Cases of memory deficits after electroconvulsive therapy (ECT) have been widely reported particularly short-term memory and to a lesser extent, long-term and autobiographical memory. Explanations for the mechanisms of ECT action have largely been limited to studies of the effect on brain metabolism, neurochemistry, and areas of the brain such as the hippocampus and frontal lobes. However, passing a current of electricity through the brain is clearly a holistic treatment, and consequently, a holistic theory may offer a better understanding of ECT action. Because of its effect on memory systems both positive and negative, it is possible that aspects of memory function could hold the key in explaining how and why successful ECT treatment functions. It will be argued that successful ECT treatment is effective because it facilitates and restores the function of specific memory systems that are deficient in the course of a severe depressive episode. It is these memory systems that link a person to the very essence of their existence and personal identity.