1 Department of Psychiatry, University of Cambridge; Cambridgeshire and Peterborough NHS Foundation Trust, Cambridge.
2 School of Population Health, University of Sheffield, Sheffield.
3 Human Development and Health, Faculty of Medicine, University of Southampton, Southampton.
4 School of Medicine, Keele University, Keele; Division of Psychology and Mental Health, University of Manchester; Psychosis Research Unit, Greater Manchester Mental Health NHS Trust, Manchester.