1. Unit of Neurology, Department of Clinical and Experimental MedicineUniversity of Pisa Pisa Italy
2. Section of Statistics, University of Pisa Pisa Italy
3. Regional Center of Nuclear Medicine, Department of Clinical and Experimental MedicineUniversity of Pisa Pisa Italy
4. Clinical Ageing Research Unit, Translational and Clinical Research Institute, Newcastle University Newcastle upon Tyne United Kingdom
5. Department of Clinical Medicine, Nuclear Medicine and PETAarhus University Aarhus Denmark