1 Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, SE5 9RS, UK; King's College Hospital, London SE5 9RS, UK. Electronic address: ammar.al-chalabi@kcl.ac.uk.
2 Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, SE5 9RS, UK.
3 Department of Neurology, Brighton and Sussex Medical School, Sussex, UK.
4 Department of Pharmacology, Pitié-Salpêtrière Hospital, Paris, France.