1. Department of Clinical Physiology and Nuclear Medicine, HUS Medical Imaging Center, Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland
2. Department of Health Sciences, University of Jyväskylä, Finland
3. Department of Public Health, University of Helsinki, Finland
4. Institute for Molecular Medicine, University of Helsinki, Helsinki, Finland
5. Clinical Neurology, Turku PET Centre, University of Turku, Turku, Finland
6. Department of Health, National Institute for Health and Welfare, Helsinki, Finland