1. Hjelt Institute, Department of Public Health, University of Helsinki, Finland
2. Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland
3. Institute for Molecular Medicine, Helsinki, Finland
4. Unit for Genetic Epidemiology, National Institute for Health and Welfare, Helsinki, Finland
5. Institute of Clinical Medicine, Family Medicine, University of Turku, Finland
6. Department of Internal Medicine, Turku City Hospital, Finland
7. Department of Neurology, University of Turku and Turku University Hospital, Turku, Finland
8. Department of Mental Health and Substance Abuse Services, National Institute for Health and Welfare, Helsinki, Finland