1. Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, Maurice Wohl Clinical Neuroscience Institute, King’s College London, London, UK,
2. Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, UK,
3. Trafford Centre for Biomedical Research, Brighton and Sussex Medical School, Falmer, UK, and
4. Department of Medical Statistics, London School of Hygiene and Tropical Medicine, London, UK