1. Department of Neurology and Neurosurgery, University of Tartu, Tartu 51014, Estonia
2. Department of Psychology, University of Tartu, Tartu 50410, Estonia
3. Department of Neurology and Neurosurgery, University of Tartu, Tartu 51014, Estonia, Multiple Sclerosis Center, Estonian Seamen Hospital, Tallinn 10617, Estonia