[Possible mechanisms of action of electroconvulsive therapy]

Electroconvulsive therapy (ECT) remains one of the most effective biological treatment methods in psychiatry. The development of convulsive treatment methods was based on a theory of its mechanism of action, namely the presumed biological antagonism between schizophrenia and epilepsy. Later studies did not confirm this antagonistic diseases theory, but intensive research started to clarify ECT's mechanism of action. In early studies on ECT, attention was drawn to the anticonvulsant effect , its impact on cerebral circulation and the change of permeability of the blood-brain barrier. Later research focused on the effect of ECT on the neurotransmitter and neurohormonal systems. The inflammatory theory of the mechanism of action was based on the improvement of the laboratory findings observed in conditions that responded well to ECT. With the development of the imaging techniques, the volume reduction of certain brain areas in depression and schizophrenia came into focus. These changes turned out to be reversible with ECT which provided the basis of the neuroplasticity theory of ECT's mechanism of action. The network theory explanation of the effect of ECT was based on the correction of the abnormal circuits of the brain's electrical networks. Finally, in recent years, increasing attention has been paid to the microbiome-gut-brain axis, which, according to preliminary findings, is also affected by ECT. However, the extent to which this is responsible for the therapeutic effects of ECT in psychiatric disorders needs further investigations. Keywords: electroconvulsive therapy; mechanism of action; neuroplasticity; network theory; microbiome.