The authors thank the study participants for their contribution to this research. They also thank the staff at ECT units throughout Sweden and the Swedish National Quality Register for ECT (Q-ECT) for collection and sharing of data, and the BBMRI.se and KI Biobank at Karolinska Institutet for their biobank service. A special thanks to PREFECT project manager Anders Juréus, PREFECT research nurses Marie Lundin, Birgitta Ohlander, Milka Krestelica, Radja Dawoud, and Martina Wennberg, and PREFECT data manager Bozenna Illiadou. The computations and data handling were enabled by resources provided by the Swedish National Infrastructure for Computing (SNIC) at Uppsala University.