1. Research Unit of Clinical Medicine, Neurology, University of Oulu, Oulu, Finland
2. MRC, Oulu University Hospital, Oulu, Finland
3. Neurocenter, Neurology, Oulu University Hospital, Oulu, Finland
4. Work Ability and Working Careers, Finnish Institute of Occupational Health, Helsinki, Finland
5. Neurocenter, Neurology, Kuopio University Hospital, Kuopio, Finland
6. Unit of Neurology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland
7. Department of Geriatrics, Helsinki University Hospital, Helsinki, Finland
8. Clinical Neurosciences, University of Helsinki, Helsinki, Finland