1. Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland;
2. The UKK Institute for Health Promotion Research, Tampere, Finland;
3. Turku PET Centre, Turku University Hospital, University of Turku, Turku, Finland;
4. Department of Clinical Physiology and Nuclear Medicine, HUS Medical Imaging Center, Helsinki University Central Hospital, University of Helsinki, Helsinki, Finland;
5. Institute for Molecular Medicine Finland, Helsinki, Finland;
6. Clinical Neurology, University of Turku, Turku, Finland;
7. Department of Public Health, University of Helsinki, Helsinki, Finland