Electroconvulsive therapy for depression: Effectiveness, cognitive side-effects, and mechanisms of action

Electroconvulsive therapy (ECT) is currently the most effective treatment for depression. However, concerns relative to cognitive side-effects and uncertainties regarding its mode of action limits ECT use. Consistent evidence over the past 40 years indicates that, except for retrograde memory, cognitive side-effects are temporary and limited to the first few days post-ECT. During that period, memory and executive function are the most affected cognitive domains. Over the following weeks, cognition progressively improves above pre-treatment levels. Retrograde autobiographical memory can be affected for up to three months, and possibly longer with bitemporal ECT. However, this retrograde amnesia is limited to a small number of specific personal events, does not affect every treated patient and is reversible for some individuals. ECT most likely exerts its antidepressant effect by promoting both structural and functional neuroplasticity. The decreased cerebral resting state and increased bilateral hippocampal volume that follow ECT may be central in explaining its effectiveness and cognitive side-effects. An integrated model of existing evidence on the neuronal, synaptic, structural and connectivity changes is proposed for ECT’s therapeutic action