1 Alzheimer Scotland Dementia Research Centre, Edinburgh, United Kingdom; Edinburgh Dementia Prevention and the Division of Psychiatry, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom. Electronic address: T.C.Russ@ed.ac.uk.
2 Department of Epidemiology and Public Health, University College, London, United Kingdom.
3 Alzheimer Scotland Dementia Research Centre, Edinburgh, United Kingdom; Department of Epidemiology and Public Health, University College, London, United Kingdom.