Clinical, Cognitive, and Functional Effects of Ambulatory Electroconvulsive Therapy for Mixed Mood Disorders in a Naturalistic Setting

Abstract

Mood disorders (major depressive and bipolar spectrum disorders) have devastating effects on quality of life, with individuals who do not respond to pharmacological interventions showing a greater risk of impaired functioning, suicidality, and symptom relapse. Electroconvulsive therapy (ECT) has demonstrated consistent efficacy for treating mood disorders. However, there is a relative paucity of research examining the effectiveness of ECT in ambulatory settings and for patients who present with psychiatric comorbidities. This thesis sought to characterize the clinical, functional, and neuropsychological profile and outcomes (i.e., effectiveness and side effects) of a mixed mood disorders population undergoing ambulatory ECT with minimal research-related restrictions. In study one, we demonstrated that ambulatory ECT patients were clinically severe and complex, with frequent psychiatric multimorbidity, high symptom severity, and elevated functional impairment. ECT was effective at significantly reducing depressive symptoms in the short- and long-term; yet the rates of remission and response were lower than expected. In study two, we found that objective cognitive functioning remained largely unchanged following ECT, a finding that should be interpreted with caution given the use of a brief cognitive screening battery. Interestingly, whereas patients who responded to ECT reported a lessening of subjective memory complaints, those who did not respond showed an increase in memory complaints post-ECT. In study 3, we sought to identify clinical and cognitive predictors of ECT outcomes using machine learning methods; we were unable to predict remission status, response status, or percent change in depressive symptoms in our sample. Overall, this thesis advances our understanding of the clinical, cognitive, and functional characteristics and outcomes of ambulatory ECT delivered under naturalistic conditions. This work highlights the importance of considering clinical comorbidities and cognitive functioning in ECT research and delivery and encourages a collaborative approach to clinical care aimed at enhancing treatment of patients with severe mental illness.