1. Headache Group, Wolfson Centre for Age‐Related Diseases, Division of Neuroscience, Institute of Psychiatry, Psychology and Neuroscience King's College London London UK
2. NIHR King's Clinical Research Facility King's College Hospital London UK
3. Centre for Neuroimaging Sciences, Institute of Psychiatry, Psychology and Neuroscience King's College London London UK
4. Department of Neurology University of California, Los Angeles Los Angeles California USA