power toassess non-inferiority of high-dose RUL ECT. The primary outcome was the Hamilton Rating Scale for Depression (HRSD-24) score at end-of-treatment and the pre-specifiednon-inferiority margin was 4•0 points. Secondary outcomes included response, remission and relapse rates plus cognitive performance during and after theallocated ECT course with a six-month follow-up.

Recruitment wasfrom May 2008 until November 2012. Overall, high-dose RUL ECT was non-inferior toBT ECT with respect to the HDRS-24 at the end of ECT course(mean difference 1.2 points in favour of RUL ECT (95% CI, −1.510 to 3.995). Analyses of the effects of age on recovery of orientation after individualtreatments and cognitive performance soon after completion of the ECT courseand during the six-month follow-up will be presented and discussed.