1. Department of Public Health, University of Copenhagen, 1014 Copenhagen, Denmark
2. The Danish MS Society, 2500 Valby, Denmark
3. NAFKAM, University of Tromsø, 9037 Tromsø, Norway
4. Department of Neurology, Akershus University Hospital, 1474 Nordbyhagen, Norway
5. Department of Neurology, University of Southern Jutland, 7100 Vejle, Denmark
6. Department of Clinical Neuroscience, Karolinska Institute, 14186 Stockholm, Sweden