1. King’s College London, Institute of Psychiatry, Psychology and Neuroscience London SE5 8AF, UK
2. Division of Psychiatry, University College London, Rockefeller Building, Gower Street, London WC1E 6BT, UK
3. Bexley Substance Misuse Service, South London and Maudsley NHS Trust, London, UK
4. Addictions Clinical Academic Group, South London and Maudsley NHS Foundation Trust, Marina House, 63-65 Denmark Hill, London SE58RS