John R. Geddes is Professor of Epidemiological Psychiatry and Head of the Department of Psychiatry, Warneford Hospital, University of Oxford, Oxford, UK. Nancy C. Andreasen is Professor of Psychiatry and Andrew H. Woods Chair of Psychiatry, Department of Psychiatry, University of Iowa Carver College of Medicine, Iowa City, IA, USA. Guy M. Goodwin is Senior Research Fellow, Department of Psychiatry, Warneford Hospital, University of Oxford, Oxford, UK.