1. Division of Applied Health Sciences; University of Aberdeen; Foresterhill Aberdeen UK
2. Department of Research, Section of Biostatistics; Stavanger University Hospital; Stavanger Norway
3. The Norwegian Centre for Movement Disorders; Stavanger University Hospital; Stavanger Norway
4. Institute of Clinical Medicine; University of Bergen; Bergen Norway
5. Department of Neurology; Haukeland University Hospital; Bergen Norway
6. Network for Medical Sciences; University of Stavanger; Stavanger Norway