Immediate and long-term effects of bilateral electroconvulsive therapy on cognitive functioning in patients with a depressive disorder

Background: Electroconvulsive therapy (ECT) is the most effective treatment for patients suffering from major depression. However, its use is limited due to concerns about negative effects on cognition. Unilateral ECT is associated with transient cognitive side-effects, while case-controlled studies investigating the effect of bilateral ECT on cognition remain scarce. We investigate the effects of bilateral ECT on cognition in depression in a longitudinal case-controlled study. We hypothesize that adverse cognitive effects of bilateral ECT are transient rather than long-term. Methods: A total of 48 depressed patients and 19 controls were included in the study and assessed with a battery of cognitive tests, including tests of: working memory, verbal fluency, visuospatial abilities, verbal/visual memory and learning, processing speed, inhibition, attention and task-switching, and premorbid IQ. Patients underwent three cognitive assessments: at baseline (n = 43), after ten ECT sessions (post-treatment; n = 39) and six months after the tenth ECT session (follow-up; n = 25). Healthy controls underwent the same cognitive assessment at baseline and after five-weeks. Results: Within the patient group, transient adverse cognitive side-effects were observed for verbal memory and learning, and verbal fluency. None of the cognitive domains tested in this study showed persisting impairments. Limitations: A relatively high attrition rate is observed and autobiographical memory was not assessed. Conclusion: This study shows that bilateral ECT has negative cognitive effects on short-term. These effects could be explained by a decrease in cognitive performance, a lack of learning effects or a combination. However, the decrease in cognitive functioning appears to recover after six months.