1. Department of Neurology, Kuopio University Hospital, Kuopio, Finland
2. Institute of Clinical Medicine, Neurology, University of Eastern Finland, Kuopio, Finland
3. Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
4. Aging Research Center, Karolinska Institutet, Stockholm, Sweden
5. Department of Radiology, Kuopio University Hospital, Kuopio, Finland
6. Department of Clinical Medicine, Neurology, University of Oulu, and the Clinical Research Center, Oulu University Hospital, Oulu, Finland