1. Institute for Clinical and Applied Health Research, Allam Medical Building, University of Hull, Cottingham Road, Hull HU6 7RX, UK
2. National Addiction Centre, Institute of Psychiatry, Psychology and Neuroscience (IoPPN), King's College London, 4 Windsor Walk, London SE5 8AF, UK
3. Hull York Medical School, Allam Medical Building, University of Hull, Cottingham Road, Hull HU6 7RX, UK
4. South London and the Maudsley NHS Foundation Trust, Bethlem Royal Hospital, Monks Orchard Road, Beckenham BR3 3BX, UK