ABSTRACTBackground:It is generally assumed that the elderly patients are more vulnerable to cognitive side effects after electroconvulsive therapy (ECT) than younger depressed patients. The current study aims to evaluate the nature and extent of changes across multiple domains of neurocognitive functioning in a group of elderly depressed patients after ECT.Methods:In this prospective naturalistic study, we included 42 depressed patients aged ≥55 years. Global cognitive function, memory, and executive function were assessed before ECT treatment and within one week (short-term post-ECT) and six months after ECT (long-term post-ECT). Associations between cognitive functioning and electrode placement, total number of treatment sessions, age, and the severity of depression at the time of cognitive measurement were studied.Results:Our data offered no evidence of decline for any of the neurocognitive tests after ECT, given its power to detect the difference. Post-ECT improvement of neurocognitive functioning was statistically significant for the Mini-Mental State Examination, Visual Association Test, 10 Words Verbal Learning Test, and Expanded Mental Control Test. Effect sizes were medium to large. After six months, compared with post-ECT performance, statistically significant improvement was found only for the Trail Making Test-A and the Letter Fluency Test with small to medium effect sizes.Conclusions:In our severely depressed elderly patients, neurocognitive performance improved or did not change after ECT. Patients with poor cognitive function were not able to participate in neuropsychological assessment before ECT started. Consequently these results may not apply to patients with more severe cognitive impairment prior to the start of ECT.