Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: In the last 5 years, R.H.M.-W has received fees from American Center for Psychiatry & Neurology, United Arab Emirates, British Association for Psychopharmacology, European College of Neuropsychopharmacology, International Society for Affective Disorders, Janssen, LivaNova, Lundbeck, My Tomorrows, OCM Comunicaziona s.n.c., Pfizer, Qatar International Mental Health Conference, Sunovion, Syntropharma, UK Medical Research Council and Wiley; grant support from National Institute for Health Research Efficacy and Mechanism Evaluation Panel and Health Technology Assessment Panel; and non-financial support from COMPASS Pathways. S.T.A. is a consultant to Neuronetics, LivaNova, Janssen, Sage Therapeutics and Genomind. He also receives research support from Compass Pathways and Neuronetics. C.R.C. has received research support from Bristol Myers Squibb, the Stanley Medical Research Institute, the National Institute of Mental Health, NeoSync, Inc., LivaNova, the Taylor Family Institute for Innovative Psychiatric Research, The American Foundation for Suicide Prevention, Assurex Health Inc., The Brain & Behavior Research Foundation, the August Busch IV Foundation and the Barnes-Jewish Hospital Foundation; he is a part-time employee of the John Cochran VA Medical Center in St. Louis and serves as the Lead Investigator of the RECOVER VNS trial in the United States. K.D. has received honorarium for attending advisory boards, acting as a consultant or being a member of the speaker bureau for Boehringer-Ingelheim, Gedeon-Richter, Johnson & Johnson, Livanova, Lundbeck, Pfizer and Recordati. P.B.F. is supported by an NHMRC Investigator award (1193596). In the last 3 years, he has received equipment for research from Medtronic and Nexstim and is a founder of TMS Clinics Australia and Resonance Therapeutics. C.K.L. is supported by an NHMRC Investigator award. In the last 3 years, she has served on a Janssen advisory board. In the last three years, P.M. has received honoraria from Janssen-Cilag Australia (advisory board membership; speaker) and Sanofi Hangzhou (speaker). A.J.R. has received consulting fees from Compass Inc., Curbstone Consultant LLC, Emmes Corp., Evecxia Therapeutics, Inc., Holmusk, Johnson & Johnson (Janssen), LivaNova, Neurocrine Biosciences Inc., Otsuka-US and Sunovion; speaking fees from LivaNova and Johnson & Johnson (Janssen); and royalties from Guilford Press and the University of Texas Southwestern Medical Centre, Dallas, TX (for the Inventory of Depressive Symptoms and its derivatives). He is also named co-inventor on two patents: US Patent No. 7,795,033: Methods to Predict the Outcome of Treatment with Antidepressant Medication, Inventors: McMahon FJ, Laje G, Manji H, Rush AJ, Paddock S and Wilson AS; and US Patent No. 7,906,283: Methods to Identify Patients at Risk of Developing Adverse Events During Treatment with Antidepressant Medication, Inventors: McMahon FJ, Laje G, Manji H, Rush AJ, and Paddock S. H.A.S. serves as a scientific adviser to Cerebral Therapeutics Inc., LivaNova PLC, MECTA Corporation and Neuronetics Inc. He receives honoraria and royalties from Elsevier, Inc. and Oxford University Press. He is the inventor on non-remunerative US patents for Focal Electrically Administered Seizure Therapy (FEAST) (US8712532), titration in the current domain in ECT (US9789310) and the adjustment of current in ECT devices (US10583288), each held by the MECTA Corporation. He is also the originator of magnetic seizure therapy (MST). A.H.Y. has received payment for lectures and advisory boards for the following companies: AstraZeneca, Eli Lilly, Lundbeck, Sunovion, Servier, Livanova, Janssen, Allegan, Bionomics, Sumitomo Dainippon Pharma and COMPASS. He is a consultant to Johnson & Johnson and Livanova. He has received honoraria for attending advisory boards and presenting talks at meetings organised by LivaNova. He is a Principal Investigator on studies funded by LivaNova, Janssen and COMPASS, and Chief Investigator on a study funded by Novartis. He does not hold shares in pharmaceutical companies.